27" JVC stereo tv model:AV-27320,chassis:A67,year:Oct 2001.After the
customer was watching tv for a few hours picture size kept shrinking
all on all four sides down to a dot within a few seconds then the tv
shut off and now only relay click followed by LED blinking.
I found Q522=2SD2499=NTE2331 and F902=1.25 amp fuse to be open,I have
not yet troubleshooted tv further anyone have any common repair tips
for such a failure?.
Thanks in advance for replies.

Sidney
Dartmouth,Nova Scotia
Canada

Only tip, don't leave the NTE sub in that set as it won't last. The
tolerances of the circuit require an EXACT replacement for Q552.

Look for bad solder connections in the power supply and sweep to have caused
the failure.

David

"Sidney" wrote in message
om...
27" JVC stereo tv model:AV-27320,chassis:A67,year:Oct 2001.After the
customer was watching tv for a few hours picture size kept shrinking
all on all four sides down to a dot within a few seconds then the tv
shut off and now only relay click followed by LED blinking.
I found Q522=2SD2499=NTE2331 and F902=1.25 amp fuse to be open,I have
not yet troubleshooted tv further anyone have any common repair tips
for such a failure?.
Thanks in advance for replies.

Sidney
Dartmouth,Nova Scotia
Canada

On 30 May 2004 13:59:32 -0700, (Sidney) wrote:

27" JVC stereo tv model:AV-27320,chassis:A67,year:Oct 2001.After the
customer was watching tv for a few hours picture size kept shrinking
all on all four sides down to a dot within a few seconds then the tv
shut off and now only relay click followed by LED blinking.
I found Q522=2SD2499=NTE2331 and F902=1.25 amp fuse to be open,I have
not yet troubleshooted tv further anyone have any common repair tips
for such a failure?.
Thanks in advance for replies.

Sidney
Dartmouth,Nova Scotia
Canada

Sidney,

I service JVC sets daily (warranty/contract and customers'), Very
rare horizotal failures. It depends on type of chassis.

If this set uses STR30134 regulator, then replace horizontal
transistor and redo all solder joints on all 1/2W and 1W resistors.
(must be exact part preferably from JVC), check D421 and R421 is good
if bad or fried, the vertical IC is fried then have to replace
vertical parts: generic will do: flameproof 1.8 Ohm, 1/2W, jelly bean
diode (RGP10J), LA7832 and 100uF 35V cap. This chassis with STR-30134
also have cap for the horizontal transformer driver but it's well out
of heat and right at the edge so there's not a problem.

If this is doesn't fit what I described, uses SMPS only for both
standby and run using (STRF-6626) then replace small 1uF 160V cap for
the horizontal transformer driver +B filter and exact horizontal
transistor. It is in middle of two hot resistors killing that cap's
ESR. Resolder all 1/2W and 1W resistors still applies, watch out for
dud vertical circuit.

Good idea to see if you have resistance between HV suction and the
ground pins on the flyback which is not supposed to be there. Also
ring fly just in case. Fly for JVC is very occasionally found bad
except for AV-32F702 series using flat CRT, it is somewhat high
failure rate.

Cheers,

Wizard

Thanks David & Jason D.

This tv belongs to a friend of mine who told me that Q522=2SD2499
(HOT) was shorted but it is fine but F902 still open (LOL),he dropped
it off to my shop and I rang the T502=FSM27A001 (QQH0028-001)=flyback
transformer by using the calibration output of my TEK-465 oscilloscope
but no ringing so upon troubleshooting I found that the 12v (D1543=RGP
XXX) secondary supply off the flyback was loaded down to about 250
ohms so I disconnected D1543 and problem still remains.
I ruled out IC1541=AN7809F & IC1551=AN7805F and I rang the yoke
unplugged and it rang good.
Anyone know if the this flyback is a common failure? also what could
be loading down the 12v source?.
This tv uses IC1101=TB1253AN & IC1921=STR30134

Sidney
Darmouth,Nova Scotia
Canada

On 31 May 2004 10:15:33 -0700, (Sidney) wrote:

Thanks David & Jason D.

This tv belongs to a friend of mine who told me that Q522=2SD2499
(HOT) was shorted but it is fine but F902 still open (LOL),he dropped
it off to my shop and I rang the T502=FSM27A001 (QQH0028-001)=flyback
transformer by using the calibration output of my TEK-465 oscilloscope
but no ringing so upon troubleshooting I found that the 12v (D1543=RGP
XXX) secondary supply off the flyback was loaded down to about 250
ohms so I disconnected D1543 and problem still remains.
I ruled out IC1541=AN7809F & IC1551=AN7805F and I rang the yoke
unplugged and it rang good.
Anyone know if the this flyback is a common failure? also what could
be loading down the 12v source?.
This tv uses IC1101=TB1253AN & IC1921=STR30134

Sidney

Flyback removed from chassis and still won't ring? If yes that's it.
Get both HOT and flyback from JVC, cost is not a problem, JVC is nice
sets and lasts long time because of nice CRTs. While at it, change
out 100uF 35V electrolytic on that vertical IC, they were always dried
up by the vertical's heatsink intense heat and cap often were 85C.
When you get it running, touch the U shaped sloped vertical heatsink.
HOT!

The 12V is used to supply these 9V and 5V regulators, also 12V is for
the vertical I think along with typical 26V. Also via diode (forward
biased) to the standby supply to "prop" up the standby supply once tv
is running. This includes the relay and small 5V with reset regulator
(5 legged thing) for micro.

Tuner only use 33V and 5V stuff.

By the way that jungle IC (TB1253AN) is digital controlled without
503kHz crystal.

The money maker was in JVC vertical frying because of that 100uF cap.
:-)

Yes, that chassis have two fuses, one (I think 4A or 5A?) for before
the diode bridge & cap and after the B+ regulator (uses 1.25A fast
blow for sure.)

Cheers,

Wizard