the unit is not working, technician checked it and told us that part is not working, but no troubleshoots performed as it was a "black box" for us.
machine is used as induction heater "specially annealing"

The ones I worked on that used a tube and a mercury rectifier bank (circa 1960), in the 10 years I serviced them, it was never the triode, rectifiers and main contactors and interlocks etc were the main cause of problems, the operating freq. was 470Khz.
Do you have any manuf. documentation? Schematic etc?
Max.

 

I agree, the tube is probably not the problem. They generally get weaker.

I also agree that this thing is lethal. I worked on a 100 kV at 0.1 A power supply and the 15 kV at 1,5 A supply (in a e-beam evaporator) used a tube as a series regulator. That was the section that failed. My predecessor just replaced the transistor driver. I got fed up and replaced a lot more parts and it was working when I retired.
I also worked on a 100 W 13.56 MHz tube transmitter. Again, you don;t want to play with this stuff. I've been working with high voltage since my teens, but this stuff was scary at least the first time I worked on it.

The discharge hook is essential. I do mean hook because bad things can happen with a straight probe.

I'd also look at failed interlocks. One issue with the transmitter was a differential pressure switch.

 

Do you have any manuf. documentation? Schematic etc?

No, there is no any documentation for that machine, I may start working on it within few weeks, now only gathering information about its "strange" components till start working on it.

 

So did it ever work in its present location?
Max.

 

Oh my.

these things are killers....

The capacitor can be discharged, leave it for a few minutes and its back up at volts with no external input.
Working on these the old " I have seen quick engineers and old engineers, but i have nether seen a quick old engineer".

work slow and think .. Else you will not be posting on here again..

 

The capacitor can be discharged, leave it for a few minutes and its back up at volts with no external input.

Yep. High voltage caps usually shipped with keepers or shorting bars.

I remember "playing" with an oil filled cap in my teens and discharging it. Probably charged to 300 or 600 V.

 

That cap only shows around 2000pf, indicates a very high frequency unit.
Max.

 

And extremely likely to be in one of the ISM bands. https://en.wikipedia.org/wiki/ISM_band

 

Fire up the old grid dip meter, and see what frequencies it absorbs.

 

The nature of the work material needs to be known as the OP mentions "specially annealing", annealing generally does not need that high a freq. case hardening is usually higher out of the two, depends on the item.
Max.

 

did it ever work in its present location?

Yes It was working from about two years, but I have not seen it working
also, the machine was used for annealing.

 

Do you know any features or pictures of what it was processing?
Or a picture of the work coil/ jig.
Max.

 

Fire up the old grid dip meter, and see what frequencies it absorbs

I did not understand, what is that "old grid dip meter"

 

Do you know any features or pictures of what it was processing?
Or a picture of the work coil/ jig.

OK, I will post tommorow some photos tomorrow of its coil.

 

by the way it was used for stainless steel annealig

 

A grid dip meter is used to read a coil to find the inductance etc non-invasively.
Stainless steel annealing used higher frequency than iron or simple carbon steel.
Max.

 

A grid dip meter is used to read a coil to find the inductance etc non-invasively.
Stainless steel annealing used higher frequency than iron or simple carbon steel.
Max.

A digital counter is much easier to obtain - but only works if you can fire up the RF heater.

And direct connection between instrument and equipment would be unwise - there should be plenty of RF field around the coil head.

OTOH: It could just be a weak emission tube - not enough power to anneal anything, but still enough oscillation to detect and measure.

 

https://en.wikipedia.org/wiki/Grid_dip_oscillator

I have one of these...AC powered.....

http://www.ebay.com/itm/MILLEN-90651-GRID-DIP-METER-WITH-COILS-and-manual-NICE-/162155416973

And one of these....battery powered....

http://www.ebay.com/itm/Heathkit-HD-1250-Solid-State-Grid-Dip-Meter-/201645715130

 

https://en.wikipedia.org/wiki/Grid_dip_oscillator

I have one of these...AC powered.....

http://www.ebay.com/itm/MILLEN-90651-GRID-DIP-METER-WITH-COILS-and-manual-NICE-/162155416973

And one of these....battery powered....

http://www.ebay.com/itm/Heathkit-HD-1250-Solid-State-Grid-Dip-Meter-/201645715130

But you can't just walk into a store and buy one.

Even a NOS dipper from eBay could be old and drifted - you need the counter to verify its calibration.

Its easier to just go straight to the counter.

Even with a low emission tube; the generator should produce enough RF field to pick up with a small coil.