Mac SE/30: Scsi problems

I have done some additional testing.

It doesn't boot from an external hard drive as well with OS 7.5.3 for an SE/30.

I get the same errors: doesn't recognise the disk, unable to mount

I have checked the 3x Bourns filters: all measure 54 Ohms pin-to-pin in circuit so I guess these are OK.

I'm thinkig for either a broken trace from the SCSI chip somewhere or a faulty chip.

I inspected the leggs of the SCSI chip under a magnifying glass and they look good, no visible corrosion.

Does anyone have schematics or picture where all the pins of the SCSI chip need to go so I can test them for continuity ?

It would save me a lot of time as sorting them all out myself would take several hours.

I hope it's not the SCSI chip as I don't have the equipment to replace it.

Someone traced out the connections for the SE/30 SCSI chipped and posted them. You'll have to hunt for it though. You might also check the Wiki. It might be in there. But there was another SE/30 thread within the last few years about replacing the SCSI chip and then discovering that it was a corroded connection or trace.

Thought of a few search terms that would help. Here's the thread:

http://68kmla.org/forums/viewtopic.php?f=7&t=12985&hilit=SE%2F30+datasheet+53c80

Zuiko21 says he has a schematic showing the 53C80 connections somewhere around mid-thread, so you might try asking him about it.

I have just finished testing all traces from the SCSI chip: not a single broken one xx(

I don't know anymore, it's just sad because it's a socketed version of the logic board.

Now I recapped another one and while it powers on: it can't find the SCSI hard drive at all: this one looks even worse as the previous board could at least find something.

Probably the end result will be the same xx(

These were 2x board I was recapping from a friend but he let them go too far: the was a lot of leakage from the capacitors on the PCB.

could you try the drive in a external enclosure?

just for giggles?

it might be a power issue acutely, maybe the HD is getting almost enough power from the PSU, but not quite enough once the head starts seeking?

could you try the drive in a external enclosure?just for giggles?

it might be a power issue acutely, maybe the HD is getting almost enough power from the PSU, but not quite enough once the head starts seeking?

Click to expand...

I already tried an external enclosure: it's not working, same reslt: tried 3x 100% known good drives.

The PSU is not the issue as well as both PSU and Analog board are fully recapped as well.

PSU is stable, no drops or spikes in voltage as I logged both the +5v and +12v lines while testing.

Could it still be the bourns filter ? I don't think so because I measure 54 Ohms in-circuit between the pins, identical on all 3x Bourns filters.

I guess this is the right way to test them: correct me if I'm wrong.

I get +5v termination voltage on the SCSI connector, verified all traces from the SCSI Chip to the SCSI Connector, UL

I used this diagram to check all traces from the SCSI chip ( it was posted a while ago in another SE/30 Scsi topic ) :




I don't know anymore now. It's weird the SCSI chip can still see the HDD on the Bus, succeeds in format and verify but then TEST and Mount fail.

Anyone with ideas as it would be a sad to give up on this board.

maybe in this situation you need to sweat off that scsi chip , replace with another scsi chip?

i hear the SE/30 is known for having scsi chip issues...

2x problems: I don't have a replacement SCSI chip, neither do I have a hot air rework station for removing the old chip and fitting a new one.

I really can't afford this kind of equipment for doing an occasional job, I whiched I could...

Do you have the right equipment and spare SCSI chips ? If so PM me what you would ask to replace the SCSI chip but I'm not convinced 100% that its the cause of my problems. I have never seen something so weird like this.

I have a 2nd SE/30 board with no SCSI at all but haven't tested the traces of the SCSI chip yet, I'm going to try that in the weekend.

as long as you get some tin foil and make a cut it out so just the scsi chip gets the heat,

you can use a 22 dollar heat gun,

I just bought one and i love it. mcdermd uses his sometimes

You want to use some long electronics tweezers to pick up the chip.

use an iron to clean up the pads (if needed) , lay some flux down, then set the chip on there and melt it in.

I do have a extra scsi chip, it's on that board I got from CC-333

PS:

Last night I removed the FPU,(from CC_333's parts SE/30 Board) The CPU and the CPU socket, A ram Slot yes the heat gun rocks!

I got lazy and didn't mask the Battery Holder (when removing the FPU)… and it partially melted (so ya gotta be a little careful that air is super heated it)

I got my mouse pad a couple times there is now a couple big black spots. haha

I use 2 dead LC PSU's to raise the board off my desk/mouse pads.

What machine have you tested the SCSI drive as good on?

I ask because your description is also consistent with a hard drive which has been formatted with incompatible formatting software. Kind of a long shot, but a possibility. What utility did you use to initialize the drives?

I used my own working SE/30 to test the hard drive. It's definately not the hard drive or the formatter.

I tried multiple drives with Apple HD SC 7.3.5 and also FWB 2.0.6: both work fine in my good SE/30 when doing exactly the same, while they don't with the "problem" board.

Also the working HDD with os 7.5.5 from my good SE/30 does not boot at all with the problematic board. So I just swapped the logic board in my good SE/30 but no boot at all. It's polling the HDD but that's all.

Hmmm. Frustrating.

Yes, I know that's not helpful, but an expression of camaraderie is the best I can do at this time.

Hi,

I'm in the process of trying to fix the SCSI on my SE30 as well, and found the original circuit diagrams incredibly useful (but that hasn't lead to any success yet ).

Don't know if you have them already but I found them here:

http://cdn.preterhuman.net/texts/computing/Apple_Schematics/SE-30%20-or-%20IIcx%20without%20NuBus/

Best of luck and I hope you get it sorted.

I believe that board connection/trace/via issues are more likely to be causing problems than a bad SCSI chip, but just in case...

questcomp.com has the 53C80 available. They want $11.55 for it. However, if you order 4 or more the unit price drops to $5.775.

I agree with trag, the SE/30 is just total crappy for rotted VIA's ///

Rotted Via's really annoy me!

i'v got one at home on my desk just waiting to suck up another 3 to 4 hours of my life

FYI I just fixed my SCSI problem, two bad vias were the cause. Seems to be a commong problem...two hours to fix and a wrecked head now....

also watch this video, you can see how techknight got through his SE/30 scsi problem

I checked all the pins of the SCSI chip, these are fine. However I didn't check every single pin of all the VIA's as this would take many hours.

I'm going to give up the board.

Don't give up!

Maybe leave it alone for a while as I know it can get very frustrating, but it would be a shame to dump it as you are so close

yeah, you are really close, it's probably just one bad trace, (via) that goes to the glue chip.

process of elimination should tell you any where the cap GOO has been, is a good place to study

I found a much more detailed schematics for the SCSI traces after digging through the Forum.

See the 3 Jpegs at top of the page below.

http://68kmla.org/forums/viewtopic.php?f=29&t=19390

Check on page 2.

For Pin 20 of the SCSI chip there’s a trace to Pin #2 ( D19 ).

Same for Pin 21 to pin #2 ( D17 ), pin 24 to pin #2 ( D13 ) and other pins of the SCSI chip

I checked the Apple Schematics but don’t find these.

Where are these D references located : its always pin #2 but what are these ?

Can someone point me into the right direction ( or post a photo with a mark where it is ) ?

These are the only unchecked points from the whole list but I doubt these would yield anything.

It was posted by phreakout but I see he hasn't logged in anymore since January so sending a PM won't help much I'm afraid..

I have the socketed version of the SE/30 board.

yeah he may be away on a state issued sabbatical

Dnn components are usually diodes/rectifiers. They only have two pins, so the pin assignment is never greater than 2. Hunt around for either little 2 pin black surface mount components (SE/30 may be too old for those to have been around yet) or little through hole components with an orange/glassy body, although they might be matte black with a silver stripe on one end. If through-hole, they'll be about the size of a 1/8 watt resistor most likely.

My SE/30s are sitting in the attic with their capacitors removed, so I do not have hands on experience with this issue (and hope I never do, yikes) but it sounds like some of the SCSI chip signals are protected by diodes, probably to avoid reverse biasing the I/O pins.

Gents,

I'm late to the party, but I agree with Trag and Uniserver that this is most likely a bad via or trace (I'm betting on the former). When my SE/30 went out I created a schematic tracing each of the SCSI pins back to at least one other chip. Eventually I discovered a bad via located near one of the failed capacitors. I had to make a solder bridge to restore the connection. It may be too late for this effort (and you may have already discovered a better schematic), but I'm happy to share the schematic that I created. Unfortunately I don't log in enough to see the requests in a timely fashion. If someone else that is more active will volunteer to take it on I'll forward the drawing.

The Dxx chips are at the back of the PCB under the Ram modules. Anyway, I have checked the complete SCSI chip against the 3x Jpeg files, which are very detailed, and the conclusion is: there are no broken traces or VIA's.

For that board I'm 90% sure the SCSI chip self is faulty. It noticed in FWB toolkit 2.0.6 than eventhough it recognises the hard drive, model and brand: it lists a wrong size. FWB says it's 64MB while it's a 80MB drive.

When I verify that with a good SE/30 board: it's indeed recognised as 80MB: this only adds to my case that the SCSI controller is faulty.

The other SE/30 board with dead SCSI was repaired quickly, I found 2x broken VIA's, repaired them with a wire and it was sorted.

Now I have to replace the SCSI chip: I did found one on Ebay, PLCC version, I hope this fits. But I don't have an SMD rework station to replace IC's.

Has anyone used this solution ? http://www.chipquik.com/

Have a look at the 40 seond youtube video on their website: it's very interesting how fast they can remove an SMD IC.

Don't forget that questcomp.com has the 53C80 also. I don't know what the pricing on Ebay is looking like, but it's often higher than questcomp.com. Ah, took a look and that $4.20 with free shipping deal looks pretty sweet.

The chip will be the correct size. There was only one PLCC-44 package used for the 53C80.

As far as removing it goes, I have used Chip Quik. It's been almost a decade since I used it, because I don't need it any more.

If you are deciding between buying Chip Quik and a heat gun, I'd get the heat gun.

Chip Quik is an alloy which you melt into existing solder using your soldering pencil. The allow, when mixed with conventional solder, lowers the melting point of the amalgam. This makes it possible to remove moderate sized chips using just a soldering pencil.

Optional step: Remove as much solder as possible from the pins using soldering pencil and braid.

The procedure in brief would be to coat all the pins on the chip to be removed liberally in solder flux. Then run a bead of Chip Quik on all sides of the chip. Then heat each pin/pad individually, to make sure that the Chip Quik has mixed with the solder.

Finally, go around the chip heating each bead of solder/alloy (4 beads in the case of the PLCC-44) in turn. Eventually, you'll get them hot enough that all four will be above the melting point at the same time and the chip will lift off the board. This requires patience. Do not pry the chip up, you'll lift a pad.

If you tried this without Chip Quik, your chances of ever getting the first bead to stay hot enough to release, by the time you get to the last bead, is very low to impossible.

However, if you use a heat gun and just heat the whole chip at once, then there's no need for Chip Quik. I have a Milwaukee brand heat gun with a dial adjustment on the back, which I bought at Home Depot for less than $40. However, they don't sell that model any more. The dial was perfect for this. Most heat guns only have one or two temperature settings.

When using a heat gun to desolder, it is important to mask nearby components. You can literally blow small componetns off the board. I did the first time I tried it. I use modeling clay. Others use aluminum foil. I like clay because it sticks to the board and doesn't blow away, but foil has advantages too.

I find with my heat gun set to 8 (out of 10) it takes about 2 minutes from a cold start to get the typical chip to release from the board. Maybe a little less for something like a PLCC-44, but a little more for some of the through hole chips with 32+ pins.

Once you have the chip removed, remove any remaining solder from the pads with pencil and braid. Clean the board thoroughly. Then tin just one corner pad. Set the chip in place carefully, and melt the tinned pad to settle its pin into place. Thin solder the opposite corner to secure the chip. Then proceed with soldering the rest of the chip. One can often get away with running a bead of solder across each side of the chip, and then coming back through and cleaning the excess solder off with braid. This can be a lot faster, but runs a (small) risk of hidden shorts.

I normally use a heat gun, they work great, but do practice on some junk boards first until you get the hang of doing it without frying the crap out of the board. On some particularly hairy ones I've used a combination of Chip Quik and a heat gun. That lets you use less heat and have less chance of removing nearby parts in the process or overcooking things while still being able to heat all the pins at once and reduce the risk of lifting pads. Just make sure you remove as much of the Chip Quik tainted solder as you can, or it ends up being tricky to solder the new part on. The solder stays molten for what seems like ages.

I'd like to re-emphasize Jame's advice to remove all the Chip Quik after the operation. You don't want any of it in your solder when you put a new part in place. Liberal use of solder flux makes it much easier to remove the Chip Quik laden solder from the board.

What's the best way to solder the new SMD chip in place if you don't have a rework station ?

Every pin by hand under a large magnifying glass or is there an easier way ?

once you remove the bad chip.

- determine what might be needed

- You can re-flow the pads with the iron.

- You could clean the pads with Solder Braid, (if needed) then flow new solder...

I just refux the pads, set the chip where its suppose to be, heat it up evenly till it seems all the pads are melted and the solder has re-reflowed to the legs, Then I press down slightly with my dental pick on the chip.

if i need to go over some legs with the iron i will do so.

I would like to say So far, Every-time I thought it was the IC, I was wrong, It was a trace or VIA issue

But I have seen on the web, the SCSI chip on the SE/30 is known for having issues.