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AWA (Mitsubishi) C4309 TV

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Franc Zabkar

Jan 1, 1970
0
I'm troubleshooting an old AWA (Mitsubishi) C4309 TV that
intermittently turns on by itself or changes channels randomly by
itself. I've replaced about 10 dry electrolytics all over the chassis,
but mainly in the standby PSU. I've also checked the electros around
the uP and EEPROM. However the problem remains. I don't think it is a
front panel issue as there is only one button to cycle through the
channels, and this button selects the next preset in ascending order.
Could a remote IR sensor cause a problem like this?

- Franc Zabkar
 
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Franc Zabkar

Jan 1, 1970
0
Just had Hitachi with similar behaviour. IR sensor was at fault.
Try disconnecting it and see what will happen. Power supplu to it may be
"dirty" too.

Rudolf

Thanks for the feedback.

The problem did not recur after I disconnected the IR sensor module. I
have now replaced three electros inside the module and the TV has been
behaving ever since. Only one of the caps (a supply bypass cap) tested
bad for ESR (11 ohms). However, I find this solution unconvincing as I
had already replaced the caps in the PSU. BTW, I don't believe the
problem was the result of IR interference, as the TV used to turn on
by itself at night.

- Franc Zabkar
 
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