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Old 8th January 2014, 11:57 PM   #1
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Default Help me fix these poor ML Sequels

I picked up a pair of ML Sequels today and unfortunately someone else beat me to the electronics

I was told the bass driver worked but the panels were silent when purchased but then they made a little sound after vacuuming.

Before I did anything I opened them and found what's shown in the photos below.

Seems they lost bias and cooked the crossover board, I would imagine from over driving them trying to get more volume out of the failing panels.

I'm going to need a schematic and maybe some handholding and maybe a stiff drink.

Where do I begin?

Any and all help is very much appreciated.

Thanks

Eric


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Old 9th January 2014, 12:36 AM   #2
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Oh My !!!!

I would just start over and build a new interface!!

Here is a good place to start,

Jazzman's DIY Electrostatic Loudspeaker Page

Jazzman's DIY Electrostatic Loudspeaker Page: The Electronics Package

How To Hook Up Electrostatic Panel

If you are lucky maybe the Step-up transformers are still okay.

jer

Last edited by geraldfryjr; 9th January 2014 at 12:39 AM.
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Old 9th January 2014, 01:15 AM   #3
X83 is offline X83  United States
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Here's another thread to read: Martin Logan Sequel II dead panels
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Old 9th January 2014, 02:38 AM   #4
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Well I'm hoping that comparing the work done with a schematic and checking components to make sure they are to spec I should be able to get these singing again. A schematic would be a huge help.

Can someone tell me how to get the stators off so I can recoating the electrostatic film?

Thanks

Eric
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Old 9th January 2014, 05:13 AM   #5
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I wouldn't attempt the thought of re-coating the diaphragm's until you get a working interface going, in order too verify that they need it.

FWIW

jer
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Old 9th January 2014, 06:46 AM   #6
Calvin is offline Calvin  Germany
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Hi,

deja vu? Or just accidental?
Why does it remind me of the recent thread, linked in #3?
What a clueless nerd ... tweaked the xover caps in closeness to the HV supply?
Somehow I wish, that those who treated the speaker so badly have been zapped in revenge ;-)

jauu
Calvin
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Old 9th January 2014, 11:30 AM   #7
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The plan is to get the crossovers back up and running using the new caps etc. and replacing anything that's out of spec. Apparently the PO followed DIY upgrade he found on the net. I've seen it, does anyone know of the one I'm talking about and is it a good choice?

How can I be sure once this is done that it is properly functioning if I have a panel that is of suspect condition?

By the way, I hear of people cleaning the electrostatic panel in the shower. How is this done? How do I get it off the speaker?

Can I, using a multimeter, check the electrostatic coating?

Thanks

Eric
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Old 11th January 2014, 08:15 PM   #8
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To remove the panel-mounting rails, you tap the end of the rails with a rubber mallet, and they slide up (or down, depending on the model!), releasing the assembly pins in the rails from their 'wedge clips' in the cabinet.

(Does somebody know the proper term for this type of mounting?)
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File Type: png Screen Shot 2014-01-11 at 13.13.44 .png (308.8 KB, 200 views)

Last edited by Andersonix; 11th January 2014 at 08:18 PM.
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Old 11th January 2014, 10:00 PM   #9
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In case it's not obvious, you must lay the speaker down on its back (on couch cushions) before loosening the rails. Somebody on ML Owners' Forum knocked off their rails while the speaker was still upright, and the weight of the ESL panel broke a solder joint.
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Old 11th January 2014, 11:43 PM   #10
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Well the second crossover is even worse than the first.

There are caps and resistors missing and this PCB is even more badly burned.

I have the hand drawn schematic that floats around the web and it confuses me a little. I know I can figure it out but if anyone has a better one that is laid out more like the actual PCB it would be a big help.

Also, what I have and what the schematic calls out are a little different. First the schematic calls for 400 volt caps, I have 250 volt Daytons in mine and the photo a friend sent me of his ML refreshed Sequel 2 crossovers show 100 volt elpacs.

I assume my Dayton's are OK but want to be sure.

Thanks

Eric
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