Help with Sequel II wiring

[desmarteau]

Hi All. I'm new to the forum and a new ML owner. I recently purchased older ML Sequel II's. They seem to work fine when they have jumpers on place (both Electrostatic Panels and cabinet speakers work in both of them) and their wired to one channel each on my apm. When I try to wire each speaker to a separate channel (one channel on the woofer and one on the electrostatic panels), one of my electrostatic panels doesn't work. I shows up as a "red" shorted/non existing light on my OSD 7 channel amp. do you have any idea why that would be happening? I've switched many cables/speakers so I know the cabling and amp isn't the problem. I even tried switching the Sequel 2 electronics and it only happens on one speaker (the same one). Hopefully I'm explaining this well enough that it makes sense. Thank you. Jay

 

[Tosh]

And it shows a red light on all 7 channels when you try the ESL alone? So the amp's fault-checker is over-cautious about the weird ESL load? Try adding a 1 Ohm power resistor inline or try using the wimpiest cables you have there.

 

[desmarteau]

thanks tosh for responding. The only channel with the red light on the amp is the one connected to the electrostatic panel of my "left" sequel II. The woofer on that left sequel II is blue (and works). The right Sequel II has 2 blue lights for the electrostatic panel and woofer...both work. If i install the jumpers the on the left one it works fine from the woofer and the electrostatic panel. strange.

I've used monster cable speaker wire, as well as 14 gauge...doesn't make a difference. Not sure how to add an inline resister

 

[Tosh]

Do the other amp channels act the same way with that ESL?

 

[desmarteau]

Do the other amp channels act the same way with that ESL?

Yes. I’ve changed speaker wire, tried different channels to see if my amp is bad , and even swapped out the speaker electronics …same electrostatic panel has the issue . Showered the electrostatic panels too!

 

[JonFo]

Could be that some element in the crossover for that speaker is failing and presenting a different load than when it's paired up with the XO of the woofer (and the woofer itself of course).
Might require opening up the crossover boxes and seeing if one of the caps is failing, or a resistor is burnt.
And, it might be the step-up transformer, but that's harder to diagnose.

 

[Tosh]

It shows up as a "red" shorted/non existing light on my OSD 7 channel amp.

What does the amp's owner's manual say about the meaning of the red light? Does it really indicate 'shorted'? Someone's gonna have to open up that speaker...

 

[Tosh]

https://www.diyaudio.com/community/threads/martin-logan-sequel-ii-dead-panels.245751/
Hope yours doesn't look as burned-up as these!

 

[desmarteau]

Here are mine…a couple of the circuits look burnt …

 

[desmarteau]

What does the amp's owner's manual say about the meaning of the red light? Does it really indicate 'shorted'? Someone's gonna have to open up that speaker...

OSD Nero user Manual

 

[JonFo]

Here are mine…a couple of the circuits look burnt …

Yes, that diode ladder area in the lower left does not look good. The board will need to be checked, and likely, some of those diodes will need to be replaced.
That is part of the diaphragm polarization voltage circuit, so it is likely the panel is not getting the appropriate voltage, and it is harder to drive.

However, earlier you mentioned:

I even tried switching the Sequel 2 electronics and it only happens on one speaker (the same one).

If you did move the crossover box between the two physical units, a short in the wiring between the XO box and the 'left' panel could be the cause of the burnt diodes, so check that very carefully.