hv sparking problem

[[email protected]]

I am working on a Toshiba 32hf72 chassis N2PS. Found a bad flyback and
replaced it. Now there is a problem with the HV sparking. At first it
sparked around the anode connector. I cleaned that with no effect. I
have found a couple things that don't make sense to me:

Connected the HV to another tube and connecting the dag together with
no other connections yield proper start up with no sparking.
Connecting the tv together normally, but using a different yoke that is
not on the tube makes the tv start up, but it sound wrong. there is a
sound like sizzling inside the tube. Hard to describe. if the yoke on
the tube is connected instead of the other yoke, I get sparking again.
ANY ideas?

 

[Ancient_Hacker]

I am working on a Toshiba 32hf72 chassis N2PS. Found a bad flyback and
replaced it. Now there is a problem with the HV sparking. At first it
sparked around the anode connector. I cleaned that with no effect. I
have found a couple things that don't make sense to me:

Connected the HV to another tube and connecting the dag together with
no other connections yield proper start up with no sparking.
Connecting the tv together normally, but using a different yoke that is
not on the tube makes the tv start up, but it sound wrong. there is a
sound like sizzling inside the tube. Hard to describe. if the yoke on
the tube is connected instead of the other yoke, I get sparking again.
ANY ideas?

Bad CRT? Air in CRT?

 

[[email protected]]

[email protected] wrote:

Bad CRT? Air in CRT?

I dont know what specifically you cleaned, but I know that any arcing
converts anything present to carbon, and any cleanup has to be very
thorough indeed to work.

If youve replaced the EHT wire/rubber cap and cleaned everything
immaculately, the only remaining culprit would be the CRT, if thats
where the sound is coming from. Dont think I've encountered a tube
doing that before, but if it is, it is.


NT

 

[JW]

I am working on a Toshiba 32hf72 chassis N2PS. Found a bad flyback and
replaced it. Now there is a problem with the HV sparking. At first it
sparked around the anode connector. I cleaned that with no effect. I
have found a couple things that don't make sense to me:

Connected the HV to another tube and connecting the dag together with
no other connections yield proper start up with no sparking.
Connecting the tv together normally, but using a different yoke that is
not on the tube makes the tv start up, but it sound wrong. there is a
sound like sizzling inside the tube. Hard to describe. if the yoke on
the tube is connected instead of the other yoke, I get sparking again.
ANY ideas?

Power up the monitor while in the dark - you should then be able to locate
where the arc is occurring from and work from there. If it's coming from
where the cap meets the tube, try using RTV to seal the connection.

 

[[email protected]]

I cleaned the anode cap and the tube where it attaches. I experimented
a little more and found that the sparking happens when the horizontal
half of the yolk is connected, but using the horizontal section from
another yolk, I get a dot in the middle of the screen, so the tube
works at least a bit. Can I assume that if i get a dot, then the tube
is fine or could there still be a problem with the tube?

could a problem in the ABL circuit cause these results? I suspect
there may be one because I found some blown resistors.

 

[[email protected]]

definatly coming from under the cap. Is it possible the HV is WAY to
high? if so and I manage to seal it, would this cause problems?

 

[Art]

??Have you checked the operating B+ voltage, and the HV ?? Check the inside
of the anode cup to see if there are any carbon tracks that have built up,
if so you may need to replace the actual suction cup assembly for another
fly, such as the original one. Is the number on the new flyback the same as
the original? Does the neck of the CRT glow a strange bluish colour when
the arcing occurs?

 

[Sam Goldwasser]

definatly coming from under the cap. Is it possible the HV is WAY to
high? if so and I manage to seal it, would this cause problems?

Of course it can do harm to you and the TV.

But first clean the area again and lift the rubber suction cap away from
the tube so that any carbon tracks on it aren't an issue. See if it powers
up without sparks.

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[[email protected]]

I cleaned the anode cap and the tube where it attaches. I experimented
a little more and found that the sparking happens when the horizontal
half of the yolk is connected, but using the horizontal section from
another yolk, I get a dot in the middle of the screen, so the tube
works at least a bit. Can I assume that if i get a dot, then the tube
is fine or could there still be a problem with the tube?

definatly coming from under the cap. Is it possible the HV is WAY to
high? if so and I manage to seal it, would this cause problems?

These 2 paras appear to contradict each other, so I can only say I dont
know whats happening. As you didnt replace the rubber cap and lead,
really its hard to conclude much.

could a problem in the ABL circuit cause these results? I suspect
there may be one because I found some blown resistors.

ABL? whats that?


NT

 

[[email protected]]

auto beam limiter.

 

[[email protected]]

auto beam limiter.

no connection


NT