Hi
    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.

Rod Smallwood




On 28/11/15 21:09, Robert Jarratt wrote:

-----Original Message-----
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Terry
Stewart
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 believable.
..
I do think there are not nearly enough arrows pointing upwards
LOL Rob, Mark.
I agree with Mark, needs more upwards arrows, more cycles (some without an exit 
at the bottom). :-)


Today 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
collection.
Of course we all know something ELSE unexpected will happen.
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!

Terry (Tez)
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.

Regards

Rob


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