Ghosts in the machines!

AVForums

Help Support AVForums:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
G

Gliding Dutchman

Guest
This is what I entertain myself with at the moment:

2008_03_13022sml.jpg


Yes, it is a set of Martin Logan CLS mkI electrostats but not so fast - it took a great deal of work to get them to where they are at the moment.

Arrived last Saturday from a fellow forum member in pieces. They are designed in such a way to dismantle easily for ease of transport.

One panel's out put was nearly 0 whilst the other played relatively fine.

In this shot I quickly connected the panels to the electronics - very dangerous - 5 kV HT!!

2008_03_09004sml.jpg


Somewhere a previous owner thought it a bright idea to do some DIY tweaking and removed the factory wiring between binding posts and PCB - replacing it with domestic mains cabling. He also fitted aftermarket fuses, probably to protect his amplifiers.

2008_03_09007sml.jpg


In this process he screwed up the wiring scheme of the audio transformer - it is a miracle no amplifiers were damaged by this nifty trick!

Getting back to the dead panel...

I carefully, very carefully, sliced the tape holding the front stator in place to remove it and expose the diaphragm. Initially I had no sure clue as what caused the fault. (I have checked the electronics by swapping then around on the functioning panel).

With the panel "open" I could do a closer inspection of the HT supply lead and diaphragm. Most of the time the coating (applied by ML with a $20 000 000 machine) loses its ability to conduct the HT charge due to age. You cant see this with the naked eye...

2008_03_10002sml.jpg


Secondly I found that the copper strip on the parameter of the mylar diaphragm were badly corroded. A-ha! This could be the reason the panel is a dud!

I carefully installed a new copper strip after having removed the old one. Low and behold I found the very same 3M double-sided tape at my local Mica to reattach the front stator.

2008_03_11004sml.jpg


With fingers crossed I connected the panel to its HT supply and played some music - to my surprise this dodgy procedure worked more or less like I hoped it would. Only problems that remains is that the panel buzzes on certain bass notes - irritating. I'll probably redo both panels in the near future when funds permit - this will be another story on its own with a 50/50 chance of total failure.

This morning I carefully restored the electronics boxes to factory standard with some help of schematics supplied by Martin Logans' helpful service manager Jim Power. Thanx Jim! He was also kind to have shown me that the electronics were heavily modified...

2008_03_13018sml.jpg


Box here attached to oak frame holding esl panel.

2008_03_13021sml.jpg


GD



 
Top