Curious - BA23 power supply size - 345W?

[MattCarp]

I was reading the MicroPDP Tech Reference and it states that the BA23 enclosure has the H7864 power supply which is rated for 230 watts.

On the back of my MicroPDP there is a label that says 345W? I thought maybe the MicroVAX or VAXStation II upsized the power supply, but the references for those machines also list the power supply at 230 watts.

Are there any thoughts about why my supply doesn't seem to match up?

This is a hybrid machine pieced together, so I believe the cabinet was originally used for a VAX.

 

[saipan59]

Perhaps it is the difference between worst-case input power (345) vs the PS *output* power?

Pete

 

[MattCarp]

Yeah, I don't know.

Even the ratings of the power supply listed in the manual are more than 230W.

Anyway, I'm a little close on 12V, but those are peak (drive startup) values.

Interesting too that the DEC manuals all say "Don't insert more than one fixed disk in the BA23", but the signal distribution board was clearly designed for it.

I suppose they could design the power supply to crank out a couple more amps at 12V.

Whoa - I just looked up the 12V requirement for the RD54 - it requires up to 3.9A at startup! That would explain it. Put two of those in the cabinet and you'll overload the 12V supply after you throw in an amp or two for logic boards.