My first CLS and several questions.

I found a really nice looking pair over the weekend in beautiful shape but I've never owned Martin Logan speakers before so I'm unfamiliar with the problems I encountered once I hooked them up. I can barely hear anything from either speaker with the volume turned way up, and what I do hear is distorted. I realize the panels deteriorate over time but I can't believe someone listened to them until they got to this point. I would think that once they started sounding a little off, they'd put them aside until they could afford to repair them but these are way beyond that point. Could they have gone bad from being in storage possibly, or hot or cold conditions because I don't know their history? Or could there be something wrong with the electronics, but it's both of them and they sound the same? I'd hate to replace the panels only to find out there was something wrong with the electronics.

I'd also like to know where to find the serial number because the only serial number I find is on one of the boxes which says it's serial # 1260.

I've already learned a lot from this forum and can see it's going to be a good forum to learn from. Thanks guys! Bernie

Hola Bernie and welcome. Do you have any electronics skills? First thing is, unplug the AC cable to the speaker, and remove the four nuts that are securing the top of the electronics. Inspect for an open fuse. Be careful, because the PSU (Power Supply Unit) has high voltage. If you want, you can PM to me, and I will try to guide you for some testing. Also, you can contact Martin Logan service dept. You will find there a very helpful guys, ready to help you with your problems. To me, your problem is that the panels are not being energized by the PSU. Other possibility is that you could have bad panels...but they will be dead or a partial of the panel might be working. Just beg that you will not need new panels. Are expensive!.

The fuses are good. Without realizing it, the speaker I was working on came unplugged from the wall, but when I plugged it back in it never changed at all. Does that mean the panels are not getting charged and it may be a problem with my crossovers? Odd that both are like that though.

Please, we need the model of your CLSs...I do recall a tone shape, but there are no crossovers. You need a high voltage probe. Do you have it? The voltage at the red wire that goes to the panel should have at least DC 1.2KV to 1.8KV.

roberto said:

Please, we need the model of your CLSs...I do recall a tone shape, but there are no crossovers. You need a high voltage probe. Do you have it? The voltage at the red wire that goes to the panel should have at least DC 1.2KV to 1.8KV.

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It just says The CLS.

I would check the high voltage power transformer between pins five & eight which should have around 280-Volts AC. Also ohm check all the 1/2-Watt resistors as in the schematic.

http://www.diyaudio.com/forums/atta...cls-schematics-martin-logan-cls-schematic.pdf

Thanks for the help #Zero. You are always very handy!!! I was trying to explain it, but with your pic made me speechless. And also right with the advice...should check all the resistors.

I think your advice was the same as what Roberto advised me to do also. I couldn't open the schematic because I'm not a DIY member but I did check the resistors Roberto told me to and I did find issues. Apparently my speakers are very early versions according to Roberto. Serial # 1260.

If you want to PM your e-mail address, I can send you the pdf schematic as it's too large a file for this forum.

Looking at pictures of the CLS and the CLS II, am I correct in seeing that the panels on the CLS did not have the vertical edge sections but the CLS IIs did? My speakers have the vertical edge sections but the old power supplies, so if I'm right, someone replaced the panels already. Is the old power supply compatible with the CLS II panels or is this my problem?

ILKML said:

Looking at pictures of the CLS and the CLS II, am I correct in seeing that the panels on the CLS did not have the vertical edge sections but the CLS IIs did? My speakers have the vertical edge sections but the old power supplies, so if I'm right, someone replaced the panels already. Is the old power supply compatible with the CLS II panels or is this my problem?

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This is a CLS Panel. CLS2 panels are asymmetric. Outer bass section is wider than the inner one. Number and positions of the tweeter/midrange spacer fields and even the coating may vary from year of production. As far as I can see your panel matches the electronics.

bluenote56 said:

This is a CLS Panel. CLS2 panels are asymmetric. Outer bass section is wider than the inner one. Number and positions of the tweeter/midrange spacer fields and even the coating may vary from year of production. As far as I can see your panel matches the electronics.

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Yeah, I see it now. I'm new to ML but I'm taking it all in with the help of this forum. Thanks guys!

Nice find ILKML.

Should you decide you are not able to work on the electronics yourself, located in southern Illinois is http://www.kenealeyaudio.com/. He will rebuild and improve the interface for all CLS models. He also mods and repairs specific amps and preamps.

I am currently on his waiting list to ship the interfaces from my CLSIIz's for repair and upgrade.

He charges $660 plus shipping to replace caps, power supply, wiring and upgrades the bias circuitry and changes that improve the bass in both interfaces.

Let us know how you proceed with your project.

ILKML said:

I think your advice was the same as what Roberto advised me to do also. I couldn't open the schematic because I'm not a DIY member but I did check the resistors Roberto told me to and I did find issues. Apparently my speakers are very early versions according to Roberto. Serial # 1260.

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What issues did you find? I can't really see anything wrong in the photos. Did you measure for continuity and voltages?

MPS said:

What issues did you find? I can't really see anything wrong in the photos. Did you measure for continuity and voltages?

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To hear anything at all, the volume has to be all the way up and then the sound is distorted. I then accidently unplugged one speaker and realized that when plugged back in to the wall outlet, it made no difference at all so I came to the conclusion that the power supply wasn't supplying any power. Roberto thinks it's the low profile transformer that may be the problem. I find it odd though, that both speakers have the same issues. I can see one going out but both for the same reason? Were there problems with these early power supplies? I think the resistors are ok. I had my meter set wrong at first but they seem to be within allowances. I'm not real handy with my multimeter to check anything else but certainly can learn.

Brad225 said:

Nice find ILKML.

Should you decide you are not able to work on the electronics yourself, located in southern Illinois is http://www.kenealeyaudio.com/. He will rebuild and improve the interface for all CLS models. He also mods and repairs specific amps and preamps.

I am currently on his waiting list to ship the interfaces from my CLSIIz's for repair and upgrade.

He charges $660 plus shipping to replace caps, power supply, wiring and upgrades the bias circuitry and changes that improve the bass in both interfaces.

Let us know how you proceed with your project.

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Thanks for the info Brad225. I'll probably end up going that route eventually but first I need to just get these power supplies operational to see what shape the panels are in. I don't want to do a complete rebuild only to then discover they still sound bad due to bad panels. Because of their age, they're probably going to need new panels but judging by how clean these are, I don't know how much use they've gotten over the years. There wasn't even any dust or dirt on them as if they'd been in storage. I'm thinking maybe a power surge or something wiped them out since both are down with the same problem.

I need to ask a basic (stupid?) question: have you verified that there is power in your wall outlets that supply the speakers?

Bernard said:

I need to ask a basic (stupid?) question: have you verified that there is power in your wall outlets that supply the speakers?

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Hi Bernard! (same name as mine) That's not a stupid question at all but yes, it's the same outlet my system is plugged into. I even thought maybe the power cords went bad but no luck there either. I'm waiting back for a response from ML for their thoughts before I start ordering new transformer parts. Bernie

ILKML said:

To hear anything at all, the volume has to be all the way up and then the sound is distorted. I then accidently unplugged one speaker and realized that when plugged back in to the wall outlet, it made no difference at all so I came to the conclusion that the power supply wasn't supplying any power. Roberto thinks it's the low profile transformer that may be the problem. I find it odd though, that both speakers have the same issues. I can see one going out but both for the same reason? Were there problems with these early power supplies? I think the resistors are ok. I had my meter set wrong at first but they seem to be within allowances. I'm not real handy with my multimeter to check anything else but certainly can learn.

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Ok, I'm not sure what you have measured but be careful - there are possibly lethal voltages inside PS units. I would leave speakers unplugged for 24 hours before doing any measurements.
I would measure both PS-transformer and audio-transformer primaries and secondaries for continuity and resistance. Also measure all passive components for resistance and continuity and diodes if possible without removing from circuit boards might be good to measure capacitors too if you can. Also check all joints. It's relatively easy to compare left and right side values for reference.
If you really know what you are doing you could also measure AC- and DC-voltages at least prior to voltage multiplier but I guess if you need this advice then you lack competence to safely do so.
Unless you have the skills and equipment to do all by yourself just find someone who can do it for you.

Anyway give both panels a really good vacuuming coz thats what they need even if sound was coming out

Dana from ML sent me a set of new ps transformers since the thinking is that somehow they were damaged from a power surge of some sort. I installed one of them and it didn't solve the problem so today I'm heading to my amp repair guy who said he would take a look at them for me. I also found out he has a lot of experience with electrostatic speaker repairs and owns a pair of Acoustats. He can at least let me know if they've been the problem, and then make the repairs. If they aren't the problem, then I have a bigger panel problem. More to come.