Help needed with JVC TV

[Zman]

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.

My problem is you had to register to the site at a cost to get details of
the fault but since I seldom fix TV's it's not viable for me to do so.

I do have an old fault book but unfortunately it's too old and doesn't
contain details for this particular set.

Anyway, It appears this problem is a common problem and therefore if anyone
out there in cyber world has one of those updated TV common fault books
could you please look up the fault for me I would be eternally grateful. The
make and model number if JVC AV-G25AV.

Thanks for any help.

 

[James254]

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.

My problem is you had to register to the site at a cost to get details of
the fault but since I seldom fix TV's it's not viable for me to do so.

I do have an old fault book but unfortunately it's too old and doesn't
contain details for this particular set.

Anyway, It appears this problem is a common problem and therefore if anyone
out there in cyber world has one of those updated TV common fault books
could you please look up the fault for me I would be eternally grateful. 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

 

[Zman]

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.

 

[James254]

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 datasheet 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

 

[Zman]

that

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 datasheet 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

Thanks for all the info and your suggestions James.

I'll give it a go

John.

 

[Zman]

Thanks James what you suggested worked.
I was fortunate to have a universal remote which contained the "Display"
button. I just tried every button until I hit the right one.

Thanks again.

John.