Tek465 question

[andy3055]

Can someone please give me some ideas on the 465 as below?

Attaching pages from the Tek 465 manual that shows the high voltage section of this scope and the parts list. What would be the reason to have some of the caps in this part of the circuit rated at 6kv, 4kv etc? The diagram shows TP 1423 at -2450 volts and I was trying to figure out how they came up with those values. Is it possible that there will be a surge of some sort at a given time?

For ex: C1487  .0047/6kv and C1488  .0012/4kv

Any feedback is much appreciated.

Thanks.

[jxjbsd]

I think it's to reduce leakage
Last week, I just repaired the HV part of this equipment

[tautech]

The HV caps are part of the DC restorer circuitry and need to be HV rated with a sufficient derating for reliability.
Quite normal to have 4 or 6KV ratings where they are used.

[jxjbsd]

Lower voltage can prolong the service life of capacitor。465 brightness failure is often related to the leakage of these capacitors

[Shock]

If you look at the schematic you can see they are connected to the tube.

[andy3055]

Thank you to all. I did not think about the de-rating under high voltages. The replies are very much appreciated.