All checked out OK
I just completed the voltage checks on page 27 of the assembly manual
Here's a comparison of the results when working versus now
U1 pin 1 was 4.94v now 19.5mV
U3 pin 6 was 6.05v now 2.47v
D2 Anode was 14.83v now 2.7v
D2 cathode was 13.75v now 2.5v
Voltage measured at the supply is 12.3v (Astron AS-35)
The input power seems to be shorted to ground. This could be a shorted
capacitor at C5 or C7 or possibly voltage regulator U8 or U9 has an
internal short.
With power disconnected and S1 and S2 in the OFF position, measure the
resistance between ground and the cathode of D2. If you have a short,
then C2 is probably shorted. If this is not the case, next measure
between ground and the out put of each voltage regular (U8, U9) in turn.
If you have a short on either regulator then it is probably bad. If you
still don't have a short then measure between ground and the input of
either voltage regulator. If you have a short then C7 is probably
shorted. Replace the bad component and repeat these measurements before
turning power back on.
Larry
KB5DXY
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