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#32
02-28-2021, 09:56 PM
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Gents,
As of todate, I've replaced all the resistors and capacitors on the vertical oscillator and balance amplifier and the thin white line remains. I've check both vertical sawtooth waveforms and they are both identical 180 degree out of phase. All the high voltage rated capacitors (6KV) used for deflection were replaced last month. Cheers 
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#34
03-01-2021, 11:12 AM
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But could the CRT really be causing it? Seems kind of unlikely to me, but then again, I have little experience electrostatic deflection TV sets, beyond working on oscilloscopes.
BTW, I'm NOT a gent! 
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#35
03-01-2021, 11:29 AM
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Quote:
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| Audiokarma |
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#37
03-01-2021, 11:52 AM
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Is there waveforms provided with that schematic? I see something on there marked point V, right out of the video det, before the video amp, and if it is anything like most sets I have seen, and the video signal there is about 1.1v ptp, one could try coupling in an external monitor, and see if the video is clean there.
I did this on my FADA. It will rule out any problems there and before that point.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#38
03-01-2021, 12:41 PM
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Hello,
I will compare with the waveforms provided in the Admiral chassis 19A1 schematic. Unfortunatly, I don't have an external monitor. I disconnected the coupling capacitor c43 .05 mf and the thin white line remained. Cheers
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#39
03-01-2021, 12:48 PM
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Quote:
And since the line moves with the vert centering adj., the blip has gotta be modulating CRT beam intensity. I still say look for the blip on pin 5 or 9 (focus anode and accelerator(?) anode respectively.
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#40
03-01-2021, 12:57 PM
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That pretty much rules out that it's coming from any video source, you could try hooking an oscilloscope to c32a/ the brightness pot, while c43 is unhooked, there SHOULD be nice clean power there, and that will rule out any PWS issue, I doubt that is the problem, but you never know.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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| Audiokarma |
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#41
03-01-2021, 01:21 PM
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This may be way out in left field, IE making a wild guess here, as I said, I have not worked on this type of TV before, could this possibly have something to do the HV power supply being off frequency (too high/low) and causing an odd resonance on the screen?
There only seems to be the .005 cap on the line, and if the osc is somehow de-tuned a bit, who knows what weird stuff it may do.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#42
03-01-2021, 01:38 PM
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Hello,
I will look for the blip on pin 5 or 9 knowing there are some high voltages. I'm trying to figure a way how my scope will be able to read such voltages without causing any damages to the equipment. Please advise me. Cheers
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#44
03-01-2021, 01:51 PM
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Quote:
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#45
03-01-2021, 01:58 PM
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I wouldn't want to advise you on using a scope considering the voltages present.
As an alternative, I would do this - take a cap of .1 uf or higher, and jump it from pin 5 to ground and see if it kills the blip. Then from pin 9 to ground and see. Try the cathode too for the heck of it (pin 2). But as a precaution, first measure voltage on the pins to be sure it doesn't exceed the cap's voltage rating.
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| Audiokarma |
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