Jeff,

What ship are you working on?

We have a pair of CV-3510As at the AWA Museum, but I've never had a chance to check them out.

On 08-Mar-23 23:39, Jeff G wrote:

The demod board is a mess, mostly around the bandpass filters. It actually works...mostly...but for example, if I feed a solid 1575hz mark signal to it from a signal gen, it'll be good for maybe a minute or two, and then "fade" out. 1-2 mins later, fades back in again. When its good, it decodes and prints, but then out of the blue, it fades and just stops printing for 1-2 mins, and starts printing again.I think it's adjustments, but the manual is fairly hard to follow in this regard. The patterns on the CRT look like a trippy 1960s disco video vs what I expect.

Sounds like a bad connection/solder joint. When things heat up, connection is broken. When cools down, connection is remade and thing work OK. You just need to follow the circuit to see where it quits. Or try poking at the board when it quits to see if you can make it come back..

Also the CRT is very dim; heater voltage looks OK, and I have the brightness as high as it'll go.

That is typical of the old CRTs. I've replaced the CRT in the Museum's Dovetron a couple of times in the past ten years.

Good luck & have fun,

Duncan Brown, K2OEQ
USASA 31J30

i-Telex: 212503

Antique Wireless Assoc. Museum,
Asst. Curator, Commercial Equipment
(also chief TTY op & repairman)

www.antiquewireless.org