[GreenKeys] Navy CV-3510A Converter Repair/Recap

[Jeff G]

Duncan, I'm working on the Battleship NJ. Yeah after doing through the
manual some more with my work laptop and a full version of Adobe, I found
that you really need to have certain parts of the manual available
side-by-side, as the board silkscreen only shows test points, and even
then, half of them are UNDER the parts, so you'll see "TP 2"... and find
out it was TP21. The other reason for needing the diagrams is the chip
numbers are not labeled on the boards - you need the diagram from the
manual to show what's what.

I printed all the various board diagrams and read the operations
description of the bandpass filter, so I have a better understanding of
what it's doing. I do think its really just adjustments, although it's
still a little weird in how they describe it. For example, the manual reads
"adjust xyz for minimum AC using oscilloscope", yet the scope shows a
digital/square wave on that test point, sooo not sure what to do there.

I also looked up the spare CRT I have (3BP1) and found out (Despite what
one would think) that the 3BP1 CRT has a different pinout from a 2BP1, so
no bueno for testing there. I had to set it aside for a few days to take
care of some things around the house, but may play with it later tonight or
next week.

Jeff KC3GJX



On Thu, Mar 9, 2023 at 10:54 AM Duncan Brown <duncanancy at earthlink.net>
wrote:

> 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)
>
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