[TechAssist] Re: JVC TV AV2749S, yoke arcing at CRT neck [UPDATE]
- From: "teltek3" <teltek3@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Fri, 15 Aug 2003 14:13:05 -0400
Gary...besides that...I would keep an eye on the Temp of the H/O for a day.
This may come back to bite you.
-Ed-
Tel-Tek Electronics
Ontario-Canada
teltek3@xxxxxxxxxxxx
----- Original Message -----
From: "Gary McCartney" <gary@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, August 15, 2003 1:47 PM
Subject: [TechAssist] JVC TV AV2749S, yoke arcing at CRT neck [UPDATE]
> I have this set running now. I applied epoxy to the spot on the glass
> and covered it with tape. I have a good picture except for one problem.
> It has too much width, about 1 to 1 1/2 inches too much. The geometry
> look fine though. The used yoke I installed did not have a JVC number on
> it and did not have the same connectors, but the yoke itself appeared to
> be the exact same. I realize that even though it looked exact the
> winding could be slightly different.
> Assuming the new yoke is the same as the old, I have removed the 2 blue
> caps C525 and C524 from the HOT collector to ground. Can anyone identify
> the valuse of these caps please?
>
> C524: labelled PH7001H 1.6KV
> C525: labelled PH6201H 1.6KV
>
> I believe these are 0.007uF and 0.0062uF but I'd like this confirmed if
> possible.
> SAMS is having techical problems with their web site else I'd look up
> the SAMS number for this set.
>
> What else can cause too much width in this chassis? Is it safe to change
> the value of one of these caps enough to narrow the picture up a bit? I
> am concerned that perhaps the yoke burnt in the first place because of
> to much current going through it.
>
>
> Thanks for any help.
>
>
>
>
> Gary McCartney
>
> McCartney Electronics
> Guelph Ontario Canada
> Est. 1984
> email: gary (at) number63.ca
>
>
>
>
>
>
> My Original message:
>
>
> I have this JVC TV model AV2749S in the shop and I have found that the
> yoke is shorted where it wraps around the neck of the CRT, causing a
> black burn mark on the glass. I took a knife and scraped it off but
> there is a slight crater in the glass now, maybe 1/64 of an inch or so
> deep. Is this a weak spot from now on, meaning that this spot will be
> suseptable to more arcing in the future or worse yet, a crack in the
> neck? Can I apply some epoxy to the spot to give it insulation, or
> should this tube be scrapped? I have a used yoke which looks to be in
> great shape which I can use in the set so I hate to tell the customer it
> is garbage.
>
>
> Here is a photo of the mentioned spot on the glass:
>
> http://www.number63.ca/tube-neck.jpg
>
>
>
> How I found the bad yoke:
>
> The set came in with F902, 1.25 Amp fuse open. I couldn't find any
> defective parts so I installed a new fuse in case that was the only
> problem. Pressed power button and saw LED blink and that was all- the
> fuse was open again. Next, I looked up tips and found one that mentioned
> the yoke as a possibility, so I pulled the CRT board and the yoke
> connectors. The LED came on and stayed. Then I reconnected the hor.
> winding and put a new fuse in. Had to use 1.5A instead of 1.25. I used a
> variac set at 90VAC and plugged it in. The LED came on and I heard the
> arcing and saw smoke coming from the yoke/ CRT neck.
>
>
> Thanks for any help.
> --
>
>
>
>
>
>
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