Anyone have an Atari STacy I could borrow at VCF?
Heya! I pulled out my STacy, and I am getting stuck in this issue where the power supply cycles. Something is shorting and dragging down the PSU. I am not seeing a dead short tho, it happens after it comes up. I had recapped the power supply board when I got the machine -- and it was working. Mostly. I've had some strange issues. It's an annoying design where the machine gets 17vdc center pin positive which hits a sub pcb that is a switchmode supply generating 5/12v and running the inverter for LCD backlight. It's connected via pin headers and humps the main board -- so it's not possible to easily run the power supply without the main board until I build a test harness. I just got done recapping main board hoping one of the electrolytics was going to short after power on but still getting same issues. I plan to continue to troubleshoot it, but as a backup plan does anyone have one I could use for my display @ VCF if mine continues to not cooperate? I plan to run Notator or Cubase on it with midi synths and stuff.
Just a reply to myself. STacy issue was interesting. Apparently cap juice had wicked up the 5v POT. I recapped it a while ago, but didn't catch that. That is what was causing the 5v instability. I was looking for other parts dragging down the power supply, isolating various things like the motherboard, the PSU, etc etc. But since the problem was intermittent it was a little tough to catch. Reggie had a spare 10ohm potentiometer, went to solder it in. Immediately got that fish smell and found some of the solder "crunchy." Replaced that potentiometer -- rock solid power. Sometimes the obvious thing is the actual issue.
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Ethan O'Toole