Siemens Pandoros 1200/triode problem

It is very old Siemens Generator, it need special tools to check the triode do you have these parts ( check the STC service tools Catalogue )

Swap it with the anode side & see if the problem moves with the tube.

I had some experience to service the Siemens Somatom DR2/3 CT with Pandoros generator 20 years ago, to makesure if minus side was defect, just swap +/- triode to see if problem is came to plus side or not, but becareful to shutdown the generator for at least 10 mins before servicre to really discharge the capacitor inside the HV tank, then use ground stick to touch each triode(there should have discharge point in the triode) for secure discharge again for safety, thank you.

DEar All,

I checked inter changing the triodes. The conduction changing sides.

There are some more test results.

1. With SS 'off' the feild plate current flows for both anode and cathode sides.(Supply voltage of 81V comes down to around 7.5V at emmitter side of V1 and V2)

2.With SS 'On' there is only field current flow on the conduction side. (One side the voltage does not drop)

3. SS 'off' Grid voltage is approx 2600Vdc. Comes down to almost to 0 Volts when Floro switch pressed. ( Could not check with SS 'On' due to want of suitable tools)

Kindly suggest a likely fault.

Also suggest is worth investing on the repairs since it is very old and replacing Triodes are expensive. I need advice also about availibility of spares for this unit.