DEC H7822 power supply

Maciej W. Rozycki macro at
Sat May 14 08:19:13 CDT 2022

On Thu, 12 May 2022, Peter Coghlan via cctalk wrote:

> > Wayne:  I just got an Dec AlphaStation 200. Look like its running NT though. 
> >
> It's probably ok but check the power supply for leaky capacitors!

 Definitely, watch out for possible damage!

 Prompted I had a peek in mine (an Astec SA180-3505) and it does have lots 
of the dangerous Chemi-con LXF parts!  While mine looks clean and tidy yet 
(LXF series seem sturdier than older SXF ones), I need to get this sorted 
sooner rather than later.  Thankfully last time I booted it a couple weeks 
ago it worked just fine.

 (Strictly speaking I have either an AlphaServer 300 or an AlphaStation 
250 system, which are hard to tell apart and the only difference mentioned 
in DEC documentation between the two mainboards is the maximum amount of 
DRAM supported, 512MiB vs 256MiB.  However both are essentially the same, 
up to the dedicated sound connector (unused with the AlphaServer), so it's 
not clear to me if it was a manufacturing option such as a wire bridge put 
somewhere into the PCB or just a matter of software support.  Both kinds 
of systems use the same firmware, which does not report the system model!  
And in any case my mainboard has a 54-23787-01 designation, which I'm told 
is an AlphaStation 250 (an AlphaServer 300 would be 54-23787-02), and also 
an early version, dated week 51 of 1994, S/N 60, and with lots of hardware 
patching present, however without the sound option and with an AlphaServer 
300 badge and a 1997 date code on the case.  Which in any case is exactly 
the same as with the AlphaStation 200, so the PSU is likely the same as 
well, so again, do check yours!)

> Have a look around for batteries that might leak while it was/is in
> storage too!

 There's a 2032 Lithium coin cell in these systems only, so while it might 
have been depleted it won't do any harm.


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