1240 Logic Analyser display problem


Kevin Wood G7BCS
 

Hi Guys,

I wonder if anyone has ever troubleshooted display issues with a 1240
Logic Analyser?

Symptoms are that I get a stable raster on the screen if brightness is
turned up but no display.

All power supply rails measure fine.

Both main and I/O processors seem to be going through their self tests
successfully and entering normal operation according to the LEDs on their
respective boards.

Display board gives HD sync output but no VD or luminance.
.
I've traced the VD output back to the MM5321 sync. generator IC on the
display board. It has a clock input, both power supply rails and the
vertical reset input is inactive (High). The horizontal outputs are
present but no vertical drive output.

I'm thinking the MM5321 is dead, but just wondered if anyone else has been
down this path before, or has any other suggestions?

Next question is where to find an MM5321. Littlediode have them at a
price, but any other ideas?

Thanks in advance,

Kevin

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