开云体育

----- Original Message -----
From: rchrdpett
To: hp_agilent_equipment@...
Sent: Sunday, January 14, 2007 9:44 PM
Subject: [hp_agilent_equipment] Re: 141T storage failure


Chris
I had the same problem ,12.6V on the flood gun pin - no obvious flood
gun operation.
It turned out to be the ground lead from the "cold" side of the flood
gun ( pin 11, black wire )was not continuous to ground. The black
lead inner conductor was broken at the push-on connector to the HV
board. These connectors are known for poor crimping which fails after
several pushon /pulloff events.

Cheers
Richard Pett (owner of 2 systems)

--- In hp_agilent_equipment@..., "Chris van Lint"
<chrisvanlint@...> wrote:
>
> I have a problem with my 141T/8555A spectrum analyzer. The gear
works
> perfect in the conventional mode, but it will not store. When I
push the
> "store" button, the screen simply goes blank. Pushing either the
STD or FAST
> button makes it operate as a conventional CRT.
> Don Collie has very generously swapped my pulse circuit board in
his
> analyzer and has confirmed that the pulse board is OK. Indeed I
have
> checked all voltages and waveforms / amplitudes on the pulse board
and
> confirmed that they operate as expected. I have also checked all
supply
> voltages and adjusted them to be spot on. The voltages at the
various pins
> of the CRT have been checked, including the -12.6V heater voltage
for the
> flood gun and are all within limits. I have not checked the heater
voltage
> for the main gun, as the unit operates fine as a conventional
analyzer.
> Similarly I have not checked the
> 6.6KV supply, as the unit is fine in conventional mode. I did
check the
> voltage at the anode of CR23, which is -1350V as specified. The
voltage at
> the anode of CR24 varies between -2518V to 1591V in what I would
describe as
> being almost a saw tooth like fashion. Perhaps the experts can
find a clue
> in this observation.
> In sheer desperation I replaced the CRT with a brand new one I
have, (which
> of course includes a brand new infamous 3 conductor ribbon cable),
but it
> has not solved the problem. In other words everything is fine as a
> conventional analyzer, but when the "store" button is pushed,
nothing
> changes. Again voltages have been re-checked and re-adjusted and
are as
> expected according to the circuit diagram.
> I cannot perform the pulse circuit adjustments described in section
5-0 of
> the manual, simply because I cannot get past sub paragraph f, which
requires
> the fast collimator adjustment A5R14B to be adjusted so that the
entire
> flood gun illumination is visible. I cannot get any illumination
> whatsoever.
> I would be grateful for any suggestions as to what my next move(s)
should
> be.
>
> Cheers,
>
> Chris
>