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luRaichu’s 68k spelunking
Posted by: luRaichu on 2024-10-22 10:06:34 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.
Posted by: luRaichu on 2024-10-29 15:46:35 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
Posted by: finkmac on 2024-10-29 17:26:32 use this digikey list. better to use polymer than improperly derated tantalum
Posted by: olePigeon on 2024-10-29 17:41:26 @finkmac Würth. The affordable quality cap. My favorite brand. Too bad they don't make axials.
Posted by: finkmac on 2024-10-29 17:48:16 Yeah it's unfortunate. Fewer and fewer companies making axials... red capacitor is automatically cool though
Posted by: luRaichu on 2024-11-26 12:34:55 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.
Posted by: luRaichu on 2024-11-26 12:58:19 Whoops, I realised the sound it makes IS the full death chime. I was used to the LC's 😅
Posted by: luRaichu on 2024-11-26 13:49:15 Attached are photos of the logic board and memory SIMMs I used.
Posted by: finkmac on 2024-11-26 18:06:28 I really hope you didn't top solder these death chime without a video card is normal
Posted by: luRaichu on 2024-11-27 08:07:13 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.
Posted by: luRaichu on 2024-11-30 10:06:10 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.
Posted by: finkmac on 2024-11-30 10:28:31 try filling a single bank with 4x the same sort of simm
Posted by: luRaichu on 2024-11-30 10:29:49 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
Posted by: luRaichu on 2024-11-30 10:35:06 Ok it works now. RAM was the problem!
Posted by: luRaichu on 2024-12-02 11:23:13 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 😊
Posted by: luRaichu on 2025-05-04 16:08:54 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
Posted by: nathall on 2025-05-04 20:32:43 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.
Posted by: finkmac on 2025-05-05 11:29:35 bomarc schematics here.
Posted by: croissantking on 2025-06-30 00:57:38 649. 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.
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