Toshiba 32BV701B loss of audio

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Hi

Got this tv, the audio works fine for about 30minutes then cuts off, the psu

17pw25-4

the main
17mb60-4.1

What I have noticed is when the audio is working the backlights are very slightly flickering, when the audio packs up the B/L's stop flickering.

I am getting confused with the 2 schematics for both the psu and main

On the psu's connector block pin 26 says +24VAUD, is this for the audio? And should I check the components that drive this..I dont seem to be getting 24v when the audio is working or not

On the Main Board Schematics it references 3.3v & 5v the 3.3v being HP-Detect...oh and the headphones dont work either when the sound goes.

Could someone just have a quick look at the schematics and tell me if it is 24v that drives the audio, or any other pointers


Cheers in advance

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Re: Toshiba 32BV701B loss of audio

Anyone?

[tom66]

Re: Toshiba 32BV701B loss of audio

24AUD would be audio.
Crappy "Toshiba" Vestels are dying... I knew they would only last so long....

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Re: Toshiba 32BV701B loss of audio

Cheers Tom will start looking at the components on the 24vAUD and report back

[tom66]

Re: Toshiba 32BV701B loss of audio

...How about actually measuring 24VAUD and seeing if that works?

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Re: Toshiba 32BV701B loss of audio

There is no 24VAUD when the sound goes, Can you tell me what OP3, OP4 and what will S907 S908 relate too

Sorry forgot to add when the sound is working it raises from 25-27.3v then dies

[tom66]

Re: Toshiba 32BV701B loss of audio

OP: transformer outputs (trace to other arrow with OP on it, will be near transformer... just a stupid way of drawing it because they fit everything onto one or two pages.)

Sxxx: Jumper links in the board (kind of nice of them to do that as can be helpful in tracing the circuit out, but I wish they'd draw the diagrams better...!)

I'd investigate L908, check it's not intermittent or cracked.

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Re: Toshiba 32BV701B loss of audio

Grrrr vestel, all the components on the schematic are not on the board

ie

D921, D922, D930, D929 C969, C970 are all labelled on the schematics around the 24VAUD but not there.

The pw24 seems to be the worst for revisions and changes as I have about 3 faulty ones and they are all different

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Re: Toshiba 32BV701B loss of audio

There is no L908 in the board either

[tom66]

Re: Toshiba 32BV701B loss of audio

What suffix board do you have?
Pic of board area?

24AUD maybe connected to +24V?

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Re: Toshiba 32BV701B loss of audio

I must of made a mistake with the sound working or not working there is no 24v at pin 26

Attached images

[tom66]

Re: Toshiba 32BV701B loss of audio

I looked at 17MB60 and the audio is powered by the 12V on this so check the 12V supply is good.

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Re: Toshiba 32BV701B loss of audio

Yes mate 12v is fine doesnt move with or without sound

[tom66]

Re: Toshiba 32BV701B loss of audio

Pic of main b/d around amplifier chip then please (TPA3113)

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Re: Toshiba 32BV701B loss of audio

Here you go

[tom66]

Re: Toshiba 32BV701B loss of audio

OK, locate pin #1 on the device. Directly below it is pin 2. Can you see if the pin has a trace coming off it? Try measuring the voltage on it while it is working and when it fails. I'm expecting around 5V in operation, and 0V when failed.

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Re: Toshiba 32BV701B loss of audio

I cannot get the tv to come on with sound at the minute, but off pin 2 is 0.03v

[tom66]

Re: Toshiba 32BV701B loss of audio

OK with the set switched ON with no audio what do you get?

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Re: Toshiba 32BV701B loss of audio

0.03v

[tom66]

Re: Toshiba 32BV701B loss of audio

OK when it starts working measure it. If it is still 0.03V they do not use that pin. At that point you will need to get an oscilloscope to trace through the audio signals.