HP 5061-3476: Which boards go where

Chris Zach cz at alembic.crystel.com
Tue Sep 14 20:31:44 CDT 2021

Ah ok. So that first transistor on Q6 serves as a chopper to double the 
DC voltage up to 360v when using 120. When you reconfigure the jumpers 
for 240 you basically bypass that thing.

I have 240 in my shed so I'll start by seeing if there is 360v on the 
input rail. If not then I'll re-jumper to 240 and see if it appears 
then. Then trace everything forward from there....


On 9/13/2021 1:22 AM, J. David Bryan via cctech wrote:
> On Saturday, September 11, 2021 at 21:31, Chris Zach via cctech wrote:
>> Ok, thanks!
> You're welcome.
>> I just tried mine again, it's a dud so I am going to have to figure it
>> out. First step was to see if the rectifier had any voltage so I
>> disconnected the + side and checked it with a voltmeter. With 120v
>> plugged in I saw 200v DC which is probably not too far off. That seems
>> to go to the inverter card, which I don't know what it's doing with
>> that.
> There's a reasonably complete theory of operation of the "B" power supply
> (which is what you have) in section IXB of the HP 1000 M/E/F-Series
> Computers Engineering and Reference Documentation.  There were several
> revisions of the "B" supply, but they all used the same motherboard (as far
> as I know), so the various plug-in card functions would be pretty much
> equivalent across versions.
>> Is there a block schematic of what does what on this PS?
> Page IXB-6 of the above manual has one.  There's also a troubleshooting
> flowchart on page IXC-3.  Section IXC is specifically for your supply
> version and has the appropriate schematics, but the theory from the earlier
> "B" supply should be broadly applicable.
>                                        -- Dave

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