JVC Standby Transformer Contaminated

[TV-VCR]

I have JVC model AV-27230 chassis A67 sitting on bench.
Standby power supply and degaussing is on a little separate
circuit board on the right side. Standby transformer has
open primary winding, and visual examination reveals that
some sticky, corrosive fluid has leaked out of the primary
side of the transformer bobbin, puddled around the legs,
rotted off the wire, ran over to the edge of the board
and dripped off and out the bottom ventilation slots.

The location of the part, and the traceable path of flow
eliminates all possibility that this somehow could have
gotten into the set from outside, rather the transformer
itself is obviously the origin of the problem. Maybe the
part maker had some kind of accident with the impregnation
or cleaning process. If so, it may not be an isolated case;
there may be a whole batch of bad transformers out there
eating themselves and their circuit boards up.

Anyone else seen this? Is there a service bulletin or recall?

Number on transformer is 28KAZ21GU. Where's a good place to
buy one to make the repair?

 

[Jason D.]

On Mon, 19 Apr 2004 18:15:49 GMT, TV-VCR <DontSpam@Me.Net> wrote:

I have JVC model AV-27230 chassis A67 sitting on bench.

Very interesting fault. I think the standby transformer shorted and
heated up then oozed out it's burned junk then finally winding blew
open.

Uncommon. I have NOT seen a dead transformer for any reason in those
JVC sets (with or without the ick) YET despite I service JVC TV sets
daily, over 100 of any kind. Only one time I saw a dead standby
transformer was caused by a shorted filter capacitor in a RCA TV
(CTC167 or something like that.)

Anyone else seen this? Is there a service bulletin or recall?

No bulletin on this one, as I said this is a fluke, once in a blue
moon thing.

Number on transformer is 28KAZ21GU. Where's a good place to
buy one to make the repair?

Get one from your nameless scrap pile and jury wire it safely in that
is appox 16 VAC max assuming this set using 12VDC relay. The raw DC
is for relay that all, also raw DC feeds to two standby regulators,
one for jungle IC (9V) and 5V reset IC (5 leg small upright IC).

Make sure that JVC is actually using 9V relay then u have to use lower
voltage standby transformer not 12.

Cheers,

Wizard

 

[TV-VCR]

In article <40848564.18032713@news1.on.sympatico.ca>, jpero@sympatico.ca
says...

Very interesting fault. I think the standby transformer shorted and
heated up then oozed out it's burned junk then finally winding blew
open.

I'd have thought that, too, but no signs of heat, no smell,
just slightly sticky residue with blue-green (Copper Oxide?)
sediment, and the remnant end of primary wire looks eaten,
not a little ball like blown-open I have seen. Odd.

Get one from your nameless scrap pile and jury wire it safely in that
is appox 16 VAC max assuming this set using 12VDC relay.

Yeah, it's 12V, and I can cobble something in if I have to, even
Rat Shack in a pinch, but prefer exact fit if at all possible.
Set otherwise is very clean. Thanks for feedback.