OKI MSM561RS (FT101ZD display driver) pinout/datasheet?

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OKI MSM561RS (FT101ZD display driver) pinout/datasheet?

Postby M0KRD » Mon Jun 24, 2013 2:34 pm

I can still get these chips on eBay and elsewhere, but I can't find a datasheet with the correct pinout listed online anywhere. Google is definitely not being my friend. They're used in FT101ZD mk0 and mkI with the discrete logic IC based frequency counter, as well a some other late-1970s Yaesu frequency displays. I have an ft101zd with a defect pointing to a single defective display driver chip of this type. However, I am to some degree guessing about the defect, and I'd like to test the both the original and replacement chip before risking re-soldering the old circuit board. I am unfortunately having to guess at pin functions based on the circuit diagram in the FT101zd maintenance manual, as I can't find an original datasheet for the IC. Based on the schematic they seem to use a non-standard pinout compared to all other DIP16 7-segment display drivers, so I can't even find an equivalent part to compare.

BTW the defect is that the frequency display fails to display odd digits for the third-most significant (100KHz) position. The display goes 0, 2 , 4, 6 etc. and goes though the less significant digits twice. It's unlikely to be the counter as bit 0 of the counter needs to work t propagate the chain.

Any suggestions? Does anybody have a datasheet in scanned/PDF form, or even a paper one they'd be willing to scan for me? I suppose I could try to ask Rohm, who took over OKi's semiconductor business some years ago, but the datasheets are definitely not online at their site.


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