RCI 2995DX CF troubleshooting help needed

[michael178]

rci 2995dx cf 2 channel or same channel help

If I'm listening to channel 6 then I go to channel 7 It is same channel than 6 same as ch9 it same ch10 and ch28 same as ch 29 I need help

 

[Eldorado828]

rci 2995dx cf 2 channel or same channel help

If I'm listening to channel 6 then I go to channel 7 It is same channel than 6 same as ch9 it same ch10 and ch28 same as ch 29 I need help

A little background on the radio would help. Is it new? Has work been done to it? Did it just start doing it out of nowhere? Etc

 

[BC Coyote]

If I'm listening to channel 6 then I go to channel 7 It is same channel than 6 same as ch9 it same ch10 and ch28 same as ch 29 I need help

Check that you don't have the +10 KHz switch turned on. It should be off for normal operation.

 

[nomadradio]

Do you have access to a frequency counter? A way to read the actual channel that it transmits on would be a good start.

Has anyone been tweaking internal adjustments? This is not a common problem in that radio, but if someone twisted the wrong tuning slug, odd things could result.

73

 

[michael178]

A little background on the radio would help. Is it new? Has work been done to it? Did it just start doing it out of nowhere? Etc

I purchased this unit from Ebay. The seller said that this receiver is working fine but it does have a bad amp. When I received the unit? I check it out Amp it was not working. But the problem is on the AM band with the receiver same channels I could hear same if I went channel up or down more on the up channel from the channels I am trying to listen?
When I was checking the circuit board, connecting, wires, any new solder all that look good. But someone was inside the unit to try to repair the amp. So that is what I know so far. That is why I am stuck on this problem?
I did some troubleshoot the CPU board I replaced it and still did not work.

 

[michael178]

Check that you don't have the +10 KHz switch turned on. It should be off for normal operation.

To my knowledge this receiver does not have a 10KHz switch on the front panel.

 

[michael178]

Do you have access to a frequency counter? A way to read the actual channel that it transmits on would be a good start.

Has anyone been tweaking internal adjustments? This is not a common problem in that radio, but if someone twisted the wrong tuning slug, odd things could result.

73

Yes I do have a frequency counter I ck on channel 6 Tx and it is on money.
could you tell me which adjustment they should not touched i will ck to see if there is any damage. Thank You

 

[brandon7861]

rci 2995dx cf 2 channel or same channel help

If I'm listening to channel 6 then I go to channel 7 It is same channel than 6 same as ch9 it same ch10 and ch28 same as ch 29 I need help

If I understand this correctly, you have doubling of the channels, but only every two channels. So 6 and 7 are the same, 9 and 10 are the same, and 28 and 29 are the same, but 7 is not the same as 9. Is that correct?

This sounds like the least significant bit of the binary is not registering, but I imagine this symptom could be caused by other things besides an internal PLL failure. Maybe the micro output is being corrupted, maybe a delay in the enable line could be truncating the serial data, or maybe a PLL configuration setting from a bad memory register got flipped. This may turn into an o'scope job (after a day in the datasheets to understand what those signals should look like).

 

[loosecannon]

ive seen the channel encoder on these things go bad and cause strange problems like this.

they use a very substandard encoder on these radios, and some users just spin them like they are a VFO and can wear them out.

still just a guess though.

if you want to try a replacement, there is a place called Barkett Electronics that may have one in stock.

if you can take a picture of the channel encoder for your radio from inside the radio that could help us pick one for you.
LC

 

[nomadradio]

Some 2990 type radios in the 90s had a surface-mount resistor stuck on a mixer chip in the PLL where it didn't belong. Caused the radio to hear channels every 10 kHz up and down from the selected channel. And transmit this way as well. The fix was to unsolder a surface-mount resistor from under one chip, bridged across two adjacent pins. Never tried to look at the schematic to figure out how it caused this. Went to look for our notes about how to undo this factory boo-boo a while back and couldn't find them. The PLL in this radio is not so complex as the 1990s versions. Just makes me wonder if there isn't an open capacitor in there somewhere.

73

 

[michael178]

If I understand this correctly, you have doubling of the channels, but only every two channels. So 6 and 7 are the same, 9 and 10 are the same, and 28 and 29 are the same, but 7 is not the same as 9. Is that correct?

This sounds like the least significant bit of the binary is not registering, but I imagine this symptom could be caused by other things besides an internal PLL failure. Maybe the micro output is being corrupted, maybe a delay in the enable line could be truncating the serial data, or maybe a PLL configuration setting from a bad memory register got flipped. This may turn into an o'scope job (after a day in the datasheets to understand what those signals should look like).

I do appreciate to answer my question I do Thank you. But is correct Ch 7 is not same as Ch 9. but I do not know if the hole AM band is doing same thing the AM band has been very quiet so only Channels I could hear.

Is there anything I could do check maybe voltage or parts. Thank You

 

[BC Coyote]

AM band has been very quiet

You may want to check your receive as well. The entire CB band has been very busy with signals most of this week. You should at least be hearing stuff on 6, 11, 19, 28 etc. If those channels are quiet too you may have more than one issue.........

 

[michael178]

You may want to check your receive as well. The entire CB band has been very busy with signals most of this week. You should at least be hearing stuff on 6, 11, 19, 28 etc. If those channels are quiet too you may have more than one issue.........

Yes but in East NC most of the time it been very quiet. I do have another system set up so I can listen to compare the receiver AM band it is working good I just have channels problem but I did Eject RF signal into the hole AM band has issue all of the channels it look like are doing the same thing. I was thinking if the cause is the PLL IC2 MC145162D what do you think?

 

[nomadradio]

If you have a second radio, see if it hears this radio transmitting on the same "extra" channels that it's receiving. Would go a long way towards focusing on where to look for the fault.

73

 

[michael178]

If you have a second radio, see if it hears this radio transmitting on the same "extra" channels that it's receiving. Would go a long way towards focusing on where to look for the fault.

73

I do appreciate your help. Thank you.

To your question? Yes, ok when I transmit I same channel like ch6 and I put my spare receiver on same ch6 I have no problem. Then when I change channel on the spare radio to ch 7 I do not receive signal the only thing I hear is a low crackling audio.