/34 & ba11-k regulator allocation?
ak6dn at mindspring.com
Fri Oct 13 12:47:06 CDT 2006
John A. Dundas III wrote:
> At 10:07 AM -0500 10/13/06, Jay West wrote:
>> Exactly what regulators are required as a minimum for a /34 that is
>> just a dd11-pk with no expansion? Assume just a processor, one memory
>> board, RL11 controller, one DL11W... nothing heavy.
> A timely question as several of us seem to be working on this model
> currently. [Thanks to Julian, Tim, Don, Al, Henk, and all others that
> have contributed to my own success...] Others will no doubt correct
> my errors but...
> I believe for the configuration above one H744 (position 2) IS
> required. I believe a H745 (position 1) IS also required. A second
> H744 (position 3) does NOT appear to be required based on your
> configuration above. I'm not clear whether or not a H754 is required
> in position 4. My take is that regulator is used primarily for core
> memory (+20, -5), though I could be wrong.
> Note that there are other regulators that can be used in place of the
John is exactly correct in his analysis WRT the H744 +5V in slot 2 and
H745 -15V in slot 1. The second H744 in slot 3 is not needed unless you
have expansion backplanes. The H754 +20V/-5V in slot 4 is only required
for core memory. Later generation BA11-K series boxes allowed for a
battery backup regulator that would go into slot 4 (for MOS memory) in
place of the core voltage regulator.
The H744 is a +5V/25A module; the later generation H7441 is +5V/32A and
is plug compatible. Technically there is an upgraded power distribution
board (54-something-YA) that is supposed to be swapped in when the
H7441s replace the H744s (-YA has beefier wiring for +5V distribution)
but this is only an issue if you are pushing the limit on an H7441.
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