Martin Logan (Vantage): panel arcing --> any chance to fix this?

Hello there!

I owns a pair of Martin Logan Vantange since about 5 years. A few days ago, I heard some arcing noise on one of the speaker. Looking more closely with lights dimmed, I could clearly see a small quite permanente brilliant arc between the mylar film and the back stator (metallic grid). On the mylar film I can clearly see a small black dot where the arcing occurs. I cannot see anything on the stator (poor access)

Picture attached (I hope :ROFL:

I've contacted ML for help, in their opinion I need a new stator...

I have the impression that the stator insulation has locally failed and that it could be relatively easy to fix if I could recoat the damaged area with some kind of varnish.

Is there anybody here that has experienced such failure, and attempted to fix it?

Many thanks from a DMLO (Desperate ML Owner)

It does indeed look like the insulation failed there, and a very careful application of varnish to the area might fix it.

I'd also ask if you have been consistent with vacuuming the panels, as sometimes deposits or small insects can accumulate or get stuck and cause the arcing.

And no, never happened to me, and I've owned ML's for 20+ years.

I agree with JonFo... Vacuuming is vital to keep stuff off the panels. I had a bug get zapped on my Summits once.. Never had an arcing problem though...

Ok Jonathan/Tom, thanks for your inputs. I vaccuumed my panels only a couple of times, fearing to stress them. Probably could have done better, though I'm not sure this is the cause as they seem to be very clean (no dust/insects visible on the mylar nowhere).

Any recommandation about the kind of varnish I could use? Thanks

Try a vigorous vacuuming. I had similar issue with one of my Vantage panels. Third Vacuum was the charm.


J

Some news: I "fixed" the sparking spot with a drop of "Plastik 70" from Kontakt Chemie, a high voltage varnish. This spot is not sparking anymore, but now another one is sparking on the same panel at at totally different location...:banghead:

So I'm suspecting there is another root cause. BTW (and I forgot to mention this), the little blue led on top of the ML logo on the panel is off... could it be related in your opinion (problem with the panel supply, for instance?

End of the story: I've exchanged the panels and... surprise: the "bad" panel works like a charm on the other power block, while the "good" panel is arcing... So clearly the problem was on the electronics side. After discussion with a nice ML service guy (thanks Scott ), we conclude that the internal HV power supply could be “running away” and putting out too much voltage on the panel, high enough to exceed and damage the insulation on the panel. He adviced me to procure a new High Voltage power supply from ML, ref BCFS7HV.

I bought one, installed it, and... it works. The 'bad' panel is back to life.

Conclusion: This costed me 400 bugs for a tiny power supply board... not at all happy about that after only 5 years of usage... but it works.

Thanks a lot guys for your advices.

Tom, glad to hear your back in a state of sonic bliss ! I agree on the 'expense after only five years' thing ………..My Spire's are five years old today

Tom, good to hear, and thanks for sharing the results.

I had thought about HV bias issues, but those are exceedingly rare. Yours is the first case I can recall on the forum. The usual HV bias problem is not enough (or no) current vs your case of too much.

Hi Tomiseur

I think I've got exactly the same problem as you with my Summit. A blue arc making a horrendous noise and an ozone smell.

I think the EHT power board is probably the culprit - the panel was completely dead, then I got hold of a replacement - it worked fine for a short duration but now an arc has appeared!

Interested in how you applied the Plastik 70...did you somehow dab it onto the stator around where the arc was forming? WIth a cotton bud or something? Must you be careful to not get any on the diaphragm?

Many thanks,

Tim