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

[kvflyer]

Originally Posted by 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

I restored my TS630 a few years ago. Whilst it works well, I should see if the 39 ohm cathode resistors on the video IF tubes have gone high. I don't remember if I did that. Many of the resistors were still within tolerance. But, it's been a few years ago. Thanks.

[Chris K]

Thanks all for your helpful suggestions. I’ll get back to the tv this weekend and post what I find. This is a beautiful example and has the matching original stand/table and magnifying bubble. If I can get it working well, I’ll go all in on a full restoration of the chassis, cabinet, table and magnifier.

[kvflyer]

A note on the set that I restored, I have posted this before. Make no mistake, I am well aware of electrolytic capacitors that can go south, especially if they are about 80 years old.

I will say that in my 630TS, it was obvious that the electrolytic capacitors in it were from two different manufacturers and I will refer to them as a style. You could tell because the bottoms were two different styles. I found that one of the style absolutely did not respond to reforming. It continued to leak even after slowly bringing up the voltage. When I unwound the paper, it was obvious that they were bad and had gotten hot.

Now the other style, responded very well and as they were reformed, they had the equivalent leakage and value of a new capacitor. For the one style that leaked, they were uncrimped and new 105°C capacitors were stuffed into the cans. After testing to ensure that all was good, I re-crimped the bottom and installed them.

The ones that reformed were left alone and still work to this day. Mind you, when I tested them, they were completely out of the circuit; all components or wires removed.

Had I restored this set for someone else, I would not have been inclined to leave 1946 manufactured capacitors in place. But every wax capacitor was methodically replaced and mica caps left alone.

Just me, "Your mileage may vary" as they say.

[Chris K]

Agreed and I am going to restuff them but I didn't want to go through the effort until I had video...which I do from the plate of the second detector V114A. I don't have it when I inject it to the cathode of the same.

[Chris K]

Originally Posted by bandersen

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

I have video on the CRT injecting at the plate of the 6AL5 pix 2nd detector. When I inject into the cathode of the same there's no video. I've swapped tubes 3 times and all three test OK. Wiggles don't change anything either.

[Yamamaya42]

Originally Posted by Chris K

I have video on the CRT injecting at the plate of the 6AL5 pix 2nd detector. When I inject into the cathode of the same there's no video. I've swapped tubes 3 times and all three test OK. Wiggles don't change anything either.

To input a signal at the cathode of the defector, you have to match the IF frequency and level it's expecting there. The BK Precision 1077 can do this, but it's a lot more touchy injecting an IF signal than inputting straight video.

[Chris K]

Yes of course. I’ve done this before. Don’t know what I was thinking!

[Chris K]

An update...The IF string is fine. I injected an IF signal just after the T2 converter transformer through the entire video IF circuit and I have a strong video image on the screen...distorted of course because I've done nothing as far as capacitor replacement and testing any further than the power and deflection circuits, but a good video output from beginning to end. So it looks like the next step is to focus on the tuner. I guess I'll check tubes and antenna connections first and move on from there.

[Chris K]

Lord Almighty...loose tube and dirty tuner. OK, well at least I know everything in the video circuit is good and I can start working on the electrolytic caps. What a stupid rabbit hole!