Cobra 2000 GTL frequency counter issue

[nomadradio]

use a Dremel and cut the pins

Much safer to use a diagonal cutter with sufficiently thin and sharp jaws to clip the pins at the shoulder, up against the plastic. Much less risk to the circuit board. Too easy for a Dremel to get away from you.

73

 

[nomadradio]

By gum, it worked! The fix from TSB1232 and new caps did the trick. No more 32 MHz.

Gotta love it when a plan comes together.

73

 

[Cable Guy]

By gum, it worked! The fix from TSB1232 and new caps did the trick. No more 32 MHz.

Gotta love it when a plan comes together.

73

Great job, do you remember if the 32 MHZ changed in 10 khz increments when changing channel?

 

[Cable Guy]

Probing deeper, and all things being equal, the IC506 5032p pins 12 & 13 aren't outputting a signal whereas the working counter does emit some timing signal spikes. I think it's either the IC506 or the chip it feeds, IC503. Checked both in the same mode with the same vco input. I might as well replace the IC506. It now only displays 33.3333 regardless of mode or channel.

 

[Cable Guy]

Got a socket in today, replaced the IC506 and she's counting on all fingers again.

I think one finger is longer than it should be, reads 500 hertz high and CT501 won't adjust any lower. I see X501 is running about 250 hertz lower than the stated 10.4858 mhz, maybe it's aged, maybe I can nudge it? I will try.

 

[Cable Guy]

Yep, C537 was a 56pf, replaced it with the schematic value of 47pf and it's adjustable to spec now. I love it when things work out like that.