🚀 go-pugleaf

In article <13783277@zl2tnm.gen.nz>, don@zl2tnm.gen.nz (Don Stokes) writes:
> I've got two disk drives running in my BA23, of the elderly power-hungry
> variety.  The power budget is knocking against the limit, but repacing
> drives with more modern ones would pull things down quite nicely.

  Two problems to watch out for (I know Don knows, but perhaps this may save
some other reader's system):

  1) There are two flavors of BA23 power supplies. The old one provides 6A
     of +12, while the new one provides 7A. Check to see which one you have
     before believing the numbers on the configuration worksheet.

  2) BA23's (and BA123's) have a defect in the wiring harness which can cause
     electrical fires. IMHO, DEC did not publicize this as well as the should
     have. Anyway, look at the harness (1 in a BA23, 2 in a BA123) that con-
     nects the power supply to the backplane. If it has yellow connectors or
     "webbed" wires, it should be replaced. If it has individual colored wires
     with white connectors, you're Ok.

> The BA123 has a _lot_ of space for drive mounting, but it is assumed that
> some of those drives will be either floppies or tapes and not suck a lot
> of power all the time.  Again, putting in more modern drives helps -- an
> RD54 pulls a _lot_ less juice than an RD52 for example.  

  I have a BA123 with 3 RD54's, a TK50, a Wangtek 5150EQ tape, and an RX33 and
have had them all running at once. 3 of the BA123's drive bays are on one PS,
and the remaining two are on the other PS. The trick is in shuffling things
around to balance the load. BTW, DEC's RD54's have a lower start-up current
than stock Maxtor XT-2190's. Mine are all generic Maxtors.

	Terry Kennedy		Operations Manager, Academic Computing
	terry@spcvxa.bitnet	St. Peter's College, Jersey City, NJ USA
	terry@spcvxa.spc.edu	+1 201 915 9381

In article <1992Oct4.165306.4028@spcvxb.spc.edu>, terry@spcvxb.spc.edu (Terry Kennedy, Operations Mgr.) writes:
> In article <13783277@zl2tnm.gen.nz>, don@zl2tnm.gen.nz (Don Stokes) writes:
>> I've got two disk drives running in my BA23, of the elderly power-hungry
>> variety.  The power budget is knocking against the limit, but repacing
>> drives with more modern ones would pull things down quite nicely.
>  [...]
>   I have a BA123 with 3 RD54's, a TK50, a Wangtek 5150EQ tape, and an RX33 and
> have had them all running at once. 3 of the BA123's drive bays are on one PS,
> and the remaining two are on the other PS. The trick is in shuffling things
> around to balance the load. BTW, DEC's RD54's have a lower start-up current
> than stock Maxtor XT-2190's. Mine are all generic Maxtors.

Note that if you are close to the edge on power it is easy to buy a $50 generic
PC 200 W supply to run the "excess" 5-1/4 devices.  Three of them will suffice
to completely replace the twin power supplies in a BA123, should yours ever
die. 

Heck, in most places you can find used PC *cases*, power supply included, for
$50. 

	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
uucp 'g' protocol guru and release coordinator, VMSnet (DECUS uucp) W.G., and 
Chair, VMS Programming and Internals Working Group, U.S. DECUS VAX Systems SIG 
Internet:  jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
Uucp:  ...{crash,eisner,uunet}!cmkrnl!jeh