[TechAssist] Re: RCA proj. TV P46734BA, Chassis PTK178LA finally FIXED
- From: Al L <alleathe@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Fri, 24 Jun 2005 07:39:10 -0400
Moral: ALWAYS remove all rodent crap from chassis before calling warranty
people! Glad ya got it Gary.Probably all that happy feeling after the
wedding did it!
Al Leatherman
224 RT. 46
Mine Hill, NJ 07803
973-361-5796
WWW.ALS-TV.NET
----- Original Message -----
From: "Gary McCartney" <gary@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, June 23, 2005 11:31 PM
Subject: [TechAssist] RCA proj. TV P46734BA, Chassis PTK178LA finally FIXED
> RCA proj. TV P46734BA, Chassis PTK178LA finally FIXED (after 5 years!)
>
>
> First, an explanation:
>
> Back in 2000, my friend's TV (above mentioned model) was acting up such
> as turning off after a few minutes of use. He bought it with extended
> warranty. At that time, ext. warr. was in effect so he took it where he
> bought it and they had their authorized RCA depot come get it. Six weeks
> later they said warranty would not be honoured because they found traces
> of a liquid and some mouse droppings in the chassis. They estimated
> $700.00 to fix. Friend refused and they charged him $100.00 for the
> parts they put into it. (HOT, etc.)
>
> I got the set to fix for him. He hasn't needed the TV since then because
> he has been renting small houses where theres not enough room for a big
> TV. Now he is ready to move into his brand new house he just built.
> About time I finish the repair eh? I've only been daddling with it on
> and off whenever I'm not busy on the bench, and then only when in the
> mood.
>
> When I first worked on the set, it would click 3 times but not start up.
> I suspect this condition may have been born with the help of the first
> tech who worked on it. Here are the events, by memory so there may be
> other things tried or whatever during the process.
>
> - First I cleaned off all signs of corrosion and dirt from the boards.
>
> -Pulled flyback anode from HV splitter but didn't solve.
>
> -found tip to check for cracks in trace around C1474 on I/O board
> because it sticks out horizontally a ways. Yes there were cracks and
> fixed them but no help.
>
> - found R4912, the trim POT for B+ adjust to be open. Changed it with
> regular trim pot, not the RCA kit. Also changed U4101, PWM controller
> which by memory is a UA3843. May have also changed a few associated
> parts but can't remember. THis made the power supply react differently
> but can't remember how.
>
> - Used Chipper Checker to figure out why the shut-down. It told me
> problem could be in the audio section. Yes, I found U1600 stereo decoder
> IC (CXA1734S, RCA# 225700)to be corroded and defective. Replaced but
> still not starting up. Chipper checker no longer saw this error.
>
> -I decided to try a new eeprom and micro kit because there was some
> corrosion on the micro and I suspected eeprom anyways. RCA # 212119. Set
> reacted differently but still not starting correctly.
>
> -next I seem to remember soldering the power transistors on the heatsink
> along the front of the chassis. Finally, the set fires up but after a
> few seconds, I see smoke coming from the vertical output IC TDA8132.
> Replaced it and now the set fires up and runs.
>
> - Hissing sound from the HV splitter. I removed all leads and install
> new gaskets and add silicone grease. No more hissing.
>
> - Adjust B+ pot R4912 for 135V B+ at cathode of CR4110. Check X-ray
> protection test- ok.
>
> - test run and check for sound output and check for tuning of channels
> and also check video input- all ok.
>
> - now set is ready to go back to the cabinet for final alignments.
> --
>
> Thanks to all who helped me with this repair through the years.
>
>
> Gary McCartney
>
> McCartney Electronics
> Guelph Ontario Canada
> Est. 1984
> email: gary (at) number63.ca
>
>
>
>
>
>
>
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