JVC AV36950 cap C921 question

[Guest]

Hi all. I have a JVC AV36950US tv here. Cap C921 has died badly, so I cannot
read its' original value. Does anyone know its value? It was a small disk
type coming off the B+ diode, past the relay for that diode.

The symptom when power button is pushed is quick flash of front panel lamp,
and p/s, when scoped, works well in low power standby, then does its'
instant overload protection when power button is pushed.

I found nothing else shorted or broken, (HOT, diodes nearby, etc) so this
may be all it needs.

Many thanks in advance,

Danny

 

[Jason D.]

Hi all. I have a JVC AV36950US tv here. Cap C921 has died badly, so I cannot
read its' original value. Does anyone know its value? It was a small disk
type coming off the B+ diode, past the relay for that diode.

The symptom when power button is pushed is quick flash of front panel lamp,
and p/s, when scoped, works well in low power standby, then does its'
instant overload protection when power button is pushed.

I found nothing else shorted or broken, (HOT, diodes nearby, etc) so this
may be all it needs.

Many thanks in advance,

Danny

That capacitor smoothes out the 13V supply also this 13V supply is
part of feedback to this smart switching power supply that shut down
bec of no feedback preventing more destruction.

Change it with new 1000uF 35V high freq low esr 105C rating cap. This
will fix yours in a jiffy. Fairly common actually.

Reason for the cap's death was that guide + module is power hungry
made diode next to that cap heat up more hotter, drying cap out then
it finally dies. Nothing you can do about it, change that cap. In
other models without this gude + module had much better reliablity
because diode is not as hot.

While at it, resolder all 1/2W and 1W dull colored resistors, resolder
vertical IC (IC421) I think. Also change 10uF 160V near the
horizontal transformer driver. This driver drives base pin of the
horizontal transistor.

Cheers,

Wizard

 

[Guest]

Hi. Thanks for the advice on the cap. The cap C921 turns out to be a 152K HR
C designation, same as C925 and a couple others coming off the switchmode
transformer. They run paralell to the diodes coming off the switchmode
transformer. I verified they were the same by calling JVC on a hunch. They
won't give technical data out, but they did give the same part number for
this cap as for C925. Nothing real special. Replaced and fired up on bench.
Runs like a champ.

The JVC part number, if anyone is interested, is QCZ0132-152Z

Cheers, Danny

 

[Jason D.]

Hi. Thanks for the advice on the cap. The cap C921 turns out to be a 152K HR
C designation, same as C925 and a couple others coming off the switchmode
transformer. They run paralell to the diodes coming off the switchmode
transformer. I verified they were the same by calling JVC on a hunch. They
won't give technical data out, but they did give the same part number for
this cap as for C925. Nothing real special. Replaced and fired up on bench.
Runs like a champ.

The JVC part number, if anyone is interested, is QCZ0132-152Z

Cheers, Danny

Danny, Bravo!

Doesn't have to be from JVC. A decent electronic supplier can sell
you one or from another shop.

By the way, this C926 cap (your typo?) is only cap off the diode not
two caps in parallel.

Cheers,

Wizard

 

[Guest]

Hi. I put chassis back in his box last night. Worked like a champ. I had
gotten replacement cap from Forbes, our local elec parts house. On this
chassis, the bad cap and its comrade, which paralells another diode, were
indeed labeled C921 and C925. I went back and had a closer look before
giving it back. C921 paralelled the horizontal voltage power diode and C925
paralelled another diode from switchmode transformer. On a hunch I called
JVC again and they verified loc numbers as C921 and C925, with same part
number for both. May be some slight variation in chassis over different
years. First time I have seen this chassis before. I don't see many dead JVC
sets around here. I get many Mits, RCA, Toshiba, etc but few JVC.

I also repositioned the diode over a bit so new cap had a bit of breathing
room, and wasn't squashed up against the diode. Maybe it will hold up
longer. Last one made it 6 years, 1998 model.

Cheers, Danny