Newbie's First Questions RCA TS 721 Restoration

[Chris K]

I'm back my new friends. Picking up where I left off. I have sound now but I've lost the HV. Crap! Not sure what I did in rearranging some wiring on the electrolytic caps but there's no HV. I guess I'll have to start by opening the cage once more and check the flyback for continuity then go from there. The HV circuit is the simplest and first area the power hits so I'm not sure how what I did to get audio caused this. Pin 8 on the damper and socket 10 on the CRT feed are supposed to be about 340V DC and I'm getting about 100V less than that.

[old_coot88]

Originally Posted by Chris K

Pin 8 on the damper and socket 10 on the CRT FEED...

Chris, a suggestion. Er, more like a recommendation. When calling out 'pins', put in parentheses which element a pin goes to. Like, cathode, plate, G1, G2, filament. It'd be a huge help to the reader.

For instance, pin 8 of the 5V4 damper is cathode. Pin 10 on the CRT is Grid 2 (or just G2).

Actually, I prefer calling out the element first, with the pin number (in parentheses of course) left optional.

[Chris K]

Will do...actually, I have both HV and sound now but, again, no picture. Oy veh! I tried playing again with the ion trap but to no avail. Maybe I should walk from this one for now???

[Notimetolooz]

How do you know that there is HV?
Once you have something like the ion trap adjusted it isn't useful to go back and mess with it without a logical reason.
If the HV is OK and the set had raster before then something like the voltages on the CRT socket have changed. Check them.

[Chris K]

Originally Posted by Notimetolooz

How do you know that there is HV?
Once you have something like the ion trap adjusted it isn't useful to go back and mess with it without a logical reason.
If the HV is OK and the set had raster before then something like the voltages on the CRT socket have changed. Check them.

I checked the anode with a HV probe...5 KV which is what I had before when I had a picture. I can't keep the ion trap on because this CRT is not attached to the chassis and it needs to be removed whenever I want to turn the chassis on its side to do work or analysis underneath although I did mark position and orientation on the trap and CRT neck with a Sharpie. I had a pattern from a signal generator before. I'll check the CRT voltages. Thanks!

[Notimetolooz]

You might want to download a book here. "How to Troubleshoot a TV Receiver" by Johnson. It is too big for me to make into an attachment.
https://worldradiohistory.com/BOOKSH...helf_RIder.htm

Look about half way down the page and on the right for a book with a blue cover. It has some good pictures and explanations of problems. It probably doesn't help that much at the moment but it may in the future. Published in 1953, so for a much later set it may not be accurate.

[Chris K]

Originally Posted by Notimetolooz

You might want to download a book here. "How to Troubleshoot a TV Receiver" by Johnson. It is too big for me to make into an attachment.
https://worldradiohistory.com/BOOKSH...helf_RIder.htm

Look about half way down the page and on the right for a book with a blue cover. It has some good pictures and explanations of problems. It probably doesn't help that much at the moment but it may in the future. Published in 1953, so for a much later set it may not be accurate.

Oh thank you so much! yes, I need learned instruction and guidance!

[Chris K]

Originally Posted by Notimetolooz

You might want to download a book here. "How to Troubleshoot a TV Receiver" by Johnson. It is too big for me to make into an attachment.
https://worldradiohistory.com/BOOKSH...helf_RIder.htm

Look about half way down the page and on the right for a book with a blue cover. It has some good pictures and explanations of problems. It probably doesn't help that much at the moment but it may in the future. Published in 1953, so for a much later set it may not be accurate.

What a treasure trove! Thank you! I've downloaded several of these online books. Amazing basic information and believe me, I need it!