Beginner problems with rci-2990

[sonoma]

a good chance you are in way to deep to try to repair the radio your self. I am in Oklahoma so luck in giving you an idea who to take it to.since you have a mobile try to contact some truck driver to see if they know of a repair shop in your area. that is usually the best way to find out who is doing radio repair work.
giving you a price is hard to do as far as repairing the radio.since it depends on just what is wrong with the radio. be sure to unplug the mic to see if you still have a carrier.
on another radio close by do you hear any thing coming out of it?
is the radio receiving any thing at all when you just turn it on. you mentioned your wife tried to talk to you. did anything come out of it?
does the TX light come on when you key the radio?
so many things you need to verify to at least see what it is doing.

 

[Hollerhunter]

a good chance you are in way to deep to try to repair the radio your self. I am in Oklahoma so luck in giving you an idea who to take it to.since you have a mobile try to contact some truck driver to see if they know of a repair shop in your area. that is usually the best way to find out who is doing radio repair work.
giving you a price is hard to do as far as repairing the radio.since it depends on just what is wrong with the radio. be sure to unplug the mic to see if you still have a carrier.
on another radio close by do you hear any thing coming out of it?
is the radio receiving any thing at all when you just turn it on. you mentioned your wife tried to talk to you. did anything come out of it?
does the TX light come on when you key the radio?
so many things you need to verify to at least see what it is doing.

The on air light lights up and so does the tx light. I could hear her but she didn’t seem very strong and she has no idea how to adjust anything on the radio and I didn’t want to spend a lot of time txing with the antenna because it wasn’t tuned properly. I attached a couple pictures of the meter this morning. I believe one is with mic hooked up and one unhooked. NEITHER is with the mic keyed as I did not have a coax hooked up at the time. The meter is reading lower than it normally does. I think if I would have keyed the mic the meter would peg out

I took a video but it is too long to upload. It shows the way the needle swings w the mic plugged in/unplugged. The meter is consistently higher with mic plugged in. But If memory serves me correctly, the meter was functioning the way it should when I first received the radio

 

[sonoma]

I have been thinking about your radio all night now.
I have not worked on this radio for years but some items are coming back.
this radio is controlled by the cpu on the front of the radio. should have a metal shield on the cpu covering it up, could be getting this mixed up with another radio. but look at the bottom of the cpu and there should be 2 resisters side by side and they are prone tro go bad. they will look burned or just crusty looking. it they have gone bad can cause the same problem you are having. look close and if the are bad you need to change them out. I have just changed them out in the past when working on this type of problem. i think one is a 100 ohm and the other about a 82 ohm. change them out and see if it takes care of the problem.

 

[sonoma]

does it do the key problem on SSB and AM also. at least look for the resisters and make sure they are not going out.

 

[Hollerhunter]

I have been thinking about your radio all night now.
I have not worked on this radio for years but some items are coming back.
this radio is controlled by the cpu on the front of the radio. should have a metal shield on the cpu covering it up, could be getting this mixed up with another radio. but look at the bottom of the cpu and there should be 2 resisters side by side and they are prone tro go bad. they will look burned or just crusty looking. it they have gone bad can cause the same problem you are having. look close and if the are bad you need to change them out. I have just changed them out in the past when working on this type of problem. i think one is a 100 ohm and the other about a 82 ohm. change them out and see if it takes care of the problem.

I will deffinately try and see the resistors when I get home tonight. Thank you very much. I have not tried to key it up on anything other than am since I hooked up the antenna and discovered my problem. I will try that also when I get home

 

[Hollerhunter]

I will deffinately try and see the resistors when I get home tonight. Thank you very much. I have not tried to key it up on anything other than am since I hooked up the antenna and discovered my problem. I will try that also when I get home

Oh and I might add that the channel adjustment knob kind of goes haywire when you turn it. Like skips all kinds of channels. Hard to tell where you might land. And some of the rubber buttons make a different tone of beep when you push them. Like maybe an error beep or something

 

[sonoma]

if the resisters are bad it will cause all the problems you just mentioned.all the channel functions are controlled by the cpu in the front of the radio

 

[Hollerhunter]

if the resisters are bad it will cause all the problems you just mentioned.all the channel functions are controlled by the cpu in the front of the radio

Awesome. Looking better for me. This is a long shot, but that wouldn’t cause the radio to get hot by chance would it?

 

[sonoma]

if the cpu is shorting the finals into TX mode and you do not have it hooked to a antenna is a good chance it is getting hot due to no antenna hooked to it.
with your lack of radio test equipment every time you hook it up you could be making things worse. you sure need a dummy load to hook the radio too so you are not burning the finals up if it is TXing.
anything is possible at this time. so be careful with the radio.

 

[nomadradio]

Okay, so what I'm getting is that the radio transmits as soon as you power it up, and won't allow you to receive at all.

When the computer thinks the mike is keyed, it disables the tuning controls, so you can't change frequency. If it's stuck in transmit mode, you'll be stuck on that frequency.

The way to tell is at the bottom-right corner of the orange LCD display window. A small square outline with the letters "TX" inside it.

This tells you that the computer thinks that you have keyed the mike. So long as it's visible, the computer will, in turn key the radio.

That's how this one is wired. The mike keys the computer. If the computer thinks it's okay, it will then activate an output from the computer board to the radio that actually puts the transmitter on the air. The mike only triggers the computer. The computer keys the radio's transmit/receive switching circuit.

As a general rule, when I see this fault it's because someone found a way to feed more than 5 Volts into pin 3 of the mike socket. Could be someone got frustrated trying to make the built-in linear key properly and hooked up a 12-Volt relay to pin 3 of the mike socket.

Could be that someone wanted an accessory relay to key a ham-type linear without having to use a foot switch. Looks easy. Just connect one side of the relay coil to the main 13.8-Volt power, the other end to pin 3 of the mike socket.

Bad juju.

Whatever the reason, anything that causes more than about five and a half Volts to appear on pin 3 of the mike socket *WILL* assassinate the computer.

5-Volt computer chips are famously sensitive to any voltage higher than that.

You could plug in the wires behind the mike socket wrong, and make it key up, I suppose. Can't think of any other fault besides a blown CPU that does this.

And if the "TX" in the lower-right corner of the LCD display goes away when you unplug the mike, this isn't what's wrong.

73

 

[OldTech03]

Oh and I might add that the channel adjustment knob kind of goes haywire when you turn it. Like skips all kinds of channels. Hard to tell where you might land. And some of the rubber buttons make a different tone of beep when you push them. Like maybe an error beep or something

Just for the record did you happen to turn the RF Power all the way clockwise? If so you may want to turn it all the way counterclockwise as this would be a better place to make measurements as long as there is at least a couple of watts on the meter and it would also let all of us know if the power control even controls power?

The channels or frequency bouncing around is most likely the infamous " Switch contact bounce " RCI could make that go away with higher quality switches but it has been an issue with the 2900 series radios for as long as I can remember, you do get lucky and find 2900 series radio that doesn't exhibit that issue but it is common it may also be that it's not switch contact bounce?. Sometimes if you just slow down how fast twirl the channel knob it's not so bad I have worked on literally hundreds of these and have found this issue in at least half of the radios it's one of the first things I check for to see if it's an issue. Now if your problem persists you may have issues in the regulator/modulator circuit and it was not exactly clear, did you say you tried to hear the radio on your mobile outside but didn't really elaborate on what the results of that did you see signal on the meter in the car when you wife keyed 2990 up and didn't hear her talk or was there some sign of audio coming from her talking it would help to know. There is much that could cause you issues we just need some test

 

[Hollerhunter]

Okay, so what I'm getting is that the radio transmits as soon as you power it up, and won't allow you to receive at all.

When the computer thinks the mike is keyed, it disables the tuning controls, so you can't change frequency. If it's stuck in transmit mode, you'll be stuck on that frequency.

The way to tell is at the bottom-right corner of the orange LCD display window. A small square outline with the letters "TX" inside it.

This tells you that the computer thinks that you have keyed the mike. So long as it's visible, the computer will, in turn key the radio.

That's how this one is wired. The mike keys the computer. If the computer thinks it's okay, it will then activate an output from the computer board to the radio that actually puts the transmitter on the air. The mike only triggers the computer. The computer keys the radio's transmit/receive switching circuit.

As a general rule, when I see this fault it's because someone found a way to feed more than 5 Volts into pin 3 of the mike socket. Could be someone got frustrated trying to make the built-in linear key properly and hooked up a 12-Volt relay to pin 3 of the mike socket.

Could be that someone wanted an accessory relay to key a ham-type linear without having to use a foot switch. Looks easy. Just connect one side of the relay coil to the main 13.8-Volt power, the other end to pin 3 of the mike socket.

Bad juju.

Whatever the reason, anything that causes more than about five and a half Volts to appear on pin 3 of the mike socket *WILL* assassinate the computer.

5-Volt computer chips are famously sensitive to any voltage higher than that.

You could plug in the wires behind the mike socket wrong, and make it key up, I suppose. Can't think of any other fault besides a blown CPU that does this.

And if the "TX" in the lower-right corner of the LCD display goes away when you unplug the mike, this isn't what's wrong.

73

The radio is in receive mode until I key the mic. Then it switches to tx as it should, unkey the mic and it goes back to receive.

 

[Hollerhunter]

Just for the record did you happen to turn the RF Power all the way clockwise? If so you may want to turn it all the way counterclockwise as this would be a better place to make measurements as long as there is at least a couple of watts on the meter and it would also let all of us know if the power control even controls power?

The channels or frequency bouncing around is most likely the infamous " Switch contact bounce " RCI could make that go away with higher quality switches but it has been an issue with the 2900 series radios for as long as I can remember, you do get lucky and find 2900 series radio that doesn't exhibit that issue but it is common it may also be that it's not switch contact bounce?. Sometimes if you just slow down how fast twirl the channel knob it's not so bad I have worked on literally hundreds of these and have found this issue in at least half of the radios it's one of the first things I check for to see if it's an issue. Now if your problem persists you may have issues in the regulator/modulator circuit and it was not exactly clear, did you say you tried to hear the radio on your mobile outside but didn't really elaborate on what the results of that did you see signal on the meter in the car when you wife keyed 2990 up and didn't hear her talk or was there some sign of audio coming from her talking it would help to know. There is much that could cause you issues we just need some test

The rf power knob does not bring the needle down much, if any at all, with the mic keyed or not keyed. The signal sounded like it was very very weak when she was talking to me through the 2990. Like she was in Ohio and I am in central wv. Sounded very weak. The mic I have is a d104 silver eagle. Could this have caused problems with the computer and over driven it?

 

[Hollerhunter]

The radio receives very well. It has clear audio and very solid sound on recieve

 

[OldTech03]

The rf power knob does not bring the needle down much, if any at all, with the mic keyed or not keyed. The signal sounded like it was very very weak when she was talking to me through the 2990. Like she was in Ohio and I am in central wv. Sounded very weak. The mic I have is a d104 silver eagle. Could this have caused problems with the computer and over driven it?

Ok, it may have sounded weak but was it? If receive signal on the radio you were listening to her on was pegged as it should have been sitting right outside the house then the transmitter is probably working? "A watt meter would be nice". The low mod or nearly none could simply be the main regulator is the issue. The D104 should not be an issue unless it's not working or the battery is dead or missing? I DON'T KNOW. If I was making a guess at this moment it sounds like the REG/MOD circuit is the problem since it sounds like the RF pwer control is not making any difference and the modulation is none existent most likely the main regulator shorted?

OldTech