29 Apr
2011
29 Apr
'11
7:34 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of Rob Jarratt
Sent: 29 April 2011 09:11
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: new here
I loaded one of the +5V outputs on one of the backplane connectors and
tested every 5V output I could find on the backplane connectors, they
were all the same voltage. I used a 6V headlamp bulb on the 5W part,
so drew about 1A. I could try again to make doubly sure and perhaps
load one of the
some
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of Rob Jarratt
Sent: 28 April 2011 21:10
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: new here
> -----Original Message-----
> From: cctalk-bounces at classiccmp.org [mailto:cctalk-
> bounces at classiccmp.org] On Behalf Of Tony Duell
> Sent: 28 April 2011 20:31
> To: cctalk at classiccmp.org
> Subject: Re: new here
>
> > I have just this minute attached a dummy load to one of the 5V
> > outputs and powered it on. Using a multimeter I measured 5.4V on
> > the 5V outputs and
>
> There are 2 independant 5V outputs on this supply, the logic +5V and
> the memory +5V. Which one did you load, and did you check both of
them?
other 5V outputs. Do you know off hand which
output is the one for the
memory so I can load that too. I have two 6V bulbs available to me now
so
I
can load logic and memory if I know which is
which. Would you
recommend me using the 21W filament instead? I am not sure how much
current the PSU will supply, but guess 5A should not strain it.
I just tried again this morning and got some different results, which
concerns me. This time I connected the 6V 21W bulb and I measured 5.7V
and 16.8V on the 5V and 15V outputs, yesterday they were 5.4 and 15.8
respectively. I also noticed that the DC ON light did not come on, but I
*think* yesterday it did come on. I did inadvertently power on the machine
without any load for a few seconds yesterday, not sure if this has done damage. I tested again with the 5W bulb just to see if
it made a
difference
but it didn't.
The bulb was connected to the 5V outputs that go to the backplane. There
does not seem to be a difference between the 5V for memory and logic, all
the 5V outputs from the two connectors at the right of the PSU (labelled
P2
and P4 on the plugs) go to the same connection point
on the backplane.
Just a bit more info. I loaded the PSU a bit more. I used two 6V/21W
filaments on the 5V output and now I measure 5.4V. I used a 12V/21W filament
on the 12V output and got 12.8V (forgot to check this before) and one
12V/21W on the 15V which now gives me about 16V. When I used two bulbs on
the 15V output it went down to about 10.5V.
> > 15.8V on the 15V outputs. I ran it with just the fans running
> > (forgot to disconnect them) for about 5 minutes and then switched
> > it off. Are those
>
> The fans are not a worry. The fans themselves are simple AC motors
> and will not be damaged by (sensible) overvoltage. The fan control
> electroncis might be, but that's on the PSU control board, not in
> the
fnas
themselves.
so
red
it can be repaired.
no
voltages within tolerance do you think? They seem
close enough to
me to warrant putting some boards back, but I would like a second
opinion before risking the boards.
The 5V is a little high, biut no hgih enough to do any real damage.
I have ideawhat load you used, it may well be that with
more load it gets
closer
to
5V.
I think it;s safe to try the boards and see what happens. I would
re-check
the
PSU votlages with the boards fitted, though, in
case one of the
drops when mroe heavily loadesd (this can cause some diffiuclt to
trace faults, well, dififuclt to trace if you don't check the PSU
voltages...)
strup
I am not sure what you mean by barrier strips,
you mentioned them
before but I could not see what you are referring to.
It's a type of screw terminal block .The basic construction is a
plastic with little metal plates fixed to it. Each plate
has 2 screws that
you can
fix
wires under. There ar plastic ridges, or barries;
between the plates
so
that
odd ends of wires on one matal plate can't
come into contact with an
adjacent plate, hance the name.
I think Farnell and RS sell them under that name, a look at either
web
site
will give you a picture.
In that case I think I do know what you mean, it is just that there
are no wires, just black ones.
>
> -tony
Regards
Rob