PDP-8/M H740 PSU woes
Jose carlos Valle
josecvalle at gmail.com
Thu Jul 2 15:33:06 CDT 2009
I am curator of Museu do Computador(Computer Museum Brazil)
And my Museum still closed for 2 years..
I do not have any solution, support, sponsor etc to reopen.
We are a Non profit org.. But, I am a technician since 60's.
I am not expert in to raise founds to open again my Museum.
If someone have any idea, I will appreciate.
Jose Carlos Valle
2009/7/2 Tobias Russell <toby at coreware.co.uk>:
> I'm just in the midst of rebuilding a PDP-8/M which has the H740 PSU in
> it (also fitted to 5.25" PDP-11/05s).
> I've cleaned the PSU up and reformed its capacitors, checked the
> transformer is working fine. On replacing the switch mode circuit board
> and powering up, I'm getting a blown fuse (F1 on circuit diagram) which
> supplies the 5V and 15V rails. The -15V rail is working fine.
> Does anyway have any suggestions as to the best approach to locating the
> problem? I've been pondering whether it would be possible to isolate
> either the 5V or 15V circuit so I can see which of them is causing the
> problem, but I can't see any simple way to achieve this.
> Also, is my practice of powering the PSU up without any load a foolish
> one? I've not had any problems in the past using this approach but I
> have seen people previously mention that running switch modes without a
> load is a bad idea.
> A circuit diagram of the H740 can be found here:
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José Carlos Valle -
Museu do Computador - desde 1998
Fones: (+5511) 4667-8079 e (+5511) 8794-6730
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