RCI-2980 frequency counter issue?

[Cable Guy]

Hi guys, I have been working on the above radio and noticed that during power up, the on-board frequency counter flashes random numbers, then the correct frequency, then random, then correct, and so on for about 5 seconds, then works correctly. I assume it's a counter issue, as the radio is RX on frequency during this period. It is almost like it's trying to flash some codes like a POST code after boot. Is this an issue that anyone has observed before? This radio has the ept3600-14b main board, I don't know when it was manufactured. I did find a faulty electrolytic cap in the af amplifier chain and faulty ta7222ap, could this be a capacitor issue inside the counter enclosure? Thanks for reading my inquiry.

 

[Cable Guy]

I also have been told the power supply can fail in this chassis and supply full unregulated voltage to the main board, frying the CPUs. I have a 30 amp supply I can retrofit into this radio, same as what the 2995dx has. That should be interesting, if necessary. Good day.

 

[Cable Guy]

Is this thing on? Can I BE anymore dismissed? I got it, thanks.

 

[jrd426]

Hello Cable Guy. I have the same radio and also plan to transplant in a new power supply maybe as a winter project before the stock one packs it in. The counter module used is the same as in many other radios using that same main board. I assume you already checked all connections to and from the counter module including cold solder joints. I know there are old threads here that discuss the frequency counter and its common faults. Use the search box and you will likely find alot of related info in this.
Enjoy the weekend

 

[Cable Guy]

I ain't sore, just figured someone could've said that a month ago. I use the search box and can't seem to find much info or anything about the fc being the same across many units. I only heard about the power supply issue from a post elsewhere but it didn't offer any more info and a search was futile unless im missing something. The search tosses out anything less than 3 characters so that makes it a little more difficult but im probably missing something there too.

 

[nomadradio]

Don't know what year the 14B main board was first used, but I'm pretty sure it was after they stopped using the "large" counter module. That one is particularly failure prone, especially as a result of being 30-plus years old. The older "large" counter module was mounted alongside the far right-hand side rail of the chassis. The 'large' module uses an old-tech dedicated TC5032 counter chip, same as the Cobra 2000 and dedicated circuits with a mixing crystal to translate the radio's VCO frequency to the selected channel frequency.

The 1995 update to the counter module shrunk it down to about two by three inches, mounted on a right-angle bracket at the front edge of the radio chassis. This version uses a microcontroller chip to do the display arithmetic with far fewer parts. Pretty sure that one displays all "8s" when first powered up.

But for now, we still don't know for sure which counter module you're trying to straighten out.

73

 

[Cable Guy]

But for now, we still don't know for sure which counter module you're trying to straighten out.

It was the first you mentioned, vertical mount on the right side. I recapped it and it straightened out. Thank you nomad. That rig was old, but I think it may have been rebuilt using different parts as there were header connectors on the rear panel but the wires were cut inside the cabinet. No location I could see where they may have connected inside. There were around a dozen wires on that header.