Re: Kicker test Nr 2

[Gary Wait <wait@triumf.ca>]

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