[time-nuts] Re: HP z3816a DC power supply DIP switches

[Hal Murray]

spbach1234 at gmail.com said:
> Here are some pictures of the PSU and power connector area, if anyone has any
> insight into what voltage this thing is expecting.  What's confusing to me is
> that the original marking, 20-72 V was crossed out, 48V written over the top,
> and then the DIPs internally being set to 24A.  I'm not really sure what the
> A and B positions mean, either.

I haven't worked with the Z816A.

It was common for gear of that era to work with either 24 or 48V.  The input 
range was typically 2:1.  Thus 48 meant anywhere from 36V to 72V and 24 meant 
18 to 36.

I have no idea what the A in 24A means or what the manual would say about the 
switches.  The label has a 24B so maybe there are 2 input connectors.  If it 
was on my bench, I would take it apart and look at the bottom of the power 
supply board and/or try to trace out the switches.  That's not a high power 
switch so maybe it selects some switching mosfets.  But I don't see any.  So 
maybe the switch is good for the amp or 2 and maybe they run 2 in parallel.

If it's designed for 24 or 48, it might not explode if run with 48 when setup 
for 24 so I wouldn't be too surprised if the label didn't match the switches.  
Maybe somebody tried it on 48 and it worked.


> Is the female DE9 on this wired so I can just plug a USB-Serial adapter into
> it directly, like a Trimble Thunderbolt, or do I need to make a null-modem
> cable?

The Z3811/12, KS-24361 L101/2 units that were available a few years ago send 
RS-422 (5V differential pairs) on a 9 pin connector.

I'd put a meter or scope on some of the pins.  If you see 5V, the pinout for 
the KS-24361 should be in the archives.  Mine worked with the right set of 
direct connectios to a typical PC serial port.



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