RE: Kicker overcurrent

[Mulhauser Francoise <francoise.mulhauser@psi.ch>]

Dear Peter and co,

Following all the explanation of Mike, I am still wondering if you should do
the test with a new card inserted in place of the one you removed yesterday
to diagnose it. It is clear that the card itself is not reponsible for the
over-current. However, the lack of red LED on that particular card is not a
good sign. 
Because you have some spare one, I would suggest to insert one of them
before doing the last test that Mike is suggesting. 

Another technical important point. De-soldering the two small wired (from
both stacks) to the main connector is a very easy task. Re-soldering them is
much nastier. You need a big solder-iron. The standard one is not hot enough
and you have to heat the braid so much each time that you desolder the rest
of it. Be carefull. The braid is attached to the isolation part by
soldering and "melting". It took Julia and myself many hours to make it
right from start to the end. 

My first test suggestion would be to remove the connector from the beam pipe
(pull firmly strait out), set it in a "safe" position inside the cabinet and
perform the test. If the result is NO CURRENT, that means that the problem
is inside the pipe. If there is current, then you need to start de-soldering
the cables.

Another question is related to the over-current protection. If the NEG1 LED
was on, you performed a reset of the box before trying something else? I
imagine that the answer is yes. 

Make sure that the next tests you make are done with the pulsed gate (1kHz,
1 mus in), such that you are in known conditions and that the results can be
compare with what existed before.

Best regards
Francoise

-----Original Message-----
From: Michael Barnes
To: Peter Winter
Cc: Michael Barnes; Mulhauser Francoise; kammel@npl.uiuc.edu; Brendan
Kiburg; hertzog@uiuc.edu; michael.barnes@triumf.ca; wait@triumf.ca; Robert M
Carey; Anatoly Gafarov; rmcnabb@uiuc.edu
Sent: 29/11/05 17:33
Subject: Re: Kicker overcurrent

Dear Peter,

You should be looking for strands of wire, carbon tracks, tools left in
the cabinet, etc. which could cause the breakdown (or in the case of the
carbon track, show the path of breakdown). The problem is most likely
near
the output of HV1. It could be a problem associated with the output
connector, deflector plates etc, so may not be readily visible.

One thing you could try is to disconnect (desolder) the output of both
stacks in HV1 from the cable to the output connector and apply voltage
to
the wire to the connector (e.g. from a suitable current limited HV
supply). Slowly turn up this supply and see if it draws current. If
there
is nothing wrong with the output from the HV1 cabinet there will be NO
current flow during this test. Current flow would indicate a problem.
If you do this correctly there should not be any voltage applied to the
stacks during this test.

Good luck,
Mike

> Dear Mike,
>
> we just inspected the kicker cabinets. Since we didn't know what to
> exactly look for we tried to find any differences between the lower
and
> upper stack in HV1 and we compared it to the other cabinets. Nothing
> obvious could be found.
> Just for information: Tomorrow there will be no beam the entire day.
> Therefore, this is an ideal time for us to do any extensive
diagnostics
> if that's necessary. Today, we will now continue taking data so we
have
> no direct access to the kicker.
> Greetings
> Peter
>
>