Another 630TS On the Bench

[Chris K]

Was never able to track down the horizontal sync flakiness in the one I was working on during the summer. It got put aside until my enthusiasm gets recharged. I have another I'm working on with a slightly different approach. I'm taking Penthode's advice and putting some initial trust in the slow reform I did on the electrolytic caps in this chassis. The cans are typically the first thing I went after in a restoration but this chassis is something of a mess, all there but a mess, and I didn't want to start restuffing cans until I had a few functionality benchmarks confirmed. I've actually been restuffing the wax paper and foil caps in the power supply and horizontal/vertical deflection circuits first going after good HV and full deflection. It's actually not too bad. Really messy but not too bad. Heat gun, melt out the wax, pull out the paper/foil innards, cleanup the tube and restuff it with a modern MPT capacitor. I seal it with hot melt glue and color in the ends with a Sharpie. Going well so far.

Last night I hit the first stop sign. I hooked it up to my Sencore video analyzer and I got sound but no video. All of the tubes have tested good but I haven't done any recapping in the sound or video IF circuits as of yet. There aren't that many anyway and I don't want to move forward until the circuit is passing video. I'd like to skip forward in the analysis process and use my B&K 1077 analyzer and use it correctly which is something I haven't done successfully in the past. Here is the circuit




So, here's where I've been instructed to begin the process (using my 5" electrostatic test CRT). Inject the video signal at max output from the 1077 into the grid of the video amplifier. Of course, there are 2 video amp stages. If I go in the 6K6 first, am I going to get enough amplification of the video signal to make sense of anything? Hopefully, if I start with the 6AU6 injection and get an image I can start to move upstream. Do I need to remove the first upstream video circuit tube from the injection point to get the best image?

I'm sure this will be another delicious, dizzying and fruitless ride but I'm gonna try anyway!

Thanks!

[Yamamaya42]

I went through this with my FADA 895, the signal at the G1 of the 1st video amp is pretty much near composite video level, so it will take it very well, a bane of these sets have always been failed peaking coils, so don't be surprised to find open ones like I did.

[Chris K]

Ok thanks. I have several parts chassis for this and I can usually find what’s needed.

[bandersen]

Also common for the 270pF coupling mica caps to go bad. You can leave all the tubes in circuit when injecting.

[Yamamaya42]

Not to mention the 39 ohm cathode resistors on the video IF tubes, they were all way high on mine, I still need to try an alignment on mine one of these years, it works, not as well as it could, no snow seen with no input and peak best picture does not match peak best sound, :/ these silly split path sets.
But at least it will pick up local FM radio if I tune it slowly with a long antenna! :P