Sync Problem

[vts1134]

Originally Posted by old_coot88

That's a huge ripple in the B+ supply to the sync and horiz. osc areas, caused by a bad filter cap (or caps).
The sync loss appears to "come and go" due to the slight difference between the 60hz powerline frequency and the vertical sweep rate.

Of course it is! I feel like I should have recognized that .

Originally Posted by earlyfilm

VTS,
You are in no way ready to start a horizontal alignment on this set until you fix this problem.
James.

I figured that was the case. I knew enough to know this wasn't a normal state of affairs, just didn't put the puzzle together.

Originally Posted by earlyfilm

A oscilloscope might be a help in narrowing the problem, especially if it is from a wiring error made while recapping.


James.

I'd like to use my scope on this one to learn more about how it functions. It sounds like the problem could be coming from a bad electrolytic, a wiring error, or an HK short in a tube. I test every tube in every set I work on as one of my first steps so I will say that is the least likely candidate (of course not impossible though). I have replaced every electrolytic in the set so that is the next possibility, but the most likely would be a wiring error. I can look for a wiring error manually, but if I wanted to use a scope to check wiring error or bad electrolytic how would I do that? Bear in mind I have no formal training in how to use a scope at all, but a great desire to learn.

[old_coot88]

Since you've replaced all the electrolytics (and verified they're all in correct polarity), i would tend to suspect wiring error at this point. Does the schematic show any of the electrolytics "floating" (ie., not connected directly to chassis ground)?
Is this set the RCA 630ts that was having the low B+ issue?

There are a number of good oscilloscope tutorials on Google. But the problem at hand should be easy enuff to resolve without a scope.

[Geist]

Hi All;
Since I have taken out all my Electrolytics on my 630, I can speak to this.. And the answer is that there are "two" caps that are Isolated from Ground, on top.. C220 and C222 and "two" that are underneath the cabinette.. C221 and C225.. All four of these are not connected to ground, but If I remember correctly there is a Ground connection to one of the caps, for a reverse polarity.. The can is positive (in comparison to the other caps).. I would recheck all wiring against schematic, make a copy of your schematic on another paper(s) and as each wire is checked, draw thru it with a marker, your choice of color.. I prefer yellow markers, but blue also works..
THANK YOU Marty

[Geist]

Hi All;
VTS, I have looked at your old postings, So, I have some questions .. In your Bleeder Resistor -- What did you use or replace the Bad Bleeder or Bleeders with ?? Check, to make sure that not only you have the correct value but also wattage.. and of course wiring.. Your next posting was asking about your power supply/ bleeder voltage.. What did you find there ?? And what did you do to correct that ?? Either one of these issues could possibly be the cause of your current problem.. Retrace your work against your schematic.. and get the Riders/RCA manual for the 630.. It may give you additional insight into something.. Once I get my Caps taken care of, I may be looking at some of the same issues.. As I have a couple of the bleeder resistors to replace as well, just not the same ones as you have.. And a Ton of wires to re-connect to the right/correct place.. Not that it will help, it may not, but I took alot of pictures, while taking each cap out, before and after I removed each wire, until the cap had no wires on them.. Starting with the cap fully wired.. I know I have some wires to replace, as the insulation came off.. Good Luck !!!!
THANK YOU Marty

[vts1134]

Originally Posted by old_coot88

Since you've replaced all the electrolytics (and verified they're all in correct polarity), i would tend to suspect wiring error at this point. Does the schematic show any of the electrolytics "floating" (ie., not connected directly to chassis ground)?
Is this set the RCA 630ts that was having the low B+ issue?

There are a number of good oscilloscope tutorials on Google. But the problem at hand should be easy enuff to resolve without a scope.

I tend to think wiring error also, nobody's prefect least of all me . There are four floating electrolytics and two which are at ground.
This is the 630 with the low B+. I went through section by section and found where it was bogging down and fixed that problem.
I did find some nice tutorials on youtube about scopes. I think I'll keep this set out of the cabinet for a bit after I'm through with her and get some practical experience.

[Geist]

Hi All;
What did you find that was bogging down the power supply ?? You said that you found it, but didn't say what it was..
I would also suggest (If you do not have it already) that you get the Riders/RCA Manual for the 630.. Phil Nelson has a link from his site.. The Riders show where and the path of each of the wires, (Sometimes its hard to follow) but it all seems to be there.. and by following that you can find where each end is connected to.. Check with an ohm meter and mark it on a seperate piece of paper, as done and as wired correctly.. That seperate piece of paper should be a schematic.. Please let us know of your progress and what you did and what you found that was wrong.. It may help the rest of us when we have to go and do the same kind of thing in our sets..
THANK YOU Marty

[old_coot88]

Originally Posted by vts1134

...There are four floating electrolytics and two which are at ground.

Um.. if they are at ground, they wouldn't be floating.

This is the 630 with the low B+. I went through section by section and found where it was bogging down and fixed that problem.

Just curious, what wuzzit?

I did find some nice tutorials on youtube about scopes. I think I'll keep this set out of the cabinet for a bit after I'm through with her and get some practical experience.

Excellent idea. Become reasonably proficient with the scope first, then it can be a useful tool in troubleshooting (such as looking at the waveform of ripple on a B+ line and measuring its amplitude).

[Geist]

Hi All;
Old Coot, I think what He is trying to say, since I have the same set and the same schematics, is that out of the Six Electrolytics, Four are Floating and two are grounded.. Not that two are floating and grounded at the same time..
THANK YOU Marty

[old_coot88]

Aha! Makes perfect sense now.

[vts1134]

This capacitor was the problem. I thought I had gotten all of the caps the first shot around but this one snuck past me.



It was C169 in the schematic below. The picture is rock solid now. Time to move up the chain and improve the picture and sound.

[vts1134]

Originally Posted by old_coot88

Just curious, what wuzzit?

I think it must have been a tin whisker. I went though the set section by section removing B+ to one area at a time until I found where it bogged down. The problem area was in the lead to the tuner, however when I re-soldered the lead back in the problem disappeared.