[time-nuts] OT: Tektronix 7000 Series Switch Mode PSU contoller IC 155-0067-02 replacement?

[David C. Partridge]

Posted here as well in the hope of widening the audience - please respond
OFF list to david dot partridge at dsl dot pipex dot com.

I have found over time a number of 7K 'scope PSUs that had failed because
the 155-0067-02 SMPS controller chip had failed.

I have just completed the initial design work for a circuit that is intended
to replace these ICs.   I have not as yet done any PCB layout or decided
whether to go for a larger board using 74HC parts for the logic or a smaller
board using a PAL or GAL to do the logic.

Please note that so far, this is just a theoretical design backed up with
quite a bit of simulation (i.e. assume more work needed).

When I developed the replacement for the SG504 levelling head, I just
"pressed on" with the project in the naïve belief that I would be swamped by
the demand.  How wrong I was.   To date the sales of this haven't covered
the cost of PCBs and parts (though the loss isn't massive).   I would prefer
not to "go there" again.

So, is it worth pursuing this to the stage of producing replacements for
this IC or not?  

Cheers
Dave