Mac SE/30 board no chime or video

[iamtheSpicer]

I have been working on a stray SE/30 board I have had laying around for a while. It's had some clock battery damage and capacitor leakage unsurprisingly. I heavily cleaned it up as best I could, and also recapped it (not very well...). I've tried testing it in my fully working SE FDHD system, which boots and runs System 6 great on its regular SE board. I used the known good RAM out of my SE and used the ROM SIMM that came with the SE/30 board. However, on the SE/30 board, I get no chime, and no video output. The reset function does work.
On the board itself, I noticed that the diode D1 is missing, D2 doesn't look very good, and Oscillator Y1 is missing. Not sure how that happened, but would that cause that severe of an issue?
This board is in pretty bad shape as you can see, so I'm not super sure where to go with trying to get this working, or if it is even realistically possible. Guess next steps would be to pick up a scope...

 

[GreenBar0n]

A scope is always nice to have, but a microscope/magnifying light might be better. I noticed your row of U-chips is pretty corroded, specifically UE8, and UF8. There's probably more corrosion elsewhere, but zooming in you can see the rotted pins/traces, with just a camera phone and the zoom feature.

An inexpensive desk magnifier lamp is easy to get, and makes all the difference for tracking down these issues, visually.
https://www.walmart.com/browse/home/magnifying-desk-lamps/4044_133012_133113_4887881_6171890_4536080

I noticed you still have electrolytic SMD caps, instead of the tantalum, in some spots.


Did you verify that your new caps have continuity to the board, with a DMM?

 

[croissantking]

I noticed you still have electrolytic SMD caps, instead of the tantalum, in some spots.

K768 caps are aluminium polymers. (Link to datasheet)

 

[croissantking]

@iamtheSpicer Not that it would prevent you seeing/hearing things, but I see you have only two sticks of RAM in the board. I don’t know your level of expertise so don’t be offended at the question, but… just checking that you’re aware you need sets of 4 matched SIMMs, 120ns or faster.

 

[finkmac]

as far as soldering goes... you need to use more flux and probably more heat. I like MG Chemicals 8341 flux.

 

[iamtheSpicer]

@iamtheSpicer Not that it would prevent you seeing/hearing things, but I see you have only two sticks of RAM in the board. I don’t know your level of expertise so don’t be offended at the question, but… just checking that you’re aware you need sets of 4 matched SIMMs, 120ns or faster.

Don't worry, I'm almost clueless with the SE/30 (I'm decent with SGIs and G3 and G4 era Macs!) and just getting together learning how to solder. That was very silly of me to not think of that kind of thing! Does having not sufficient RAM prevent it from even booting far enough to do a Simasimac pattern or Sad Mac?
I fixed up my soldering and tried my best to clear some more gunk / corrosion off, as well as installing that missing oscillator for what it's worth.

 

[iamtheSpicer]

Tested it with a full bank of 4 from my Mac llvx / Performa 600 board...no change

 

[finkmac]

a lack of ram won't prevent a picture from showing.

does your CRT tube actually work? check the neck for a glow with power applied.
if your analog board/tube is working, then there's something wrong with the video generation circuitry.
the video circuit will work without a working/running CPU.. so if you aren't seeing the simasimac pattern or the pixelated noise pattern it means something is wrong there.

if you're curious, the simasimac pattern is just the initial value of a particular brand of video dram. the other pattern is the initial value of the other brand. I can't remember the companies... fujitsu and TI?
a lot of things can cause it but the biggest culprit is the ROM/CPU connection.

as @GreenBar0n said, check the UXX ICs. UE8 and UF8 tend to be hit hard by leaking capacitor fluid.

in your picture they look real bad. check continuity to each pin, consider removing them and replacing completely.
i had a machine with no picture, replacing UE8 brought it back.



looking over the image again, I realize the PRAM battery is missing and I see a lot of evidence of battery damage .

The ROM SIMM area is likely to be an issue once you get the video back.

check continuity between the ROM pins and the CPU.

 

[croissantking]

I can't remember the companies... fujitsu and TI?

I’ve seen TI, NEC, Hitachi and Micron chips on stock SE/30 boards. Each has a unique default pattern. TI seem to be the most common, followed by NEC. I’ve not seen Fujitsu yet.