Mac SE FDHD freezes after 5 minutes

[captjon320]

I have three different SE FDHDs that I have been refurbishing over the years and noticed that they all suffer from the same problem. After successfully booting to desktop and running for a short time (5 - 10 minutes) they will all end up freezing with a person unable to move the mouse or use shortcut keys on the keyboard. All of these units have 4MB of RAM and it doesn't matter if I am running 6.0.8 or 7.1 or 7.5.

I have tried with a BlueSCSI and also regular old Apple 40/80mb hard drives that are working and it makes no difference. I have also tried different boards on different compact Macs thinking it was a PSU issue, same problem. Lastly, I put a working SE 800 board into the same compact Mac that the boards were freezing on and it works fine.

Therefore, this leads me to believe that it is something on these boards that needs to be replaced (and NOT a PUS issue on the analog board). The most logical answer is capacitors. However, I have refurbished probably 20 or 30 SE 800 boards and have never had this problem. Is there something that changed on the FDHD board that I'm missing? I just thought that the chips were different to handle the 1.4 drives vs the 800 drives.

I would appreciate any and all help so that I can get these up and running and back out in the community for people to use.

Thanks in advance.

 

[bibilit]

Never seen this before, the only difference between 800k and FDHD is Rom and SWIM, you can even upgrade the former one in last one.

For me more a peripheral issue, keyboard or mouse not the issue ?

 

[captjon320]

Same keyboard and mouse that I've been running with both boards. Yes, this is strange. I just got another FDHD to work on and this board acted the same way as the previous two that I pulled out of storage after having this issue.

This is the first post I've made because I had not thought of swapping the boards until I was working on the new one.

 

[ymk]

Try running a game demo. Maybe the machines aren't locking up, but a peripheral is jamming the ADB.

 

[captjon320]

Update.

Tried different peripherals and the board is working. This was the issue on all three boards. Funny thing is the peripherals worked with 800k. boards. At least it is solved.

Thank you.