Galaxy 29hp no modulation

[sonoma]

the voltage on C looks a little low. should be closer to 5 or 6 volts. per the voltage chart I have.. is the one you have in there a PNP trans.

 

[sonoma]

see what the voltages you have on the tip 36c unit. the center leg should be around 5 volts and the 2 outer legs will be close to 12 to 13 volts. the leg to the front of the radio will a little lower than the rear leg.
I am going to bed so we can look at what you have tomorrow.

 

[Mk121]

Yes it's a 1869 pnp so I think it might of had the voltages flip flopped. Tr51 is 13.5 3.2, 14. That's rear to front solder side up. So that doesn't look good either then. Ok thanks for the help, have a good one.

 

[nomadradio]

TIP31 is a NPN type. Not right for this circuit.

TIP32 is the PNP equivalent of the correct part.

73

 

[Mk121]

TIP31 is a NPN type. Not right for this circuit.

TIP32 is the PNP equivalent of the correct part.

73

I already switched the tip31 out for the original transistor since it tested good. Thanks

 

[Mk121]

Put a new tip42c in at tr50. I'm back to a maxed out dead key with no modulation. Also tp7,8,9 back to 12.5+v. Need a little guidance on tracking this fault. Thanks

 

[nomadradio]

Somebody is shorted, or reversed. Can't install TR51 backwards. If the metal back of TR50 isn't facing away from TR51, that would do it. The metal back of TR50 faces away from TR51 when it's turned around the right way.

Next thing I would try is to unsolder and isolate the center lead (collector) of TR49. This transistor controls TR51. If doing this shuts down the transmit carrier, change TR49, a 2SC945. If it's shorted, you'll get a slammed carrier and no audio.

And if the old TR50 checked shorted, this can cause surge damage to TR49 and cause it to short.

73

 

[Mk121]

Somebody is shorted, or reversed. Can't install TR51 backwards. If the metal back of TR50 isn't facing away from TR51, that would do it. The metal back of TR50 faces away from TR51 when it's turned around the right way.

Next thing I would try is to unsolder and isolate the center lead (collector) of TR49. This transistor controls TR51. If doing this shuts down the transmit carrier, change TR49, a 2SC945. If it's shorted, you'll get a slammed carrier and no audio.

And if the old TR50 checked shorted, this can cause surge damage to TR49 and cause it to short.

73

Nomad,
Ok I had some time to mess around with this again finally. Pulled tr49 and still slammed carrier. Tr51 brand new and tr50 new. Just wanted to give an update,thanks.

 

[nomadradio]

Time to pull TR50 and see what you get. A VERY close inspection of the foil pads under TR50 might reveal a tiny solder bridge between pads.

That's the next step "downstream" in the circuit.

73