[TenTec] Corsair II UV EPROM failure

Clayton Brantley clayton_n4ev at yahoo.com
Fri Feb 14 19:53:24 EST 2014

Allen:  I have a programmer and can read a good eprom and make a duplicate.
I'll check it tomorrow to see if your eprom is on  the list.  If someone has a good
one, I can make you one providing my programmer can handle the chip.

The only caveat is will TenTec look the other way?  The only $$ would be the
mailing on my end.

Clayton N4EV 

On Friday, February 14, 2014 7:44 PM, A R <raf_3 at msn.com> wrote:
My recently acquired Corsair II has a failed logic board UV eprom (MC68705P3S) that prevents me from operating CW. The eprom failure is the keyer "dit" input stuck close enough to a "low", that about 30 minutes after power-up, the eprom temp reaches 50C, and the "dit" input is  low enough that all I have is a continuous, uninterruptable transmitted string of dits. Unfortunately, the architecture doesn't have provision to defeat the keyer function in CW mode. The eprom temp reaches the 50C temp after about 30 minutes, with an ambient temp of 22C.

I've talked to Garry Green at TenTec, but they don't have any proms for this ancient Corsair II. But, the unprogrammed MC68705P3S's are available elsewhere, and Garry agreed to search the TenTec operation to see if they have the programming fixture and the Corsair II program. I'm hoping that Garry can find the fixture and the program. But, I'm not very optimistic he'll be successful.

So, my options are to either find a "surplus" programmed CORSAIR II MC68705P3S (anybody have a spare or surplus one?), or modify the Logic Board enclosure to provide forced air cooling in an attempt to keep the processor temp below the critical 50C.......and hope the processor "dit" input doesn't further deteriorate.

Does anyone have a spare or "surplus" programmed processor for the CORSAIR II?

Thoughts on cooling/controlling the temp of the processor? Forced air may get the job done (maybe in combination with a dip heatsink bonded onto the processor). But I recall (from a former life) that ss heat exchangers for dips may be a solution that's not as messy as shoe-horning a 25mm pc fan onto the logic board enclosure, but would necessarily contribute a slight ? temp rise in the CORSAIR's interior. 

Any help or suggestions welcome.


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