31000Re: [midatlanticretro] Acquired a PDP-8/E
- May 27, 2013On Mon, May 27, 2013 at 12:47:21AM -0500, Kyle Owen wrote:
> On Tue, May 21, 2013 at 11:09 AM, David Gesswein <djg@...> wrote:V2 is power good. It isn't a voltage bus. The manual says 3.75-5 is good.
> Measuring the voltages again, I see the 5V bus is 5.12V, 15V is 15.24V,
> -15V is -15.12V, and V2 is 4.32V. V2 sounds pretty low...what should I
> check for this bus?
Its just driving gate inputs to shut down core access when the power falls.
8/E, 8/M processor maintenance manual volume 1 table 4-7.
> Also, what's the fix for the melting fuse holder problem? I see thatHere's DEC's official information.
> there's a 10A fuse in the fuse holder, but the rating next to the holder
> says 25A. I'd expect a 25A fuse to have a lower resistance, yes? Would that
> help then?
Sounds like its the holder and not the fuse. Since your load is low if you
have inspected it and didn't see any problems you should be ok. I have
two heavily loaded backplanes and did have that faulure. I put another
holder in and added an additional 5V power supply for the second backplane
so I wouldn't be stressing my power supply.
> I also noticed that my 8/E has only one Unibus. Did they not by defaultIt was an ordering option. I know of several systems with only one backplane.
> come with two? Maybe that's why there's a 10A fuse?
The wire contacts rating may be the limiting factor so with you only having
one set connected that may be why your fuse is lower value.
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