[sebhc] IC information

[Lee Hart]

Glyn Firth wrote:
>> I have just began to rejuvenate my H8 system. I have discovered
>> that the -5volt voltage regulator on the CPU board is bad...
>> The part # is 79MGT2C.

Barry Watzman wrote:
> You can probably get one at Radio Shack, it's just a 7905, in an
> appropriate case (probably TO-220, but 7905's come in lots of
> different case styles, the letters don't matter). Very, very
> common and inexpensive part.

No, Glyn is right. The H8 8080 CPU board uses a *very* unusual part,
nothing like a generic 7905. The 79MGT2C (Heath 442-618) looks like an
8-pin DIP, but with pins 2,3,6,7 replaced by large wide "bat wing" ears.
It is actually a -2.25v regulator, and uses two external resistors to
program the output voltage to -5v.

Finding an exact replacement *will* be a challenge! However, if you just
want to get the H8 functional, I would replace it with a 7905 (or
equivalent 3-terminal regulator.

This is pretty straightforward if you have the schematic. If you need
instructions to do this, ask.
-- 
"Never doubt that the work of a small group of thoughtful, committed
citizens can change the world. Indeed, it's the only thing that ever
has!" -- Margaret Mead
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Lee A. Hart  814 8th Ave N  Sartell MN 56377  leeahart_at_earthlink.net

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