repairing a RCI-2990

[KD2GOE]

I am going to be in here a lot.. I am trying to get this radio back to stock.

The radio works but I have no control over SSB power it seems to be full on all the time. on AM it will swing to 200 watts. dead key on low at 3 watts and 30 on high.

I have to have the mic gain set to 2 for AM or SSB or it well be crazy over modulated.

what do I set the Bias to? and do I do that on AM or SSB?

I need a parts list or a detailed schematic

Q32 had been removed
R49 was swapped I need to know the right value right now it has a 33K ohm resistor in there.

as I fined out more ill be back and ill have pics on the way


I am capable of doing most of the work I will be sending it out for a final look over and alignment when I am done.

 

[KD2GOE]

ok this is what I found


(Q32) <<<can be removed for more modulation>>> I need to confirm that it is a 2SC945P is there an alternate part number
Adjust VR14 (AMC) for maximum forward modification. Mod limiter Q32 can be removed for more modulation, but it also disables VR12 (SSB ALC) and disables variable power for SSB. I do not recommend removing Q32; you'll have plenty of modulation as is.

so I need to find a 2SC945P to replace it


R49 stock was 100K ohms I didn't have a 100K ohm so I added 2 resistors to get 97K ohms


one other thing I found was R281 was cut I replaced that with a new resistor

 

[9C1Driver]

Good luck, a 2990 is in the same boat as an old school orange display 2950. If the cpu takes a dump you are screwed.

 

[KD2GOE]

Good luck, a 2990 is in the same boat as an old school orange display 2950. If the cpu takes a dump you are screwed.

o Wow dude thanks for the pickup in confidence.. right on!

good thing I have a spare display board!

 

[KD2GOE]

any how it looks like I had a 2SC945P laying around from my uniden Washington 2sc2999 reserve upgrade... every thing is working good now!! WOOHOO!

and all that it needs for me to do now is the Shockley diode 2sc2999 upgrade, and send it out for alignment.


I love the feeling of a job well done!

 

[jon666]

cool

good job

 

[Robb]

any how it looks like I had a 2SC945P laying around from my uniden Washington 2sc2999 reserve upgrade... every thing is working good now!! WOOHOO!

and all that it needs for me to do now is the Shockley diode 2sc2999 upgrade, and send it out for alignment.


I love the feeling of a job well done!

Congrats!

Yes on the Schottky diodes; no on the 2999 transistor.
You will find out . . .

 

[Shockwave]

The 2950, 2990 board has plenty of receive gain if it's aligned properly. Changing the front end transistor here is not needed. The detector diodes could stand improving. Another interesting thing is I noticed the 2990 has high levels of RF on the mic amp IC.

Inspecting the wiring to the mic gain revealed they had reversed the audio feed and ground connections on the shielded cable. Both ends of the cable from the mic gain to the board had the unbalanced audio feed on the braided shield and the ground connected to the inner shielded wire.

Stupid mistake at the factory but easily corrected by pushing the pins through the connector and reversing them on both ends. The center wire is correct and all wires are making the proper connection. It's just they are using the wrong conductors in the cable and bypassing any RF shielding in the process.

 

[KD2GOE]

Congrats!

Yes on the Schottky diodes; no on the 2999 transistor.
You will find out . . .

well I did it and no I didn't notice anything for the 2999 transistor

are you saying the 2999 transistor will do bad things or just wont notice any improvement?

the main reason I when with the swap was I needed the transistor "2SC945P" from Q16 SSB detection for Q32 "2SC945P". Q32 is the modulation limiter and it was taken out I had a 2SC945Q but it didn't work right.

 

[dreamer98513]

o Wow dude thanks for the pickup in confidence.. right on!

good thing I have a spare display board!

Hello, saw this old post. My 2990 powers up shows frequencies but no receive audio and no transmit power showing on meter, only beeps when mike pushed. Any ideas?

Mike and antenna are fine.

 

[Tokin]

Hello, saw this old post. My 2990 powers up shows frequencies but no receive audio and no transmit power showing on meter, only beeps when mike pushed. Any ideas?

Mike and antenna are fine.

Yeah, its a 7yo thread lol. Welcome to the fun house!
What state are you in? Sounds like you have a bit of a mess. If youre in the Florida area I can refer you to one of only 2 ranger certified technicians in the USA at this time. His name Tony and he owns Mesa cb in Wildwood Fl just south of Gainsville on I75. He can't help you over the phone much though he may be able to answer a few of your questions. Hes a good guy but still a grumpy set in his ways 70 something so dont tell him I sent you lol. Wish I could be of more help.

 

[nomadradio]

A 2990 that's silent on receive and won't transmit suggests two possibilities.

First, a voltage regulator chip gone bad, or unsoldered on one pin.

Second, the PLL has lost its lock on the selected frequency. This will mute the receiver audio and shut down the transmitter when it happens.

Never learned how to troubleshoot PLL problems without a 'scope. If you don't have one available, could be an uphill climb.

Like the man said, the CPU that runs the show has demonstrated a tendency to just die. No replacements exist. The power supply regulator in this radio is famous for running away and jamming 24 Volts into the 12-Volt radio. This has fried more than one computer in this model. Might check DC voltage on the power switch to see that this is not part of the picture.

73

 

[Blackdog202]

A 2990 that's silent on receive and won't transmit suggests two possibilities.

First, a voltage regulator chip gone bad, or unsoldered on one pin.

Second, the PLL has lost its lock on the selected frequency. This will mute the receiver audio and shut down the transmitter when it happens.

Never learned how to troubleshoot PLL problems without a 'scope. If you don't have one available, could be an uphill climb.

Like the man said, the CPU that runs the show has demonstrated a tendency to just die. No replacements exist. The power supply regulator in this radio is famous for running away and jamming 24 Volts into the 12-Volt radio. This has fried more than one computer in this model. Might check DC voltage on the power switch to see that this is not part of the picture.

73

My Eagle 5000 is doing this as well but it will receive or transmit for a few seconds then goes silent. Help me up there Nomad. Haven’t seen you in a few years, hope you’re doing well. 73’s

 

[nomadradio]

Sure enough, everybody here is doing well.

When the Eagle 5000 goes from working to silent, the same causes mentioned above are where to start. The PLL section in this radio is more complex than the radios with a 40-click selector. Those only work in steps of 10 kHz. This one has multiple PLL sections, needed to get the 1 kHz and 1/10 kHz steps. Makes it trickier to track down the cause of 'dropped' lock. Good chance that it goes comatose because the PLL is not locked.

Best possible case would be that a voltage regulator chip failure is what shuts down the PLL.

Plenty of more-obscure things that can go south in one of the PLL sections.

Plenty.

73

 

[James2020]

Good luck, a 2990 is in the same boat as an old school orange display 2950. If the cpu takes a dump you are screwed.

I have a few CPU if need 1