2950 not working

[longhaireddwb]

I just bought a rci2950dx from a electronics guy here in town. He had it sitting on his shelf for a few years and has no interest in radio. He said it didn't work when he got it and thought that maybe the PLL was bad so he replaced it and it didn't help. He put it back on the shelf and I bought it from him for 60.00. It is showing power on my watt meter when I key up but when I key up into a frequency counter it is showing a long ways off from what it should. With the radio set on 27.185 or 28.000 I'm getting a reading of 20.950. I know that he put in the PLL correct as that is the stuff he does for a living. SMT.

So I guess what I need to know is where should I go from here? Can anyone point me in the right direction to test what is needed next? I will need to buy parts but it would be nice to do some testing first. I have fixed a dozen cobra radios in the past but never messed with a 10 meter radio. BTW, This one has been opened up for 11 meters.

 

[RADIOOMAN]

Ranger RCI-2950 Service Manual

 

[MudDuck442]

Check the rig for the KIA7310P ICs, if present, order up some TDA7310P. For some reason they go bad or get flaky over time. And yes, I know it doesn't make sense theoretically that they would, but THEY DO. Replace the KIA's with the TDA's and then check both VCOs to make sure that the reference crystals are oscillating. (if not replace them) You can even use an HF rig nearby tuned to the appropriate frequency as a "probe" if you don't have a frequency counter available and when you set the VCO frequency, do it by "zero beating". Of course, make sure that your voltages are correct on your test points as well by going through the alignment procedure. This will tell you that both VCOs are working correctly. I'd be willing to bet i once you have done all of this and checked these areas you will get it to "lock". Then just finish the alignment procedure and it should come to life. If not, let me know and we can go through it step by step.

 

[longhaireddwb]

Thanks for the reply. Ill check into that next week when i get home.

 

[Captain Kilowatt]

Somebody may have attempted a 15m mod to that radio. Check and see if the expansion module is installed and also check the expansion pins on the back of the display board. There should be no jumpers if the radio is using the E-chip expansion module.

 

[longhaireddwb]

No expansion modual. Thanks for pointing that one out. As far as the chip (tda7310p) om not having any luck finding this chip online. They are discontinued.

 

[MudDuck442]

Did you check to see if it already has the TDAs? Some did some didn't. Also check the VCOs and make sure everything is locking. Sometimes if you are lucky a simple alignment can bring it back to life.