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uniden washington
- Thread starter kaos513
- Start date
Sounds like it might be TR34. It's originally a 2SC1419, but later production might use a different type.
This transistor is a TO-220 bolted to the heat sink panel near the right-rear corner. Should have 13.5 Volts DC or so on the collector, the center pin.
With the mike keyed in AM, the leg nearest the front should have 6 or 8 Volts DC on it. If not, TR34 may be bad.
See what this check turns up.
73
This transistor is a TO-220 bolted to the heat sink panel near the right-rear corner. Should have 13.5 Volts DC or so on the collector, the center pin.
With the mike keyed in AM, the leg nearest the front should have 6 or 8 Volts DC on it. If not, TR34 may be bad.
See what this check turns up.
73
Well, hopefully it's something really SIMPLE , like maybe a wiring swap or something with a Blown cap preventing power from getting to the AM carrier thru D42. It's a Germanium diode 1N60 - so if that quit - threre goes the carrier but you'd have audio - so something in that line...even the AMC Sense line that feeds TP7 and TP8.
I've also found R185, that 220ohm 1/2W resistor - played with, you may want to put that back in. Or at least check to see if it's in value.
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SIX-SHOOTER
ICOM CENTRAL.7610,9100,PW-1,HEIL FIN & HEIL PR-781
I have a Sam's Photofacts CB repair manual for it if you need one.I owned the radio several years ago but no longer have one nor will I be.
SIX-SHOOTER
SIX-SHOOTER
Well try unsoldering the finals collector and then see if you have any signs of life coming from the driver, You know, like RF maybe even transmitting into another radio on the bench. Even if the final is bad the driver may still be kicking and it would be modulated " ASSUMING TR34 IS GOOD" so you would hear it in another test radio which I'm sure you have. I'm suggesting this based on your testing of the transistor Nomad was talking "34" about but if you are simply looking at the internal modulation meter and seeing full deflection at least the rectifier circuit for the mod meter is working and most likely some stage of the final section is might be working. which to make a short story longer most likely means the final is bad? There I Know I could have drug that out even more but I was getting carpal tunnel...
ok it doesnt get hot any more i cleaned up some bad solder job but still do not get am power or on usb and lsb .whem i turn radio off front meter does refelect back
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Any time the meter pegs after work is done to the circuit board around the final, look for a solder bridge across adjacent foil traces. A bright light and a magnifier help a lot.
If the meter did NOT peg before you cleaned up the soldering, this is almost certainly the cause.
Sure would be nice if you had a way to test the final transistor. Does make it sound as if the fault that made it get hot has damaged it.
If it checks bad, you should also check R163, a ten-ohm 1/4-Watt resistor on the final's input side. You don't have to unsolder it to do this, just place the two probes on each foil pad, and measure its resistance in the circuit. Most any reading under 12 ohms is probably okay.
73
If the meter did NOT peg before you cleaned up the soldering, this is almost certainly the cause.
Sure would be nice if you had a way to test the final transistor. Does make it sound as if the fault that made it get hot has damaged it.
If it checks bad, you should also check R163, a ten-ohm 1/4-Watt resistor on the final's input side. You don't have to unsolder it to do this, just place the two probes on each foil pad, and measure its resistance in the circuit. Most any reading under 12 ohms is probably okay.
73
Just a thought if I understand what you said here correctly. USB and LSB has no carrier but modulation swings to 100%. Since SSB has no carrier and is all modulated watts then your saying SSB seems to work?
My Madison is doing this right now, AM does not work but it's perfect on LSB which is where I talk 90% of the time. Dropped it off to the local tech yesterday.
When I whistle to the mic I get only modulation in am mode only as for usb and lsb I get no audio or carrier as well but the receive works very well and all the front buttons work as well .
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One of the reasons I didn't necessarily think that TR34 was bad was exactly for the reason that you said the modulation meter was showing modulation while not developing output, "IT STILL NEEDED TO BE CHECKED for the sake of getting that possibility out of the way" I didn't bring up the schems but, in these radios the mod meter is driven by a pure audio signal and maybe a half wave rectifier circuit that drives the meter so without TR34 working that meter most likely would not show anything or very little. This is why I focused on the final section and whether or not the radio showed any signs of RF from any stage in the final section including the pre-driver. These are not hard steps to take it a simple logical approach which often times leads you to the problem.
So I read after posting this and went to the schems and if the meter is pegged most likely it's close to tr44 or maybe r169 is now shorted with solder.
OldTech
So I read after posting this and went to the schems and if the meter is pegged most likely it's close to tr44 or maybe r169 is now shorted with solder.
OldTech
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