The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

I have no power to channel readout on a Galaxy 77hml. But, there is power to chanel meter. Does not TX or RX. What are the possible causes? Thanks Fella's!!

Sounds like the voltage regulator.Check TR-41.Voltages should
be as follows Base-12.5 v.d.c. Collector-8.5 v.d.c. Emitter-13.2 v.d.c
If the voltages are off.Then replace TR-41 with a 2SA-473,,also
if you cant find one a 2SA-1012 will work.

Thanks, ramblingman. I checked tr41 and replaced it, it had no voltage anywhere. There is voltage and tr51 Base 8.5 v.d.c. Collector 0 v.d.c. Emitter 8.7 v.d.c witch doesn't make sence to me. I think maybe my VOM is bad. I will have to check it out tomarro and try again. I replaced tr41 anyway. But, still no power to channel readout. The radio was working I didn't work on it at all just hooked up to RF power scanner Freq Counter and Dummy load with 1.2 swr the radio dead keyed about 4 watts with no modulation showing at all on my meter. Turned roger beep on and it modulated. And, after a couple of minutes sitting Idle. The channel counter quit. But, the rf scale still had light. Completely dead on TX and RX. I will see If I can find another VOM tomarro and try again. Thanks Fella's

My Volt Ohm Meter was bad. Got new one now. tr51 Base 13.76 v.d.c. Collector 0 v.d.c. Emitter 13.32 v.d.c TR41 Base 0 v.d.c. Collector 0 v.d.c. Emitter 0 v.d.c IC8 has 0.0 volts at every pin. Can't find any voltage to TR41 and it is newly replaced. D93 checks ok. I am still learning and open to any suggestions guy's. Maybe someone has a knowledge of what the possible causes are. Thanks Fella's

You maybe doing the test right but it is strange that you have no volts at TR41.

It looks like you are maybe not using your meter correctly.
With your negative (Black) meter probe connect it to (power ground) and not the chassis the black negative wire coming from you power supply is the best one to connect it to us this is to ground.

Now you can use the positive (Red) meter probe to do your voltage test.

Check TR41, looking at the transistor from the front and from left to right the legs are Base, Collector, and Emitter.
The Emitter should be about 13 to 13.8 volts.
If the voltage is missing check the copper track from the Emitter back to the Audio IC (IC8) it should be connected to Pin1 to find Pin1 look at the audio IC from the front and the last pin to the right is Pin1, it should be about 13 to 13.8 volts.
If the voltage is missing check the copper track from the Pin1 back down the PCB and you will get to the On/Off switch again check for volts at the On/Off switch and see if you have volts on each connect of the On/Off switch, (I think the wire colours are Orange and Red) each one of the wires should have 13 to 13.8 volts.
If you have on volts on the Orange wire, then it looks like the On/Off switch has gone south. You can check the switch by temporally putting a jumper wire across the Red and Orange.
Hope this helps. Lets us know how you get on.

You probably have a bad trace from the TR51 to TR41.This trace runs in the side of the board.

Unit 67 wrote:You probably have a bad trace from the TR51 to TR41.This trace runs in the side of the board.

Unit 67
The track from TR41 does not come from TR51, as TR51 always has volts on its Emitter is because it direct connected to the power socket.

The volt for TR41 comes from the On/Off switch.

If the volts came from TR51 to TR41 you would not be able to switch the radio Off.

Check any EPT3600xxx diagram and you will see how it works.

Hey fella's. Thanks for all the info and tech help on this. After all your input and help, I final located the problem after finding a schematic I found that Ramblingman and Rick are right on the money. The power to tr41 comes from the on off switch. What was confusing is. The switch was good and I could no find any bad traces, tr41 checked ok, I even replaced it. There is a resistor in the curcit r256 I think, It was ok too. The RF meter was working because it is supplied at tr51. After play'n with it for too long. I found that all that was wrong was a lose wire on cold solder jount at the on/off switch. It hit me in the face like a brick! Thanks for being patient with me fella's. Keep up the good work, and Never let this site die!