Zenith SR3587DT Sound OK, No Picture????

[Mike]

C3203 I guess either opened or changed in value.

it was 1.8Vp-p on one side, and .1vp-p on the other.

I shunted the cap, and as soon as I powered it up, the flyback made a sick
ring, and instantly shorted the HOT.

back to square 1.

that cap, i THINK was the problem. then the flyback made a sick ring for a
sec, i could hear the HV comming up, and blew the HOT.

bad flyback or focus block?








"Bill Jr" <bill@nospam.usa2net.net> wrote in message
news:1IUWa.10985$K4.455734@twister.tampabay.rr.com...

IS the frequency of that square wave accurate?
IS the amplitude sufficient to turn on the horiz driver transistor?

Bill Jr


"Mike" <mbates14@fuse.net> wrote in message
news:syUWa.34437$hc.14352@fe3.columbus.rr.com...
P.S., the heatsink on the QX3201 stays cool.

the other 3 in the chopper circuit get regularly warm, thats the only
one
that stays cold.

could that be something? it junction tests good.




"Mike" <mbates14@fuse.net> wrote in message
news:LsUWa.34403$hc.14392@fe3.columbus.rr.com...
ok, I finally got to it.


All volteges are presant and none of the fuses are blown.

now, there was a pin problem.

Now, I set my scope up, and did some more testing on the tv,

the scan gen IS working. there is a square wave pulse on the pin 8.
there
is
a square wave pulse on the base of the horizontal driver transistor.
BUT,
there is NO DRIVE PULSE on the collector of the driver transistor. so,
i
guess its a bad transistor. I did some voltege measurements, and there
is
about 41VDC on the collector.

There is 158VDC B+ on the HOT.

I did a BtoC, and BtoE check in circuit on the transistor, and it
checks
OK,
but i never pulled it out of circuit.

Any Ideas?








"Q.E.D." <qed@verizon.net> wrote in message
news:f7tlivg8e0atun19067h7feu8qt0d94drm@4ax.com...
Looking for input into whether this June 1996 build TV is worth
having
repaired.

TV has worked great since purchase in 1996. Never got a great deal
of
use...maybe 10 hours a week on weekends to watch mainly movies on
DVD
or HBO. I figure less than 4000 hours total use. Set had been on
for
about 4 hours one day and the picture just went blank...like someone
turned it off. No warning of trouble before that...no picture fade
or
blooming, it just went dark. Sound still works OK.

The TV is long out of warranty but due to it's light use I was
thinking it might be worth repairing. Can anyone give me an idea
how
much would be a fair rate for a repairman to come out and diagnose
(I
live in Philadelphia, PA)? What's an average repair cost on a 35"
set? I realize the repair costs would be on top of the initial
estimate depending on what is wrong. On that note, are my TV's
symptoms indicative of a common problem? Based on my novice
research
I think it could be a high voltage problem.

The neighborhood repair guy went out of business about three years
ago. Choosing a repair service, I'm finding, is almost impossible
to
decide on blindly.

Any advice would be appreciated.

Thanks

 

[Mike]

the capacitor was bad.

when I changed it, boom.

I had a pulse on the base of the HOT. im not sure if its a good pulse or
not, but from most tv experiance its pretty damn close, give or take a scope
calibration.

now, I need a flyback. it made a sick squeek and blew HOT. i pulled it out
and checked the waveform, it has one now.

but since that incedent, the B+ is now gone. even with the transistor out. i
guess one of the fuses went, but the sound is still there.







"Mike" <mbates14@fuse.net> wrote in message
news:sKVWa.34513$hc.7908@fe3.columbus.rr.com...

C3203 I guess either opened or changed in value.

it was 1.8Vp-p on one side, and .1vp-p on the other.

I shunted the cap, and as soon as I powered it up, the flyback made a sick
ring, and instantly shorted the HOT.

back to square 1.

that cap, i THINK was the problem. then the flyback made a sick ring for a
sec, i could hear the HV comming up, and blew the HOT.

bad flyback or focus block?








"Bill Jr" <bill@nospam.usa2net.net> wrote in message
news:1IUWa.10985$K4.455734@twister.tampabay.rr.com...
IS the frequency of that square wave accurate?
IS the amplitude sufficient to turn on the horiz driver transistor?

Bill Jr


"Mike" <mbates14@fuse.net> wrote in message
news:syUWa.34437$hc.14352@fe3.columbus.rr.com...
P.S., the heatsink on the QX3201 stays cool.

the other 3 in the chopper circuit get regularly warm, thats the only
one
that stays cold.

could that be something? it junction tests good.




"Mike" <mbates14@fuse.net> wrote in message
news:LsUWa.34403$hc.14392@fe3.columbus.rr.com...
ok, I finally got to it.


All volteges are presant and none of the fuses are blown.

now, there was a pin problem.

Now, I set my scope up, and did some more testing on the tv,

the scan gen IS working. there is a square wave pulse on the pin 8.
there
is
a square wave pulse on the base of the horizontal driver transistor.
BUT,
there is NO DRIVE PULSE on the collector of the driver transistor.
so,
i
guess its a bad transistor. I did some voltege measurements, and
there
is
about 41VDC on the collector.

There is 158VDC B+ on the HOT.

I did a BtoC, and BtoE check in circuit on the transistor, and it
checks
OK,
but i never pulled it out of circuit.

Any Ideas?








"Q.E.D." <qed@verizon.net> wrote in message
news:f7tlivg8e0atun19067h7feu8qt0d94drm@4ax.com...
Looking for input into whether this June 1996 build TV is worth
having
repaired.

TV has worked great since purchase in 1996. Never got a great
deal
of
use...maybe 10 hours a week on weekends to watch mainly movies on
DVD
or HBO. I figure less than 4000 hours total use. Set had been on
for
about 4 hours one day and the picture just went blank...like
someone
turned it off. No warning of trouble before that...no picture
fade
or
blooming, it just went dark. Sound still works OK.

The TV is long out of warranty but due to it's light use I was
thinking it might be worth repairing. Can anyone give me an idea
how
much would be a fair rate for a repairman to come out and diagnose
(I
live in Philadelphia, PA)? What's an average repair cost on a 35"
set? I realize the repair costs would be on top of the initial
estimate depending on what is wrong. On that note, are my TV's
symptoms indicative of a common problem? Based on my novice
research
I think it could be a high voltage problem.

The neighborhood repair guy went out of business about three years
ago. Choosing a repair service, I'm finding, is almost impossible
to
decide on blindly.

Any advice would be appreciated.

Thanks

 

[LASERandDVDfan]

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting, not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

no, no no, you must have not read my other posts.

the cap was changed in value, and I replaced it, I only shunted it to see if
I had a drive at the base, which I did.

as for experimenting, that is my way of troubleshooting, or basically
tracing something back until it stops, and then look around in the circuit
for bad parts in the area that stopped, and thats the area that had the
nearly open cap.

so, thats how I troubleshoot things, and I dont have a schematic, nor feel
like ordering one for any TV I do, and it works for me every time. I have
fixed every TV i ran into so far.

I just study the boards, then do my work. I dont need to have experiance in
"one or another chassis", It would be nice, but I dont.

I just get down to the basics. I know how each function, and each circuit
works, and I study the boards to examine and show me how the circuit is
designed.





"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

this is how I work, my technique of troubleshooting is half and half, both
expermintation, and troubleshooting, but it works for me everytime.











"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

another thing, I didnt automattically assume. I have made posts in the past,
people like jerry greenberg and bill jr know what happened, and what I have
been trying to approatch.








"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

I shunted the cap with a cap of the same value and ratings.

so, it tells me to do these things in my repair handbooks. Thats how I
learned how to even deal with electronics, more or less, repair them. unless
you want to confront Homer L. Davidson.




"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

you must have not read my other posts.

the cap was changed in value, and I replaced it, I only shunted it to see if
I had a drive at the base, which I did.

as for experimenting, that is my way of troubleshooting, or basically
tracing something back until it stops, and then look around in the circuit
for bad parts in the area that stopped, and thats the area that had the
nearly open cap.

so, thats how I troubleshoot things, and I dont have a schematic, nor feel
like ordering one for any TV I do, and it works for me every time. I have
fixed every TV i ran into so far.

I just study the boards, then do my work. I dont need to have experiance in
"one or another chassis", It would be nice, but I dont.

I just get down to the basics. I know how each function, and each circuit
works, and I study the boards to examine and show me how the circuit is
designed.

"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

That is how I work, my technique of troubleshooting is half and half, both
expermintation, and troubleshooting, but it works for me everytime.



"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

I didnt automattically assume. I have made posts in the past,
people like jerry greenberg and bill jr know what happened, and what I have
been trying to approatch.



"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

I shunted the cap with a cap of the same value and ratings.

so, it tells me to do these things in my repair handbooks. Thats how I
learned how to even deal with electronics, more or less, repair them. unless
you want to confront Homer L. Davidson




"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[Mike]

The capacitor wasnt even an electrolytic, it was blue, and polyester type
one or something like that.

I did check bad joints, that was the whole problem in the first place. The
picture was too wide, and it was bowed in, and I recieved it with no
horizontal deflection, but it had HV.

well, just shortly after the flyback began to squeel, squal like it shorted,
and as soon as it did, it lost the picture as it was squeeling, and then it
blew the HOT, and it took me awhile to find out it opened a series cap to
the drive transistor.

I pulled the HOT to run tests, I shunted the cap, and the drive came back. I
replaced it, and then put the HOT back in, and tried to power it up, the
flyback made the same squeel, but it only happened for a split second before
the HOT shorted again. I heard the static pops, like the HV was trying to
kick up, the HV was there and gone under a second.







"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20030803015047.24239.00001227@mb-m16.aol.com...

one more thing, the square wave pulse is continous, its not shutting
down, probably because its not getting to the flyback, or the base of the
HOT, it dies off at the driver xistor. its there on the base, gone on the
collector

Forgive me for being blunt, but it sounds more like you're experimenting,
not
repairing.

You should have checked the simple stuff first, like bad caps or even cold
joints, but you automatically assumed that it was a major problem.

When you thought it may have been a cap, you shunted it in circuit?!

What you should have done was take the suspected cap out of the chassis
and
tested it for high ESR and to see if it can hold to its rated capacity. -
Reinhart

 

[john]

Man !

 

[Mike]

what do you mean by that.

I am a damn good technician, Its just the way I try to describe things. like
im a blooming ideot. but, im not, I can verify that one.








"john" <va3mm@niagara.com> wrote in message
news:newscache$8jv1jh$wwb$1@newsfeed.niagara.com...

Man !

 

[William R. Walsh]

Hi!

A Technician would never ever think of disableing
the Shut Down circuit like you wish to do.
Do it the correct way ..The right way.

Not say who is or is not, but sometimes you've got to disable a protection
or shutdown circuit to fix a problem--even if the only result is burning up
something.

I'm not a tech, and I haven't had to do so very often, but sometimes it just
takes a "plug 'er in and see what smokes" test to get to the bottom of
something.

William

 

[john]

You are totally wrong William with your thinking
a real Tech would never ever disable a shutdown circuit,
maybe a non tech Guy would as per yourself.
I have been in this buis for 36 yrs and have never
even thought of disableing one to find a fault.
Do it the right way...........

kip

Not say who is or is not, but sometimes you've got to disable a protection
or shutdown circuit to fix a problem--even if the only result is burning
up
something.
I'm not a tech, and I haven't had to do so very often, but sometimes it
just
takes a "plug 'er in and see what smokes" test to get to the bottom of
something.

William

 

[Mike]

you can get a life, and get lost.





"john" <va3mm@niagara.com> wrote in message
news:newscache$zp72jh$boc$1@newsfeed.niagara.com...

You are totally wrong William with your thinking
a real Tech would never ever disable a shutdown circuit,
maybe a non tech Guy would as per yourself.
I have been in this buis for 36 yrs and have never
even thought of disableing one to find a fault.
Do it the right way...........

kip


Not say who is or is not, but sometimes you've got to disable a
protection
or shutdown circuit to fix a problem--even if the only result is burning
up
something.
I'm not a tech, and I haven't had to do so very often, but sometimes it
just
takes a "plug 'er in and see what smokes" test to get to the bottom of
something.


William

 

[David]

FYI you can disable a shutdown circuit as a last resort for troubleshooting
when all standard procedures with the schematic fail but NEVER the XRAY
protect, PERIOD.

There are far too many other safe ways to troubleshoot a problem that
triggers the xray protect. i.e. lowering the B+ voltage to the flyback
circuit for one.

BTW you still need to pull the shaping coil and pincushion coil on that set
as those are very common failure items, as are electrolytic capacitors in
the smps and the little filter one on the hv driver coil, as well as high
failure of the flyback tripler causing an effective short (for 25kv) between
the hv anode and ground, plus the tubes have been known to arc back to the
yoke and blow a hole in the glass on these from flyback failure.

David



Mike <mbates14@fuse.net> wrote in message
news:RqhXa.9492$IQ2.9205@fe1.columbus.rr.com...

john, now that you told me off, and told him off,

I see that YOUR NOT a technician, and you need to kiss my ass and
bug off.



"john" <va3mm@niagara.com> wrote in message
news:newscache$zp72jh$boc$1@newsfeed.niagara.com...
You are totally wrong William with your thinking
a real Tech would never ever disable a shutdown circuit,
maybe a non tech Guy would as per yourself.
I have been in this buis for 36 yrs and have never
even thought of disableing one to find a fault.
Do it the right way...........

kip


Not say who is or is not, but sometimes you've got to disable a
protection
or shutdown circuit to fix a problem--even if the only result is
burning
up
something.
I'm not a tech, and I haven't had to do so very often, but sometimes
it
just
takes a "plug 'er in and see what smokes" test to get to the bottom of
something.


William

 

[Tom MacIntyre]

On Sun, 3 Aug 2003 19:42:49 -0500, "David" <dkuhajda@locl.net.spam>
wrote:

FYI you can disable a shutdown circuit as a last resort for troubleshooting
when all standard procedures with the schematic fail but NEVER the XRAY
protect, PERIOD.

I have done this once, awhile back, when I was feeling my way along in
the on the job learning process...disabled the XRP, fired the set up,
heard the crackle of the HV, shut it off, knowing my suspicions were
confirmed. What would've/could've happened in that one second that is
that serious? Just asking...

In that case it was a faulty component in the XRP, and not excessive
XRP that caused the problem. I forget the make/model of the set.

I have a bit of training in the operation of another type of device
that uses X-rays and, despite the fact that its radiation levels in
operation are far less than some normal daily situations, the specific
precautions against any exposure are stringent. X-rays have a lot of
respect, don't they?

Tom

David

just
takes a "plug 'er in and see what smokes" test to get to the bottom of
something.


William

 

[Mike]

i meant that for john. no one else, but john.

anyway, I didnt need to. I "assume" the flyback is bad, it is showing all
the symptoms of it, and I need to do further testing to do so.

but since the HOT shorted for the second time, I pulled the HOT, and I no
longer have B+ at the collector pad. I guess either the winding in the
flyback opened, or the series fuse opened.




"Mike" <mbates14@fuse.net> wrote in message
news:XJhXa.37867$hc.10552@fe3.columbus.rr.com...

you can get a life, and get lost.





"john" <va3mm@niagara.com> wrote in message
news:newscache$zp72jh$boc$1@newsfeed.niagara.com...
You are totally wrong William with your thinking
a real Tech would never ever disable a shutdown circuit,
maybe a non tech Guy would as per yourself.
I have been in this buis for 36 yrs and have never
even thought of disableing one to find a fault.
Do it the right way...........

kip


Not say who is or is not, but sometimes you've got to disable a
protection
or shutdown circuit to fix a problem--even if the only result is
burning
up
something.
I'm not a tech, and I haven't had to do so very often, but sometimes
it
just
takes a "plug 'er in and see what smokes" test to get to the bottom of
something.


William