Sharp LC-42SB45U No audio, need part identification

[mu2]

Hi,

I've got a Sharp LC-42SB45U with no audio out on any input. The audio chip is a TDA8933BTW and has been replaced. My scope shows audio at both inputs to the ic, main voltage looks correct. The mute function appears to work.
The main board in this set is a CBPF82MKP7 and the other number is 715T3252-2.
The service manuals that I've found on line show the 71T3252-1 main board.
This set is very close but there is another smd transistor on the bottom of the board listed as Q601. That part isn't listed on the service manuals I've found.
Does anyone have the service manual that shows my main board or can identify the transistor? I've tried with every magnifying device I have and I just cannot make out the number. I think it's pnp but I'm not sure and it's in the general area of the audio ic. Looks like it's damaged to me.
Thanks,
Mike

[tom66]

Re: Sharp LC-42SB45U No audio, need part identification

Have you checked voltages on ENGAGE and POWERUP pins?

ENGAGE and POWERUP must both be >2V to turn it on and produce audio.

Just so you don't chase a wild goose. Also check for shorted speakers and tweeters. Isolate one channel at a time. Check for good Vcc/Vdd.

[mu2]

Re: Sharp LC-42SB45U No audio, need part identification

Tom,

I've checked the speakers and both the engage and power up. The power up is over 2 volts and I'm pretty sure I saw a momentary rise above 2 on the engage pin.
The transistor in question seems to be in that general area. I'd really like to know how it's used.
Thanks.


Mike

[tom66]

Re: Sharp LC-42SB45U No audio, need part identification

Momentary rise on engage isn't good enough, needs to be continuous, so try and see if that transistor might control it, would be odd though, the levels are high enough for MCU to drive directly, can't see why it needs a transistor.

[selldoor]

Re: Sharp LC-42SB45U No audio, need part identification

How about a close up picture of it?

[mu2]

Re: Sharp LC-42SB45U No audio, need part identification

I don't have the time today to take a photo. I assume you mean a photo of the part in question?

Mike

[tom66]

Re: Sharp LC-42SB45U No audio, need part identification

And the surrounding area - top and bottom sides.