Galaxy Saturn (14b board) no xmit

[Hawkeye351]

On the bench is a Galaxy Saturn with the 360014b main board.

Came in with no xmit. I know the owner. He bought this radio, used it for about 2 months with no issues (sounded awesome on air), until one day the xmit dropped out.

Getting 13.91v from the ps unit on rcv, 13.85v On xmit.

Passthrough voltage absent in both rcv and xmit, replaced it with same results.
AF voltage is absent in both rcv and xmit, replaced it with a 1012y with same results.
Voltage regulator voltage is absent in both rcv and xmit, haven't changed yet.
Voltages on the audio IC is absent in both rcv and xmit.
BCE of the driver and finals is 0v or 0.3v in both rcv and xmit.
Receives monitor radio transmission great, has great receive.


There is receive audio as normal, hashy but it's there.
Nearby monitor radio shows xmit but not full scale.
No watt meter movement at all.
Xmit light does come on when keying up.
Nothing getting hot or warm at all, everything is as cool as though it's not turned on.

This radio has no mods whatsoever from what I see, no sloppy solder work, no hack booger jobs. Looks factory.

No xmit issue is in all modes. And no xmit audio.

I also should mention, if I touch the chassis of the radio then the hashy rcv volume drops substantially. If I move my hand around but close to the chassis, i can hear that rcv hash sound being affected. If I barely touch the top of the pre driver the rcv volume is affected and the monitor radio shows more xmit signal but still nothing on a watt meter.

 

[Hawkeye351]

Update:

Reasoning for no voltages in specific areas was the fault of a bad mirror board (bias plate). Replaced it, then all voltages on passthrough, af, 8v and audio ic fell into place.

Driver. In rcv
B - 0.1v
C - 1.03v
E - 0v

Driver in xmit
B - 0.1v
C - 0.97v
E - 0v

Final 1 rcv
B - 0.1v
C - 1.15v
E - 0.2v

Final 1 in xmit
B - 0.1v
C - 1.1v
E - 0v

Final 2 in rcv
B - 0.2v
C - 1.11v
E - 0v

Final 2 in xmit
B - 0.1v
C - 0.99v
E - 0v

I did remove c174 and c164 (both electro) to test out of circuit. The values are bout right, esr is bout right, so I put those back in.

Now here is the strange part:
While I was turning down the Mic gain from wide open down to 3 o'clock, the volume of receive comes up until I get to 12 o'clock then goes back to normal. Weird, lol...

 

[Hawkeye351]

Update:

Removed driver and both finals, along with all 3 m1vy diodes.

Checked all 3 diodes = all 3 check good.
Checked driver = checks good at hfe-47
Checked 1st final = shows as 2 diodes
Checked 2nd final = shows as capacitor

Gonna replace both finals.
Will post an update.

 

[nomadradio]

Gonna replace both finals.

Very good chance both finals are toast.

I have had some quirky test results with larger RF transistors. A chinese tester we use a lot will get all confused with a 2SC2879 transistor on it. Tries to tell me that it's a PNP with a very low gain. Leads me to think the transistor is oscillating, and causing the tester's DC measurements to come out all wrong. That same tester works perfectly with MOSFETs, bipolar radio finals, drivers and smaller transistors.

You can probably take the "2 diodes" and "capacitor" test results to the bank.

Sorta.

73