JJ E34L (brand new) emitting a white light - has anyone seen this before?

[prairie]

Has anyone seen this before? The amp is a JCM2000 DSL100, tubes are biased to factory recommendations, nothing is redplating, but there is a distinct white light coming from one of the brand new JJ E34L’s.

I’ve never seen this before. If it’s nothing I should worry about, I’ll leave it be. Checking the Internet hive mind before putting in a return claim.

[Stephen1966]

With just one image to go off it looks to be arcing. You could forward the photo to the supplier but only as preface to returning it anyway.

It's probably part of a matched set as well, yes? In such a case, it might be necessary to return the whole set.

Best to contact the supplier and take it up with them directly. This isn't normal.

[prairie]

With just one image to go off it looks to be arcing. You could forward the photo to the supplier but only as preface to returning it anyway.

It's probably part of a matched set as well, yes? In such a case, it might be necessary to return the whole set.

Best to contact the supplier and take it up with them directly. This isn't normal.

Yeah, I reckon it’s either arcing or there’s some contaminate on the cathode. The fact that I was able to play the amp for 20 minutes at stage volume without any failure has me thinking it might be the latter.

Either way, I sent the supplier an email and we will see what they say tomorrow.

[R.G.]

Very unlikely to be a spot of contamination on the cathode/plate/etc. The white color of the light indicates a temperature over 5000K of the source. There's no reactive gasses in there to speak of to support a reaction that vigorous if it passes audio at all. It's very, very, very likely to be an arc. Send it back.

[xtian]

Wild! Thanks for posting!

[Stevem]

Interesting that no fuse blowing has taken place!

If you know anyone with a good tube tester like a Hickok 600 or such a test out in it for shorts would pick that right up.

I would love to know what it’s internally arcing to.

If that tube is removed from the amp does the bias voltage seen on pin 5 of any of the other output tubes change drastically?