Cobra 2000 GTL Counter issue

[Crambone]

Guys my 2000GTL is showing 7.4750 fluctuating up and down but staying in the same range. The clock works perfectly and its doing it in AM/ USB & LSB.
Pin 3 of IC512 shows 35MHz
TP 502 shows 7.799MHz in LSB & USB
CT501 shows no change on frequency meter

 

[nomadradio]

Bad electrolytic caps on the clock/counter board can cause wacky symptoms. The DC power that feeds to the chips on this board must be stable and clean as the driven snow. Any noise pulses on the DC power tend to cause twitchy behavior from one or more chips. And this is what those electrolytic caps are there to do, filter the power to the chips.

If someone has 'tweaked' the slugs of the two input coils this can muddy the water even further.

Bad news is that if you have one or more bad chips on this board, you'll have to change all those electrolytics, just to make troubleshooting possible.

Most likely.

Can't track down a bad chip if the good ones are misbehaving.

The "7.4750" reading is not one of the often-seen typical failures.

73

 

[Crambone]

OK, I replaced all the electrolytic capacitors (Nichicon) but I’m still getting the same. The frequency does fluctuate a bit but not much.

 

[nomadradio]

Really don't know how to troubleshoot this item much further without a 'scope. Only way I ever learned how.

Any way you can get your hands on one?

73

 

[Crambone]

I have a scope just not sure how to troubleshoot this. Also have a signal gen if that helps

 

[Crambone]

Really don't know how to troubleshoot this item much further without a 'scope. Only way I ever learned how.

Any way you can get your hands on one?

73

Got a scope on hand now