Galaxy Saturn growling noise from echo board

[RF Krazy]

I would try operating the radio without it's on-board power supply. Leave the unit unplugged, the power switch OFF, and connect a good 13.8 VDC supply to the Red (+) wire going from the on/off switch to point # 22 on the main board, and the (-) supply wire to a suitable ground point. If the growling noise goes away, then the noise is being generated by the power supply. If the noise is still there, at least you've eliminated the supply as the culprit.

- J.J. 399

Hello Unit_399,

Sorry I had missed your post.

Great idea about by-passing the eternal supply. If it had a 12 volt connection on the back I would had tried that because the thought did crossed my mind when Nomadradio first told me about checking voltages and mentioning the supply.
But I will admit I did not think of connecting external voltages across the switch and such.
Again great idea and thank you for helping. What a pickle I have gotten myself into.

RF Krazy

 

[RF Krazy]

Yeah, I bypass it like you tried to do it, using jumpers if i want to keep the connectors for reinstalling later. You are creating a mic/ptt pass-thru with the jumpers. Let me check my notes on that and pour over the voltage readings.

Hello Cable Guy,

This morning I figure the out the wiring as far as the audio in and out.
I simply took an ohm meter to the pin 2 (audio) of the mic jack and then probed around on the echo board connections until I had continuity. Then study how it was connected, along with the PTT in the same connector housing. I assumed the other wire (Output) and I just happen to be correct!

Orange and yellow being PTT. White being mic input and brown being mic output that is connected to the echo board. The black wire between the brown and yellow wire is ground. There was a CUT/snub gray wire between the yellow and the white wire but I have no idea what it was or if it was ever used.

So I have the audio working with by-passing the echo board entirely.
I am told the audio is not that loud though.

The echo board probably has a bad transistor or a a bad diode on board I am guessing.

I have found TR32 AMC shunt switch cut with a diode not far from the circuit also cut on the main radio board. Not sure what the diode did in the circuit but I will be looking at the schematic to try to figure it out and then replace it.

Now to figure out why the audio is low is another question. Perhaps replacing TR32 and that Diode will give it a boost. I really don't know.

Thank you NomadRadio, Cable Guy and Unit_399 for helping.
It really makes a difference when someone is there lending a hand.

73
RF Krazy