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Equipment Repairs => LCD TV forum => Topic started by: flipflup on July 23, 2008,09:22:49

Title: Defective PSU board LG 32LP1R Chassis ML051-A
Post by: flipflup on July 23, 2008,09:22:49

Dear all,

I'm battling to get this PSU working (it has suffered from a design fault - a conductive adhesive tape has come loose and short circuited the board to the ground -).

Unfortunately I can't find the PSU schematics of this tely (it seems that LG doesn't put the PSU's  into the numerous service manuals that I've downloaded   :diablo:) .

Apparently this chassis (ML-051A) is also used in the next models : 26LX1R, 26LX2R, 32LP1R, 32LX1R, 32LX2R, MW-30LZ10.

I also found a reference for the complete PSU board (6871TPT316B ) but I'm not too sure if this is correct.

Any help would be appreciated  :cheesy1:.

All the best,

Philippe

Title: Re: Defective PSU board LG 32LP1R Chassis ML051-A
Post by: tv tony on July 23, 2008,09:35:51

oh dear, the dreaded sticky tape fault, we get a lot throughout the range.
which voltage are you missing, 1st to establish is the standby 5v, is that there, after that a signal from the micro establishes the 24, 12, 6 and 5v. which are u missing, and yes, the circuit is not available,

Title: Re: Defective PSU board LG 32LP1R Chassis ML051-A
Post by: flipflup on July 23, 2008,10:06:33

Hi Tony ,

Thanks for this quick answer.

Well, I *think* the 5V is there (I'm in the office now, not in my workshop...).
If it may help, when I switch it on, the green stand-by at the front lights for a long while, then turns red for a short while, then back to green, etc...

Oh yes, I've already replaced a fried main diode bridge and a shorted "e" to  "c" 2N2907. I've also suspicions about one of the 3 optocouplers.

I'll check tonight to be sure of this 5V led...

All the best,

Philippe

Title: Re: Defective PSU board LG 32LP1R Chassis ML051-A
Post by: flipflup on July 23, 2008,11:49:12

Hi again,

Just checked : 5V is present (control led lights).

5.5 PST, 18V and 12 V are not present (no led indication).

Front panel stand-by led cycles as explained before.

 Does this help ?

Philippe

Title: Defective PSU board LG 32LP1R Chassis ML051-A
Post by: flipflup on July 25, 2008,13:34:38

Hello again,

I'm still working on this tely ...

I found a LG service manual which surprinsigly enough comprises the PSU schematics (32LP1DC-UA, chassis AL-04CA).

Unfortunately, it is not exactly the one I was looking for, but it shows a lot of ressemblances with mine.

I attach it to this post, to whom it may help.

Greetings,

Philippe