Capacitor Failure

[Baggy Trousers]

The wish list poll recently has touched on (figuratively!) high voltages and the possible susceptibility of the WAD 6550 or, at least, its owner, in the event of a capacitor failure.

Which capacitor is this and do I need to panic yet?

Ta ever so,

Richard.

[Richard]

Hello Richard,

Can you refer to the post that has you concerned?

Rich

[Baggy Trousers]

Originally Posted by Richard

Hello Richard,

Can you refer to the post that has you concerned?

Rich

Er, well, in a word, no. 'Fraid I can't! I have searched with all due diligence but failed to find the sources. They were there, I promise.

In the context of what we might like to see in new WD amplifiers, there was some discussion of the level of voltages which might be acceptable for a kit to be put together by novices and I recall at least a couple of separate references made to the possibility of unspeakable things happening if a capacitor in the 6550 went to ground.

It was just curiosity on my part - I'm not really worried about it but thank you Richard for your concern. Nick Lucas never did send the original knobs so the combination of a couple of bakelite thingies from an old Pamphonic and my venerable brothel-creepers should get me close to bullet-proof if this capacitor decides to let go. I imagine it is the one off the first plate of the ECF80; I have little understanding of the mysteries of these things. But I am looking forward to building the new KT88/6550PP monoblocks . . . .

Richard.

Originally Posted by Richard

Hello Richard,
Can you refer to the post that has you concerned?
Rich

Richard,
The post was probably #17 in my '300B PP' thread, NickG was referring to an exceptional circumstance that could happen to any 'big' capacitor.

[NickG]

Ah yes, I remember, I was just referring to the voltages that were lurking in the amp, nothing to worry about though, all within the design limits.

[Richard]

Yes I see the post. Kit 6550 doesn't seem to have any particular weakness. Richard, it would be the same situation for almost any valve amp I think.

The issues seems to be of exploding caps (which should be OK if the strong metal cover is securely screwed down) and electrocution which again should be OK if you have a mains fuse fitted which is below the rating of the mains flex and the chassis is connected to mains earth.

In the case of component failure passing current to the chassis the component/path would either burn out and stop conducting or the mains fuse would blow.

The biggest danger from kit building is having your face over the amp whilst testing and having both your hands in there together. Really we should all wear a face mask, or glasses at least, and be very careful about what we touch.

Rich

[Baggy Trousers]

Well, I'm glad it turned up - I was beginning to think I had dreamt it.

Thank you all for your responses.

Richard.