exxos's Atari, Amiga & retro forum

Bikerbob wrote: 02 Nov 2021 15:41 So, start at the CPU I am guessing because we thought originally issues might have started there??

A logical start. Normally something like 3 seconds spray is good enough.

no luck yet. No area on the board seems to have a positive effect.

Of couse I cannot spray the bottom while the machine is on.

I did cpu.. I did Glue, I did MMU I did rows 1&2 of memory.. then tried all memory..

Did not do anything up in the IO area.. none of that seems affected.

james

Just backtracking a little bit, I don't think you have tried a known working power supply in this machine? This all just sounds like a power supply problem.

But I am using PSUs from other megaSTs?? if they run other (exact same machine) should it not run this one??

I can recap it.. I have all the caps.. I do will do one..

Any tests I can check with a multimeter?? the voltage is still over on the 5v rails.. steady 5.2v

James

Bikerbob wrote: 02 Nov 2021 22:27 But I am using PSUs from other megaSTs?? if they run other (exact same machine) should it not run this one??

Doesn't matter. A few more mA across each DRAM chips and boom, it pushes the old PSU over the edge and dies. Could even be failing caps on the motherboard. But honestly you need to start at the beginning which is power.

So this was this morning with a new delta PSU.

This was only the first pass, so it happened pretty quick.

James

OK so you need to do the bus resistors next.

OK, Bus resistors :)

Hmmm thought I bought them.. seems I did not.

edited.. sorry saw it was 8 pin. I need 9 pin.

Looking again :)

on the megaST all 6 are being replaced with 2.2k correct?

James

Just looking at the cartridge screen that's red with an error, I've seen this before caused by a wobbly cartridge, or if it gets knocked for any reason.

Can I suggest a check/clean of the cartridge port just so we can rule it out.