HV load for test - Videokarma.org TV - Video

DaveWM · #1 11-11-2013, 12:25 PM

I have a color set that I need to do some checks on the vert circuit, since it needs boost voltage I need to keep the FLY working.

I don't want to hook up a CRT but just the yoke so I can scope around. I was thinking of just hooking up the HV Prob to the anode lead (well insulated of course). Its a zenith which uses the pulse regulation on the fly rather than the shunt tube type.

its well regulated and I can set it for about 22kv no load with the HV setting.

old_tv_nut · #2 11-11-2013, 03:31 PM

Not sure if the HV probe will provide enough filtering like the CRT dag would. If it doesn't, not sure if that's critical or not.

old_tv_nut · #3 11-11-2013, 03:36 PM

Just saw the comments over in B&W, and I agree - no HV load should not be a problem for running the set; but I'm not sure about connecting the HV probe (concern for the probe, not the set).

DaveWM · #4 11-11-2013, 04:19 PM

well I think its the vert out trans, it was sputtering in the audio, would colapse,jumpy vert scan then if finally gave out, and the HV went away as well. My guess is it was killing the B+ with a short, maybe in the convergence windings. I unplugged the convergence and the HV came back, the scan is about 1/2 what it should be but no more sputtfering around or colapsing.

I have a 1076 that I can try driving the vert out trans with, but at this point I need to check a few more things. the Screen voltage on the vert out was only about 1/2 the voltage it should be, not sure if its drawing massive current or if a resistor has gone high, but it would be a lot easier to work on with the chassis out. Its a combo so I guess I could try mounting the chassis back in and working thru the service saver, but its a major pita being a combo.

Findm-Keepm · #5 11-11-2013, 09:42 PM

Dave, what chassis/make/model? I have a stack of old PF Reporter/Electronic Servicing and E-T/D magazines with the old Symcure pages, full of vintage repair tips.

My CTC16 was repaired twice with help from those pages - first with an AGC coupling cap problem and then with a horizontal drive issue with an open ceramic cap.

Cheers,

DaveWM · #6 11-12-2013, 06:51 AM

http://www.youtube.com/watch?v=Gwuiv...CVtyRrqXVtll-g

I think I am getting close, by part 4 I found an open power resistor that was in the plate circuit of the vert out tube. It was hard to find at 1st as the vert was still partly working, after trying to check some other stuff if finally opened up completely losing all vert, after that it was easy to find the problem.

I still need to check the decoupling cap (18uf) off that resistor to make sure its not shorted which could of course take out the resistor as well.