Re: Help needed with JVC TV

"Zman" <zman@xxxxxxxxx> wrote in message
news:42a8573a$0$7585$afc38c87@xxxxxxxxxxxxxxxxxxxxxxx
>
> "James254" <james254@xxxxxxxxxxxx> wrote in message
> news:42a806a5$0$13583$5a62ac22@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > "Zman" <zman@xxxxxxxxx> wrote in message
> > news:42a63303$0$30959$afc38c87@xxxxxxxxxxxxxxxxxxxxxxx
> > > I performed a search on the internet a while back for information
> > regarding
> > > the problem of. "WHITE PICTURE WITH BLACK VERTICAL BAR RUNNING DOWN
THE
> > LEFT
> > > HAND SIDE OF THE SCREEN" and found this fault listed on a site which
> > > provided TV/VCR faults and solutions. Can't seem to find the link now
> > > though.
<SNIP>

> > >The make and model number if JVC AV-G25AV.
> > >
> > > Thanks for any help.
> > >
> > >
> >
> > Hi Zman,
> >
> > You don't clearly indicate that you are a technician and are aware that
TV
> > sets contain very high voltages at dangerous currents. If you are not
> aware
> > of the risks involved please do not open the TV. Take it to a
experienced
> > technician for repair. The life you save may be your own...
> >
> > However, given the above warning you might like to try the following
> >
> > 1. Add a wire link between pin 2 and pin 7 of IC703 (The EEPROM)
> > 2. With the customer's remote control (RM-C457) press the 'Display' key.
> >
> > This should solve your problem.
> >
> > Hope this helps!
> > James
> >
> >
> Hi James,
>
> Yeah, I was a technician for approximately 4 years but that was over 7
years
> ago and haven't been in the industry since.
> Thanks for the advice and the warning, problem is I don't have the
original
> remote so I'm not sure how I'm going to follow your instructions.
> I have a universal remote I could probably use but I'm not sure how that
> will work since there is no was of working out which key will end up being
> the "Display" key. I might just have to try all the buttons and hope one
> works, but I sense that might end up being a disaster. Does this process
of
> pressing the "Display" key, while pin 2 and 7 are shorted, in some way
> reprogram the EEPROM?
>
> I don't know what to make of this problem, EEPROM's were seldom found in
> TV's back in the days I worked on them.
>
> Thanks again,
>
> John.
>
>

Hi Zman,

I'm not the designer so I can only guess what happens from experience with
this model and later JVC designs. Pin 7 of IC703 is not connected to
anything, it's floating. From what I can understand from the data*** the
IC factory use this as a test pin. In later JVC designs the pin is shorted
to ground.

So the solution appears to be two steps.

1. Short circuit pin 7 to ground permanently. Pin 2 of IC703 is ground so
this is the easiest way...

2. 'Reset' the EEPROM. This is done by pressing the 'Display' key on the
customer remote control. The display key brings up and clears the on-screen
channel number. Doing this must force a change to a specific location in the
EEPROM and this resets the EEPROM.

I understand that replacing the microcontroller or the EEPROM has the same
effect. However when you replace the EEPROM you must perform a full factory
setup which involves putting the unit into test mode. To do this you need
the customer's remote control!

My feeling is that a universal remote just isn't going to cut it.

You may get away with using a later model JVC remote control but this is
only a guess...

Hope this helps,
James



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