viewsonic monitor P810 with vertical problems

[HoustonEE]

Chassis HV8SA

All,

Originally monitor would not power up, made ticking sound only. Thanks
to postings found here, found several bad parts around HOT
(q855,q719,q550)

Now monitor has no horizontal sync, and vertical is top half of screen
only, with horizontal white line in the middle. Have found and
replaced bad C408. All diodes in vertical section check OK.

Anybody have any suggestions on what to check next? Also, I found it
very difficult to probe anything on the chassis to make measurements.
Is there a trick to making this feasible?

I was going to offer to trade schematics for advise, but I'm instead
just going to post a link and trust in the kindness of the readers.
It's for a panasonic monitor, but it uses the same chassis.

http://rv6llh.rsuh.ru/panasonic/TX-D2162.ZIP

Thanks in advance for all assistance.

 

[William Buchholz]

I had a similar problem, the vertical sync was very erratic, sometimes
almost good depending on the scan rate. I replaced the C1883CT IC, it
controls both the vertical and horizontal synchronization. Check the
tiny smd transistors around the chip as well, I found one bad, the
sync signals pass through some of them. Also check the electrolytic
caps and the vertical IC itself in the vertical section, I had to
replace these as well. To probe the chassis I constructed a special
jig from some wood that would support the pcb close to its installed
position without the metal cage on the bottom. The service manual for
the G810 is here:
http://members.rogers.com/tcomsite1/
It is almost identical to the P810.
Good luck.
kgoodman@houston.rr.com (HoustonEE) wrote in message news:<80674ac1.0308301822.20172276@posting.google.com>...

Chassis HV8SA

All,

Originally monitor would not power up, made ticking sound only. Thanks
to postings found here, found several bad parts around HOT
(q855,q719,q550)

Now monitor has no horizontal sync, and vertical is top half of screen
only, with horizontal white line in the middle. Have found and
replaced bad C408. All diodes in vertical section check OK.

Anybody have any suggestions on what to check next? Also, I found it
very difficult to probe anything on the chassis to make measurements.
Is there a trick to making this feasible?

I was going to offer to trade schematics for advise, but I'm instead
just going to post a link and trust in the kindness of the readers.
It's for a panasonic monitor, but it uses the same chassis.

http://rv6llh.rsuh.ru/panasonic/TX-D2162.ZIP

Thanks in advance for all assistance.

 

[HoustonEE]

Thanks for the feedback - As it turned out the -16 V fusible resistor
was open - replacing that fixed vertical deflection problem. After
that the problem with the horizontal sync was still there. That turned
out to be the fusible resistor on the H_PULSE signal. Now it seems to
go in an out of focus. Also the thing seems really noisy - high picked
whining, plus clicking popping. I can't see any arcing in the dark,
and nothing seems to be getting hot that I can find. As always, I'm
open to suggestions.

kgoodman@houston.rr.com (HoustonEE) wrote in message news:<80674ac1.0308301822.20172276@posting.google.com>...
Chassis HV8SA

All,

Originally monitor would not power up, made ticking sound only. Thanks
to postings found here, found several bad parts around HOT
(q855,q719,q550)

Now monitor has no horizontal sync, and vertical is top half of screen
only, with horizontal white line in the middle. Have found and
replaced bad C408. All diodes in vertical section check OK.

Anybody have any suggestions on what to check next? Also, I found it
very difficult to probe anything on the chassis to make measurements.
Is there a trick to making this feasible?

I was going to offer to trade schematics for advise, but I'm instead
just going to post a link and trust in the kindness of the readers.
It's for a panasonic monitor, but it uses the same chassis.

http://rv6llh.rsuh.ru/panasonic/TX-D2162.ZIP

Thanks in advance for all assistance.

 

[HoustonEE]

Thanks Wayne for the feedback and links.

Another question: where can you find 0.47 ohm 1/2 W & 2.7 ohm 1/2 W
fusistors? I saw somebody suggest using flameproof metal film, but I
can't even find those in that low of a value. I looked in digikey and
mouser without success.





whmrs@mrbc.ca (Wayne) wrote in message news:<3f53e514.13004980@shawnews>...

Might be bad FBT

Search the archives of sci.electronics.repair for the words 'P810
flyback' at http://groups.google.com/advanced_group_search

"...Viewsonic P810 and G810 are notorious for the flybacks failing.
They are $85 plus S&H any where you can find them. ..."

http://www.noahtec.com/fbtest.htm is a good page on some basic FBT
tests you can do

Wayne