the counter-on-a-chip is a MK50398N
the multiplex chips are 75491APC and 75492apc
there's two 491's they are the segment multiplexer and the 492 is the
display multiplexer
( I guess technically, the 50398 does the multiplexing, and the three
other chips are used to decode and drive the LEDS)
both the 75491APC and 75492apc are not stocked anymore by ten tec.
These chips are really hard to come by, but again, there's the part
miners out there that have them listed, but with $250 min to buy.
I did a quick look at NTE and they seem to have a replacement for the
491, but have not looked deeper into the project.
there's three possibilities here with a dead Ten Tec Omni LED display
1. Get another junker for parts
2. Use a external freq counter
3. The dead one becomes the part donor
and...
there's a few places that sell "digital dials" that maybe used,but
none that I have seen drive LEDs, they are usually for LCD displays.
Mike, WB8VGE
What are the chips?
73, Jerry, K0CQ
|