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avatar_Blurredman

Which is bank 0 and which is bank 1 on 6128?

Started by Blurredman, 12:16, 21 January 19

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Blurredman


Bryce

Check the continuity between each data and signal pin to the next point they should be connected to.

Bryce.

Blurredman

I've done as much as I could do given my lack of expertise.

Bryce.. Is it alright if I send you a PM to post this board to you, as well as the other I was having an issue with on a different post?

Bryce


Bryce

Hi Blurredman,
     had a few minutes free and took a quick look at the first CPC you sent me. The one with Bank 1 not working. Looks like the RAMs weren't all good, although you said you had somehow checked them. One was bad and after swapping in a good one Bank 1 now works. Should I leave the replacement (good) RAM in it, or do you have further spares yourself?

I still have 15 minutes before "Bedtime story" with my son, so I might take a look at the other board now... :)

Bryce.


Bryce

Just took a look at CPC 2. The one that turns off after a few seconds. It's turning off because the PSU can't handle the load. Keeping it forced on with a constant current limited supply, the voltage drops to 2V and almost every RAM IC on bank 0 gets to a temperature that you could fry an egg on. Did this computer suffer an over-voltage? Or do you know its history?
Looks like the entire bank needs to be swapped out, but I don't have time tonight. I'll get back to it tomorrow if possible.

Bryce.

Blurredman

Bryce.

Thank you for looking at these.


IE board 1... Strange.. Yes.. I tested all my chips on a socketed CPC..  Just throw the bad chip away and leave the socket open.  :-*



Board 2 - I have no history at all on this board.

If you want. You can just put open sockets on the first bank to see if it will boot up? Then simply test with chips you have available? If the problem is chips I have a large excess of RAM chips so don't need them. Obviously, replacing said chips with sockets and your own test chips may open up other problems however..

Bryce

Ok. I'll isolate the known shorted RAMs and see if it boots to the grey screen with border, which would show me whether the rest of the board is good. If it passes that test I'll socket bank 0 and try it with some spare RAMs. After posting last night, I noticed that the main electrolytic cap is getting hot, so I'll swap that first and see what changes.

Strangely, one of the RAMs in Bank 0 stays completely cold which either means it's good or completely fried open circuit, but I can test that too before removing it.


Bryce.

Bryce

So unfortunately we've come to the question I never like asking: How badly do you want this 6128 fixed? It's definitely had a bad over-voltage or reversed polarity. Almost every chip on the board is fried. Unless this is the board your favourite Grandfather gave to you for your birthday shortly before being run over by a bus and has serious sentimental value, then I'd leave it. Fixable yes, but at a crazy cost.

Bryce.

Blurredman

That's unfortunate..

:(

Give me a PM of payment details and for my address. I guess...., send them both back. I can at least make use of the board for scroungy bits.. :(

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