Heath SB-650 help

[Alan 'A.J.' Franzman]

---- Original Message ----
> I recently acquired an SB-650 Frequency Display with no documentation. 4 =
> of the 6 nixies do not display certain digits. If I move the nixie tubes =
> around the fault remains at the socket position nor is there a change in =
> the digits that don't appear.  I've removed each nixie and IC chip and =
> used deoxit but the symptoms remain the same. Can someone provide me =
> with a schematic diagram and I also would appreciate the setup =
> procedure. I have the wiring information for my HW-100 and have already =
> wired it.
>
> Thanks & 73
> Tom K3TVC

Tom,

Did you try moving the ICs nearest the nixie sockets around?  These are
probably 74141s, BCD-to-decimal nixie decoder/drivers.  If you swapped them
around with no change in symptoms, the fault lies elsewhere.

Best regards,

A.J.

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