Switches don't work on Masuda TF1495 CTV - Problem fixed.

[Russell Griffiths]

Problem solved.
Using the CRO, I found a problem at pin 24 of the M34300-012SP.
This pin outputs pulses to scan the switches.
When they weren't working, their amplitude was only around 1 1/2 volts.
When they were working, they were at 5 volts.

The problem was traced to one of the switches connected to pin 24.
It was a slightly different type than the rest. Somehow the switch
was conducting between one of the switch terminals and the ground
mounting bracket of the switch.
I solved the problem by cutting the ground track to this bracket.

Hope this helps someone some day.

Russell Griffiths.

rg26ce1991@hotmail.com (Russell Griffiths) wrote in message news:<13cdb672.0307270538.3f9f10a3@posting.google.com>...

Greetings group.
Masuda TF1495.

Original fault repaired:-
Frame collapse (TA8403K vert. defl. chip) shorted.

Caps replaced with high ESR
C616 100uF 160 VOLT
C620 1000uF 16 VOLT
C610 47uF 25 VOLT
C609 22uF 50 VOLT

The front panel switches were found to only work sometimes.
But a universal remote will always change channel, volume tv/av.

I replaced the chip the switches connect to (M34300-012SP),
but this has not helped (BUGGER).

Could it be the 80011A?

Can anyone email me a copy of the schematic?
Data sheet for the M34300-012SP?

Any other advice?

Thanks in advance,
Russell Griffiths
Vic. Australia.