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Omnidrive FDS-366 PSU Fault
chickenfizz
Posts: 4
Hello,
Got a problem with 2 omnidrives, they both power-cycle, one gets as far as displaying the software version then immediately reboots, the other gets as far as drawing the curve on the screen, then reboots, occasionally this one will become stable and pass audio but it's not happy and the 'chopper' is squealling away.
I had this problem with a different unit a few years ago but can't remember how I resolved it.
The voltage instabillity is visible on the +8v rail and +15v rail, 5v seems (almost) stable. I have replaced all electolytics on in the PSU.
Any clues??
Cheers
Got a problem with 2 omnidrives, they both power-cycle, one gets as far as displaying the software version then immediately reboots, the other gets as far as drawing the curve on the screen, then reboots, occasionally this one will become stable and pass audio but it's not happy and the 'chopper' is squealling away.
I had this problem with a different unit a few years ago but can't remember how I resolved it.
The voltage instabillity is visible on the +8v rail and +15v rail, 5v seems (almost) stable. I have replaced all electolytics on in the PSU.
Any clues??
Cheers
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Comments
1 - reflow all solder pads in the suspect area
2 - use freeze spray to cool components while monitoring voltages ( probably need a scope for this to see fast transients
3 - wiggle things ( 3 terminal regulators, zener diodes, caps of all sorts ) while monitoring voltage looking for mechanical issues
4 - and most important - connectors are the devils work - remate all and everywhere