[fixed] CT2760 - Busted SIMM socket repair, but something went very wrong... Help? \ VOGONS

[fixed] CT2760 - Busted SIMM socket repair, but something went very wrong... Help?

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First post, by Jed118

Posted on 2022-02-03, 00:04

Jed118 Offline

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So today I decided to replace the very broken SIMM sockets in my AWE 32 (I had already replaced three ripped out caps and a mangled joystick port - this card has been through hell) and I mostly succeeded, burning only 2 traces (which I bodged, no biggie, they were going from bank 0 to bank 1 on the same pins) BUT the biggest problem is pin 26 - in removing the solder, I had a lot of trouble, and it seems I removed the pad entirely. There's nothing for the solder to hold onto, the pin is just in the hole.

Before

After

Here's the problem, maybe:

Pin 26 is burned out, but the other pin 26 up top is OK. I ran a multimeter to check continuity from the top one, and it doesn't go anywhere at all on the board (I tried most of the close by ICs) - most of the other pins do register some kind of continuity. On a SIMM itself, pin 26 goes to a chip:

However:

It says Pin 26, 28, and 29 ar enot connected on non-parity SIMMS.

Can someone confirm that Pin 26 doesn't connect to anything on this AWE, or at least doesn't use parity? I may have just gotten very lucky if so!

(Edit - actually, in documenting what I'm doing, I decided to check pins 28 and 29, and they are also unused (no continuity anywhere) . Nothing to do now except plug it in and do some testing with the RAM, something I'd have to read up on as I've never loaded sound fonts before)

Last edited by Jed118 on 2022-02-03, 03:03. Edited 1 time in total.

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Reply 1 of 3, by BitWrangler

Posted on 2022-02-03, 00:47

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The reason why you might have had trouble is if it was taken to the bigass groundplane in the middle layer of the board... meaning all the heat sucking out of it.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 2 of 3, by snufkin

Posted on 2022-02-03, 01:00

snufkin Offline

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Had a look on a CT1920 AWE32 add-on. I'm not going to take off the simm holders, but I can see the traces for pin 30 and 27, and can't see any traces for pin 26. So should be ok I think.

Reply 3 of 3, by Jed118

Posted on 2022-02-03, 03:01

Jed118 Offline

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Rank: Oldbie
Posts: 1012
Joined: 2015-02-03, 17:15
Location: Simcoe County

BitWrangler wrote on 2022-02-03, 00:47:

The reason why you might have had trouble is if it was taken to the bigass groundplane in the middle layer of the board... meaning all the heat sucking out of it.

That had crossed my mind... 😐

snufkin wrote on 2022-02-03, 01:00:

Had a look on a CT1920 AWE32 add-on. I'm not going to take off the simm holders, but I can see the traces for pin 30 and 27, and can't see any traces for pin 26. So should be ok I think.

Thank you for your confirmation, it gave me the push to take it to the next step: I decided to insert the card into the BL and give it a DIAGNOSE.EXE run through - and all the sound tests and internal memory works.

Then I found some non parity 4Mb SIMMS (2 of em) and plopped them in, and moved the jumper to External DRAM:

It picked it up!

And it passed!!

Looks like I got lucky with that Pin 26 Pad, and the bodges are working. Good stuff!!

Now I have the unenviable task of figuring which resources are in conflict between the AWE and the 1520C - jumpers and switches.... But after that, I should be able to put the cover on my Blue Lightning and finally start using it (after about 3-4 years 🤣)

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