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Macintosh SE/30 logicboard recreation (thread revival)
Posted by: croissantking on 2023-01-16 06:09:50
Thanks guys, it's a great feeling to get it sorted. The next board is going to be fully socketed, it will seriously aid in troubshooting I'm thinking.
Posted by: Cam on 2023-01-20 19:18:25
AAAHHHHHH!

So I've got almost everything desoldered from the sacrificial SE/30 board and moved over to the new board, sounds good right?
I just desoldered the PDS connector and of course ONE bloody pin snaps!
Looking at the schematics it seems pins 1, 2, and 41 aren't connected to anything, and so open to repositioning?

Can anyone confirm or correct me please?
Posted by: mdeverhart on 2023-01-20 21:41:58
Here’s the pin out of the SE/30 PDS slot, if that helps.

1674279715778.png
Posted by: croissantking on 2023-01-21 04:04:34
@Cam looks like you’re safe!
Posted by: Cam on 2023-01-21 15:01:55
Thanks.
I feel kinda stupid now that I think about it. I have the Gerber files, all I really need to do was find a viewer and take a look at the traces on the connector . . .
Posted by: croissantking on 2023-01-26 17:05:57
349AA18A-A7C3-4D62-97AA-EDF5AA06D39E.jpeg
My second board is coming along great. I’ve gone for PLCC sockets for ease of diagnosing bad chips. I thought I’d find them ugly, but I’m actually really pleased!
Posted by: Cam on 2023-01-26 18:17:22
My second board is coming along great. I’ve gone for PLCC sockets for ease of diagnosing bad chips. I thought I’d find them ugly, but I’m actually really pleased!
Looking real good!
Posted by: daanvdl on 2023-01-27 08:53:32
View attachment 51637
My second board is coming along great. I’ve gone for PLCC sockets for ease of diagnosing bad chips. I thought I’d find them ugly, but I’m actually really pleased!
Very Nice! Where did you find the sockets for the 2 VRAM chips?
Posted by: croissantking on 2023-01-27 09:12:25
Very Nice! Where did you find the sockets for the 2 VRAM chips?
From Mouser:


Are they hard to find?
Posted by: Cam on 2023-01-27 10:39:10
I ended up cutting the mid socket supports out of a socket I had on hand, but was to narrow.
Posted by: croissantking on 2023-01-27 10:50:54
I ended up cutting the mid socket supports out of a socket I had on hand, but was to narrow.
But your solution is just as good. Is there any advantage to gold contacts on those?
Posted by: Cam on 2023-01-27 11:16:10
But your solution is just as good. Is there any advantage to gold contacts on those?
I was just what I had in my spare parts bin. Probably bought the socket because it was available when I needed one for a past project and it was all that was available. The only advantage of gold contacts (if they are gold plated), is that gold doesn't corrode.
Posted by: croissantking on 2023-01-28 15:10:22
65C5B323-47EC-42EE-BEA6-6FC887F7BC84.jpeg
Boom. Board 2 up and running.

Initially it did not start (slow chimes of death) and I thought I was going crazy, but after cursing to myself I had a closer look at the board and I eventually realised I’d missed a few legs of some of the Bourns resistor networks near the RAM. I’m trying not to be hard on myself as I expect a higher standard of workmanship from myself, but these builds are so much work!
Posted by: Cam on 2023-01-28 17:29:24
Wow - two reloaded boards done!
I'm torn between being super impressed and jealous that you had two donor boards to work from.

🙂
Posted by: croissantking on 2023-01-28 18:17:33
@Cam thank you! How many have you built, and how did it go for you? I think I’ve seen a bit of your YouTube content.

Board 2 has a graphical issue - based on the attached video does anyone know offhand which chip is likely to be the culprit before I start blindly swapping?

View attachment IMG_9168.MOV
Posted by: Garrett B on 2023-01-28 19:47:08
@Cam thank you! How many have you built, and how did it go for you? I think I’ve seen a bit of your YouTube content.

Board 2 has a graphical issue - based on the attached video does anyone know offhand which chip is likely to be the culprit before I start blindly swapping?

View attachment 51696
Whoa! My board has exactly the same problem. Question- are you using an ATX power cable extender to run the board out of the chassis? Are the symptoms the same after it has been running a bit? I have some theories but nothing solid yet.
Posted by: Bolle on 2023-01-29 01:23:35
anyone know offhand which chip is likely to be the culprit before I start blindly swapping?
What kind of VRAM are you using on the board that does this? I think I have seen something similar and swapping the VRAM for a set of chips with faster access time solved it. Surprisingly the chips I used at first came off a donor SE/30 board so they should have been good…
Posted by: croissantking on 2023-01-29 01:50:43
Whoa! My board has exactly the same problem. Question- are you using an ATX power cable extender to run the board out of the chassis? Are the symptoms the same after it has been running a bit? I have some theories but nothing solid yet.
Yes, I’m using an ATX extender, and yes, the graphical glitches start after a few minutes. What are your theories?

@Bolle The VRAM chips are TMS4461-12NL. I have some 100ns VRAM on a different donor board that I will try, then, thanks for your suggestion.

If it makes any difference, UG8 - UA8 are brand new chips.
Posted by: Cam on 2023-01-29 08:22:38
@Cam thank you! How many have you built, and how did it go for you? I think I’ve seen a bit of your YouTube content.

Board 2 has a graphical issue - based on the attached video does anyone know offhand which chip is likely to be the culprit before I start blindly swapping?

Nah I'm not on Youtube - I 've got a face for radio, and a voice for print LoL!
I'm just finishing up my first SE/30 reloaded board (waiting on a new CPU, praying the RTC works), but I've resurrected an SE and a Color Classic.

My first thought was VRAM as Bolle suggested as it seems to repeat in a pattern. If it happened sporadically I'd have said its more likely an analog source - loose wire, bad connection, that kind of thing.
Posted by: croissantking on 2023-01-29 13:24:30
My first thought was VRAM as Bolle suggested as it seems to repeat in a pattern. If it happened sporadically I'd have said its more likely an analog source - loose wire, bad connection, that kind of thing.
I’ve replaced the VRAM with different (faster) chips and the problem is still there.

It takes a few minutes to manifest and gets gradually worse. The artefacts are only visible when the image on screen is changing, if nothing is happening it is stable.
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