Re: Defective Power supply in HP8711a Network Analyser.

Sorry guys, I have not checked this newsgroup for several months...shame on me!

The 8711 family used a 3rd party power supply and CRT. While I do have schematics for most of the "Agilent" parts, I don't think any schematic exists for either of these parts....or at least I have not found any. If I remember, I will ask around tomorrow....but don't get your hopes up. Most of the people that would have had a schematic are long gone.

Our service department will be moving to a remodeled building on our Santa Rosa site in June and there will be no room for much of our spare obsolete equipment. If I find any junked 871x power supplies I will try to salvage them (which, btw, is against policy.)

We are preparing for the move by throwing out many, many manuals that would be useful to hobbyists. However we are trying to keep anything that is not already digitized and on the web. There is no profit in supporting hobbyist, so management will not support me, however I will try to do a best-effort support if it is not too time-consuming.

If you need to contact me; use caesarv-at-email.com. This is not my real name. This is my "junk" email address, but I do check it every couple of days.

CV




Rivendel_Ivo wrote:
Hello Massimo.

Going back to basics it proved that the SMPS of the HP8711a hates it
to be plugged into the cabinet, even only connected to the backplane;
result: hickup mode. (so no 8711 units in the 8711 rack at all!!)
In the open the SMPS works fine (all voltages unloaded), but I found
out that the -15 Volt GND return hates it to be connected to GND of
the cabinet (this connection is on the backplane of the 8711) or to
GNDs of the other voltages.
All voltages are fine, no DC shorts between anything, and I can GND
all voltages, except the -15V. By grounding only a few mA will float
though, but this brings the SMPS in the hick-up mode, like it does in
the 8711.

Could no-load situation bring this? Or is something wrong with the
current sense system, so the SMPS does not boot?

Do you have any idea?

Ivo.
.

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