Troubleshooting SE/30 garbled screen, no chime before and after recap

[reallyrandy]

Any ideas?
I didn't replace the axials because they still look good.
I have a working SE, can I put the SE/30 board in the SE to see if it works there? Are they interchangeable?

 

[Nixontheknight]

SE/30 boards and SE boards are interchangeable I believe, just like the boards between the Classic and Classic II are

 

[Volvo242GT]

Yup. Just swap it into the SE and see if it works there. One thing to check on the SE/30 is the harness between the analog board and the logic board. I've found that my SE has some issues with the harness, verified by flipping it around, so the plug that was connected to the analog board is now connected to the logic board and vice versa. If I move the harness around, with the bucket off, I can cause the computer to either checkerboard or boot with the power supply turned on.

 

[Elemenoh]

Swapping it into the SE is not going to help. A few things to try:
Try one bank of RAM at a time in bank A.
Clean the contacts on the ROM.
But most likely this is due to a broken trace to/from the ROM or RAM or bad / dirty video mux. UE8 (74F253) is a common failure point due to its proximity to C7.

If you have access to an ultrasonic cleaner, try cleaning it in that, especially around the muxes. If not, give it a very very good scrub with a toothbrush and 99% IPA.

You can use these schematics and cheat sheet in this PDF to help with your troubleshooting.

Lastly, some of the solder joints on your new caps could use a little love. C5 for instance looks not well adhered. Try applying some flux and reflowing anything that looks like that. It probably won't solve your issue, but will make your caps tidier and more reliable.

Good luck!

 

[reallyrandy]

I swapped out 4 different sets of RAM in bank A and also swapped out the ROM with my ROMinator and got the same problem. The Dead Mac Scrolls says check the ROM chip but that can't be it since the ROMinator shows the same problem. I do get a flashing "?" with the original ROM since the SCSI and floppy aren't plugged in. When the ROMinator is in there I get no flashing "?" as expected.
So, maybe the UE8 chip? It does look a little corroded and the painted numbers are missing. Could I just remove it and clean it and solder it back on? Where would I get another UD8, UE8 and UF8 chip if I had to?

I'm not all that experienced in component level hardware so please forgive my noobness!

 

[Elemenoh]

It does look a little corroded and the painted numbers are missing. Could I just remove it and clean it and solder it back on? Where would I get another UD8, UE8 and UF8 chip if I had to?

I think the fact that you're seeing a garbled flashing ? is another indicator that your issue may just be with the muxes. Yes, remove with hot air, clean underneath with IPA, scrub the pads with solder wick/fresh solder and reinstall (using lots of flux). If that doesn't help you can find replacements on DigiKey, Mouser etc.

If you're lucky, it's just a dirty or bad IC, but you may have to deal with that and/or hunting down broken traces.

Bruce probably has a bunch of videos covering the procedure.
@Branchus do you have a link handy of you removing and cleaning under those chips?

 

[Elemenoh]

Also, this trace is looking questionable. Refer to @Branchus 's videos for how to scrape it down, check and repair it if needed.

Lastly, the ROMinator tends to not make good contact with the pins on the SE/30. I wouldn't rely on testing with it unless you have an ATX extension to test with the board out of the system and are holding the ROMinator in place to ensure contact. You can get/make 3D printed hold down clips for it too.

 

[reallyrandy]

I guess if I'm going to spend the effort of removing UE8, UF8 and UG8 and scrubbing the board underneath, I should just put new ones on instead of cleaning and re-installing the old ones. The link you have is for UE8, right? it is stamped TIF291CS LS166A.
"If that doesn't help you can find replacements on DigiKey, Mouser etc."

UF8 and UG8 are stamped TIF149BS LS393. These would be different parts I'm assuming?
It's only a few dollars so I might as well just order everything up front.

Edited to add: How do you know which new part replaces which old part? The Digikey SN74F253DR part page has no mention of the stamp on the SE/30 part (TIF291CS LS166A). So if I wanted to find replacements for SE/30 parts stamped "TIF149BS LS393" how would I know what Digikey part to buy?

I know very little about component level electronics but I really want to get this working. I've already restored my 128k, 512k, Plus and SE. Then I'll have every model from the Lisa 2/10 to the SE/30 restored. After this it's the IIci and then recapping the 2 LCIIs. Then on to the Mac II with the Radius Rocket. I have some 5300s and clamshells I'll restore after that. Whew!

 

[rikerjoe]

About a year ago I undertook the same repair on my SE/30 using chips purchased from Digikey. Here are the ones I ordered:
Texas Instruments / SN74LS166AD
Texas Instruments / SN74LS393D

I’m at work and thus don’t have my board in front of me to tell you which chip went in which location, but I’m sure you can match the above with the chips on your board. Good luck!

 

[Elemenoh]

UF8 and UG8 are stamped TIF149BS LS393. These would be different parts I'm assuming?

I was off by one silkscreen looking at your photo.

UA8, UB8, UC8,UD8 are SN74F253
UE8 is SN74LS166
UF8, UG8 are SN74LS393

 

[caver01]

I can confirm ordering the same parts as rikerjoe above for my SE/30 from Mouser, and in addition, I ordered
Texas Instruments / SN74F253DR
I tried to find a picture of the board post-fix, but I don’t think I took one. I replaced the whole column of chips, possibly overkill, but it allowed me to make sure it was absolutely clean underneath. UE8 made the difference for mine I think, as I was getting similar vertical ”chain” patterns. Once I had a more “conventional” simasimac pattern I realized I had to reseat the ROM. In all of my troubleshooting, taking RAM in and out, removing the ROM SIMM, I just wasn’t getting good contact.

I will add that the above steps came after a hard-fought battle armed with a multi-meter and schematics. I had already continuity-checked every single trace between those chips and other destinations (ROM, CPU, GLU VIA etc. etc. etc.). Once you get the hang of it, you can move through them pretty easily, but it takes some heads-down time to buzz the traces.

Finally, I will share that I used ChipQuik de-soldering alloy to easily remove these chips. This was very handy for me. I have a good iron, but not hot air, heated plate or anything like that. ChipQuik melts at a lower temp and stays molten so you can grab the component. Basically, you lay down a bunch of flux and run a bead of the stuff across the pins at the same time. You then need to do some cleanup, but you can also re-use the alloy blobs on the next component. It will eventually gather the actual solder and become less effective, but for me, I was able to use mostly the same blobs of the stuff for the whole job and again for something else—a little goes a long way.

 

[reallyrandy]

I do have hot air but i might wanna try some ChipQuick anyway. it looks really easy and doesn't heat up nearby components.

 

[reallyrandy]

Ordered. Wish me luck!

 

[Elemenoh]

It looks like you only ordered 1x SN74F253 but there are 4 on the board.

 

[reallyrandy]

Ya, I realized that after the order was placed

 

[reallyrandy]

Testing the 470µF 16V Axial cap at C2 gives me .511 while testing a brand new 470µF 25V gives me .458.
I usually don't replace the axials because they rarely ever leak. Knowing very little about caps, what do these numbers mean? What should be the tolerance on a 470? is .511 OK? Is 458 OK? Am I measuring correctly?
Please advise.

The enameled wire is for fixing a lifted pad on UF8.

 

[Elemenoh]

.511mF (millifarad) = 511uF (microfarad)

All capacitors have a tolerance. These are probably 20%. For a 470uF capacitor that'd mean 376uF—564uF would be considered OK.

Capacitance isn't the only measure of capacitor health though. Ideally you'd be able to check ESR, dissipation factor etc. It's an old capacitor and cheap to replace. IMO you should replace them so you won't have to worry about them again for a very long time.

 

[Branchus]

Testing the 470µF 16V Axial cap at C2 gives me .511 while testing a brand new 470µF 25V gives me .458.
I usually don't replace the axials because they rarely ever leak. Knowing very little about caps, what do these numbers mean? What should be the tolerance on a 470? is .511 OK? Is 458 OK? Am I measuring correctly?
Please advise.

In order to get an accurate measurement of a capacitor, it can't be tested in-circuit. It needs to be removed from the board first. However, I can say with a fair degree of certainty that those axial caps are not the problem.

I agree with @Elemenoh that replacing those Ux8 chips on the board is the best course of action at this stage.

 

[YMK]

I'd check the lower address lines of the video mux section.

Based on what I can see of the floppy icon, I'd say UE8 is fine and video data is ending up in, or being retrieved from, the wrong place in VRAM.

 

[pfuentes69]

What is worrying is that there's no chime.
I had to replace several of those chips on my SE/30 because the cap juice damaged it, but I always had chime. I'm curious to see the outcome of this repair.