Acoustic solutions lcd32761hdf

[Hamie]

Working on this tv for a neighbour.
It's the tv their kids use to play the Xbox on.

Symptoms. Stuck in standby.

Powersupply - dreaded vestel 17pw26-4

Originally had a few obvious caps bulging. Replaced and the power supply appears to be working. All voltages ok 24 volts to the inverter etc.

Tv still remains the same turns on looks like will power up then back to stand by.

Unplugging the inverter and the tv powers up steady voltage and runs fine. Has sound etc

Looks like and inverter problem. Or possibly has a bulb drawing too much current.

Don't mind replacing the inverter as can get one for a only few quid.
But will this resolve the issue?

What's the best way to test to see if it's the inverter or bulb issue?
I also have not found a way to jump the back lights on without the mainboard as I don't know the pin layout.

Any advice would be great.

[selldoor]

Re: Acoustic solutions lcd32761hdf

Sorry double post

[selldoor]

Re: Acoustic solutions lcd32761hdf

Please can you post pictures using manage attachments. Rather than in line or off site so that they will remain to help others.
Is there a fuse on the inverter board - tested?
Is 24v getting to the fuse?

[Hamie]

Re: Acoustic solutions lcd32761hdf

There is voltage getting to the board.
24v on all positive legs of capacitors.

Transformers all 3.9k ohm resistance between output legs.

[tom66]

Re: Acoustic solutions lcd32761hdf

May not be the inverter.
Did you replace the 15n 630V caps near top of transformer?

[vinceroger69]

Re: Acoustic solutions lcd32761hdf

http://www.tv.quuq.org/forum/index.php?topic=2278


post 5 int or no iverter

[Hamie]

Re: Acoustic solutions lcd32761hdf

Cheers, I actually have a working powersupply that I've just installed that I reclaimed from a smashed up Alva, I know this power supply to be good because I've tested it on a Toshiba.
The fault remains. I'm convinced the fault lies with the inverter/bulbs.

I decided just to removed all the transformers from the inverter and jump them. To try and exclude bulb failure.




The fault remains. Therefore I'm pretty convinced the inverter has a fault.

Apologies about photo format, can't seem to upload any other way from my phone.

[tom66]

Re: Acoustic solutions lcd32761hdf

Jump... the transformers? How?

[budm]

Re: Acoustic solutions lcd32761hdf

I cannot see how that will work, the MOSFETS will basically drive the <1 Ohms loads which are supposed to be the primary windings of the inverter transformer, now they driving short piece of wires, and the lamps are now just sitting there without high voltage drive from the transformers. I wonder if those MOSFETs are still OK, now the inverter circuits will really draw lots of current.

[Clydeuk]

Re: Acoustic solutions lcd32761hdf

You'll probably get the inverter connector pinout by looking online for the datasheet for the panel. The pinouts tend to be fairly standard in my experience over a range of panels from different manufacturers.

[Kilroys]

Re: Acoustic solutions lcd32761hdf

How about the voltage on pin 12 BL_ON/OFF, the blue wire
PL802. Whats the name of the controller ic on the inverter,
beginning with OZxxxx ?

[Hamie]

Re: Acoustic solutions lcd32761hdf

Ok so put the inverter back together.
I'm now thinking my other powersupply has developed a fault.

Basically If you turn the tv on without the inverter plugged in. Let it start up for around 30 seconds then plug in the inverter the tv works fine.

Unsure where to turn with this one! :-/

[Hamie]

Re: Acoustic solutions lcd32761hdf

Just thought id update some voltages going to the inverter.

With the inverter unplugged.
Red wires - 23.94 on all wires.
Black ground.
Orange 3.32
Blue - 3.23

When I turn the set on for 30 seconds then push in the inverter the voltages change to:

red wires - 22.29
Black all ground.
Orange - 3.32
Blue - 2.99

With the inverter plugged from start up all voltages briefly appear apart from the blue wire that gets to .5 - .7 volts then shuts down.