I had the exact same fault on my VAX.
I took one look at the PSU and ordered up another one pronto.
Trouble shoot in that small space no thank you.
It works just fine. One day a VAX PSU guru will tell us how to fix it.
On 28/11/15 21:09, Robert Jarratt wrote:
From: cctalk [mailto:cctalk-bounces at classiccmp.org
] On Behalf Of Terry
Sent: 28 November 2015 20:05
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: A stored collection piece is a Schrodinger's cat
I see a big problem with this flowchart, the path
on the far right does
not exist, please delete it and then the flowchart will be
I do think there are not nearly enough arrows
LOL Rob, Mark.
I agree with Mark, needs more upwards
arrows, more cycles (some without an exit at the bottom). :-)
it's all going to come together and hopefully the outcome will be
a fully working PET4032 and an extra diagnostic tool to add to the
Of course we all know something ELSE unexpected
Yes, I love the case design of the PET. It looks just so retro and
'80s futuristic if
you get my meaning...
I designed that tounge-in-cheek flowchart as a kind of catharsis having just
spent the last three weeks, firstly fixing my Apple II+ which was a non-starter
on checking (a faulty F8 ROM in that case) then followed by the next unit I
tested, whose 74LS500 in the video circuit failed after about 5 mins. I'm almost
afraid to turn on any more...but then...Schrodinger's cat
and all that. I need to know!
I had my own episode last week when I turned on my VAX 4000-500 after
a few months of not running it. It ran for a few minutes and then powered off. Now it
won't power on for more than a few seconds before cutting out. This is the second PSU
to do this to me (the first actually failed outright) and I am wondering if the fault is
with something in the machine itself rather than the PSU. Although, now, even with
different combinations of boards removed (so there is at least some load), the PSU
won't stay on for long, so I don't think it can be one of the boards, but perhaps
something in the machine has caused a fault which has now damaged the PSU. I have another
spare PSU but I am not going to risk it yet until I have had time to investigate.