Are these two little boogers the ones you are referring to? I touched the Burt looking one with my finger and it was smoking hot. Could this be my problem?
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Beginner problems with rci-2990
- Thread starter Hollerhunter
- Start date
Are these two little boogers the ones you are referring to? I touched the Burt looking one with my finger and it was smoking hot. Could this be my problem?
I believe I fixed the issue. I opened the top on the radio and found where someone had been in here before and a wire on the back on a board connected to the heat sink had been messed with before. I wiggled all wires and made sure they was plugged in good and the swr rf power meter works perfect now. The standing wave is a little high still though at about 1.8 or 1.9 on all channels but that may be my coax. Thank you all very much for so much help. Awesome group of folks here. Again, thank you
those 2 resisters need to be changed also since you are in there. if one was so hot it burned your finger it is going bad. see if you can get 1 watt resisters for the replacements. if not put in 1/2 watt ones.
glads you have it going again
on those two resisters it would be best to put the flame proof resisters in there. they cost a little more but are a safer choice.
I think one is a 82 ohm and the other a 100 ohm. do not take me being right on the ohms. I am doing this from memory and the last one I worked on was about 18 years ago. I do not have the schematic for it but it should be the same as a 2950 DX radio. I will look and see if I can find the specs for you.this way you can use the radio until you get the proper ones purchased.
on those two resisters it would be best to put the flame proof resisters in there. they cost a little more but are a safer choice.
I think one is a 82 ohm and the other a 100 ohm. do not take me being right on the ohms. I am doing this from memory and the last one I worked on was about 18 years ago. I do not have the schematic for it but it should be the same as a 2950 DX radio. I will look and see if I can find the specs for you.this way you can use the radio until you get the proper ones purchased.
are you able to see what numbers are on the board? I think they are.
R606 56 ohm 1/2 watt
R604 82 ohm. 1/2 watt
here is the layout that should be the same as yours.
http://www.cbtricks.com/radios/rci/rci_2950dx/graphics/rci_2950dx_70dx_cpu_sch.pdf
R606 56 ohm 1/2 watt
R604 82 ohm. 1/2 watt
here is the layout that should be the same as yours.
http://www.cbtricks.com/radios/rci/rci_2950dx/graphics/rci_2950dx_70dx_cpu_sch.pdf
Generally I will refuse to replace the two brightness resistors. We hook up the meter and display lights directly, using LEDs.
The reason is the heat will crumble the body of each resistor, but most importantly it will crumble the circuit board laminate. If foil traces near the two resistors get damaged, getting it to work again will be a nightmare.
If there were a source for new board for this radio I wouldn't be so cautious.
But it's made from unobtanium. Don't want to break it.
73
The reason is the heat will crumble the body of each resistor, but most importantly it will crumble the circuit board laminate. If foil traces near the two resistors get damaged, getting it to work again will be a nightmare.
If there were a source for new board for this radio I wouldn't be so cautious.
But it's made from unobtanium. Don't want to break it.
73
Nomad years ago I had a 2950 radio that those 2 resisters shorted and they damaged the board but I was able to repair it. I have not worked on one in years but you said changing the bulbs to LED's took care of the over heating problem so the board would not turn crispy and start falling apart.. just wanted to make sure I read that right.
Just be careful how ever you'd like to dim the lights, it easy to damage a circuit board by applying too much heat/pressure (you should not apply force or pressure using the iron) take your time and practice on a circuit board from something that is already really broken.
Take your time and get a feel for what you're doing, it doesn't take much to create serious damage to a PCB, so practice first now, to avoid headaches later on.
If you practice enough, hopefully you won't damage anything.
A 10$ iron at your local China-Mart and some Lead/Tin 40/60 (Pb/Sn +Rosin Core Flux) solder can produce stellar results in the right hands.
Best of Luck
-Leap
Take your time and get a feel for what you're doing, it doesn't take much to create serious damage to a PCB, so practice first now, to avoid headaches later on.
If you practice enough, hopefully you won't damage anything.
A 10$ iron at your local China-Mart and some Lead/Tin 40/60 (Pb/Sn +Rosin Core Flux) solder can produce stellar results in the right hands.
Best of Luck
-Leap
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try dimming the lights and see if the resisters still get hot.
Nomad will be the best to answer dimming the bulbs.
I know if they burn the board they are mounted on can cause a lot of problems. the last one I did the board was burned but at least I was able to repair it.
I never have understood when the radio suppliers cut so many corners knowing they will have a problem
just like the newer Cobra 148 radios they put a small resister in line to feed the PLL. it gets hot and stops working as far as the radio goes dead. Cobra did put out a repair for this fault for the 148. just took them a few years to take the blame for the resister being to small and not able to carry the voltage.
here is the fix they put out for the 148.
http://downloads.cobra.com/CB/TSB/TSB10002.pdf
Nomad will be the best to answer dimming the bulbs.
I know if they burn the board they are mounted on can cause a lot of problems. the last one I did the board was burned but at least I was able to repair it.
I never have understood when the radio suppliers cut so many corners knowing they will have a problem
just like the newer Cobra 148 radios they put a small resister in line to feed the PLL. it gets hot and stops working as far as the radio goes dead. Cobra did put out a repair for this fault for the 148. just took them a few years to take the blame for the resister being to small and not able to carry the voltage.
here is the fix they put out for the 148.
http://downloads.cobra.com/CB/TSB/TSB10002.pdf
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