SE/30 Simasimac persists after recap

[Riilu]

I tested all the connections, i saw go from ROM simm slot to the chips on the card itself and i could trace everything back to a pin somewhere and test (couldn't test some things because the traces disappeared in under the chips and i didn't know where it would go), I feel so lost right now, literally no idea what to do next. Wash it again and hope for the best?

 

[Bolle]

Take things step by step. I was pretty lost as well on my first SE/30 but things start to make sense the more you stare at it and poke around

Next thing would be to check the connections of all address and data lines between the CPU and the ROM SIMM.

As said, schematics for the SE/30 are floating around the web and can easily be found.

 

[Riilu]

I tested all the pins coming from the SIMM socket to all it's corresponding connections, Data 0-31, Adress 2-22, "rom" line to the "glue chip" +5v and ground, there's continuity on all of them. Do you think it's possible the ROM i have is just bad?

 

[techknight]

Next thing is to bring out the oscilloscope. 

With the ROM SIMM removed, the CPU should walk the bus and the transitions should be a full swing from 0-5-0v. 

if this is good, with the ROM SIMM inserted you need to check again. I have ran into 1 case where the CPU was bad and once the ROM was inserted, the state transitions couldnt make it to a full 5V. they ended at around 2 to 3V. 

replacing the CPU fixed it. 

So we need to rule that out next. 

Last but not least, check all Data bus and Address bus traces against each other, I have seen 2 instances where the data bus and address bus got shorted together via a hard to find solder blob. 

 

[Riilu]

Sadly, I do not have an oscilloscope, or the money to buy an oscilloscope, so I cannot test for that. but I'll see if i can find any shorts between traces.

 

[Bolle]

You can still partly do that test if your multimeter can do frequency measurements.

You can probe all the address lines and the outputs on the RAM muxes that way. You won‘t see if it is doing full 0V-5V-0V swings on all address lines that way though but you might be able to see on the higher bits with the multimeter in voltage setting.

 

[Riilu]

Sorry, my multimeter is complete crap, it doesn't even do capacitance test, it only does voltage and resistance test, and it updates at a rather low frequency,so i dont think it's going to be useful. I'll just wash the board again and hope in the slim chance i missed some electrolyte that's been causing shorts

 

[Riilu]

After washing the board, and rinsing it again, after it had dried for a while, weird white spots had appearad around some of the caps, now all of the caps i installed were brand new, installed with the right polarity, and the water i used was just warm, but not hot tap water and dish washing soap, it seemed to center around capacitors, could this have been old electrolyte that i missed getting off the first time, or is it from my fresh installed caps? I rubbed some off with a finger and it didn't smell fishy. Anyway it came off easily with a Q-tip and denaturated ethanol. Could be flux from my sloppy soldering job

https://imgur.com/a/xkjCy7b

 

[Riilu]

Drying it in front of a space heater for a few hours (very effective, heats the entire board up, so there was no water at all left), tried it again, no dice. Seems this board is just no good. Poo, guess i can sell for spare parts since i wont be able to afford anything to test the damn thing with in many months.

 

[techknight]

Ship it to Bolle, he would be the closest to you that could possibly fix it. 

 

[Riilu]

How much would such a fix cost, including shipping? @Bolle

 

[Riilu]

Yo, I just went to double check the voltages, the +12 volt going to the motherboard was 9.20-ish volts, could this be the cause? -12v is around where it should be though

 

[bibilit]

Probably...

 

[Riilu]

would it be safe to throw the SE/30 board over into my Classic II? I think the power connectors are the same, but I just want to be sure so i dont mess things up even worse

 

[CC_333]

I once posed that same question, and while it may theoretically be possible, the pinouts are likely different, and you risk blowing up the Classic II's power supply, the SE/30 board, or both if you don't rig up some sort of adapter.

Probably best to try another SE/30 power supply (one from a plain SE should work too, as they're the same part).

c

 

[Riilu]

Well then, I don't think I can get just the supply without buying a whole functioning SE or SE/30 where I live, so i'm probably better off inspecting the analog board on the SE/30 tomorrow and look for any bulged or leaking capacitors, might as well take out the CRT and retrobright the thing, it's a bit yellowed. Yes I will discharge the CRT and handle the analog board like it's a bomb

 

[Riilu]

Cant really spot any bulging or leaking capacitors, anyone have any suggestions? https://imgur.com/a/63OqN3r

 

[Riilu]

So there's this brown stuff around a lot of the solder joints on the PSU board https://imgur.com/a/2peDcek

I think it's best i replace the PSU entirely like this http://bylenga.ddns.net/index2.php?page=SE_ATX.php

 

[mjhagen]

I think that's just flux.

 

[Riilu]

Hello, finally got around to doing the modification, great news, i have startup sound, bad news, it's the death chime. And there are still horizontal bars on the screen. Any ideas of what is next to do?