Uniden Washington PC-385 PCB Final keeps exploding

[mike269]

My Washington (MB8719) keeps blowing finals. I have gone through 2 originals and 2 Eleflows....getting to be a costly fix. I have spent days inside checking everything I could think of...Bias settings, Transistor voltages, component values in the surrounding circuitry all seem to check out ok. I can transmit on am ok, on side band with no modulation ok, but very shortly after talking into the mic you can see high current being drawn (3 to 4 amps) while power levels are at 12 watts then the Eleflows explode with a bang and shatter into several pieces and the Mitsubishi's fissile and go up in a puff of smoke.

If anyone has had this problem before can you please point me in the right direction

 

[mike269]

My Washington (MB8719) keeps blowing finals. I have gone through 2 originals and 2 Eleflows....getting to be a costly fix. I have spent days inside checking everything I could think of...Bias settings, Transistor voltages, component values in the surrounding circuitry all seem to check out ok. I can transmit on am ok, on side band with no modulation ok, but very shortly after talking into the mic you can see high current being drawn (3 to 4 amps) while power levels are at 12 watts then the Eleflows explode with a bang and shatter into several pieces and the Mitsubishi's fissile and go up in a puff of smoke.

If anyone has had this problem before can you please point me in the right direction

Hi All,
I finally fixed the fault if anyone is interested. R88 had one solder joint bad, once fixed the radio is working great.

Cheers,
WR269 Mike

 

[9C1Driver]

Good deal, nice old radio.