8 Nov
2005
8 Nov
'05
1:53 p.m.
I think I would check C3001, in case it's
shutting the PSU down before
it's properly started. Then look at the collectors of Q3002 to see if the
thing is detecting an overvoltage.
The under voltage protection is always active :( When power is applied, the collector of Q3001 goes
high (about 4.5V)
Well, it shoud be until the PSU gets going :-).
immediatly, after about 0.5 seconds, the SCR is fired
and the power supply
enter in protection mode.
I presume that delay is that 47uF capacitor charging up. So that's probably
not defective.
During the short time of outputs presents, I have
check the value (with
scope, multimeter in not enough fast) but they are of the correct value (+5,
+12, -5, -12) but I ignore the tolerance of the under voltage protection.
Maybe IC3001 or IC3002 defective ?
Or the transistor is open-circuit?
Still, you're now down to one simple-ish stage that presumably you can
debug.
Incidentally, I should get a copy of the schematics to Dave at the
weekend for scanning.
-tony