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Got a head scratcher for you all...

Hawkeye351

Well-Known Member
Jun 27, 2021
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Got a Galaxy DX - 55V (EPT360014B) on the desk. This radio came from the old local technicians shop when he quit the hobby years ago. It was taken from the shop with this issue already, he never got it fixed before he quit the hobby, so I don't have any info on what caused this failure.

Issue:
No output power.

Evaluation:
Bad Passthrough regulator, hole blown out the front of it.

Bad AF regulator. Showed signs of heat damage, also tested as a short in tester.

Blown driver transistor. Final tests as good.

Fixed:
Replaced all the above parts with new parts (tested before installing).

Results:
No output still.

Ongoing:
Checked D77 (?, under mic socket board). Tests fine, shows as a good working diode.

Checked BCE from TR45, TR46 in receive and transmit. Voltages are correct.

Collector of driver and final is getting the 5.45v from the Passthrough with no issues when keying up.

But I only get 0.02v on the base of both the driver and final in transmit mode. Although C175 (directly in front of the driver, connected to the base of the driver), shows around 8v on the front side of the cap, it only shows 0.02v on the other side of the cap which is connected directly to the base of the driver. I pulled out C175 and checked it, it tests fine as a disc capacitor with a value of 678pf, so it's good.

Pin 5 of the mixer IC is producing around 8v in transmit.

Still no output whatsoever. Another radio on the desk right next to it will show it keying up, but if you space the radios apart, the keyed signal drops dramatically. The transmit/receive switch is working. The transmit/receive light (in the meter) changes color from clear white for receive to red for transmit. Radio receives great, all other functions work as they should.


Any ideas guys/gals?

On a side note, had to put the rci-69 to the side for a bit, we'll finish it up later. I need to get this one going. And by the way, I have rechecked the driver and final (although they have never been used) and they still show fine, I've replaced them twice anyway just to be on the safe side, still nothing. And nothing gets hot, not even slightly warm after holding key down for a long time.
 
Last edited:

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