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Questions about Oil Filled Caps

RobinTW

RobinTW

Well-Known Member
I opened up my new collection, Trio KA-6004 made in 1972, and found 4 of those axial caps in the power supply board. They look like e caps but are listed as oil filled caps in the service manual.
Do they last long? Should I replace them if they are tested ok? Why did they use caps of 630V here? Do I need to use the same voltage rating if replacing them?

thanks a lot

oil filled caps.jpg
 
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The ones in slightly older Japanese tube gear were terrible. Its a paper in oil capacitor, but the seals weren't much good and the caps would fail. I'd ditch that for whatever flavor of film cap you like. They're probably snubber caps so it doesn't need to be anything real exotic. Illinois MPW should be fine.
 
RobinTW said:
I opened up my new collection, Trio KA-6004 made in 1972, and found 4 of those axial caps in the power supply board. They look like e caps but are listed as oil filled caps in the service manual.
Do they last long? Should I replace them if they are tested ok? Why did they use caps of 630V here? Do I need to use the same voltage rating if replacing them?

thanks a lot

View attachment 1862706
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They used 630v because of the surge from frequency. They appear to be the caps on the bridge rectifiers to quell "ringing" oscillations. I would yank them suckers in a heartbeat and replace them with modern axial film 630v caps for reliability and never look back. I would also be inclined to change those "ball" diodes out with modern quiet diodes to eliminate any hash noise.I don't know about your electric grid, but here in the States, we're up to an average of 121vAC where back in the 1970s it averaged around 117vAC and that puts a stress on older silicon, especially if it has grown any silver migration internally.
 
Skywatcher said:
They used 630v because of the surge from frequency. They appear to be the caps on the bridge rectifiers to quell "ringing" oscillations. I would yank them suckers in a heartbeat and replace them with modern axial film 630v caps for reliability and never look back. I would also be inclined to change those "ball" diodes out with modern quiet diodes to eliminate any hash noise.I don't know about your electric grid, but here in the States, we're up to an average of 121vAC where back in the 1970s it averaged around 117vAC and that puts a stress on older silicon, especially if it has grown any silver migration internally.
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Thanks for your reply. You make me think again to replace them plus the diodes. I have not decided yet.

The mains voltage here in Taiwan is 110V 60Hz. The power is quite stable here. This Trio is a Japanese version using 100V. So I have a 1000VA Toroidal step down transformer for it and all my other Japanese amps.
 
Skywatcher said:
No, they are "safety" caps. X1 at 400v, Y2 at 250v. X type "shorts" upon failure to force a fuse or breaker to trip. Y type opens up upon failure and becomes useless.
500v "Plain Jane" Ceramic capacitors will work.
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Thanks for your help. I have a follow up question. Is it ok to use film caps for safety caps?
 
RobinTW said:
Thanks for your help. I have a follow up question. Is it ok to use film caps for safety caps?
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No, not really. They are used to eliminate a possible shock hazard, hence the name "safety capacitor". Although functionally a "regular" film would work, but the safety element would be lost.
 
Skywatcher said:
No, they are "safety" caps. X1 at 400v, Y2 at 250v. X type "shorts" upon failure to force a fuse or breaker to trip. Y type opens up upon failure and becomes useless.
500v "Plain Jane" Ceramic capacitors will work.
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I don't want to hijack this thread. But I've long wondered: How can a cap be both a type X and type Y at the same time?
 
info:

https://www.vishay.com/docs/48251/_checklist_safety_caps_vmn_ms7357_1707.pdf
https://sh.kemet.com/Lists/FileStore/900 Series Product Training Module.pdf

do you need/want them?
https://sound-au.com/articles/psu-snubber.htm

Conclusion: you can take them out, leave them in, use the nice new blue ones you have, or buy good film caps to put in.

Scott75s1974 said:
If I'm reading it correctly, this image of the same board seems to have films in those positions? I see these are "restored and upgraded."

(Edit: Not advocating replacing them. Just noting that other caps have been used there.)

http://select45rpm.com/pages/hifi/hifi-sold/TRIOKA6004.html
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Those LOOK very small and if films they will probably be 50 or 100V types, so in that case that modification was probably not too smart, for the reason @Skywatcher already stated.
 
gslikker said:
info:

https://www.vishay.com/docs/48251/_checklist_safety_caps_vmn_ms7357_1707.pdf
https://sh.kemet.com/Lists/FileStore/900 Series Product Training Module.pdf

do you need/want them?
https://sound-au.com/articles/psu-snubber.htm

Conclusion: you can take them out, leave them in, use the nice new blue ones you have, or buy good film caps to put in.


Those LOOK very small and if films they will probably be 50 or 100V types, so in that case that modification was probably not too smart, for the reason @Skywatcher already stated.
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I wonder why they blurred out all the capacitor values?? Must be some sort of "State Secret".. :rolleyes:
 
Skywatcher said:
I wonder why they blurred out all the capacitor values?? Must be some sort of "State Secret".. :rolleyes:
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Having this beer and leisure time after late shift you got me confused and in "investigation mode".
I first looked at the PDF's and did see nothing blurred before I realized it was about the Kenwood amp pictures :)
I am not able to identify te big black ones.
But I enlarged the screen and sniffed at it, and it turned out the smaller blurred blue ones having one revealing "FC" smell like Panasonic :rflmao:
 
gslikker said:
Having this beer and leisure time after late shift you got me confused and in "investigation mode".
I first looked at the PDF's and did see nothing blurred before I realized it was about the Kenwood amp pictures :)
I am not able to identify te big black ones.
But I enlarged the screen and sniffed at it, and it turned out the smaller blurred blue ones having one revealing "FC" smell like Panasonic :rflmao:
Click to expand...
:p :beerchug: Yes I could also "smell" they are FC since I use a lot of them too, but the values and voltages are blurred out. The main filter cap values are also blurred out, but also possibly Panasonic too by the looks of the "shade" of dark brown/black and the somewhat "familiar" pattern of markings. But geeezzzz, why hide them? I just got a Kenwood KA-7002 in for service, but it's further down the queue. Heck, I'll gladly post clear sharp photos of my work once it is done for anybody to see. I keep no "State Secrets" from anyone.. :beatnik:
 
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