Ron,
You may be lucky and only the final and the audio output stages acted as
fuses.
To prevent this in the future fuse the power supply wiring, and add a back
biased diode, (cathode to plus 12), across the power input to ground. This
will blow the fuse in the future in case of polarity reversal, and save the
rig.
I would take loose the final and the Audio output stage, and then power up
the rest. Use a high impedance earphone to listen to the coupling capacitor
which formerly went to the audio output stage, (across it to ground with the
phones). Or use low z phones and a high to low transformer, and see if the
receiver is working at all up to the audio driver. The most likely failures
before you shut down would have been transistors opening up, or shorting.
There are not so many and you could test then individually. Especially if
you have a diode check feature on your DVM, you could check each junction of
the bipolar types, (NPN, or PNP types). And that can be done in circuit
provided there are no discrete diodes bridging junctions. About the only
one would have been at the collector of the final, and you know that final
is gone.
The voltage measurement tables in the book should help you get other failed
components located.
GL and 73,
Stuart K5KVH ---This is a great chance to learn troubleshooting!
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