Panasonic TX-21MD1C colour problem
 

"Kota" wrote in message
om...
I've got a Panasonic TX-21MD1C colour TV with a colour problem. The
colour image is stripy, totally wrong and impossible to watch.
When setting the colour system explicitly to PAL (which is the
national system here in Holland), the image is B/W.
When setting the colour system to SECAM, the image is exactly the same
as with the Auto setting.
The B/W picture is OK.
I tried to trace the problem. It seems that the VDP3108 video
processor is producing the error, as this is where the video signal
enters and RGB is put out (digital and analog). The VDP3108 does all
the processing digitally, including the color decoding.
I tried S-VHS, as this has a Luminance and Chrominance channel. It
produces the same effect. I replaced the caps at the 2 ref inputs of
the VDP3108, without any result.
I watched the video signal entering the VDP3108 on a scope. It looks
fine to me, including the colour burst.
The colouring of the on screen menus is ok though.
My guess is that the VDP3108 is defect. As this is a part of around 50
Euro, I'd like to be sure before replacing it. It seems strange to me
that a digital processor like this would not perform this specific
task, but all other tasks it should perform are OK.
Anybody have experience/can help?

Its probably the VDP3108 , you need to buy the VDP3108 Kit if its the
old VDP3108 (obsolete) , the new one is VDP3108A PPA1.

The kit also contain Eprom , 2 Surface mounted capacitors.
Kit Art.Number TZS9EK0021

/ Per-Olof

Panasonic TX-21MD1C colour problem
 

"Per-Olof Ahl" wrote in message ...

Its probably the VDP3108 , you need to buy the VDP3108 Kit if its the
old VDP3108 (obsolete) , the new one is VDP3108A PPA1.

The kit also contain Eprom , 2 Surface mounted capacitors.
Kit Art.Number TZS9EK0021

/ Per-Olof

Thanks Per-Olof.

I already ordered and received the kit TZS9EK0021 you mentioned. It
contains all the items you said. The chip on the PCB however, is the
VDP3108A, so I suppose its the new one. The chip in the kit also says
VDP3108A. I suppose I can use this chip to replace, and not use the
provided EPROM. Or should I still order another replacement?

Erik

Panasonic TX-21MD1C colour problem
 

"Per-Olof Ahl" wrote in message ...
I already ordered and received the kit TZS9EK0021 you mentioned. It
contains all the items you said. The chip on the PCB however, is the
VDP3108A, so I suppose its the new one. The chip in the kit also says
VDP3108A. I suppose I can use this chip to replace, and not use the
provided EPROM. Or should I still order another replacement?

As the price is about the same here in sweden for the kit VS the
"VDP3108A PPA1" i allways order the kit.

If i remember correctly the VDP3108A on that kit is the "A1" version
of the VDP , are you sure it isnt printed "A1" on the ic on that kit?

If it is, and the faulty VDP hasnt that mark "PP A1" or "A1" then you
need to change the eprom and add the capacitors!

/ Per-Olof

Thanks Per-Olof

I already performed the surgery succesfully. I did use the provided
EPROM and caps. I also tried the old EPROM after the operation. It
worked. Nevertheless the program inside it was different from the new
one, so I did put the new EPROM in.
If I remember correctly there was an A1 mark on the new processor,
while on the old one there wasn't, so you're correct.

Erik