Acoustic Solutions LCD40F1080P stuck in standby

[mattlumb]

Got one of these Vestel TVs stuck in standby.  Plug in, press the on/off switch on top of TV and the blue LED comes on for a few seconds, goes out for a second and then comes on again.
Power board: 17PW16-2 
Main board: 17MB26-2
I uploaded a PS schematic to the service manuals pages, but this board seems a variant more like the one I later found is included on p.55 of the 17MB26 service manual in the same section (different top left of schematic page). All the rails are good except +12V_2 (in the middle of the schematic page) which is about 9.5V.  Removing all cables except the one to the on/off switch and mains, PS starts and works normally - (i.e. rails don't shut down after a few seconds).
Weird thing is, there was one time after I had reconnected the ps to its outputs and switched on - it started up and went to a blue screen - no response to remote though.  Anyhow, changed the usual caps (even though good) after checking the many threads on this subject and checked the capacitance and ESR of the main PFC output smoothing cap but made no difference.  The pfc seems to be working - gives 385V on the main PFC cap.  No dry joints on power resistors.  When the blue LED goes out the main switcher (all rails from TR805) stops.  I checked the internal power rails on the MB but all seems hunky-dory... 
Thanks in advance quuqers,
Matt   

[Turnip]

Hi Matt,

Had problems in the past and Quuq folks came to my aid - might be useful -

No problem Chris
Here are the faults ive remembered to write down,
Allot of these faults will apply to 17pw15-? As well,
17pw15-6 only - stuck in sby smd cap between earth and ic827 (diode?) remove and fit 1uf 50v cap(this mod was done in the factory on later production runs.
in sby then shuts down when power pressed - d845
int off - broken wire on tr806 - r830 dry - c878+c877 - dry smooth block on pcb + pegs - q818 leaky under load - c982 dry - check pcb for solder snots not removed during manufacture, can cause int shorts
Stuck in sby - c818+c857 4700uf - c878+c877 - q837 bsh103 - check all 1000uf caps in secondary - ic829 -q823 short -
int or no inverter - c904 remove and fit 1uf 50v - q829 short
dead - ic806 blown + c892 +c801 - bridge - there are kits available for major failures but check everything as often more components fail other than in the kit -
psu fitted to 42 inch ver 17pw16 i think - very int sby bad print under q804 causing a short ,remove and scrape around pads and refit.
There are many more faults but didn’t write them down, which is silly because I have the memory of a goldfish. Will post more as a remember them.
1.   17PW15-6 only. Stuck in S/by. SMD cap between earth and IC827 (bottom of board) Remove and fit 1/50 (done later facorywise in production runs.
2.   Intermittent S/by – shuts down when Power button pressed. D845
3.   Intermittent off. Broken wire on TR 806/R830. Dry on C878 and C877. Dry Main cap on PCB or pegs. Q818 leaky under load. C982 Dry. Check also for ‘Solder Snots’ not removed in manufacture as can cause int shorts.

[mattlumb]

Hi Chris,
Many thanks for those, I've tried all the capacitor ones and some others and the leaky transistor ones are a possibility.  I am going after the low internal +12V_2 rail after that - both variants of the schematic seem to have this at 12V not 9.5V.  The optocoupler or shunt regulator seems a possibility, as do the overvoltage- shutdown zener pull-up on the +24V and 5V but only if things go open-loop under load not zero load - seems a long shot.  Maybe I should stop waffling and get on with it. Probably won't get the chance to take another look for a week and a bit though after a session tonight.
Cheers again,

Matt

[mattlumb]

 
TV is no longer stuck in standby.
A combination of stupidity and nearly dead remote batteries. DUH!
Seems with this TV turning it on at the switch on the TV always puts it into standby, you then have to power it up with the remote...so, now I have lots of horizontal and vertical lines, but picture is responding to remote buttons - band and lines where menu should be etc.  I'm thinking LVDS cable - anything else to try before buying one ?
Thanks guys and gals.
Matt