29 Apr
2011
29 Apr
'11
1:40 p.m.
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
This worries me too. Thos voltages are high, but more worryingly, the PSU
seems not to be regualting properly.
Now, an SMPSU, of even a simple switching regulator, cna have an output
votlage that papears to rise under load if the output electrolytic
capacitors have a high ESR. But this doens't explain why the voltages
don't go back to the original value when you go back to the 5W bulb.
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 some
damage. I tested again with the 5W bulb just to see if it made a difference
but it didn't.
I asusme you've conencted the bulb between the same 2 connections each time.
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.
Is there a '+5VB' connection too?
I am going to have to look in the printset....
-tony