luRaichu’s 68k spelunking

[luRaichu]

I bought a Delta SMP-120EB for cheap on eBay auctions. Now I'm looking for a NuBus video card that can do 24-bit color.

 

[luRaichu]

PSU is here now. Works fine except -12V rail is actually -9V. I wouldn’t expect the voltages to be regulated properly with no load though!

Are these tantalum caps ok for the logic board? https://www.digikey.com/en/mylists/list/JCN214DW84

 

[finkmac]

use this digikey list. better to use polymer than improperly derated tantalum

 

[olePigeon]

@finkmac Würth. The affordable quality cap. My favorite brand. Too bad they don't make axials.

 

[finkmac]

Yeah it's unfortunate. Fewer and fewer companies making axials...

red capacitor is automatically cool though

 

[luRaichu]

Just recapped the IIcx logic board. It starts up, plays part of the startup chime and then makes the death chime. Any clues? I don't have a NuBus video card attached yet.
Will grab pictures & an audio recording if they are needed.

 

[luRaichu]

Whoops, I realised the sound it makes IS the full death chime. I was used to the LC's

 

[luRaichu]

Attached are photos of the logic board and memory SIMMs I used.

 

[finkmac]

I really hope you didn't top solder these


death chime without a video card is normal

 

[luRaichu]

View attachment 80761
I really hope you didn't top solder these


death chime without a video card is normal

No, of course I did through-hole. I'm sure they'd break off fast if they were only connected on the surface!
I have a Radius PrecisionColor 8-24X coming soon (totally not flexing!!). We'll see if the logic board works then.

 

[luRaichu]

NuBus card arrived, I plugged it in and still get the death chime. I don't know if the problem lies with the card or the logic board. I feel the chips getting warm on the card though so it must be doing something. Also, I haven't tested the power supply under load yet. Will do next.
I read similar threads on this forum and a bad ROM could possibly be the culprit too.
Or bad RAM. Is it okay to leave bank B empty? Just for testing.

 

[finkmac]

try filling a single bank with 4x the same sort of simm

 

[luRaichu]

try filling a single bank with 4x the same sort of simm

Yeah that's what I did on bank A. Let's try bank B now

 

[luRaichu]

Ok it works now. RAM was the problem!

 

[luRaichu]

I narrowed down the RAM issue to a single bad SIMM. It was the one marked NMBS at the bottom of the picture with a serial no. ending with 649. The four NMBS SIMMs are oddly 2304K each - or 2MB + an extra 256K. I wouldn't bother doing surgery on a single SIMM.
Where can I get new SIMMs on the cheap? They're all pretty generic

View attachment 80761
I really hope you didn't top solder these


death chime without a video card is normal

I tested this and found the IIcx will start up properly without any NuBus cards installed. Not sure where you got that info

 

[luRaichu]

I've been using the IIcx without a PRAM battery up until now. After installation it still won't remember any of my settings. Why?
I did try zapping PRAM but of course that'd never help

 

[nathall]

I don’t know why, but my IIsi is like this too. Remembers everything until you unplug it, battery installed or not. Fully recapped, I imagine the old caps must’ve eaten through a trace somewhere crucial to the battery. Since the machine is 100% functional otherwise and usually remains plugged in all the time, I just pulled the battery and called it a day.

 

[finkmac]

bomarc schematics here.

 

[croissantking]

649. The four NMBS SIMMs are oddly 2304K each - or 2MB + an extra 256K.

They’re parity modules but the IIcx will ignore the extra chip. So you could replace the dead module with a normal one and it would work fine.