Uniden 78xl no TX or Rx

[BAGEBOY]

I was just given a uniden pc 78xl seems to be in good condition. How ever I can see the signal meter moving but No audio on recieve.i switch the PA no audio. I checks C 112 I change the driver and the finals(mosfet). No power out Any ideas..

 

[Handy Andy]

Mic wiring comes to mind.

IF it can't send power to the rear final and driver, it can damage the audio transformer ( as in arcs a short) but it will kill and pop the transformer like a fuse but you'll still have a working radio with no power to TX or speaker, but show RX and seem to work just no TX - so when you get back in there - use a standard bulb (12V automotive tester) to place a load across on the output Diode, to foil ground battery negative from the mod transformer and see if it will light - if it lights you have a heartbeat.

You just have to figure out the CB/PA switch and see if it's been rewired for something else.

One side of the CP PA switch (pole) wires Speaker to rear output terminals - the other goes to Pre-Driver and makes(CB) or breaks(PA) the POWER connection to the Pre-driver.