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RCA expert help needed -CTC177 chassis

Hello RCA guys - I'm trying to solve one of the weirdest problems I've seen in this chassis yet. Your advice is appreciated.

Everything works fine but no audio of any kind. I know you will say do tuner grounds and replace eeprom....I did all that. In fact I did much more than that: replaced mute transistor Q1903 (I grounded the Emitter on the previous one without help), went into SETUP and switched speakers to ON (they were in OFF position), replaced audio output chip just in case (chip is getting B+), tried new speakers, pin 29 of micro is low so I know TV is not in MUTE condition, checked for bad joints everywhere. I do not have schematic and the only last option is to replace LA7610. Has anyone ever had this chip cause no audio ? Is it possible I overlooked one single connection in the tuner which may cause loss of audio (which I doubt) ? Thank you.

moonlite

Reply to
moonlite
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Did you do the eeprom audio alignment? Or the rest of the eeprom alignment? Do the A/V inputs get sound? Is the tv set to SAP audio mode?

Reply to
dkuhajda

Thanks for the response. Eeprom audio alignment ? What parameter is that ? I never heard the eeprom also has a setting for audio alignment. Please enlighten me as to how this is done. The only thing I know is that the speakers have to be switched to ON in the SETUP menu and I did that.In the VIDEO mode there is no audio as well but picture is fine. No, the TV is not in SAP mode. Thanks again.

moonlite

Reply to
moonlite

Yes, the T chip can cause no audio, but there are too many other areas that sound can be lost in this chassis. The audio leaves and reenters the chip at least twice from memory (mine :). There is an outboard MTS chip near the jacks IIRC, and that can cause no audio. You should pick up a SAMs for this chassis as it would be somewhat useful in almost every 17X and 187 you will likely run across.

John

Reply to
John-Del

moonlite ha scritto:

Audio is present with SCART or other inputs (not cable) ?

I.

P.S. = Not an RCA expert, !

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I.
Reply to
inti2

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