Soniq QV190L Lcd Tv

[graham68]

Hi All, I have a Soniq qv190l lcd tv that seems to have a shorted component to earth.

The Tv powers up then goes black screen, one of the pins out of the board measures about 4 volts then quickly drops to zero volts.

I have been looking for a diagram of this tv but have had no luck, anyone know if this tv has the same board as others?

The only numbers on the board are SHFA060151587 on a label - poss serial number?

And PA-0153----2TG on the board itself. The tv is made in China so (just guessing) I thought these boards maybe used by other brands.

BTW Tv has sound just goes black screen.

Any help would be great thanks.

[joester]

Since you mentioned reading 4 volts at one point, I'll assume you have reasonable skills to repair the TV.

Check the inverter for + voltage (S/B 12V I think). If you are not getting a reading around this voltage, I would suspect the power supply. Many supplies have the voltages marked either on top or under the board itself near the connectors.

I'm suspecting that the inverter may be at fault, but I could be wrong. Also, double check the ferrite bead locations on the board. You could have missed one, and since you now have sound it's entirely plausible that one was inadvertently missed.

Joe

[graham68]

I have uploaded some pictures of the board in the hope someone may be able to tell me if the board is used in other brands.

[url]http://s984.photobucket.com/albums/ae321/graham68_photo/Soniq%20QV190L%20Lcd%20Tv/ [/url]

The main chip is a Philips QM8370

Thanks for looking.

[Guest]

Joe, yes it seems to me that it is a power supply problem.

With the suspect circuit showing voltage for a little while before going to zero volts do you think it is possible that one of the caps is going short after it charges up? Is that possible? Sorry but I have limited experience with electronics.

I have traced the voltage back and am loosing the 12 volts that supplies a regulator. The voltage comes via a B764 Transistor which has 12 volts to both outside legs and 12 volts to the middle leg which then goes to zero volts.

I have looked for a replacement for the transistor just to test it but have had no luck finding one local.

[joester]

You mentioned capacitors, and that's s very real possibility. for several years, major manufacturers unknowingly used inferior electrolytic oil, and the result has been failing capacitors.

Look for ANY signs of bulging or leaking from any of the can type caps.
Replace as required.

Since you get a temporary 12V that suddenly drops, this could easily fix it... but then again, maybe not. If there is a bad winding in the transformer, a bad solder joint, or even a weak regulator, the failure can occur.

HINT: your link should look have (bracket)url=http://www.whatever.com(end bracket) LINK (bracket)/url(end bracket)
Your link almost worked and only needs a little tweaking in format.


Please post similar pictures as the main board, but of the power supply. I think that's where your problem is.

Joe

[graham68]

Joe, The power supply is a seperate switch mode (like a plug pack). There is only the main board in the tv and another smaller board that runs the back light and screen I guess. There are no obvious caps with problems so will keep looking.

I rang the Company and found out they charge $88 (aud) for a quote which is deducted from the final repair cost. They also said that repairs are likely to be up to the $200 mark.

For about $300 I can get a tv with a built in hd tuner which this tv lacks.

Might start looking after Christmas or ask Santa!!!
Am still interested in fixing this one though I get curious and just have to fix things.