Scope leader LBO 508 A High voltage capacitors

[gilbert gh]

Hi,
I have oscilloscope Leader LBO 508 A .It worked fine Years ago.Now I wanted to use it again , and when I switched it on, it worked fine , but after some minutes the lines on the screen fade away and it went dark. Next time same but in shorter time , now when I switch it on ,only control lamp went on , nothing on the screen.
I opened it and voltages on testpoints 1 2 3 4 are ok , but on tp 5 (should be -2000v) nothing.
930v ac is present , desoldered and tested diodes D112-113-114-115 : ok .
desoldered and tested hv capacitors c 117-118-119-120-121 : 117 and 119 defective (12pF & 2pF) rest around 500nF=0,5µF.
I want to replace all five but these are oil capacitors MARCON K160DCLU504K not to find in Europe.
What can I use instead ?
Thanks,
Gilbert

 

[kellys_eye]

Most major component suppliers will have 0.47μF/1600V capacitors in stock and they would suit the application in place of the oil-filled versions - modern component manufacturing technology not requiring the oil for insulation these days.

Googling around I can see 'OEM' oil filled replacements are around $40 EACH!!!!! but bog standard devices that will do the same can be had for $5-$10.

If you were keen to retain original appearance you could find a capacitor that fits INSIDE the existing packaging and do what a lot of antique radio restorers do and 'stuff' it (i.e. put the modern part inside the old housing).

Here's a selection from Farnell:

http://uk.farnell.com/w/c/passive-c...rs/prl/results?voltage-rating=1.6kv&st=0.47uF

 

[gilbert gh]

Thanks , I want to order
Wima MKP1T041007H00KSSD MKP 1 µF 1600 V/DC
Is that a good replacement ?( two in series gives 0,5µF)

 

[kellys_eye]

That would work and half the voltage across each capacitor (although I'd put 'balancing' resistors across them) although you don't need to hit 0.5μF that accurately - 0.47μF in a single package would work just as well.

 

[gilbert gh]

Thanks for the info