I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs from
the convergence board and the problem went to the blue so I was fairly
confident the problem was with the red convergence amp (STK392-110) and
I replaced it. The problem still exists. I took a picture of it and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the convergence
amp swapped so problem is on the blue). Anybody have any suggestions?

***CAUTION!!!!*** This is one of the JVC units that you have to unplug
the set to prevent the "booby trap" eeprom info failure from light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value resistors.
....5, or 1.0 ohms approx. The booby trap is the optical sensor under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this model
uses long retangular convergence board (no screws, held in place with
snap hooks with metal box. you can get it out from front and reach
deep to release one of cables from holders and unplug from the small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs from
the convergence board and the problem went to the blue so I was fairly
confident the problem was with the red convergence amp (STK392-110) and
I replaced it. The problem still exists. I took a picture of it and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the convergence
amp swapped so problem is on the blue). Anybody have any suggestions?

Dont forget there maybe a open Pico fuse as well.

kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to unplug
the set to prevent the "booby trap" eeprom info failure from light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this model
uses long retangular convergence board (no screws, held in place with
snap hooks with metal box. you can get it out from front and reach
deep to release one of cables from holders and unplug from the small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs from
the convergence board and the problem went to the blue so I was fairly
confident the problem was with the red convergence amp (STK392-110) and
I replaced it. The problem still exists. I took a picture of it and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the convergence
amp swapped so problem is on the blue). Anybody have any suggestions?

Dani wrote:
***CAUTION!!!!*** This is one of the JVC units that you have to unplug
the set to prevent the "booby trap" eeprom info failure from light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of this
model without removing the back and setting off the booby trap.

Thanks for the info. I am working from the front.

Replace both STK convergence IC's, also check low value resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor under

I have already checked the resistors and replaced the one STK
convergence IC that controls the red (Blue is controlled by the other
and green is controlled by a combination of the two).

a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this model
uses long retangular convergence board (no screws, held in place with
snap hooks with metal box. you can get it out from front and reach
deep to release one of cables from holders and unplug from the small
stand up PCB.

Yes this is that model and the convergence board came out nicely but I
found no problems with it and after replacing the STK the same problem
is still present. Any other ideas? I really appreciate the help.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs from
the convergence board and the problem went to the blue so I was fairly
confident the problem was with the red convergence amp (STK392-110) and
I replaced it. The problem still exists. I took a picture of it and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the convergence
amp swapped so problem is on the blue). Anybody have any suggestions?

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to unplug
the set to prevent the "booby trap" eeprom info failure from light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this model
uses long retangular convergence board (no screws, held in place with
snap hooks with metal box. you can get it out from front and reach
deep to release one of cables from holders and unplug from the small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs from
the convergence board and the problem went to the blue so I was fairly
confident the problem was with the red convergence amp (STK392-110) and
I replaced it. The problem still exists. I took a picture of it and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the convergence
amp swapped so problem is on the blue). Anybody have any suggestions?

We they are there you have to trace back and locate them if no voltages to
Stk,s.

kip


wrote in message
oups.com...

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to unplug
the set to prevent the "booby trap" eeprom info failure from light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this model
uses long retangular convergence board (no screws, held in place with
snap hooks with metal box. you can get it out from front and reach
deep to release one of cables from holders and unplug from the small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs from
the convergence board and the problem went to the blue so I was fairly
confident the problem was with the red convergence amp (STK392-110)
and
I replaced it. The problem still exists. I took a picture of it and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the convergence
amp swapped so problem is on the blue). Anybody have any suggestions?

I will check the voltages at the STK. Wouldn't I get no output from
the STK if voltage was not present?

kip wrote:
We they are there you have to trace back and locate them if no voltages to
Stk,s.

kip


wrote in message
oups.com...

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to unplug
the set to prevent the "booby trap" eeprom info failure from light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this model
uses long retangular convergence board (no screws, held in place with
snap hooks with metal box. you can get it out from front and reach
deep to release one of cables from holders and unplug from the small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs from
the convergence board and the problem went to the blue so I was fairly
confident the problem was with the red convergence amp (STK392-110)
and
I replaced it. The problem still exists. I took a picture of it and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the convergence
amp swapped so problem is on the blue). Anybody have any suggestions?

First of all, you cannot just switch red and blue. There were old Sonys
that had the red and blue well matched and the convergence affected
them somwhat like the middle set of rings on a tri-color CRT.

Now, OP, you have confused the issue switching **** around, show me the
crosshatch with the connections correct.

Put the thing how you found it, post a pic then, then I will look at
it. From the pic you have, you have a foldover, but not a real bad one,
it is more like a voltage amp clipping.

Then this could also very easily be a fault in the blue channel of the
DCM. Do you know how to definitively check if the STKs are good with a
scope ?. Also, you can't even do it in that set without extreme
measures. jusat hook it back up right and let me see it.

You might find that a resistor, say a 1 ohm, overheated and became
LOWER, like 1/4 ohm. I have had it happen.

You might find a leaky Zener diode, All kinds of parts that cost less
than a dollar. Which one ?

First thing, is to put it back together, I don't mean the back, but I
wanna see all three colors with each hooked up to the proper outputs.
This color switching technique doesn't work anymore. I need to see the
problem, not the problem as modified by you.

Put the thing back right, don't put it together, I couldn't care less
if your cat crawls in there. UNtamper the set and show me the picture,
and tell me if it is with new STKs, and where they came from and if
there was a change in the symptom after their replacement.

Then we can proceed.

Any of you out there wonders why it costs $300 to fix these things,
take a crack at it.

JURB

No Voltage NO output...Simple!!

kip
wrote in message
oups.com...
I will check the voltages at the STK. Wouldn't I get no output from
the STK if voltage was not present?

kip wrote:
We they are there you have to trace back and locate them if no voltages
to
Stk,s.

kip


wrote in message
oups.com...

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to
unplug
the set to prevent the "booby trap" eeprom info failure from light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this model
uses long retangular convergence board (no screws, held in place
with
snap hooks with metal box. you can get it out from front and reach
deep to release one of cables from holders and unplug from the small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs
from
the convergence board and the problem went to the blue so I was
fairly
confident the problem was with the red convergence amp (STK392-110)
and
I replaced it. The problem still exists. I took a picture of it
and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the
convergence
amp swapped so problem is on the blue). Anybody have any
suggestions?

wrote:
First of all, you cannot just switch red and blue. There were old Sonys
that had the red and blue well matched and the convergence affected
them somwhat like the middle set of rings on a tri-color CRT.
Thanks, it seemed to me to be a decent test but I unjderstand it may
not have.


Now, OP, you have confused the issue switching **** around, show me the
crosshatch with the connections correct.
I will do this but the crosshatch was basically identical to what I
showed and that is why I posted it.

Put the thing how you found it, post a pic then, then I will look at
it. From the pic you have, you have a foldover, but not a real bad one,
it is more like a voltage amp clipping.

I appreciate your help.

Then this could also very easily be a fault in the blue channel of the
DCM. Do you know how to definitively check if the STKs are good with a
scope ?. Also, you can't even do it in that set without extreme
I don't but I do have the equipment to do it. If you point me in the
right direction I should be able to scope it.
measures. jusat hook it back up right and let me see it.

You might find that a resistor, say a 1 ohm, overheated and became
LOWER, like 1/4 ohm. I have had it happen.
I checked the resistors with a 4 wire ohm meter and all were within 0.1
ohm of value.

You might find a leaky Zener diode, All kinds of parts that cost less
than a dollar. Which one ?

First thing, is to put it back together, I don't mean the back, but I
wanna see all three colors with each hooked up to the proper outputs.
This color switching technique doesn't work anymore. I need to see the
problem, not the problem as modified by you.
I will do this.. Unfortunately I'm no where I can acccess the TV now
but I will do this shortly.

Put the thing back right, don't put it together, I couldn't care less
if your cat crawls in there. UNtamper the set and show me the picture,
and tell me if it is with new STKs, and where they came from and if
there was a change in the symptom after their replacement.

I purchased new STKs from someone on ebay. I only replaced the one
controlling the red channel. Symptoms didn't change after I replaced
it.

Then we can proceed.

Any of you out there wonders why it costs $300 to fix these things,
take a crack at it.

I truly appreciate your help. It seems to me that it should cost more
than $300 when paying someone to fix. Either you have someone who is
really talented and deserves high hourly pay or you have someone who
isn't and just replaces everything at the board level to find what's
wrong. Either way you pay a lot.

JURB

There is voltage. I noted that on this convergence board all supplies
are tied together for the STKs, so if voltage went, RGB would all be
affected. Thanks.
kip wrote:
No Voltage NO output...Simple!!

kip
wrote in message
oups.com...
I will check the voltages at the STK. Wouldn't I get no output from
the STK if voltage was not present?

kip wrote:
We they are there you have to trace back and locate them if no voltages
to
Stk,s.

kip


wrote in message
oups.com...

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to
unplug
the set to prevent the "booby trap" eeprom info failure from light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this model
uses long retangular convergence board (no screws, held in place
with
snap hooks with metal box. you can get it out from front and reach
deep to release one of cables from holders and unplug from the small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is a
problem with the red projecting a wavy line near top of screen. I
checked all ouput resistors on the amp on the convergence board and
they were all fine. I tried switching the blue and red outputs
from
the convergence board and the problem went to the blue so I was
fairly
confident the problem was with the red convergence amp (STK392-110)
and
I replaced it. The problem still exists. I took a picture of it
and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note the
picture was taken with the blue and red outputs from the
convergence
amp swapped so problem is on the blue). Anybody have any
suggestions?

Is one stk cold yes or no ??

kip
wrote in message
oups.com...
There is voltage. I noted that on this convergence board all supplies
are tied together for the STKs, so if voltage went, RGB would all be
affected. Thanks.
kip wrote:
No Voltage NO output...Simple!!

kip
wrote in message
oups.com...
I will check the voltages at the STK. Wouldn't I get no output from
the STK if voltage was not present?

kip wrote:
We they are there you have to trace back and locate them if no
voltages
to
Stk,s.

kip


wrote in message
oups.com...

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to
unplug
the set to prevent the "booby trap" eeprom info failure from
light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of
this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value
resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor
under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this
model
uses long retangular convergence board (no screws, held in place
with
snap hooks with metal box. you can get it out from front and
reach
deep to release one of cables from holders and unplug from the
small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is
a
problem with the red projecting a wavy line near top of screen.
I
checked all ouput resistors on the amp on the convergence board
and
they were all fine. I tried switching the blue and red outputs
from
the convergence board and the problem went to the blue so I was
fairly
confident the problem was with the red convergence amp
(STK392-110)
and
I replaced it. The problem still exists. I took a picture of
it
and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note
the
picture was taken with the blue and red outputs from the
convergence
amp swapped so problem is on the blue). Anybody have any
suggestions?

If both are warm ....
Did you go into service menu sections and try and realign
sometimes when they go it will kick back the DCU..

kip
wrote in message
oups.com...
There is voltage. I noted that on this convergence board all supplies
are tied together for the STKs, so if voltage went, RGB would all be
affected. Thanks.
kip wrote:
No Voltage NO output...Simple!!

kip
wrote in message
oups.com...
I will check the voltages at the STK. Wouldn't I get no output from
the STK if voltage was not present?

kip wrote:
We they are there you have to trace back and locate them if no
voltages
to
Stk,s.

kip


wrote in message
oups.com...

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to
unplug
the set to prevent the "booby trap" eeprom info failure from
light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of
this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value
resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor
under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this
model
uses long retangular convergence board (no screws, held in place
with
snap hooks with metal box. you can get it out from front and
reach
deep to release one of cables from holders and unplug from the
small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is
a
problem with the red projecting a wavy line near top of screen.
I
checked all ouput resistors on the amp on the convergence board
and
they were all fine. I tried switching the blue and red outputs
from
the convergence board and the problem went to the blue so I was
fairly
confident the problem was with the red convergence amp
(STK392-110)
and
I replaced it. The problem still exists. I took a picture of
it
and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note
the
picture was taken with the blue and red outputs from the
convergence
amp swapped so problem is on the blue). Anybody have any
suggestions?

They both get hot. One definitely heats up quicker than the other
however.
kip wrote:
Is one stk cold yes or no ??

kip
wrote in message
oups.com...
There is voltage. I noted that on this convergence board all supplies
are tied together for the STKs, so if voltage went, RGB would all be
affected. Thanks.
kip wrote:
No Voltage NO output...Simple!!

kip
wrote in message
oups.com...
I will check the voltages at the STK. Wouldn't I get no output from
the STK if voltage was not present?

kip wrote:
We they are there you have to trace back and locate them if no
voltages
to
Stk,s.

kip


wrote in message
oups.com...

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to
unplug
the set to prevent the "booby trap" eeprom info failure from
light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of
this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value
resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor
under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this
model
uses long retangular convergence board (no screws, held in place
with
snap hooks with metal box. you can get it out from front and
reach
deep to release one of cables from holders and unplug from the
small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is
a
problem with the red projecting a wavy line near top of screen.
I
checked all ouput resistors on the amp on the convergence board
and
they were all fine. I tried switching the blue and red outputs
from
the convergence board and the problem went to the blue so I was
fairly
confident the problem was with the red convergence amp
(STK392-110)
and
I replaced it. The problem still exists. I took a picture of
it
and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note
the
picture was taken with the blue and red outputs from the
convergence
amp swapped so problem is on the blue). Anybody have any
suggestions?

kip wrote:
If both are warm ....
Did you go into service menu sections and try and realign
Yes.

sometimes when they go it will kick back the DCU..


kip
wrote in message
oups.com...
There is voltage. I noted that on this convergence board all supplies
are tied together for the STKs, so if voltage went, RGB would all be
affected. Thanks.
kip wrote:
No Voltage NO output...Simple!!

kip
wrote in message
oups.com...
I will check the voltages at the STK. Wouldn't I get no output from
the STK if voltage was not present?

kip wrote:
We they are there you have to trace back and locate them if no
voltages
to
Stk,s.

kip


wrote in message
oups.com...

kip wrote:
Dont forget there maybe a open Pico fuse as well.

Pico fuse where? I don't see any on the convergence board itself.
Thanks for the help.


kip

"Dani" wrote in message
ups.com...
***CAUTION!!!!*** This is one of the JVC units that you have to
unplug
the set to prevent the "booby trap" eeprom info failure from
light
hitting
the sensor. Be very carefull here!

You can do the convergence surgery through the front panel of
this
model without removing the back and setting off the booby trap.

Replace both STK convergence IC's, also check low value
resistors.
...5, or 1.0 ohms approx. The booby trap is the optical sensor
under
a hole in the DVI metal box. Unplug power plug and wait a minute,
remove panel, unplug all wires to the DVI module and you can work
on it safely with power on.

Also you can work from front for convergence job only, if this
model
uses long retangular convergence board (no screws, held in place
with
snap hooks with metal box. you can get it out from front and
reach
deep to release one of cables from holders and unplug from the
small
stand up PCB.




wrote:
I have a JVC 56" rear projection TV (model AV-56WP30). There is
a
problem with the red projecting a wavy line near top of screen.
I
checked all ouput resistors on the amp on the convergence board
and
they were all fine. I tried switching the blue and red outputs
from
the convergence board and the problem went to the blue so I was
fairly
confident the problem was with the red convergence amp
(STK392-110)
and
I replaced it. The problem still exists. I took a picture of
it
and
stored he http://www.signaturefactory.com/dlip/tv1.jpg (note
the
picture was taken with the blue and red outputs from the
convergence
amp swapped so problem is on the blue). Anybody have any
suggestions?

I think you are right, it looks like I need to back up and start over.
I hooked the outputs from the convergence board back up how they were
originally. The picture I get is:
http://www.signaturefactory.com/dlip/tv3.jpg

I remember the hatch looking much more like that shown in the previous
(where I had output swapped). But now, looking at the previous hatch I
see that red was very hard to see. The red lines are very faint when
hooked properly and near the top of the picture are quite wavy. When
watching TV the center of the picture looks just OK but near the top we
see a wave of red. I looked at both circuit boards attached to the red
yoke and I see no bad solder joints, no capacitors that look like
they've gone, and no other components that are obviously bad.

Any suggestions?


wrote:
First of all, you cannot just switch red and blue. There were old Sonys
that had the red and blue well matched and the convergence affected
them somwhat like the middle set of rings on a tri-color CRT.

Now, OP, you have confused the issue switching **** around, show me the
crosshatch with the connections correct.

Put the thing how you found it, post a pic then, then I will look at
it. From the pic you have, you have a foldover, but not a real bad one,
it is more like a voltage amp clipping.

Then this could also very easily be a fault in the blue channel of the
DCM. Do you know how to definitively check if the STKs are good with a
scope ?. Also, you can't even do it in that set without extreme
measures. jusat hook it back up right and let me see it.

You might find that a resistor, say a 1 ohm, overheated and became
LOWER, like 1/4 ohm. I have had it happen.

You might find a leaky Zener diode, All kinds of parts that cost less
than a dollar. Which one ?

First thing, is to put it back together, I don't mean the back, but I
wanna see all three colors with each hooked up to the proper outputs.
This color switching technique doesn't work anymore. I need to see the
problem, not the problem as modified by you.

Put the thing back right, don't put it together, I couldn't care less
if your cat crawls in there. UNtamper the set and show me the picture,
and tell me if it is with new STKs, and where they came from and if
there was a change in the symptom after their replacement.

Then we can proceed.

Any of you out there wonders why it costs $300 to fix these things,
take a crack at it.

JURB

First of all why is the "black" area red ? Have you cranked the G2 for
some reason ?

Regardless, it seems you have eliminated yokes and STKs as suspects.
That leaves the DCM. You said the symptom did not change when you
changed the STK, but did it stay EXACTLY the same ? There are alot of
out of spec STKs out there. The ones that aren't completely dead
somettimes have poor high frequency response, and that is critical in
alot of sets.

At this point in time I do not know how to get into the alignment mode,
and although you never try to adjust out a circuit fault, just how it
responds to adjustments may lend a clue. If you happen to know how to
get into the convergence alignment mode, let me know. There is no doubt
one of these things will darken my bench someday.

I don't know if it has a cursor based system or the old siz/lin/trap
etc controls. If the set allows you to see the whole picture while
adjusting the crosshairs you can see if it changes when you do so, if
not, perhaps somewhere in the service mode there is a DC offset value.
If the pattern moves uniformly the problem is in the DCM. Even if it
doesn't the problem could be in the smoothing/buffer stage at the
output end of the DCM.

You don't even want to know what the DCM costs, so all other suspects
must be eliminated first. If the problem is in the DCM, and it turns
out that the output is clipping the waveform before it gets to the STK,
that might be no more than an OP AMP, but if it is in the waveform
generator itself, we are talking some hairy ****, err scary ****. Also,
because most of it is SMD components it is not practical to swap
comonents of red and blue channels to see if the problem follows.

In the last picture, I am not really seeing the red lines, but I do see
the abberation. When you had it "cross channeled" I will say that this
is not normal though, that is if you took a normally working set and
swapped the yoke plugs I would expect the H linearity errors, but the
errors in the vertical lines at the top are defiitely not normal. The
general trapezoidal shape is to be expected (that's why you can't just
switch them), but the 'wave' in it is not right. My remaining brain
cells still scream STK, but that has been eliminated. The exceedingly
rare shorted convergence yoke is also exonerated.

I know the set is an incredible bitch to work on, but at this point I
would compare the waveforms at the + and - inputs to the red V channel.
You should have a very similar waveform on each, or practically nothing
if it is setup as an inverting amp. Those STKs are nothing but
overgrown OP AMPs. You should be able to get the spec sheet at
datasheetarchive.com. You may find that a little (pf) capacitor has
suddenly decided to be a resistor and is making the STK behave badly,
wouldn't be the first time.

In some sets you can switch the yokes, AND the DCM outputs to the STKs
as a definitive test, but I wouldn't count on it here. It would
probably entail cutting foils and installing jumpers, and then you
can't be sure of yoke polarity.

You said one STK is getting hotter, which one ? The one feeding the
offending color or the other one ? If the offending channel is cooler I
would look for perhiperal components in that stage (which are few). On
the other hand if the offending channel is getting hotter I'd look for
something across the output. Zener diodes, small caps etc.

You got a fun one there. Good luck.

JURB

wrote:
First of all why is the "black" area red ? Have you cranked the G2 for
some reason ?

Yes I did crank it otherwise the red lines are almost not visible at
all.


Regardless, it seems you have eliminated yokes and STKs as suspects.
I'm still wondering if it could be the yoke. If you look at the
picture from when I swapped outputs on the convergence board you'll see
that no red is visible. Yet blue was. So it seems like the
convergence output is fine but it must be something beyond that.

That leaves the DCM. You said the symptom did not change when you
changed the STK, but did it stay EXACTLY the same ? There are alot of
I do believe that it stayed exactly the same.
out of spec STKs out there. The ones that aren't completely dead
somettimes have poor high frequency response, and that is critical in
alot of sets.

At this point in time I do not know how to get into the alignment mode,
and although you never try to adjust out a circuit fault, just how it
responds to adjustments may lend a clue. If you happen to know how to
get into the convergence alignment mode, let me know. There is no doubt
one of these things will darken my bench someday.

I do have the service manual and so am able to get into alignment mode.
Basically you hit the button on the convergence board and then you hit
menu to do green, 100+ for red and input for blue. But red is almost
unadustable and very difficult to see.

I don't know if it has a cursor based system or the old siz/lin/trap
etc controls. If the set allows you to see the whole picture while
adjusting the crosshairs you can see if it changes when you do so, if
not, perhaps somewhere in the service mode there is a DC offset value.
If the pattern moves uniformly the problem is in the DCM. Even if it
doesn't the problem could be in the smoothing/buffer stage at the
output end of the DCM.

You don't even want to know what the DCM costs, so all other suspects
must be eliminated first. If the problem is in the DCM, and it turns
out that the output is clipping the waveform before it gets to the STK,
that might be no more than an OP AMP, but if it is in the waveform
generator itself, we are talking some hairy ****, err scary ****. Also,
because most of it is SMD components it is not practical to swap
comonents of red and blue channels to see if the problem follows.

In the last picture, I am not really seeing the red lines, but I do see
the abberation. When you had it "cross channeled" I will say that this
is not normal though, that is if you took a normally working set and
swapped the yoke plugs I would expect the H linearity errors, but the
errors in the vertical lines at the top are defiitely not normal. The
general trapezoidal shape is to be expected (that's why you can't just
switch them), but the 'wave' in it is not right. My remaining brain
cells still scream STK, but that has been eliminated. The exceedingly
rare shorted convergence yoke is also exonerated.

Why couldn't be a shorted convergence yoke?

I know the set is an incredible bitch to work on, but at this point I
would compare the waveforms at the + and - inputs to the red V channel.
You should have a very similar waveform on each, or practically nothing
if it is setup as an inverting amp. Those STKs are nothing but
overgrown OP AMPs. You should be able to get the spec sheet at
datasheetarchive.com. You may find that a little (pf) capacitor has
suddenly decided to be a resistor and is making the STK behave badly,
wouldn't be the first time.
I did get the data sheet. I'll take a look at the + and -.

In some sets you can switch the yokes, AND the DCM outputs to the STKs
as a definitive test, but I wouldn't count on it here. It would
probably entail cutting foils and installing jumpers, and then you
can't be sure of yoke polarity.
Would it hurt if I just switched the yokes?

You said one STK is getting hotter, which one ? The one feeding the
offending color or the other one ? If the offending channel is cooler I
would look for perhiperal components in that stage (which are few). On
the other hand if the offending channel is getting hotter I'd look for
something across the output. Zener diodes, small caps etc.
The red channel STK heats up almsot immediately.

You got a fun one there. Good luck.

Again thanks for all your help.

JURB