> Jon Elson wrote:
>The VAX 11/780 absolutely had power fail, and it DID work.
So did the 11/730 and I imagine the 750 as well. No core, but there was a
battery backup option to keep main memory alive and refreshed even in the
event of power failure.
>I did this quite often while swapping
On 03/30/2020 11:49 AM, Paul Koning via cctalk wrote:
Thise signals don't seem like a problem: just hardwire them to the desired
logic level. PDP-11s need a real functioning DCOK signal iff you want to do
power fail interrupt handling, otherwise they don't. Do VAXen have power fail
Vectoring through 24 was very important back in the core memory days
when the memory would still be there after a power failure and you
wnated the system to keep running, as was our Ontario Bellboy paging
controller.
cheers,
Nigel
On 30/03/2020 12:49, Paul Koning via cctalk wrote:
On
> On Mar 30, 2020, at 10:17 AM, Robert Armstrong via cctalk
> wrote:
>
>> Looks like for this enclosure an ATX supply could well work.
>> For my VAX my notes say it didn't.
>
> A VAX would certainly be harder. You'd have to kludge up the ACOK and DCOK
> signals for one thing, which I
>Looks like for this enclosure an ATX supply could well work.
> For my VAX my notes say it didn't.
A VAX would certainly be harder. You'd have to kludge up the ACOK and DCOK
signals for one thing, which I don't think the R400x uses. It'd be really
handy to find even a schematic for the
> -Original Message-
> From: cctech On Behalf Of Robert
> Armstrong via cctech
> Sent: 29 March 2020 23:15
> To: r...@jarratt.me.uk; 'General Discussion: On-Topic Posts'
> ; 'Maciej W. Rozycki'
> Subject: RE: H7874 power supply
>
> Remembering that I have
...@ntlworld.com]
Sent: Sunday, March 29, 2020 2:05 PM
To: b...@jfcl.com; 'General Discussion: On-Topic Posts'; 'Maciej W. Rozycki'
Cc: r...@jarratt.me.uk
Subject: RE: H7874 power supply
I have some notes I made about trying a PC PSU, I don't think it really worked,
there are signals to indicate power OK
Robert
> Armstrong via cctech
> Sent: 29 March 2020 19:15
> To: 'Maciej W. Rozycki' ; 'General Discussion: On-
> Topic Posts'
> Cc: r...@jarratt.me.uk
> Subject: RE: H7874 power supply
>
> >Maciej W. Rozycki wrote:
> >numerous Chemi-Con SXF parts scattered across all
; Rozycki via cctech
> Sent: 29 March 2020 17:18
> To: b...@jfcl.com; General Discussion: On-Topic Posts
>
> Cc: r...@jarratt.me.uk
> Subject: RE: H7874 power supply
>
> On Sun, 29 Mar 2020, Robert Armstrong via cctech wrote:
>
> > And then there's a giant PCB, alm
>Maciej W. Rozycki wrote:
>numerous Chemi-Con SXF parts scattered across
>all boards, some leaking
Yeah, mine is full of "Nippon Chemi-Con" electrolytic too.
What about just gutting the PS chassis and sticking in an ATX power supply?
I don't know how the maximum current per output
> On Mar 29, 2020, at 2:14 PM, Robert Armstrong via cctech
> wrote:
>
>> Maciej W. Rozycki wrote:
>> numerous Chemi-Con SXF parts scattered across
>> all boards, some leaking
>
> Yeah, mine is full of "Nippon Chemi-Con" electrolytic too.
>
> What about just gutting the PS chassis and
On Sun, 29 Mar 2020, Robert Armstrong via cctech wrote:
> And then there's a giant PCB, almost 11" square, covered with opamps, 74LS
> logic and discrete parts. There are filter caps, a transformer, and
> switching transistors on this board too so it obviously produces yet another
> power
> Rob Jarratt >robert.jarr...@ntlworld.com> wrote:
> I reverse engineered the schematic of the 12V output board. I
>don't know if that would be of any use? How correct it is I don't know.
Sure, if you don't mind sharing. Everything helps.
Looks like there are five separate PCBs in there.
OK, I posted it here:
https://robs-old-computers.com/2020/03/29/h7874-power-supply/
> -Original Message-
> From: Robert Armstrong
> Sent: 29 March 2020 15:44
> To: r...@jarratt.me.uk; 'General Discussion: On-Topic Posts'
>
> Subject: RE: H7874 power supply
Rob Jarratt via cctech wrote:
>
>
> > -Original Message-
> > From: cctech On Behalf Of Robert
> > Armstrong via cctech
> > Sent: 29 March 2020 02:29
> > To: cct...@classiccmp.org
> > Subject: H7874 power supply
> >
> > D
> -Original Message-
> From: cctech On Behalf Of Robert
> Armstrong via cctech
> Sent: 29 March 2020 02:29
> To: cct...@classiccmp.org
> Subject: H7874 power supply
>
> Does anybody have a maintenance print or service manual for the DEC
> H7874?
>
Does anybody have a maintenance print or service manual for the DEC H7874?
This is the power supply used in the BA4xx and R400x cabinets. As you might
guess, I have one that tries to power up but shuts down after a second.
Probably a bad capacitor (or several), but this thing is ridiculously
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