512k sweep/power supply help

This might help: http://68kmla.org/files/classicmac2.pdf

If not, feel free to e-shred it.

Thank you I was having trouble finding much of anything.

While nothing as detailed and sophisticated as Tom Lee's excellent technical guide, I have confirmed the following analog board information:

http://spreadsheets.google.com/pub?key=pOzKVtKz19Ab2BDc-g73ndA

Dang, that's an awesome PDF on classic Macs Tom. I've never seen it before but I'm glad to have it now. Thanks!

Dang, that's an awesome PDF on classic Macs Tom. I've never seen it before but I'm glad to have it now. Thanks!

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Thank you for the kind words. If you find any errors or have suggestions for improvement, let me know. One of these days, I hope to update it with the excellent information contributed by the folks on this forum (with proper attribution, of course).

I only noticed today that my Google docs spreadsheet (link posted above) had the first note missing. I've added that back.

I also found a Revision-J 630-0102 analog board on EBAY, which the seller claims to have come from a Mac Plus.

hey I know its been a while for this post but thank you for the information I am finally on my way to fixing it.

Quick stupid question I am in need of C6 and its a 22uf 50v and I have 2 10uf and a 2.2uf that are 50 or higher volts will the extra 0.2uf going to be too much extra tolerance for the 512k if I install them in parellel? I can always use 2 1uf ones but I would like to put as few in there as possible and I do not want to order one capacitor online and get charged a bunch for shipping. Radioshack has them but only in 35v (they are so lame) I do not think it will be but I just wanted to check.

10% tolerance is typical, so for C6, anything between 19.8uF and 24.2uF is perfectly safe to use.

While in theory you may likely be able to get away with a 35v spec part from Radio Shack, it's always best to err on the side of "higher voltage" when it comes to caps, especially caps used in power supplies or old Mac analog boards.

cool Thank youl I like to use what I have and not have to make a special order, I am going to be using nails for j1 until I get a real one. And I think I found a way to repair the battery holder, I used vinegar to neutralize the acid on it and I am going to solder in some metal plates that should work well.

I think it was doing this before, when I turned it on I saw the disk ? as expected but then the picture faded off. I could hear some small cracks or sparks at the start of the power abruptly ended shortly after, does this just sound like bad caps? I seep to recall it not fading off before but I do seem to remember a cracking or sparking.

Take a look at the pdf doc I linked to earlier. It describes the "no raster" problem, its common causes, and the simple cures. The short version: Resolder the four-pin yoke connector on the analog board, check C1 (I'd just replace it, even if it looked good), and freshen up all the solder joint on the flyback transformer. These simple steps clear up the vast majority of the disappearing/flaky/distorted display problem in the classic macs.

ok sorry i did not see it before . I need sleep soon too much excitement getting my lisa fixed and on for the first time in about 2 years since I found it. Thanks for pointing out what I should search for.

So strange, I left it unplugged for over a day to dissipate opened it up today and discharged the crt. then I took the paper cover off from the analog board. I see and hear a spark from around the transistor that is located by c40 and r41 on the back of the board and shortly after another. It seems like something that would happen with bad caps.

So strange, I left it unplugged for over a day to dissipate opened it up today and discharged the crt. then I took the paper cover off from the analog board. I see and hear a spark from around the transistor that is located by c40 and r41 on the back of the board and shortly after another. It seems like something that would happen with bad caps.

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Or from bad solder joints.

you know I read about the solder joins and did not even think about it, but that would make a lot of sense since it seems to only spark when moved around to much. I will redo the solder on the board and see if it is better or worse.

I re soldered what I could, and it did the same thing as last time I turned in on after being unplugged for a but. When plugged in then turned on it makes a crackle then I can see the screen come on then slowly fade off and turning it off and on will not bring the screen back also when turning it off I hear a squeak, (my old crate amp use to do this too).

it does not seem like Q11 is working when I test it. The one I removed is C2810 the sheet says 2SC2810 and Q11: 7A, 4-500V, 50W, 18MHz. I do not have either one here is there another equivalent that might work so I can for sure tell if that is the problem. I wish I had the transistor equivalences book right about now The Fairchild pdf says KSC2335 is the closest match but I do not have one either.

According to page 332 (Appendix C) in Larry Pina's Macintosh Repair and Upgrade Secrets, Q11 is the following type of component:

T-NPN, 12A, 100W, TO-220

Apple OEM Replacements:

2SC2827

2SC3039

2SC2810

3rd Party Replacement:

Philips ECG 379

(12A, 100W, High Voltage, High Speed, Switching NPN-Si transistor)

thank you I might have to get that book.

it does not seem like Q11 is working when I test it.

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How did you test it?

(And Pina's information about the 2SC2810 seems to be in error. I am looking at the datasheet now, and it says that the 2810 is a 50W device; 7A peak Ic, and 500V BVcbo; it's the same info that I had at the time I put together my own schematics, and summarized there -- patnukem, see the schematics at the end of that pdf; this info is there for every semiconductor I could identify)

Multimeter with transistor tester. it worked to correctly test the bad one in my lisa. yeah I was confused because I mentioned the Q11: 7A, 4-500V, 50W, 18MHz up top from your pdf as you said. Id rather use one I have here to see if that is whats wrong for sure then have to order something.

Tom, I wouldn't be surprised if Pina was in error because I've spotted other errors in his books. But for the most part, his information is quite accurate.

Pina says Q11 is to be rated at 12A. So when I looked up those Apple OEM "replacements" listed in his book, I too thought he would be in error because the data I see shows them to be rated at only 7A. However, I believe Pina is simply saying that those 3 parts are "what he himself has seen in various Apple analog boards through the years," and he therefore deems them "OEM replacements." Pina then offers the Philips ECG379 part as a proper 12A replacement.

So I think going with the Philips part or similar is the most prudent choice.

http://www.moyerelectronics.com/ seems to agree that ECG379 or NTE379 (they have a sheet for this one) is the replacement. they have a nice cross reference for ecg and nte, I had been looking for one this is very helpful. I may just stick with buying a new analog board since I do not have one that will work here and if I have to order anything I may as well just get the whole analog board. I will keep looking I may have one buried.

I replaced the two 100uf 200v caps. and reinstalled Q11 then started it up and It sparked just like before but dimmed slowly. I also noted that the brightness knob on the front seemed bad and would flicker brighter and then darker as it faded slowly, I also noted that the sides were waving in and out (like water) I will replace more caps I have here and see if it gets better.

Tom, I wouldn't be surprised if Pina was in error because I've spotted other errors in his books. But for the most part, his information is quite accurate.
Pina says Q11 is to be rated at 12A. So when I looked up those Apple OEM "replacements" listed in his book, I too thought he would be in error because the data I see shows them to be rated at only 7A. However, I believe Pina is simply saying that those 3 parts are "what he himself has seen in various Apple analog boards through the years," and he therefore deems them "OEM replacements." Pina then offers the Philips ECG379 part as a proper 12A replacement.

So I think going with the Philips part or similar is the most prudent choice.

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I heartily agree that Pina is to be trusted in most matters. I suspect that he was subtly (or not so subtly) guiding the user to an upgraded part. In switchers, however, there is a tradeoff among the various parameters, and it's not always better to seek a higher-current part. In switchers, there is considerable dissipation in the transition between states, so switching speed is important. Higher-current parts can be more sluggish, and using them can actually be self-defeating. Given that Q11 seems not to have any unusual failure modes, I'd normally be inclined to leave well enough alone.

That said, it appears, from what you've found from Pina, that Apple used a variety of transistor types for Q11 (I myself have not noticed this, so thanks for letting me know), so evidently any of the ones he cites have been proven to work well.

Multimeter with transistor tester.

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Yes, but how did you use it? Did you remove the transistor first? Or did you leave the transistor in circuit? The only reliable way to test a transistor is out of circuit. If you do it in situ, the test can be confounded by other things tied to the device.

From the intermittent behavior you are reporting, it's highly unlikely to be a transistor problem. Transistors rarely "fade out" repeatedly in this manner; they either work, or die.

I removed the transistor completely and used it as the instructions say to and it had no response at all not even a blip, I used it to test a good one the day before so I know it works and its only 4 days old (the multimeter). It is odd though my board did not have a connector to the Collector or middle pin is was just in a hole on the board with no solder or leads anywhere near it so I assume it is not meant to be connected. is there a proper schematic for this analog board, that pdf shows Q11 having all 3 pins connected.

Yes, all three terminals of the transistor are used.

The middle terminal is electrically connected to the tab.

I still have lingering doubts about the test. It is very rare for a transistor to behave in the intermittent way you describe. As I mentioned, either a transistor works, or it is dead. It is extremely unusual for a transistor to go back and forth between these two states. I cannot recall ever having encountered this myself. Indeed, I can't recall even hearing about anyone else encountering such a phenomenon. Depending on the precise method used by the multimeter, it is possible to get a false result. In the case of power devices, it is frequently adequate to do the following:

1) Check for a good diode between base and emitter.

2) Check for a good diode between base and collector.

3) Verify that there is no continuity between collector and emitter.

You also mention sparking. Is this something you see, or is it something you hear?

And have you looked very carefully at C1? Is there *any* bulging on the top?

Have you carefully inspected the yoke connector? Not only should the connections on the analog board be resoldered, but you should also unmate the two connector halves and inspect all 8 of the pins for signs of arcing, melting, oxidation, etc.

Yes, all three terminals of the transistor are used.
The middle terminal is electrically connected to the tab.

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ah ok I should have figure.

I still have lingering doubts about the test. It is very rare for a transistor to behave in the intermittent way you describe. As I mentioned, either a transistor works, or it is dead. It is extremely unusual for a transistor to go back and forth between these two states. I cannot recall ever having encountered this myself. Indeed, I can't recall even hearing about anyone else encountering such a phenomenon. Depending on the precise method used by the multimeter, it is possible to get a false result. In the case of power devices, it is frequently adequate to do the following:
1) Check for a good diode between base and emitter.

2) Check for a good diode between base and collector.

3) Verify that there is no continuity between collector and emitter.

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yeah It is a cheap multimeter has worked every other time I have used it, but who knows. I will recheck it with another meter that has a diode check.

You also mention sparking. Is this something you see, or is it something you hear?

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Well its when I turn it on so I can not see it, but the other day I had it opened and discharged the crt and it was just sitting there and it sparked

around C35 C36 and Q11 area that one I saw out of the corner of my eye and I could hear it.

And have you looked very carefully at C1? Is there *any* bulging on the top?

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Yeah It looks ok I do not think I have a replacement (or 4 1uf disk caps)

Have you carefully inspected the yoke connector? Not only should the connections on the analog board be resoldered, but you should also unmate the two connector halves and inspect all 8 of the pins for signs of arcing, melting, oxidation, etc.

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is this J1 you are talking about, I did test from the solder up to the yolk for continuity and they all were ok with no resistance. (The pins are not real but are nails I used that fit snug into the other side since I do not know where J1 went after it was removed from the board a long time ago) I did not think these had enough juice to ark to other parallel pins (I assume you mean ark to the corresponding connector and not to parallel pins) I could use some electrical tape to insulate them more and see if that helps.

Also should I try to find a real replacement for the C6 I made and posted about?

Quick stupid question I am in need of C6 and its a 22uf 50v and I have 2 10uf and a 2.2uf that are 50 or higher volts will the extra 0.2uf going to be too much extra tolerance for the 512k if I install them in parellel? I can always use 2 1uf ones but I would like to put as few in there as possible and I do not want to order one capacitor online and get charged a bunch for shipping. Radioshack has them but only in 35v (they are so lame) I do not think it will be but I just wanted to check.

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I put some more caps (noticed one was a bit swollen at the top not enough to notice unless I looked real close) I had in it, took out the transistor and tested it again it was good, (even the transistor tester that said it was good worked so it must not have been connecting properly)

re did some of the solder and it turned on and seems to be stable (now I have to fix the (floppy and the brightness dail on the front) and it should be useable.

Thank you everyone that posted here to help me. I feel accomplished this week (fixed a lisa and a 512k mac) I must be stuck in the 80's.

Congrats! That must have taken quite a while...

Thank you, I am still going to get a new analog board as a backup since all these parts were donated from other machines, or made.

So that Q11 transistor was good after all?

YEAH STUPID $3 MULTIMETER, IT WORKS WELL FOR THAT MUCH.

it does seem to fade slowly still but does stay on. I have a feeling its just the brightness knob as I said above. I have some knobs from the IIc monitor maybe one will work.

Here are the rest of the things you need.

400k drive(needs to be relubricated)

Brightness knob

I actually fixed the drive today. I used silicone lubricant (the store was closed to get the lithium white lube that is suggested) but I cleaned it first (with alc.) then lubed it with the silicone cleaner/lube spray I had. I worked it in until it became mechanically sound. I also replaced the missing felt pad with one from a disk ][ drive and put it back together and read the first disk I put in it. I am going to wait on the brightness knob since I am getting a brand new analog board (along with a mouse and keyboard) and I am going to use this repaired one as a back up. I did adjust the max bright and it seems to be nice and bright (probably a bit too bright) I will adjust it later. Also I seem to be getting weird feedback from the floppy drive. It does make some cool noises though. Thanks for the links I did see the 400k drives but It seems I have fixed mine I do not know yet if the one in my lisa works but we will see when I get some disks made on my 512k. It should work great for making the disks (lisa websites state the best machines besides lisa's to make disks on are the 128k, 512k, plus since they have the 400k drive)

Are you sure you want to? The cheapest analog board on ebay now is $80.

I found a kind person to send me one for a good price with a keyboard and mouse. not nearly that much. the ones on ebay are way over priced. I was waiting for a mac plus to take one out of but a brand new one is even better.

I am getting a brand new analog board (along with a mouse and keyboard)

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"Brand new"?

Those do crop up on EBAY about once a year. I know because I purchased such an Apple Service part, never used before, on EBAY in the past. But they are rare. And I must say that I was simply "blessed" the day I bid on it as others clearly did not spot that auction. If they had, I certainly would have been outbid. I only paid $35 for it. But it cost me another $35 to ship to Japan.

But if you mean you are buying a "used, but good condition" analog board, you still have to beware. Because any "used" board technically could have been "abused" as well. In such a case, your situation would not be different from now, and you would still need to replace some parts. At minimum, C1 needs to be replaced on many boards.

no it was a sealed service part (had to take it out of the box to fit in the shipping one with the keyboard) I told him I would feel bad using it but I got such a good deal I could not say no and he said he just wanted it to go somewhere where it would get used.

After you replace the analog board, you should use your HD 20 and a 800k drive for a nice setup!

I have two 3rd party 800 drives and a numeric pad that I am going to put with it too. I just need to get some files on to the HD20 for making my lisa disks, the first way I tried did not work so I will have to try some others.

the new board showed up today and worked great. (I have to adjust the image a bit) I also had to shorten the mouse cable about 5 inched because of a break inside cause one of the axis not to work but now it works great. now I need to figure out how to get me disks made on one of my other macs.

Now tell me, who could have caused so much damage to your Lisa and 512k? Seems like the old owners were sadistic Windows fans or something.

well the lisa I found in a pile of free stuff one day, very lucky I may add, with some kind of sticky pop residue ALL over it, still the faint spackle of silver paint on part of it (the place I got it was used by this guy here who has a van covered with circuit boards that is probably where the Memory and Cpu boards went). the 512k was acting up and that was my fault that the analog board got stuff picked off of it. but I set it right and fixed it whats the best way to adjust the picture, is it ok to do it while it is turned on, and how should I prop it up without the case?

finally got the HD-20 to boot (Had to dig for some Low D disks for the 512k) I am going to be asking in the trading post about some new 400k disks for the 512k and lisa.

You'll be hard pressed to find 400k disks. But 800k are all you need. Just format them as 400k, since you only need 1 side of the disk. And the nice part is, should you every want to reformat them as 800k, it's a snap! You can also use 720k PC disks, if you can find them.

I figured I could use 800k disks but I was also told (in the trading post) I can use HD disks? I did not think that was possible.

You were told wrong. You cannot use HD disks.

JDW is correct -- using an HD disk is a bad idea. HD and DD media are just barely different enough to cause unreliable operation. Things get a bit better if the media have been bulk-erased (or otherwise made equivalent to a virgin floppy, not merely a reformatted one), but it's still best to avoid the trick altogether, except in emergencies, perhaps.

o you know what I have a bulk tape eraser, I was thinking of using it to see if it would revive some of my dead disks (400/800k ones) I am glad I thought the disks were different and then people told me they were not and it made it all confused.

o you know what I have a bulk tape eraser, I was thinking of using it to see if it would revive some of my dead disks (400/800k ones) I am glad I thought the disks were different and then people told me they were not and it made it all confused.

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It can get confusing, indeed, especially since not all of the information on the web is correct. Here's a quick summary:

Mac 400K/800K floppies are the same, magnetically speaking, as PC 720K floppies. The only difference is in the formatting.

400K floppies are written on one side only. Both sides are used in 800K floppies.

Mac 1.4M floppies are the same as PC 1.4M (HD) floppies. These disks have an extra hole to identify the media as HD.

Some people used to drill/melt an extra hole in 720K/800K floppies to turn them into 1.4M floppies. Reliability is poor.

Some other people have put tape over the hole in 1.4M floppies in an effort to convert them into 720K/800K floppies. Again, reliability is poor, although using a bulk eraser prior to formatting can improve performance (sometimes markedly so). It's still best simply to use true 720K floppies. Although many stores no longer carry them, they can still be obtained from a variety of online sources, so there's no compelling reason to use unreliable "conversion" methods.

although I can not seem to run disk copy from the 512k I have some 400k and 800k disks that do not format I will try the bulk eraser on them and see if they are useable.