Help needed with JVC TV

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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

of

aware

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.

THE

TV

experienced

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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...

1. '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

now

that

key.

being

on-screen

the

factory

Thanks for all the info and your suggestions James.

I'll give it a go :-)

John.

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.

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