[robb]

wrote in message
oups.com...
On Nov 8, 3:16 pm, "robb" wrote:
wrote in message

ps.com...




Ignore all that.

1. As Arfa suggested, isolate the L387 output from the 5V rail.
(Probably doesn't matter if you lift Pin 5 or disconnect some
other way.)
2. Replace the 5V fuse (and only that fuse? or do you also need
the 30V fuse to feed the L387?).
3. Power up.
4. If the fuse didn't blow, measure the voltage from Pin 5 to
Pin 3
of the L387 (5V OUT to GND).
5. If you got ~5V, reconnect the 5V rail and test again. If
not,
connect a 470-1k ohm resistor from Pin 5 to Pin 3 and test
again.
6. If still no 5V, measure the voltage from Pin 1 to Pin 3 (Vin
to
GND)
- it should be ~30V.
7. If ~30V was present on Pin 1, the L387 is bad. If not, the
30V
bridge is probably bad.
8. If the fuse(s) blew, test the resistance of the bridges.

TM

thanks TM,

i'll try that tonight.

thanks,
robb