Philips 42PFL9632D/79 2-secs-to-black

[pedro]

I have a fair history on repairing LCD (ccfl) monitors, but gave it away over a year back to reclaim some time for other pursuits. I was recently presented with the above TV for investigation. Chassis is Q528.1E.LA (not .1A.LA although the significance of that is unknown).

After the usual 8-10 secs of system wakeup (aka nothing) after turn-on, the screen lights with "no input" or similar message in a banner across the top, then after a couple of secs the zzzzzzzt sound starts and then the total backlight system shuts down.

These are sets with two separate inverters for backlights, the "master" on the left and "slave" on the right (as viewed from the rear of course) - and that wank ambilight system tacked onto the rear case. Trying to locate the source of the zzzzzt is a problem - seems like BOTH inverter boards are doing it, which is odd given that the reported failure mode was "one day, when I turned it on, this is what it did".

Have had no joy locating a service manual or schematic for this monster. Google did show this as a not uncommon problem (and a number of threads about replacement inverter boards). While I know the general approach from my monitor repair days, a schematic would help a lot.

Anyone know where I might locate one? (Elektrotanya only has a four-page assembly part# listing from various models of this family).

[pedro]

Re: Philips 42PFL9632D/79 2-secs-to-black

Have had no joy locating a service manual or schematic for this monster. Anyone know where I might locate one? (Elektrotanya only has a four-page assembly part# listing from various models of this family).

Anyone?

[tom66]

Re: Philips 42PFL9632D/79 2-secs-to-black

On the back of the set there will be a model sticker. Chassis number will be indicated on the sticker in a box marked "S" or "chassis", e.g. LC8.2E.

[pedro]

Re: Philips 42PFL9632D/79 2-secs-to-black

On the back of the set there will be a model sticker. Chassis number will be indicated on the sticker in a box marked "S" or "chassis", e.g. LC8.2E.

Did you miss where I gave the chassis# in post 1? Again, Q528.1A.LA

[tom66]

Re: Philips 42PFL9632D/79 2-secs-to-black

Sorry yes.
SM:
http://www.tgohome.com/ServiceManual...&Search=Submit

Suggestions:
- Check 24V and BLON on inverter board
- See if the power LED blinks an error code

[pedro]

Re: Philips 42PFL9632D/79 2-secs-to-black

Sorry yes.
SM:
http://www.tgohome.com/ServiceManual...&Search=Submit

Very different beast unfortunately.

Suggestions:
- Check 24V and BLON on inverter board

Philips/LG seem to have set out to make these as painful to service as possible. There are NO legends near any connectors, just a connector label. So far I have accounted for +3v3, +5v0 and +12v0 supplies, no sign of +24v at this stage.

- See if the power LED blinks an error code

No it doesn't. After the B/L shuts off, the power LED stays on.

After working on monitors for quite a while, there are a number of things about this device which are alien to me (although maybe commonplace to more TV-oriented techs):

- The number of boards/subassemblies - five apart from the t-con and front/side panel. (See attached quickie pics which are for explanation/identification only and NOT diagnostic quality.)
- The lack of pinout legends near any connectors.
- The inverter board arrangement - dual boards (master/slave) each with two transformers but only two conductors to the lamp assembly.

As a further description of what transpires when an attempt is made to turn it on, the LED on the master inverter lights when the B/L system first fires up, then when the zzzzzt starts the LED dims progressively over a couple of seconds until the zzzzzt (and B/L) stops, returns to full brightness for about a second and finally extinguishes as a relay clicks elsewhere.

No components show any signs of distress. Subject to my guess(tm) that the transformer terminals nearest the lamp connector are the output(s), all secondaries measure as <0.1ohm! You can see why I hanker for a SM ....

[tom66]

Re: Philips 42PFL9632D/79 2-secs-to-black

Does this help?

[pedro]

Re: Philips 42PFL9632D/79 2-secs-to-black

Does this help?

See the last sentence of post #1 ...

[freecom]

Re: Philips 42PFL9632D/79 2-secs-to-black

99%

problem is inside panel

bad bulb

[tom66]

Re: Philips 42PFL9632D/79 2-secs-to-black

You say that with certainty, but I have -never- heard of a bad bulb in an LG panel. Not saying it is impossible but it would be unusual.

[pedro]

Re: Philips 42PFL9632D/79 2-secs-to-black

Eventually found the Service Manual for the Q528.1E.LA and downloaded it - all 89MB and X hundred pages. That's the good news. The bad news is that it contains whole swags of info on different LED board systems but nada on the B/L inverter system that this Q528.1A.LA uses.

SM URL: http://rapidlibrary.com/source.php?f...e3bdcbbcd3c03f

[tom66]

Re: Philips 42PFL9632D/79 2-secs-to-black

That's probably because the backlight is part of the LCD module (LCM) and is described in a separate document.

[pedro]

Re: Philips 42PFL9632D/79 2-secs-to-black

If that is the case, then why are there twenty or thirty pages of LED variant descriptions? Really, unless this is a LED B/L masquerading as a CCFL unit then the only LEDs in sight are indicators on the front panel and two pcb's.

[tom66]

Re: Philips 42PFL9632D/79 2-secs-to-black

Perhaps for Ambilight models?

[selldoor]

Re: Philips 42PFL9632D/79 2-secs-to-black

is there a panel number sticker on the panel?


EDIT doesnt matter just trying to find out if it was an LED panel
but its not.

[selldoor]

Re: Philips 42PFL9632D/79 2-secs-to-black

If that is the case, then why are there twenty or thirty pages of LED variant descriptions? Really, unless this is a LED B/L masquerading as a CCFL unit then the only LEDs in sight are indicators on the front panel and two pcb's.

It is not an LED panel.

It uses the same inverters as some vizios and some lgs this may be relevant
https://www.badcaps.net/forum/showpo...6&postcount=16

[JayRolla]

Re: Philips 42PFL9632D/79 2-secs-to-black

First time post, I have worked on some phillips like that model with the same issue. Turn off the lights, power up the unit and look for arching between the inverters and lcd chassis. The soder points on the back of the inverters where so large they would arch out on the board, I added insulation and cut/grinded down the soder points and it fixed the issue. Seen it on about 10 different phillips with inverters.

[Dgtech]

Re: Philips 42PFL9632D/79 2-secs-to-black

I don't know where my posts are right now but I had put together instructions for fixing these sets with faulty inverter boards. I will sum it up again in this post.

1. Check the caps on inverters. 2 each.

2. Check the driver chip visually for pin 26 burning off - common failure.

3. Measure the resistance between the two soldered leads of each of the four fets on both master and slave boards and post the results here. You should find that they should all measure the same ~ 8.5k ohms I think. If there is one reading lower, that means the driver chip (32 pin surface mount) needs changed.

[pedro]

Re: Philips 42PFL9632D/79 2-secs-to-black

Follow-on to several posts, won't try quoting them ....

I realise it's not a LED backlight type, that was a brain-fart resulting from dozens of pages titled LED-whatever in the 300-page SM when I was overwhelmed by the amount of diversity in the models described there. The references were to the wank ambilight system variants from two to six or more strips (this set has two, one on each side).

On FET testing, recognising that there is a 10K across each FET, variation around a group value is a bit worse than indicated by the readings - but all in the 8.46K to 8.51K across both boards.

What I noted somewhere else (it's all a bit of a blur about what I have trawled through with google since this set appeared here) was a comment that "if the B/L comes on then does the 2-S-T-B it's the slave, if it doesn't come on at all it's the master". How true that is I don't know.

Several days ago, in my repetitive turning On/Off while checking voltages, the damned thing actually fired up (*) and I let it run for a couple of hours with no issues. I then shut it off and it restarted happily a couple of minutes later. But twenty minutes after that run was ended it was back to 2STB.

That day was a bit warmer than the rest, so today I went at it with the hot air gun warming up the various boards and trying the On/Off bit. I was actually suspicious of a Lelon cap on the SSB but that didn't respond. Nor did the main PSU board. But the master inverter did, firing it up a few minutes after I waved the wand at it. I'll let it cool everything overnight and then apply heat to *only* the master, just to be sure where to focus my attention. Comments noted re those boards. No sign of damage on the driver chips on either. These boards have not had the zener clamp mod done, not the cut-track-add-resistor-etc mod.

(*) The pattern on the blue LED on the master is that it comes on shortly after sound appears, and B/L's light. Then it fades down and the B/L drops out, the LED then relights at full brightness for ~1 sec and extinguishes. When the B/L stays on, the bright-fade-bright is the same but it doesn't extinguish at the end.

I had already resoldered all the inverter transformer secondary terminals, as the rohs crap there was looking decidedly dodgy.

Finally, does anyone have a link to the schematics for these inverters?

[selldoor]

Re: Philips 42PFL9632D/79 2-secs-to-black

You didnt actually say what happened when you heated the master inverter from cold.
If that made it work then I would change the caps only a couple of dollars to try..

EDIT
Haha I see why - I am a day behind/ahead/below/above or something. Will look in later