Cobra 148GTL no Output power

[longhaireddwb]

Hi all. Been a while since I've been around. I picked up another radio and got a non-worker. Maybe I should quit buying these things at yard sales. LOL.

I put it on the bench and fired it up. RX is good. Key the mic and found RX/TX light functioning. Look at the meter and I have no output. Checked audio chip and found it good. I went to the driver and found the legs on the chip were broken off and no longer connected. So I replaced driver AND final while I was at it. Still no power out. AM or SSB, no output. I don't see any bulging caps, flexed the board looking for any broken solder joints and had no change. IC4 has good voltage but its also switching the LED so I think it's ok.

Does anyone have an idea of where to check next? I spent 20 bucks on this one and it's not been hacked or modded. 1992 5pin Philippines model so I was hoping to have a nice little radio. Thanks for any help.

Jerry...

 

[sp5it]

What is the voltage on TP9 AM and SSB TX?
Mike

 

[longhaireddwb]

My cheap meter is showing 2.6 volts in TX and RX at TP9. AM or SSB.

 

[sp5it]

Too low. On SSB should be PS voltage minus 1.4V drop on TR51
TR51 can be broken.TR49, 50, 52, 53 I would check too.
Mike

 

[longhaireddwb]

Too low. On SSB should be PS voltage - 0.7V
TR51 can be broken.TR49, 50, 52, 53 I would check too.
Mike

Thanks Mike. I will check the voltages on those TR's.

 

[sp5it]

Check attached file. Should help.
Mike

 

[longhaireddwb]

you sure? looks to be a for an rci. Not cobra

 

[longhaireddwb]

I've scanned the board and broke out the manual again and I still don't see a TR51. It's listed in the voltage chart. Anyone got a clue as to the location of that sucker. Ha.

 

[sp5it]

Mounted to side wall near power socket.

you sure? looks to be a for an rci. Not cobra

90% similar. Does the same job in both radios.

 

[longhaireddwb]

I guess I'm just hoping something jumps out and slaps me. As your attachment doesn't help me. Just way over my head. I cant seem to find TR50 or 49, And from your reply on the location of TR51 I'd say thats the Voltage Regulator (D1135). Its got supply voltage and 8volts. 53 and 52 match my voltage chart.

Not sure where to go now. Maybe I have bit off more than I can chew.

 

[sp5it]

Link me schematic you are using.
Mike

 

[longhaireddwb]

Ha. Im an old guy! I do everything with paper. Not that fancy computer stuff. Im lucky to figure out how to do forums. Sorry. I have an old cobra 148gtl service manual. I bet ive had it from late 90s

 

[sp5it]

Is it that one?

 

[longhaireddwb]

Mine is older. This might come in handy. Now if I can figure how to save it.

 

[sp5it]

So as you see on SSB voltage to driver and final goes through SW403C. As I wrote before it should be same voltage like on power supply. Maybe switch is faulty or driver/final is shorted?
MIke