[sdiy] Prophet 5: +5v drops to +4v

[Gil W.]

Hi all !

Really need your help on this, thanks in advance...

After building a powersupply to my Prophet 5 rev. 3.2,
and having it working just fine two days ago, getting
correct voltages, I decided to try to connect CPU fans
to the power supply so I can cool the heatsink down.

I used two 5v CPU fans and connected them in parallel
with the 5.6v powersupply rail.

>From that very point, and also after I took the fans
out of the circuit, I'm no longer getting 5v in the
main board, but rather than that - I get about
4.10v-4.00v !! When checking the voltage across the
5.6v power supply rail, it first shown about 5.30v and
then dropped to 5.00v and even below that...

Will anybody help me with where to look at ??

Is it likely that I damaged an IC on the main board ?
or did I damage anything on the power supply itself ?

One note:

When I disconnect the 1N4002 diode which goes across
the +5.6v input and the +5v main board rail, the
powersupply shows correct 5.6v ...

Really need your help on that one... Thanks !!!


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