Hello every one,
I don't know where to start to be clear and efficient.
The problem lies between the "fischer" connector, the beampipe, the cupper braid (inside the tank, between the wall and deflector plate) and the plate, all for the HV1 cabinet.
1 To do what Dave suggests, or what Gary suggests, or what Mike suggests requires to open the tank. The easy access is via the middle top or bottom flanges. When I mean easy, it is a way of speaking. Ask Rob about his "pipe riding" and I can tell you a lot about "under pipe" scrowling. You have ABSOLUTELY no visual or physical access to the cupper braid inside the beampipe without removing the kicker from the beam pipe. It is an important work.
Therefore, any changes inside the beampipe will require to take the kicker out and work outside the area. (Obviously, you have to first close manually the valve between the separtor and the kicker. Peter, you remember that I showed you how to do it. The screwdriver should still be in place! Don't forget that step)
If you have to de-solder the cupper braid, you have to use the "big" solder iron. On the deflector plate side, the braid is inserted inside a ball. It stays in place via a allenkey screw. Use the mirror to help you reaching it. I would recommend to remove the screw first, before de-soldering. Secondly, this is again a "pain in ..." job, because you need to heat the connection on the beampipe side. It takes a while. The HV1 side was beautifully made by Anatoly, so you will have a good amount of solder inside, well spread. My suggestion, if you reach this step, would be to try to bend that braid once removed from the deflector plate and to make test in this position, to avoid the de-soldering job.
2. The faulty location is at HV1, namely at one of the place where the HV power supply is located. If one would clip the deflector plates, we would not be in the same condition as last year. However, Mike and Gary may say that it is not a big problem to remove both of the 2.5kOhm resistor in the HV1 and to run the negative side with only MV1.
3. To reach the electronics of the kicker, you need to remove the metalic "floor" of the RF part of the cabinet. Unfortunatelly, the kickerr location is such that you CAN NOT open a door fully. Thus, you will ahve to remove the door (toward the magnet) from the hinges (don't remember the real english name: the stuff which allow a door to rotate on an axis). Then you can access the plate. To find the correct location of the fiber optic for DN13, you will have to follow the fiber themselves and use the special tool to remove the fiber from the board.
We can discuss some issue. You can look at my webpages about the kicker
http://www.npl.uiuc.edu/~mulhauser/mulan/kicker/.... to see some picture of the various parts.
I would suggest, if Mike is available tomorrow, to give him a ring and discuss the options lively.
Good luck and best regards
Francoise
-----Original Message-----
From: Michael Barnes
To: Gary Wait
Cc: Peter Winter; Michael Barnes; kiburg@npl.uiuc.edu; Mulhauser Francoise; kammel@npl.uiuc.edu; hertzog@uiuc.edu; michael.barnes@triumf.ca; Robert M Carey; Anatoly Gafarov; rmcnabb@uiuc.edu
Sent: 11/30/05 8:52 PM
Subject: Re: Kicker test Nr 2
Hi all,
Sorry I have been in meetings etc all afternoon so just getting around
to
reading email. It is good that you confirmed the general area of the
breakdown. Dave's suggestion may, or may not, work depending on the site
of the breakdown --- e.g. if there is a problem with one of the support
HV1 plate ceramics it will not work. However I suspect the most likely
place for the failure is the Fischer connector. Or maybe it is something
as simple as the internal connection (wire) from the plug to the HV1
plate
breaking and dropping down close to the beam pipe. If you have access to
the beam pipe this would be easy to check. In addition, if there is
nothing obvious in the beam pipe, I would suggest disconnecting the wire
from the Fischer socket (inside the beam pipe). Then repeat the HV test,
with the Fischer plug plugged into the socket. If there is breakdown, it
is the plug or socket; if there is no breakdown, the problem lies with
the
deflector plates e.g. support ceramics).
Good luck
Mike
> Peter Winter wrote:
>
>> Hi all,
>>
>> we just performed the test Francoise proposed by removing the fisher
>> plug inside cabinet HV1.
>>
>> Our test included the following steps:
>> 1) Switching to a constant high TTL level (DC mode from endless gate
>> generator)
>> 2) Ramping HV2 to see that all red LEDs are ok at 5kV with fisher
plug
>> still inside. That confirmed that we have a high TTL
>> 3) We removed the fisher plug and taped it in a safe position on the
>> plastic shelf far away any metal.
>> - ramping HV2 to 5kV with lower red LEDs ok, the upper were not
>> lightened due to DC mode
>> - ramping HV1 without current drawn to 5kV on negative polarity,
>> upper red LEDs turned on, no red LED on bottom stack due to DC
>> 4) We then decided to go to the kicking mode (5mus on at 1kHz) in
>> order to also see the red LEDs on the lower stack of cards in HV1.
>> - ramping HV2 to 5kV with all red LEDs ok (top ones bright, lower
>> faint)
>> - ramping HV1 to 2.4kV with 001mA, we observed that the red LED
on
>> the card DN-13 had NO red light, while all others were on
>> 5) We reconnected the fisher plug with DC mode:
>> - HV2 ok when ramping up
>> - HV1 has immediately a rising current of several mA
>>
>> Summarizing:
>> - It seems that the breakdown is somewhere between the fisher plug
and
>> the plate
>> - The card DN-13 still has no red light. Since this is en exchanged
>> card, could the problem be connected with the optic fibre?
>> - When we first saw this breakdown we could go up twice to 2kV with
no
>> current. Only when the breakdown occured the current remained. Now
the
>> situation changed and we immediately see the breakdown current. Does
>> that mean that the breakdown point worsened and became permanent.
>>
>> Waiting for new proposals and conclusions
>> Brendan and Peter
>>
> Brendan and Peter
> Card dn-13 is likely not getting light from the fiber optics. In order
> to turn off a card (and thus get a red led on) there must be light on
> from the fiber optic cable. A quick check on this would be to
> interchange the fiber optics cables between cards dn12 and dn13 and
> apply HV with the fischer connector disconnected. You will likely see
> that the red LED on card dn 12 will not turn on. You will need to
check
> that the faulty fiber optic cable is connected properly at both ends
and
> if that doesnt work then replace the fiber optic cable. If you cannot
> repair this fault you will have to run at a lower voltage on HV1
> cabinet. ie: 16/17*12.5kV=11.8kV to protect the remaining 16 cards in
> the stack. (or see Daves email)
>
> RE: fischer connector.
> The short circuit is either external to the tank or internal. You
could
> try cleaning the external connection with alcohol and see if it is
> carbonized anywhere. There might be tracking along Anatolies connector
> when it is plugged in, so it should be dismantled and cleaned if
> possible. It that doesnt work you will have to open the tank and check
> inside. The suggestion of Daves to run with the two sets of plates
> coupled together is probably the best plan and you will still need to
> open the tank to air. You will have to disconnect the internal
> connection of the faulty plate from the fischer connector, or you will
> still have a short to ground.
>
> Regards
> Gary
>
>