Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Jason D.
 
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Default P61310JX4 blacks out on extreme whites.

You know some breaks the "rules" by going whiter than whites (above
the standard max on the video color contents signals?

Well on dish and on certain DVD that has too bright images and extreme
flashes like "Blizzards" the opening before menu comes up is powerful
white than standard whites upsets this chassis DTV307 to black out and
return normally. The error log says code 7 (I know what it is but
forgot the exact message). Picture simply blinks out then back on
once the whites is gone.

I tried many ways to stop this blacking out episodes by decrease the
pemeters 21 (for all CRT cut offs), even R, G, B cutoffs without
decreasing the picture quality. The user picture settings are at
their defaults. Only way according to customer is decrease the
contrast which stops this blacking out episodes which is bandaiding
that problem.

Background: changed one CRT for spotty picture complaint then ended up
changed all CRT just to get acceptable picture and hopefully to stop
the blacking out which did not work out and I have bought out my big
guns to customer's and tried few things suggested in the training
sections which turned out be wrong one even it was right off the
website for the DTV307. I think the set of papers was for other
chassis. The service manual for DTV307 on CD is correct and followed
their CRT setting up instructions exactly.

HELP!

Aside: To Art who replied eariler: I copied and pasted his message:

"Pay attention to lousy solder connections every where on the main
chassis assembly, including the stand up daughter board and the
inter-connect between it and the processor board that connects at the
rear apron. Agreed, these sets are an absolute Bow Wow to work on and
fix. Thank the electronic gods that Thomson dumped them and their near
cousins.

Hopefully you have their diagnostic procedures and training materials.
If not E_Mail me and I'll see if there is an archive that can be made
available for you."

BARK BARK BARK!!! RIGHT on! I should have DTV307 in book form
somewhere but my point is that it is a major pain to work on because
way chassis is designed. I HAVE serviced several of them, all were
physical broken traces early on 2 years ago or on going rebuild
standby SMPSes that went up in smoke when a diode became a wire. What
a biggest idiot to put little 10 ohm 1/8W UNDER a SMPS transformer.
Egards! And few needed pair of caps to get them going. But this time
this latest barker really got the stinky cake for biggest mean dog of
the neighbourhood. }:

Cheers, Wizard
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Art
 
Posts: n/a
Default

?? Jason, have you tried changing values for sub brite, etc parameters just
to see if they have any variance with your specific blanking at high brite
symptom? IMHO the current sense for the beam to all three crts may be
causing the intermittent blanking. I hate the AKB on some of these sets, esp
when they cause strange problems like this one. Agreed, the engineer who put
that fuse resistor under the smps transformer should be required to change a
few hundred under on-site conditions!!
www.wa6ati.com site, post your status, may get some hits via a group of
techs from "the other side"!!!

"Jason D." wrote in message
...
You know some breaks the "rules" by going whiter than whites (above
the standard max on the video color contents signals?

Well on dish and on certain DVD that has too bright images and extreme
flashes like "Blizzards" the opening before menu comes up is powerful
white than standard whites upsets this chassis DTV307 to black out and
return normally. The error log says code 7 (I know what it is but
forgot the exact message). Picture simply blinks out then back on
once the whites is gone.


I tried many ways to stop this blacking out episodes by decrease the
pemeters 21 (for all CRT cut offs), even R, G, B cutoffs without
decreasing the picture quality. The user picture settings are at
their defaults. Only way according to customer is decrease the
contrast which stops this blacking out episodes which is bandaiding
that problem.

Background: changed one CRT for spotty picture complaint then ended up
changed all CRT just to get acceptable picture and hopefully to stop
the blacking out which did not work out and I have bought out my big
guns to customer's and tried few things suggested in the training
sections which turned out be wrong one even it was right off the
website for the DTV307. I think the set of papers was for other
chassis. The service manual for DTV307 on CD is correct and followed
their CRT setting up instructions exactly.

HELP!

Aside: To Art who replied eariler: I copied and pasted his message:

"Pay attention to lousy solder connections every where on the main
chassis assembly, including the stand up daughter board and the
inter-connect between it and the processor board that connects at the
rear apron. Agreed, these sets are an absolute Bow Wow to work on and
fix. Thank the electronic gods that Thomson dumped them and their near
cousins.

Hopefully you have their diagnostic procedures and training materials.
If not E_Mail me and I'll see if there is an archive that can be made
available for you."

BARK BARK BARK!!! RIGHT on! I should have DTV307 in book form
somewhere but my point is that it is a major pain to work on because
way chassis is designed. I HAVE serviced several of them, all were
physical broken traces early on 2 years ago or on going rebuild
standby SMPSes that went up in smoke when a diode became a wire. What
a biggest idiot to put little 10 ohm 1/8W UNDER a SMPS transformer.
Egards! And few needed pair of caps to get them going. But this time
this latest barker really got the stinky cake for biggest mean dog of
the neighbourhood. }:

Cheers, Wizard



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