[TechAssist] Re: Sony KV36FS100 turns on and off by itself-intermittent

We've seen ZCD failures on a couple PTVs --One of the boards that was
causing the fault was the G board which is actually the board with the relay
and the relay's driver transistor....that's the more common failure.
The other board was the A board (I think) which is the board that actually
has the sensing circuit on it....

Problem is that you have the Direct View tv...we haven't seen that occurance
yet.
However, since they unplugged it and it is working fine now, leads me to
believe it is the micro/sense circuit, rather than the relay driver and
relay....

The ZCD circuit design is Sony's way of turning on the TV relay at 0 Volts
so the power supply will ramp up from 0 to 169V peak. It reads 4 cycles of
AC then activates the relay when it anticipates the power is at 0 Volts.
It's cheaper than the "soft-start" circuits previously used.
Most of the failures we've seen is the "TV won't turn on, unless tried
several times"
You'll have to take this info for what it's worth (FWIW).


Damon B
Telrad Electronics
Fort Wayne IN
----- Original Message -----
From: "Service Depot-Ian" <service.depot@xxxxxxxxxxx>
To: "Techassist (E-mail)" <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, April 05, 2006 6:03 PM
Subject: [TechAssist] Sony KV36FS100 turns on and off by itself-intermittent


> Hello everyone,  I went to this customer's home, who was complaining abour
> her tv coming on by itself.  It has also turned on/off/on/off/on/off
rapidly
> and they had to unplug unit from the ac power. They removed the batteries
> from the remote in case it was causing the problem.  This set acted up for
a
> couple of days, then they unplugged it for two days.  After that, they
tried
> it again and it has been working fine now for three days.
> They do not use a liquid for cleaning the screen, just a dry cloth.
> They are afraid to go out of the house and leave it plugged in.
> Oh yes, I checked the diagnostic screen and there is an error in # 9 ZCD-
> which is the zero cross detector.  I don't know if this would be related.
> Any ideas appreciated!
>
> Ian Scott
> Service Depot
> Sudbury, Ontario
>
>
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