Atari STFM Power issue...i think

[friijy2001]

I had thought I had finished this project and low and behold another problem, am thinking it is power related...


Machine is a 520STFM
4MB upgrade (exxos)
Dual TOS (exxos)
PSU recapped
All mandatory upgrades/fixes
Internal Gotek and upgraded Sony MPF 920 Drive

Everything was working really well and was going through my disks and checking they work. The machine had been on for a couple of hours and then this happened...



Took it apart and check all the tracks again for anything loose and all ok..put it back together,

at first I thought perhaps the PSU was pushing down on the Dual TOS chip so kept these screws loose too
I then checked the Shifter and all the tracks are fine also.

Decided to plug it in and with the basics...Mobo, PSU and it booted
Added the drive tested and it booted
Added the keyboard again and after a short time, seconds it showed the screen above.

I am thinking due to the age of the PSU it is starting to fail with the tweaks above, or its the keyboard but i really don't think it is.

Any suggestions before I buy a new PSU?

[exxos]

Bad connection on ram somewhere..

[TheNameOfTheGame]

I remember some of the older STs were missing the little metal clips over the GLUE/MMU chips and they would loose connection now and then and I've had systems that were very flaky as a result.

The solution was to push on the chips until they reseated or better, get some clips and put on the sockets. Do you have the clips on your ST?

[friijy2001]

Bad connection on ram somewhere..

hmm, I have removed all the old ram modules and put a connection from the 3 resistors to a +5v side of the big cap, also checked all the tracks from the shifter.

I am assuming I can leave it like this too?

Could it be where I have removed a ram chip and a one of the connectors have lifted, I would of thought if noting is there it should not matter.

[friijy2001]

I remember some of the older STs were missing the little metal clips over the GLUE/MMU chips and they would loose connection now and then and I've had systems that were very flaky as a result.

The solution was to push on the chips until they reseated or better, get some clips and put on the sockets. Do you have the clips on your ST?

I removed the clip to fit the exxos ram upgrade as I thought it would be in the way, i'll have a look thank you.

[exxos]

If you removed all the old RAM (which you should do) then the resistors are not doing anything anyway.

I would suggest you life out the RAM board, wipe the MMU pins, RAM board pins, cable connections.. check shifter connections on the adapter board... I would assume its relating to a bad connection on the cable (or pins to the MMU itself) but a bad connection could be anyway. So lifting it all out, clean with IPA may well solve it.

[friijy2001]

Managed to ipa everything and it works again, just need to pop the lid back on and will see if it behaves itself tomorrow!

It was really odd as I said, it worked for a few hours and then stopped, fingers crossed everything is seated properly now :)

I’ll update this post if the fun continues!

[friijy2001]

Managed to have the ST on for some time yesterday and all seems fine..phew!

Thank you for the help and pointing me in the right direction.