got big problems up here i have a rci 2980wx with the EPT690010c board in it. i was doin the super ears mod and think i migh have accidentally shorted a switch to ground. power went out instantly, moved the radio around and power came back on. well radio stil received excelent put the cover back on and then the problems began. for some reason i have a dead key(20 watt) on ssb. the radio will not produce modulation in any mode at all. the rx,tx light on the radio comes on oarnge, not red or green on tx. i inspected the board and cannot see anything visible burned at all, i have tried difrent mics and nothing seemed to help. can anyone help me out please? i am inda lost without the radio to talk on thanks in advance
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rci 2980wx help
- Thread starter 123michigan
- Start date
You have overloaded one or more of the small switch transistors that feed juice JUST to the receiver until you key, and then JUST to the transmitter when the mike switch is pressed.
The red/green LED will show a yellow color when BOTH colors have juice on them. That's the clue.
If you don't have a means to test transistors, this one will probably make you crazy. Used to do "clean-up" repairs for small shops around this end of the state. This "T/R switch" section was the single most common problem in the "stumper" radios they would send me to straighten out.
First step is to verify that the "9-Volt" (approx) regulator Q37 has no more than 10 Volts on its center pin (collector). If it's more than that, or less than 9 Volts, this regulator has to get fixed first. If it's feeding out way too much, this can make the keying circuit parts act psycho, even if they are all okay.
Next we remove Q30, Q31, Q33, D70 and D71 to test. Odds are that you will find that one or more of those is hammered.
D70 is a 5-Volt 1/2-Watt zener diode. D71 is a tiny black speck with two thin wires, and a yellow dot or band at one end, unlike the black band/light color body of most other small diodes. This one deserves special mention, because it is actually two diodes in series inside one package. If it shorts, you'll get a symptom like what you describe. The original part, KB362 is hard to track down, but a series string of three generic 1N4148 diodes in series, with the banded ends the same direction as the original D71 will do the same job. The function that D71 serves is to keep the transmit side turned OFF during receive mode.
From your description, I'm gonna guess that Q30, the receive-side switch transistor is shorted, refusing to turn OFF when you key the mike.
We found there was no point in making voltage measurements until after that whole list of parts is verified as okay.
Don't see nearly as many of this type failure since those other shops closed, one by one over the last few years. Dern shame, they were good, steady customers.
73
The red/green LED will show a yellow color when BOTH colors have juice on them. That's the clue.
If you don't have a means to test transistors, this one will probably make you crazy. Used to do "clean-up" repairs for small shops around this end of the state. This "T/R switch" section was the single most common problem in the "stumper" radios they would send me to straighten out.
First step is to verify that the "9-Volt" (approx) regulator Q37 has no more than 10 Volts on its center pin (collector). If it's more than that, or less than 9 Volts, this regulator has to get fixed first. If it's feeding out way too much, this can make the keying circuit parts act psycho, even if they are all okay.
Next we remove Q30, Q31, Q33, D70 and D71 to test. Odds are that you will find that one or more of those is hammered.
D70 is a 5-Volt 1/2-Watt zener diode. D71 is a tiny black speck with two thin wires, and a yellow dot or band at one end, unlike the black band/light color body of most other small diodes. This one deserves special mention, because it is actually two diodes in series inside one package. If it shorts, you'll get a symptom like what you describe. The original part, KB362 is hard to track down, but a series string of three generic 1N4148 diodes in series, with the banded ends the same direction as the original D71 will do the same job. The function that D71 serves is to keep the transmit side turned OFF during receive mode.
From your description, I'm gonna guess that Q30, the receive-side switch transistor is shorted, refusing to turn OFF when you key the mike.
We found there was no point in making voltage measurements until after that whole list of parts is verified as okay.
Don't see nearly as many of this type failure since those other shops closed, one by one over the last few years. Dern shame, they were good, steady customers.
73
Right on, 123! Glad to hear that's all it was.
Puts you in a small, select club.
Folks ask me the difference between a tech and a wannabe.
I tell them that a wannabe is lost if anything goes sour, or a drop of solder falls on the circuit board while the power is on. Even a pro, no matter how careful, will drop a screwdriver onto a live circuit board, sooner or later.
A tech can track down what it was he broke by accident, fix it, and then get on with the job.
Congratulations and 73
Puts you in a small, select club.
Folks ask me the difference between a tech and a wannabe.
I tell them that a wannabe is lost if anything goes sour, or a drop of solder falls on the circuit board while the power is on. Even a pro, no matter how careful, will drop a screwdriver onto a live circuit board, sooner or later.
A tech can track down what it was he broke by accident, fix it, and then get on with the job.
Congratulations and 73
T
The Defpom
Guest
It didn't take us long to find the cause, we went straight to it, but had to confirm that the control circuitry as OK, it all checked out, the transistor (Q30) had shorted, I told 123 how to test the transistor after pulling it from the PCB, confirmed it had failed, checked the rest, it all checked out, TX back to normal etc.
123 showed good skills, I reckon that he would make a good tech with some experience under his belt, could understand my instructions easily, we did the repair through the chat feature of the Quack Shack / my site (Radiomods), only seemed to take us about 15 minutes all up.
123 showed good skills, I reckon that he would make a good tech with some experience under his belt, could understand my instructions easily, we did the repair through the chat feature of the Quack Shack / my site (Radiomods), only seemed to take us about 15 minutes all up.
123Michigan,
Where did you get the mod for super ears for you 2980WX?
does it work good?
Thanks,
AP
Where did you get the mod for super ears for you 2980WX?
does it work good?
Thanks,
AP
RCI2980? Ouch, that's an old radio...I mean -
Brings back memories of when gas was cheap...
Women were ...
and Men were...
And we were...
Where am I going with this???
Ok, never mind, the RF gain, with no receive, and you changed the audio chip - check PA see if the Audio works?
Low receive usually tells me the radios' capacitors are shot - they use these little guys to send audio thru into other stages that have different voltages so they can't be mixed with other stages and their voltages, so when they dry out, they short out - they act like weak resistors and you have quirky performance including poor receive.
There are other things too, like; knowing the history of the radio - was it left out in the rain? Used as a Wheel Chock? Left hooked up in a lightning storm? Or you bought it used on eBay and the kid said it was actual miles...
The more you know beforehand, the easier the repair becomes because you know what you're up against.
Brings back memories of when gas was cheap...
Women were ...
and Men were...
And we were...
Where am I going with this???
Low receive usually tells me the radios' capacitors are shot - they use these little guys to send audio thru into other stages that have different voltages so they can't be mixed with other stages and their voltages, so when they dry out, they short out - they act like weak resistors and you have quirky performance including poor receive.
There are other things too, like; knowing the history of the radio - was it left out in the rain? Used as a Wheel Chock? Left hooked up in a lightning storm? Or you bought it used on eBay and the kid said it was actual miles...
RCI2980? Ouch, that's an old radio...I mean -
View attachment 57357Ok, never mind, the RF gain, with no receive, and you changed the audio chip - check PA see if the Audio works?
Brings back memories of when gas was cheap...
Women were ...
and Men were...
And we were...
Where am I going with this???
View attachment 57358
Low receive usually tells me the radios' capacitors are shot - they use these little guys to send audio thru into other stages that have different voltages so they can't be mixed with other stages and their voltages, so when they dry out, they short out - they act like weak resistors and you have quirky performance including poor receive.
There are other things too, like; knowing the history of the radio - was it left out in the rain? Used as a Wheel Chock? Left hooked up in a lightning storm? Or you bought it used on eBay and the kid said it was actual miles...
The more you know beforehand, the easier the repair becomes because you know what you're up against.
Funny, doesn't seem that long ago...
Well I'm going behind someone else,the am reg was shot,and the so called tech before me burnt tracks back there trying to put 1 in,I put a new 1 in and still did not work properly, so I went back through it and found the other reg in front of the am reg was bad also,I replaced it and now it keys up and talks just very poor recieve,it acts just like the rf gain is all the way down.
You obviously have a lot on your plate...
Hoo, boy... Ok where do you start?
Right where I left off.
Did you Test PA?
Were you able to control its volume?
Does Mic Gain control work?
Display works but does the "S-meter" ?
Tried listening for another radio close by to see if it can be heard, how cleanly?
Hoo, boy... Ok where do you start?
Right where I left off.
Did you Test PA?
Were you able to control its volume?
Does Mic Gain control work?
Display works but does the "S-meter" ?
Tried listening for another radio close by to see if it can be heard, how cleanly?
- No one is chatting at the moment.