Thread
SE/30 with Micron Xceed Grayscale & Socketed Daystar Acceler
OK, I think I understand now. You have three unrelated problems being discussed concurrently. 
1. SE/30 logic board with all upgrades removed shows horizontal lines and won't boot (SimasiMac), even after re-capping
2. Daystar 50 MHz accelerator kind of works, but caused occasional lockups.
3. Xceed grayscale card works, but shows a vertical line whose position changes with the monitor color depth.
Does that sound right?
For 1, there are a couple of other suggested remedies for SimasiMac (other than re-capping) mentioned here: http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html#SimasiMac I know nothing about it, but maybe it helps? For all I know, you may have written that page yourself.
For 2, it could be anything really. Power supply problems is one possibility, but I'd guess it's more likely a borderline component on the Daystar card, maybe triggered by temperature.
For 3 I agree with trag's earlier statement that it's very likely a VRAM problem. The way the line moves about with color depth makes that pretty clear. His suggestion of blowing cold air on the chips sounds much better than my idea of probing with a resistor, although the end goal of identifying the faulty VRAM chip is the same. Assuming you could find the faulty chip, do you have any source for replacements?
1. SE/30 logic board with all upgrades removed shows horizontal lines and won't boot (SimasiMac), even after re-capping
2. Daystar 50 MHz accelerator kind of works, but caused occasional lockups.
3. Xceed grayscale card works, but shows a vertical line whose position changes with the monitor color depth.
Does that sound right?
For 1, there are a couple of other suggested remedies for SimasiMac (other than re-capping) mentioned here: http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html#SimasiMac I know nothing about it, but maybe it helps? For all I know, you may have written that page yourself.
For 2, it could be anything really. Power supply problems is one possibility, but I'd guess it's more likely a borderline component on the Daystar card, maybe triggered by temperature.
For 3 I agree with trag's earlier statement that it's very likely a VRAM problem. The way the line moves about with color depth makes that pretty clear. His suggestion of blowing cold air on the chips sounds much better than my idea of probing with a resistor, although the end goal of identifying the faulty VRAM chip is the same. Assuming you could find the faulty chip, do you have any source for replacements?
100% correct.
I have been performing SE/30 logic board recaps for several years now. And until now I have had one one other board (the standard, non-socketed type) which continued to show horizontal stripes at cold boot despite the new capacitors. And at that time, I tried the 1k-ohm pull-up resistor across UB11's pins 7 & 15, but to no avail. But I've never been able to figure out that UB11 part logically, since UB11 is a "sound" chip and as my video shows I am clearly getting sound -- indeed robust, high volume sound! So if UB11 really did not a pull-up, would it not adversely affect sound? And I don't see why that sound chip would result in horizontal lines on the screen. And lastly, since I've never had access to a Bourns filter (for RP2), I never have been able to rest that.
The only way for me to test if a rock solid 5.00v power source would solve the problem is to have an ATX or similar high-output PSU directly connected to the SE/30, which I currently do not have.
The underside of the Daystar board contains only ceramic SMD caps, SMD tantalum caps, and SMD resistors -- none of which are prone to failure even after many years of constant use, nor are any of these physically marred/burned/cracked:
https://picasaweb.google.com/103365672326265854011/SE30MicronXceedGrayscaleVideoWithDaystarSnapOnAccelerator#5641720098640690242
Therefore, if indeed there is a problem on this board, one would logically suspect the chip-side (which is not something to troubleshoot for the faint of heart):
https://picasaweb.google.com/103365672326265854011/SE30MicronXceedGrayscaleVideoWithDaystarSnapOnAccelerator#5641720071352856226
Well, not having a can of that cold air, I've not yet tried it. But as you properly point out, even if I do try it and identify a chip with it, I have no chip replacements nor access to any.
So for now, I look at those 3 problems in the following order in terms of repairability (with 1 being the easiest to repair and 3 being the hardest):
1. Simasimac board
2. Daystar accelerator
3. Xceed PDS video card (vertical line problem)
This by no means even 1 is "easy," as I would have solved it by now had such been the case. Further technical thoughts would be appreciated. Thanks to all for your input.
With regard to my Simasimac SE/30 logic board, I have made some headway. Aided by my Apple and BOMARC schematics, I used a DMM's Continuity Check feature (beeps when both probes are shorted) to painstakingly check the board, pin by pin. I started off in the most logical manner, assuming the problem may center around the ROM. I felt that most logical in light of past experience with the ROM showing unusual artifacts on the screen. Furthermore, the capacitor that leaked the worst was SMD cap C12 (47µF). Even though I cleaned that area thoroughly more than once with high grade dehydrated Ethanol, the problem remained. So I decided to investigate using Trag's advice about thru holes.
I checked the ROM pins one-by-one, with one probe on a ROM pin and the other probe testing various legs of different chips to which that pin should lead (accordingly to my schematics). All the "Address" pins of the ROM SIMM checked out OK except one, pin 45 (A22). Pin 45 of the ROM should lead to pins 3 & 6 of UI4, as well as to the Glue Chip (IU8) and the CPU. I found A22 connecting the IU8 to the CPU, and the CPU to IU4 and IU4 back to IU8, but none of those points led back to pin 45 of the ROM (A22). I then desoldered C12 and found the problem.
Pin 45 of the ROM goes to a via, then on top of the board nearest C12 and the battery, then to another via about 1.5cm away. It's that 1.5cm long trace that is broken (on the top of the board). And it appears the break is at the top of the thru hole via, on the top of the board. Have a look at my photo:
https://picasaweb.google.com/103365672326265854011/SE30MicronXceedGrayscaleVideoWithDaystarSnapOnAccelerator#5642529984101043730
Note the white silked text "C12" and "D1" and "D2". Now note the "+" sign above C12, and that cap's corresponding via. Just 2mm above that is another via. That leads to pin45. Follow that via straight down to just 2mm below C2, and you can see the other via. That's the broken trace, broken at the bias. It makes logical sense too, as that is where the majority of the spilled fluid was, sitting atop those two vias for a few years I would expect. The via above the "+" in the photo is hard, but the other one is soft when I press on it with a metal pin.
I could just run a wire to attach those two points, but I am not sure if that is best. This is a multi-layered board. And unfortunately, I do not know if there are more than 3 layers. Further, I have schematics but I don't have PBC layout files which would show how many wires splice off the same via. Hence, if I've got a bad via, it's easy to fix that via by running a wire on the top and bottom of the board, but that won't help me if there are breaks to that point in different layers WITHIN the board.
Since I am not experienced fixing vias of multi-layered boards, I would appreciate your advice. (And if anyone happens to know how many layers the SE/30 board is and/or have access to PCB layout files, I would certainly appreciate getting that information from you.)
PM me if you wish to have access to my BOMARC and Apple SE/30 schematics.
I look forward to your advice. Thanks.
I checked the ROM pins one-by-one, with one probe on a ROM pin and the other probe testing various legs of different chips to which that pin should lead (accordingly to my schematics). All the "Address" pins of the ROM SIMM checked out OK except one, pin 45 (A22). Pin 45 of the ROM should lead to pins 3 & 6 of UI4, as well as to the Glue Chip (IU8) and the CPU. I found A22 connecting the IU8 to the CPU, and the CPU to IU4 and IU4 back to IU8, but none of those points led back to pin 45 of the ROM (A22). I then desoldered C12 and found the problem.
Pin 45 of the ROM goes to a via, then on top of the board nearest C12 and the battery, then to another via about 1.5cm away. It's that 1.5cm long trace that is broken (on the top of the board). And it appears the break is at the top of the thru hole via, on the top of the board. Have a look at my photo:
https://picasaweb.google.com/103365672326265854011/SE30MicronXceedGrayscaleVideoWithDaystarSnapOnAccelerator#5642529984101043730
Note the white silked text "C12" and "D1" and "D2". Now note the "+" sign above C12, and that cap's corresponding via. Just 2mm above that is another via. That leads to pin45. Follow that via straight down to just 2mm below C2, and you can see the other via. That's the broken trace, broken at the bias. It makes logical sense too, as that is where the majority of the spilled fluid was, sitting atop those two vias for a few years I would expect. The via above the "+" in the photo is hard, but the other one is soft when I press on it with a metal pin.
I could just run a wire to attach those two points, but I am not sure if that is best. This is a multi-layered board. And unfortunately, I do not know if there are more than 3 layers. Further, I have schematics but I don't have PBC layout files which would show how many wires splice off the same via. Hence, if I've got a bad via, it's easy to fix that via by running a wire on the top and bottom of the board, but that won't help me if there are breaks to that point in different layers WITHIN the board.
Since I am not experienced fixing vias of multi-layered boards, I would appreciate your advice. (And if anyone happens to know how many layers the SE/30 board is and/or have access to PCB layout files, I would certainly appreciate getting that information from you.)
PM me if you wish to have access to my BOMARC and Apple SE/30 schematics.
I look forward to your advice. Thanks.
It seems unlikely after the thorough cleaning you gave it. There could be that hidden nugget of conductive detritus... I'd be more inclined to believe an eaten via which doesn't display it's destruction to the eye alone.
Ah, now I'm caught up with your latest post. I would run the bypass wire. I'm pretty sure these are four layer boards, with internal ground and power planes and signal layers on the top and bottom. More importantly, I can't imagine how running a bypass wire would do any harm, even if the board has more than four layers. At worst (I think) it just won't work.
You might also probe A22 in the PDS slot and see if it connects to either side of your broken connection. If it does connect that would seem to reduce the likelihood that there are additional broken connections inside the board.
Oh, and regarding #2, the Daystar Accelerator. I agree that there are a lot of variables, so try altering the ones which you easily can. The 68030 is socketed. Try swapping it with one from your reliable PowerCache board. Note down the date codes on the two chips first. It's surprisingly easy to get them confused in the heat of testing and not know which came from where.
Similarly for the FPUs. Those chips, at least, are easy to swap for a quick reliability check.
Finally, in my post above, it looks like I was wrong about the SE/30 on-board VRAM chips being socketed. All the chips (PALs) below them in your photo are socketed, but it looks like the VRAM is soldered down. With your discovery of a broken address line to the ROM, it's probably irrelevant, but I thought I should mention it.
First of all, thank you for the reply. And thanks for viewing my videos. I talk a lot in those videos, so you may wish to find a way to get the sound to work!
In my examination of several thru-hole vias last night, I noticed that some wires from connectors will route from a connector pin to a via, but then you cannot physically see any wires on the top or bottom of the board leading from that via to another place on the board. Yet, if you hold the board up to the light so you can see light shining through the back of the board, you can then see a tiny little wire inside the board leading away from that via somewhere else. And this holds true for "address" lines that are certainly not "ground or power planes." Because of that, I was thinking there is a "signal" plane (perhaps more than one) inside the board. And that's where a PCB layout diagram for the SE/30 motherboard would come in handy. If I know all the lines that lead to/from a particular via, I then don't need to worry about resurrecting the via itself, as I could run direct wires to all the points.
I agree with your last sentence that running a wire from the bad via on the top and bottom of the board would not harm anything, it may not solve the problem either. But then we don't know if the problem is not solved because there are other wires connecting to that via inside the board (which my new wires on top/bottom do not re-attach), or if there are other eaten traces. Only by truly fixing each problem can I then rule out that fixed section as possibly contributing to additional problems I find.
Hmm, whether or not there are broken signal traces in the inner layers, can't you proceed as you have been, checking out the board with a continuity meter and comparing to the schematics? Once you add this first wire, you can confirm that the ROM pin 45 (A22) connection is working now. If that doesn't get the Mac running, then you can keep checking for more continuity problems and fix them with additional wires, verifying each fix as you go.
Of course. But that is more time consuming and error prone as a result. A PCB diagram would show me all I need to know about each and every via at a glance.
It's not a matter of sheer laziness. I really try to make the most of each free moment because I don't have that many of them.
Furthermore, I have found some minor inconsistencies between the BOMARC and Apple schematics, which lead me to believe there could be an error or two in there. I do keep notes though, so if I do find an error, it will be documented and I will perhaps even change the schematic at some point (to provide to others who ask for them).
So later this evening I will carefully examine the schematics again, then decide if the two bad bias truly can be restored simply by soldering in an external wire between them.
That does sound like more than four layers. Perhaps six layers. I think the chances of a complete PCB diagram turning up is low. Unless someone made one by examining the SE/30 board. Apple certainly isn't going to have released it. Unfortunately.
You might apply a large dollop of solder flux and apply heat to the hole. That should remove the oxides in the hole. Perhaps use some desolder braid, or maybe blow the hole out while it's hot. I'm not certain of the best way to clean it out, but I'd work toward cleaning out the oxides and getting fresh solder adhered in there.
Once it's cleaned out, insert a bit of stripped wire wrap and solder in place. There's a pretty good chance that if there are additional layer connections in there, the solder and wire will make a connection to them.
Well, I fixed the PCB trace that had been rated by leaked fluid (in the vicinity of the battery). Unfortunately, I get the same exact response -- horizontal lines and a sad Mac chime, both exactly as they were before (and as they appear and sound in my video). So obviously, this is not the only broken trace and/or there could be a bad chip on the board.
I spent a lot of time last night checking points with the aid of my schematic. I checked all the pins on UK6 (video ROM), D0-31 (Data pins) leading from the ROM to the RAM SIMMs and to D4 - D19, I reverified that pin 45 of the ROM (Address A22) properly connected to all the points I could find on my schematics (proving my fix was good). So far, I've not found anything else bad, but there are hundreds of other places that would need to be checked, and even then one cannot know if a chip is bad. Further, I am still concerned about resurrecting vias in light of this being a multi-layered board. I could easily spend another 5-10 hours checking points and still may not come up with a remedy. I just don't have 5-10 hours or the desire to commit so much time. I will keep testing the board when I have spare time, as I am not to not sleep well at night until a problem is solved. But I must admit I am rather frustrated with this board.
Had I another socketed board, I would be content with just putting this board out of its misery. But I wanted to test the Daystar accelerator in another socketed motherboard to see if that resolved the lock-up problem I had with it. I did test the CPU of the Daystar accelerator last night. I pulled the 68030 chip from the Daystar board and put it into my known-good socketed SE/30 logic board, then I fired up the machine and ran Norton System Info (benchmark utility), followed by running extensive Norton Disk Utility tests on my 4.5GB hard drive's 3 partitions -- all of which put a good deal of stress on RAM, CPU and Disk. I left the machine on all last night (with screen brightness turned down to avoid burn-in), and the machine never locked up once. I then used it a little while this morning and it worked fine. So the CPU of the Daystar upgrade is not the reason why that upgrade is locking up. That's a fact.
I spent a lot of time last night checking points with the aid of my schematic. I checked all the pins on UK6 (video ROM), D0-31 (Data pins) leading from the ROM to the RAM SIMMs and to D4 - D19, I reverified that pin 45 of the ROM (Address A22) properly connected to all the points I could find on my schematics (proving my fix was good). So far, I've not found anything else bad, but there are hundreds of other places that would need to be checked, and even then one cannot know if a chip is bad. Further, I am still concerned about resurrecting vias in light of this being a multi-layered board. I could easily spend another 5-10 hours checking points and still may not come up with a remedy. I just don't have 5-10 hours or the desire to commit so much time. I will keep testing the board when I have spare time, as I am not to not sleep well at night until a problem is solved. But I must admit I am rather frustrated with this board.
Had I another socketed board, I would be content with just putting this board out of its misery. But I wanted to test the Daystar accelerator in another socketed motherboard to see if that resolved the lock-up problem I had with it. I did test the CPU of the Daystar accelerator last night. I pulled the 68030 chip from the Daystar board and put it into my known-good socketed SE/30 logic board, then I fired up the machine and ran Norton System Info (benchmark utility), followed by running extensive Norton Disk Utility tests on my 4.5GB hard drive's 3 partitions -- all of which put a good deal of stress on RAM, CPU and Disk. I left the machine on all last night (with screen brightness turned down to avoid burn-in), and the machine never locked up once. I then used it a little while this morning and it worked fine. So the CPU of the Daystar upgrade is not the reason why that upgrade is locking up. That's a fact.
After spending some additional hours testing and finding nothing wrong, I then came across something new. J12 is the main connector on the motherboard, which pulls power from the analog board. Within J12, pins 12 and 13 are connected together (as per my schematics) and route +5v throughout the logic board. The problem part is that when touching my DMM in Continuity Check mode between pins 12 or 13 and Ground, I get a short. So the +5v line is being shorted to ground somewhere on the board. The problem is, where?
I checked the polarity of all my replacement caps. They are facing the right way. They were all brand new caps (well, new when I bought them from Trag a few years ago), so I doubt they are bad. So now I need to find the short.
For good measure I put my DMM across pin 12 and Ground on a known-good logic board. It does not short to ground. So that proves that this short on my other board is indeed a problem short that needs to be fixed.
Interestingly, despite the +5v line being shorted to Ground, I get the horizontal lines and chimes of death at startup. I would think that with a short on the logic board, I certainly should not get any sound. Yet, the sound works fine, and is quite loud too.
Thoughts?
I checked the polarity of all my replacement caps. They are facing the right way. They were all brand new caps (well, new when I bought them from Trag a few years ago), so I doubt they are bad. So now I need to find the short.
For good measure I put my DMM across pin 12 and Ground on a known-good logic board. It does not short to ground. So that proves that this short on my other board is indeed a problem short that needs to be fixed.
Interestingly, despite the +5v line being shorted to Ground, I get the horizontal lines and chimes of death at startup. I would think that with a short on the logic board, I certainly should not get any sound. Yet, the sound works fine, and is quite loud too.
Thoughts?
It does seem like with a short that you should not be getting anything from the logic board.
Are you using a continuity meter or an ohmmeter for the testing?
If the former, try setting your DMM to ohmmeter and measure the actual resistance between the connector pins. Use the most sensitive setting which gives you a useful reading.
Do the same thing across each of the bypass capacitors. As you get closer to the short, the resistance should fall -- although that effect could be overwhelmed by simple differences in how well the probes make contact with the various test points.
I would also check across the battery holder pins. There's a lot of space under the battery holder for problems.
Do you have access to an adjustable power supply? If so, adjust it to 5V. Turn it off, connect it to the GND and 5V pins on the logic board and turn it on. How much current does it report? Try increasing the voltage a few tens of millivolts. Does the voltage increase or is too much current drawn from the supply?
Alternatively, or in addition to the above, connect the logic board outside of its frame so you have access to all of it. Power the machine up normally. Run your fingers just above the board looking for a hot sport. Touch each chip and capacitor and see if any of them are particularly warm.
Finding a short is a pain. If it was a dead short, you could try the old trick of running the voltage up until the short burns out. However, you seem to have a rather resistive short, since the machine is still getting enough voltage to kind of boot up. So the old over-voltage trick would probably fry the components on the logic board.
Thanks for the advice, Trag.
My Digital Multimeter (DMM) can measure Volts, Amps, Ohms, and also check diodes and continuity. When in Continuity/Diode check mode, the DMM beeps at me when both probes are touched together or when I touch each probe at the end of a single wire (i.e., when I get a short). It also gives me a number on the LCD when in Continuity check mode, which shows resistivity. It beeps at me when that number is about 20 or less.
I just tested the board with the DMM set to measure resistance (Ohms). And during my test I saw the resistance between Pins 12/13 (+5v) and Ground slowly increase to about 34.9-ohms. After it increased beyond 20-ohms, I switched back to Continuity check mode and put the probes across pins 12/13 (+5v) and Pin 1 (Ground), and the DMM would not longer beep at me (obviously, because resistance had increased so much it was no longer a dead short).
But if the resistance slowly increased, that would indicate a capacitor at the heart of this problem, would it not?
I also put my DMM probes across a 10k-ohm resistor, set the DMM to read voltage, and then I put the resistor across Pins 12/13 (+5v) and Pin 1 (Ground). I didn't see anything on the DMM screen, but when I put the DMM back into Continuity check mode and then put the probes directly across Pin 12/13 (+5v) and Pin 1 (Ground), it was back to beeping at me again (showing me signs of a short). And this test too would indicate a capacitor problem, with the 10k resistor having discharged the capacitance.
Thoughts?
My Digital Multimeter (DMM) can measure Volts, Amps, Ohms, and also check diodes and continuity. When in Continuity/Diode check mode, the DMM beeps at me when both probes are touched together or when I touch each probe at the end of a single wire (i.e., when I get a short). It also gives me a number on the LCD when in Continuity check mode, which shows resistivity. It beeps at me when that number is about 20 or less.
I just tested the board with the DMM set to measure resistance (Ohms). And during my test I saw the resistance between Pins 12/13 (+5v) and Ground slowly increase to about 34.9-ohms. After it increased beyond 20-ohms, I switched back to Continuity check mode and put the probes across pins 12/13 (+5v) and Pin 1 (Ground), and the DMM would not longer beep at me (obviously, because resistance had increased so much it was no longer a dead short).
But if the resistance slowly increased, that would indicate a capacitor at the heart of this problem, would it not?
I also put my DMM probes across a 10k-ohm resistor, set the DMM to read voltage, and then I put the resistor across Pins 12/13 (+5v) and Pin 1 (Ground). I didn't see anything on the DMM screen, but when I put the DMM back into Continuity check mode and then put the probes directly across Pin 12/13 (+5v) and Pin 1 (Ground), it was back to beeping at me again (showing me signs of a short). And this test too would indicate a capacitor problem, with the 10k resistor having discharged the capacitance.
Thoughts?
When putting a 3A capable 5v power supply across Pin 12 (+5v) and Pin 1 (Ground), the voltage drops to 4.83v and the current is 1.51A. Checking the same power supply when no load is applied shows 5.01v on my DMM (i.e., the voltage drops from 5.01v to 4.83v when I connect the power supply to the SE/30 logic board).
I left the power supply connected and powered ON for three minutes. During that time, 5 chips got warm, all of them the PALs: UI6, UG6, UG7, UE6 & UE7. I physically touched all the chips and capacitors with my fingers. Not even the CPU got warm. Only those 5 socketed PAL chips. I would classify it has "hot" but not so burning hot I could not keep my fingers on the PALs.
After removing power and waiting about 3 minutes, I put my DMM in Continuity Check mode across Pin 12 (+5v) and Pin 1 (Ground). This time it did not beep at me. I then switched to check resistance on my DMM and measured 43.9-ohms across those same pins. But while keeping my eye on the DMM's LCD, I could see the resistance value slowing going down. I then removed all 5 PALs from their sockets, checking the resistance as I pulled each one. The resistance continued to drop at the same pace, unaffected by my removal of the PALs.
Each of the PALs were correctly socketed. I know this based on the Apple part numbers on the chips in comparison to what is written on my schematics. I also know how they were installed the first time I looked at the board, before I ever pulled the chips to clean the board.
After all this, I reconnected my power supply again, this time using 4 alligator-clip jumper wires instead the 2 that I used before. I was thinking that two wires alone may be limiting the current a bit. So I connected Pins 1 and 4 (both board Ground) to my PSU Ground, and I connected Pins 12 and 13 (both board +5v) to my PSU's Positive line, then put my DMM on to check voltage. This time I read 4.90v at 1.56A. I then slowly increased the voltage on my PSU. I saw a proportional increase in voltage on my DMM and the current increased too. And as before, the PALs got warm, but nothing else.
I would appreciate hearing your thoughts in light of this.
Thank you.
I left the power supply connected and powered ON for three minutes. During that time, 5 chips got warm, all of them the PALs: UI6, UG6, UG7, UE6 & UE7. I physically touched all the chips and capacitors with my fingers. Not even the CPU got warm. Only those 5 socketed PAL chips. I would classify it has "hot" but not so burning hot I could not keep my fingers on the PALs.
After removing power and waiting about 3 minutes, I put my DMM in Continuity Check mode across Pin 12 (+5v) and Pin 1 (Ground). This time it did not beep at me. I then switched to check resistance on my DMM and measured 43.9-ohms across those same pins. But while keeping my eye on the DMM's LCD, I could see the resistance value slowing going down. I then removed all 5 PALs from their sockets, checking the resistance as I pulled each one. The resistance continued to drop at the same pace, unaffected by my removal of the PALs.
Each of the PALs were correctly socketed. I know this based on the Apple part numbers on the chips in comparison to what is written on my schematics. I also know how they were installed the first time I looked at the board, before I ever pulled the chips to clean the board.
After all this, I reconnected my power supply again, this time using 4 alligator-clip jumper wires instead the 2 that I used before. I was thinking that two wires alone may be limiting the current a bit. So I connected Pins 1 and 4 (both board Ground) to my PSU Ground, and I connected Pins 12 and 13 (both board +5v) to my PSU's Positive line, then put my DMM on to check voltage. This time I read 4.90v at 1.56A. I then slowly increased the voltage on my PSU. I saw a proportional increase in voltage on my DMM and the current increased too. And as before, the PALs got warm, but nothing else.
I would appreciate hearing your thoughts in light of this.
Thank you.
PALs get hot. I was surprised by this when I learned it. I was fiddling with a GAL from an Outbound Floppy Controller board and thought something was wrong with it because it got so hot. But back in the circuit it worked fine. And info requested on sci.electronics.repair resulted in folks saying that PALs get hot.
So, I suspect that warm/hot PALs is not a problem.
Which doesn't help with finding your short problem.
Capacitors in a circuit, especially bypass capacitors, will look like a short until the capacitors charge. That's because the caps are a place for current to flow into while the caps are charging. A DMM does not supply much current, so it takes a noticeable amount of time for them to charge. So I do not think that your slowly increasing resistance is a suggestion of a capacitor problem. Doesn't mean it isn't, though.
One of the results you had where the resistance was still about 35 ohms when you checked it again, probably just means that the caps charged up during the first measurement and hadn't discharged before the second test.
The question is, is ~35 - 40 ohms the proper resistance for your board with all the current paths on it?
At this point, I would get out a working SE/30 board, preferably also one you have recapped. And take the same measurements on it as you have taken on this one. In other words, is its static resistance about 40 ohms from 5V to GND. Does it draw about 1.5 amps when supplied with 5V. Etc.
So, I suspect that warm/hot PALs is not a problem.
Which doesn't help with finding your short problem.
Capacitors in a circuit, especially bypass capacitors, will look like a short until the capacitors charge. That's because the caps are a place for current to flow into while the caps are charging. A DMM does not supply much current, so it takes a noticeable amount of time for them to charge. So I do not think that your slowly increasing resistance is a suggestion of a capacitor problem. Doesn't mean it isn't, though.
One of the results you had where the resistance was still about 35 ohms when you checked it again, probably just means that the caps charged up during the first measurement and hadn't discharged before the second test.
The question is, is ~35 - 40 ohms the proper resistance for your board with all the current paths on it?
At this point, I would get out a working SE/30 board, preferably also one you have recapped. And take the same measurements on it as you have taken on this one. In other words, is its static resistance about 40 ohms from 5V to GND. Does it draw about 1.5 amps when supplied with 5V. Etc.
Trag, thanks for the info and advice.
I tested my known-good socketed motherboard, using the same known-good RAM SIMMs as I used on the bad board. My known-good board was also recapped in exactly the same way and with exactly the same replacement caps (your kit of SMD tantalums and axials). I used two alligator-clip jumper wires on this board as I did in my final test on the bad board. I tested my power supply with a DMM before I connected it, and it measured 5.00v. When I connected the 4 jumpers and then switched the power supply on again (on my known-good board), I measured: 4.88v @ 1.41A. That reading is a tad lower than the reading I got on my bad board, but it is not substantial difference. The two motherboards are different revisions though, with the location of C12 being a little different, so perhaps that also contributes to the slight difference in voltage and current.
I also noted this time that, in addition to the PALs, the following components also got noticeably warm to the touch:
Y2 (OSC)
UH7
UG12
They might have also gotten warm on my bad board too -- I don't remember.
I also tested the resistance between Pin12 (+5v) and Pin1 (Ground) very quickly after I turned off my power supply. For a brief instant I measured 100-ohms. But I could see on the DMM's LCD that the resistance dropped rather quickly down after that. It took only a few seconds to go down to 63-ohms. I then removed all the jumpers and my DMM, and began typing this post for a few minutes. Then when I tested resistance again, it was down to about 28-ohms and dropping.
Before I did any of these tests on my known-good board, I put my DMM in Continuity Check mode and put the probes between Pin12 (+5v) and board Ground. It immediately beeped at me, indicating a dead short, just as it did with my bad board. So this confirms that the bypass caps show a dead short to my DMM when it is set to Continuity mode (when the caps are fully discharged).
My next test will be to remove the PALs from the known-good board and put them in the bad board to see if that resolves the problem. Hopefully, the problem with my bad board is not so such that it will fry my known-good PAL chips. If that test fails, I will then put the PALs back in the good board and test it to confirm the PALs are still good. I will then continue the painful process of checking every via and every pin, in accordance to my schematics. But I must say this is not an enjoyable process in light of the time it takes.
I tested my known-good socketed motherboard, using the same known-good RAM SIMMs as I used on the bad board. My known-good board was also recapped in exactly the same way and with exactly the same replacement caps (your kit of SMD tantalums and axials). I used two alligator-clip jumper wires on this board as I did in my final test on the bad board. I tested my power supply with a DMM before I connected it, and it measured 5.00v. When I connected the 4 jumpers and then switched the power supply on again (on my known-good board), I measured: 4.88v @ 1.41A. That reading is a tad lower than the reading I got on my bad board, but it is not substantial difference. The two motherboards are different revisions though, with the location of C12 being a little different, so perhaps that also contributes to the slight difference in voltage and current.
I also noted this time that, in addition to the PALs, the following components also got noticeably warm to the touch:
Y2 (OSC)
UH7
UG12
They might have also gotten warm on my bad board too -- I don't remember.
I also tested the resistance between Pin12 (+5v) and Pin1 (Ground) very quickly after I turned off my power supply. For a brief instant I measured 100-ohms. But I could see on the DMM's LCD that the resistance dropped rather quickly down after that. It took only a few seconds to go down to 63-ohms. I then removed all the jumpers and my DMM, and began typing this post for a few minutes. Then when I tested resistance again, it was down to about 28-ohms and dropping.
Before I did any of these tests on my known-good board, I put my DMM in Continuity Check mode and put the probes between Pin12 (+5v) and board Ground. It immediately beeped at me, indicating a dead short, just as it did with my bad board. So this confirms that the bypass caps show a dead short to my DMM when it is set to Continuity mode (when the caps are fully discharged).
My next test will be to remove the PALs from the known-good board and put them in the bad board to see if that resolves the problem. Hopefully, the problem with my bad board is not so such that it will fry my known-good PAL chips. If that test fails, I will then put the PALs back in the good board and test it to confirm the PALs are still good. I will then continue the painful process of checking every via and every pin, in accordance to my schematics. But I must say this is not an enjoyable process in light of the time it takes.
I reviewed this thread from the beginning, and was reminded that it actually makes the startup sound "bong" when powered on. That means it's actually running and getting at least part-way into the boot sequence code in ROM. Have you tried actually booting the machine, inserting a floppy? If it is purely a video problem, then maybe the computer itself is working fine. I'm not sure what that would prove, but might help narrow down the problem.
No it doesn't make a "bong." As a part of my video, you can clearly hear that it only makes the "chimes of death" which are always a part of a Sad Mac Error Code screen. And of course you unfortunately cannot see that Sad Mac Error Code due to those horizontal lines:
Because it is a Sad Mac error/fault, it will not boot. No Macs boot when the Sad Mac "chimes of death" sound. The problem that causes those chimes must be fixed first. And that is what all my recent posts have been about. Trying to find that elusive logic board fault!
Ah sorry, I re-read it too fast and misinterpreted the startup sound.
BTW, there's an SE/30 motherboard up on eBay for $1. I'm not sure what the socketed type looks like... is this one? http://www.ebay.com/itm/Vintage-Apple-Macintosh-SE-30-Motherboard-/120773451571?pt=LH_DefaultDomain_0&hash=item1c1ea89f33
It's does not have a socketed CPU. You can spot the difference right away using this as a guide:
Gold-topped CPUs are socketed:
No Gold means soldered:
In addition, the EBAY listing for that board on EBAY says it won't produce video, which on some level is the same situation I am in now with my bad socketed board. Also, that EBAY board would need to be recapped too.
Going back to issue #1, the memory chips are actually available on Ebay. Overpriced, but available.
http://www.ebay.com/itm/SRAM-MT42C4255DJ-10-MICRON-28-SOIC-SOJ-42C4255DJ-/370296183601?pt=LH_DefaultDomain_0&hash=item56375f5b31
http://www.ebay.com/itm/SRAM-MT42C4255DJ-10-MICRON-28-SOIC-SOJ-42C4255DJ-/370296183601?pt=LH_DefaultDomain_0&hash=item56375f5b31
Trag, that would in fact be "Issue #3":
viewtopic.php?p=157345#p157345
) What you are speaking of is replacing the SRAMS on my Xceed video card in an attempt to resolve the vertical line problem. And since we have not determine which specific SRAM is the culprit, I technically would need to replace all 16. Thank you for the EBAY listing. But at $10 each, it would cost me $160 in parts, plus shipping to Japan, plus my time to properly desolder those SMD components without harming the board. And without the proper tools to desolder 16 SMD chips (28-pins each), the likelihood of harm coming to the board is high. As such, I may be worse off (dead board) than where I started (1px wide vertical line).
Since I could not so easily and quickly resolve Issue #3, I turned my focus (for now) onto fixing Issue#1 (simasimac board), in hopes that by testing the Daystar card (Issue#2) in another socketed logic board, I might see something different that would help me explain why the Daystar board locks up.
Thanks to Trag, Bigmessowires and everyone else who has participated in this thread thus far. Keep the advice and thoughts flowing!
Yes, #3, not #1. Leaky memory in my skull. Fall Baseball just started and my head is full of kids' names, matching them with their parents and trying to make sense of who needs some fundamental work on what....
No, I wouldn't recommend replacing all of them. Identifying the culprit will be a pain, so probably best to do what you are doing, and focus on one issue at a time.
No, I wouldn't recommend replacing all of them. Identifying the culprit will be a pain, so probably best to do what you are doing, and focus on one issue at a time.
You could probably determine which is the bad memory chip on the card if you're willing to do some programming. (or possibly by being scientific with a paint program) If you could poke some bit patterns into the framebuffer at various color depths and determine exactly which pixel is being affected (and in what way) it shouldn't be too hard to figure out which chip in a row it is. The problem is that we're not looking at something like a Commodore 64 where's it's relatively trivial to write a program to do that.
Stupid question: If when running a paint program you "select" an area of the screen and drag it around/zoom in (or if you just drag a window around in any program) do the miscolored pixels come along for the ride? If they don't the problem is almost definitely a bad cell in the output buffer of those RAM chips, not a bad line in the main DRAM.
Stupid question: If when running a paint program you "select" an area of the screen and drag it around/zoom in (or if you just drag a window around in any program) do the miscolored pixels come along for the ride? If they don't the problem is almost definitely a bad cell in the output buffer of those RAM chips, not a bad line in the main DRAM.
Well, the PALs from the BAD logic board are good. I removed the PALs from my good board and put the PALs from the bad board into the good board and booted. No problems. I then ran a full suite of Norton System Info benchmarks and there were no problems. So the socketted PALs are not the source of problems on my bad board. It's a real bear to find the root problem on that bad board!
In any case, I did the test you asked for, within Canvas. When I move the window in Canvas, the pixels move with it. However, new pixels appear in place of the old. Furthermore, I have Windowshade installed, which means a simple double-click of the window's title bar will "roll up" the window, so to speak. When I double-click (window vanishes, leaving only the title bar), and then when I double-click a second time (to display the window body again), the stray pixels at right vanish entirely. But then if I move the window around again, they reappear in pretty much the same place. And if I move the window around more, those pixels move around with the window, and new pixels take their place (in the original positions). So it appears to be some kind of refresh problem associated with any apps that switches the gray/color palette around, rather than using the standard system palette.
Ah, but not every paint program causes those colored pixels you see at the right side of my screen shot and photo. It seems that CANVAS 3.5 is the only app in which I can get the problem to surface, and that seems linked to the fact that Canvas is trying to use its own color palette instead of the system palette, which explains the difference in gradation among the grays/colors shown in the Monitors Control Panel.
In any case, I did the test you asked for, within Canvas. When I move the window in Canvas, the pixels move with it. However, new pixels appear in place of the old. Furthermore, I have Windowshade installed, which means a simple double-click of the window's title bar will "roll up" the window, so to speak. When I double-click (window vanishes, leaving only the title bar), and then when I double-click a second time (to display the window body again), the stray pixels at right vanish entirely. But then if I move the window around again, they reappear in pretty much the same place. And if I move the window around more, those pixels move around with the window, and new pixels take their place (in the original positions). So it appears to be some kind of refresh problem associated with any apps that switches the gray/color palette around, rather than using the standard system palette.
Good news.
Keep in mind that there are two kinds of operations on the screen, for our purposes.
There are screen draws where the information for the image comes from the CPU or from system memory. These should lead to only the orignal corrupted line, caused by VRAM.
And there are screen draws where the information for the image comes from video memory. In this case, when the computer copies the image with the bad line in it, it's going to copy the bad bits that cause the line and write them to a new location.
That's why the bad line appears to move, and why certain refreshes will cause the copied image to go away, but the bad image always manifests in the original place.
The bad memory locations cause the original bad line. When the system copies an image from the bad memory locations, it gets bad information and writes it in a new memory location. The new memory location works properly, but it's just been written with bad data, and faithfully reproduces it.
I have to admit I'm really curious whether read/write operations to and from the main bus pass through the SRAM cache on the memory chips on the way into/out of DRAM ,or if they hit the bulk DRAM directly. My eyes glazed over reading it but it seemed to me looking at the data sheet that either was an option.
I'm almost rethinking whether it's *definitely* strictly the VRAM at all. Since the line seems to land on annoyingly-convenient-from-a-binary-standpoint 96/192/384(ish) word boundaries I'd place a small side bet on the possibility that it's something wrong with the RAM controller or address generation circuitry that's causing corrupt values to be placed into VRAM in the first place. Unlikely, but not impossible. (Or even, remotely possible, a software bug. Are you running the appropriate system software versions for the driver?)
To clarify, the "pixels" I spoke of in my previous post were not the vertical line pixels. I was speaking of the stray color pixels that you can see in the following screen shot:
https://docs.google.com/leaf?id=0B3mQLg8d1xThM2MzNmQ5YTctZDdiMi00NTk4LWI3ZjUtNTU3M2JmNjg2ZTU2&hl=en_US
Note the vertical "line" at left. I was not speaking about that vertical line in my previous post. I was speaking of the 8 or 9 or so stray colored pixels that are difficult to see yet appear toward the right side of the screen. Look to the immediate left of the "CC" menubar icon to see them. They do go down the screen in a vertical fashion, but they are not the same as the vertical line you see at left. The vertical line at left does not have colored pixels, and it is a continuous line from top to bottom. But the stray pixels at right are colored and not a continuous line, even though they are vertical and extend from top to bottom "with gaps."
When I asked the question I was wondering about the vertical line pixels. So they are *not* picked up or moved by a cut and paste?
Those pixels and the "stray dots" might be two mostly-unrelated problems, although it's possible the same RAM chip could be causing both of them if it has some sort of problem that affects both the DRAM and SRAM portions.