Omron NT600M does not start properly

[jodleren]

Hi all!

I got an Omron NT600M-DT122 to fix.

I starts up now somehow, but I do not get any text on screen. AFAIK I
should get _something_ when the battery has been disconnected, some
kind of optional menu.

The first problem was by some reason a resistor between reset (7705
output) and +5V, then I got some life to the data and address lines.
Next, I wanted it stable, and I have to fix the EPROM socket.

When that was done, it starts up "properly", the Run led is on when
resseting, the battery flashes for a short while, backlight comes on,
then nothing more happens.

Any ideas anyone?

BR
Sonnich

 

[jodleren]

Hi all!

I got an Omron NT600M-DT122 to fix.

I starts up now somehow, but I do not get any text on screen. AFAIK I
should get _something_ when the battery has been disconnected, some
kind of optional menu.

The first problem was by some reason a resistor between reset (7705
output) and +5V, then I got some life to the data and address lines.
Next, I wanted it stable, and I have to fix the EPROM socket.

I should add, that there were no signales on data and address lines
before this, and that the backlight did not come on. Though, for some
odd reason, the backligh came on after some 20 seconds. But the data
lines were still dead.

 

[Robbie Mayhem]

Hi all!

I got an Omron NT600M-DT122 to fix.

I starts up now somehow, but I do not get any text on screen. AFAIK I
should get _something_ when the battery has been disconnected, some
kind of optional menu.

The first problem was by some reason a resistor between reset (7705
output) and +5V, then I got some life to the data and address lines.
Next, I wanted it stable, and I have to fix the EPROM socket.

When that was done, it starts up "properly", the Run led is on when
resseting, the battery flashes for a short while, backlight comes on,
then nothing more happens.

Any ideas anyone?

BR
Sonnich

It may be worth checking the contrast pot underneath the rubber protective
flap (front of screen, bottom right IIRC), and adjusting as necessary.

Rob

 

[jodleren]

I should mention here, that it is a PLC Display panel.

Sonnich

 

[jodleren]

It may be worth checking the contrast pot underneath the rubber protective
flap (front of screen, bottom right IIRC), and adjusting as necessary.

Yep, found it, but it does not do much difference.

While looking at the EPROM it looks it is looping in something like
address $02xx... it is probably waiting for something.... so something
else can be broken too, ans it waits forever for that.

I dont have any schematics or any other information, so I'am stocked
here.

S