ESL57 restoration finally started!

[LeeS]

Very, very interesting. Well done !! Look forward to the next installation....

[cafe latte]

Very, very interesting. Well done !! Look forward to the next installation....

All being well I will do the coating tomorrow and close the stator. I want to test the unit before I proceed further with other stators and the coating is not fully dry for 4 days. There is not much point posting the same info for each bass unit so after tomorrow there will be a pause (apart the test) until I get to the treble units.
Regards
CL

[cafe latte]

Ok here is the next update
The first pic is the diaphram ready for being sprayed with the conductive coating. I used as instructed one ml of diluted concentrate per square foot. I masked the outer edge to avoid any liquid arriving on the edge of the panel causing leakage.

I do hope non of these collectable records get damaged that I am using to protect my table
The next pic shows the spray mist drying.

After the coating dried i used a soldering iron to make holes in the diaphram were the screws pass through (M3 12mm or similar).

All the screw holes done, note you dont do the one were the central wire attatches.

This is the loooong boring job of screwing the stator together. I have not tightened up any of the scews properly yet I will wait 48 hours for the coating to cure properly.

All the screws are in and the wires is fed through the panel.

Wies at the rear

I thought I would try doing the dust covers in the same way gluing to the wooden frame, I am not sure it will work yet, but I thought it is worth a go.


I cant wait to test the panel, when I tighten it all up I will insulate the edges with pvc tape and without the dust covers on connect it up and see if all is well
More soon
Regards
CL

[LeeS]

Blimey... What a long, time-consuming job CL. Well done to you, Sir. I am sure it will be worth all the effort.

[cafe latte]

Blimey... What a long, time-consuming job CL. Well done to you, Sir. I am sure it will be worth all the effort.

Thanks, but it is really not that hard, although putting all those nuts and bolts in was ... yawn . Tensioning takes maybe half an hour then you go off and do something else while the glue sets. Drilling out the rivets and putting the bolts back in dont take much longer but are B O R I N G IMO anyone can do this resto, but you need to look at it as a side project and not be in a rush to finish or you will make mistakes. I have had this on a back burner for a while now and it helps that I have other speakers so there in no desire to rush things.
Cant wait though to test this first panel and a bit worried too
Regards
CL

[13oots2]

Bloody hell! You should be shot, what are you doing to Chas N Dave?

Nice work though, so I'll let the shot gun ride for now

[cafe latte]

Bloody hell! You should be shot, what are you doing to Chas N Dave?

Nice work though, so I'll let the shot gun ride for now

It was like most of the records of that batch I bought unplayed samples from a radio station. Yes a mint copy of Chas N Dave still exists the world is not yet safe .
Actually I had a bit of a find yesterday evening gluing the dustcover to the wooden frame. I piled up all my junk records onto the frame to weight it down on the glue and spotted a copy of Pink Floyd Dark side of the moon at the bottom getting bent!!! I had previously checked all these records and taken all the good stuff out I have no idea how it got missed. Anyway I took it out and played it all last night and it too is mint and no worse the wear for its few moments on the bottom of the pile which is good because my other copy has a few scratches as i bought it used.
I will post the dust cover pics later and maybe I will test the panel
Regards
CL

[cafe latte]

Slight setback the panel has low output and has a fizz. Sunday is my shooting day but I am going to give it a miss and try and work out what is going on. It seems from first glance that my problem all along is that the holes to hold the stator together. On the bottom edge the holes are almost touching the metal strip that supplies the diaphram with power so causing a short muting the stator. I am not sure yet but when I work it out I will post what is going on.
Regards.
CL

[cafe latte]

Still a bit of a set back. The panel is still low but far better. I found the reason for three areas of clicking and buzzing and it was rings left from drilling out the rivets causing a short. The connections for the diaphram are insulated from the external part of the stator (not sure how but theere is no continuity), but the connection point is hissing which means leakage. I made an island with a dremel tool cutting the conductor with the stator exteral part for sure but it had little effect. The hiss form the bottom of the panel is MUCH reduced, but not fixed and output is still low so there is still a problem. I have had the solution for coating the diaphrams for a few years so this is a thought as an issue, but the panel has always been low output so I am guessing there is another issue somewere.
I have done a lot of research on the internet re doing this, but there is little which gives you info as to problems so I intended to try to make this as complete as possible in this regards as nothing IMO goes to plan perfectly .
Regards
CL

[paul401]

Hi,
excellent stuff, CL, fascinating to watch the project progressing.

Chas 'n' Dave ............. how could you? GERTCHA!!

[cafe latte]

Hi,
excellent stuff, CL, fascinating to watch the project progressing.

Chas 'n' Dave ............. how could you? GERTCHA!!

Cas and Dave live on, they just might be a touch more 'conductive' than before Cant be a bad thing IMO
Anyway back to the project Finally got the panel to work propery . I have a slight hum, but the coating is too fresh and I may have to remove a few bolts to check for shorts, but basically I sorted it. I am however not going to cover that panel till I have done a couple of others just in case I decided I am not happy.
Since i last posted I have learned more than I ever wanted to know about ESL 57s. There are lots of how to tutorials on the net but none I found tell you how the panels are made up, and what can go wrong with them (the actual stator)and what to do if you have issues.. Typical, well I hope I can fill a few gaps. If you go back to the pic of the seperated stator so you are looking at the inside of it probably the best pic for this is the one were I have just fitted the new diaphram. The two centeral tracks going up the middle of the stator are carbon coated and they are connected to the foil track round the edge of the panel. When you clean the panel it is very easy to smere some of this carbon onto the inside of the plastic stator giving a connection or short to the grid part of the circuit. The three grids are coated on the OUTSIDE of the stator with conductive coating and then later sprayed with an insulating paint. The three grids parts of the stator are connected together at the bottom of the panel by a thin external strip (under the paint), but this strip does not connect the two central tracks or the foil edges as they are on the other circuit.
Now my problem was a few things, first I was not getting enough coating on. It is possible I have too much now but that is not a problem as I can always redo the panel, but I should be OK as you can have a stator resistance a low as 30meg but it will start to distort but will be VERY sensitive. Normally my coating will be over 400meg so even if it is half this it really wont matter a bit so I am not going to stress right now.
The conductive strip that links the grids at the bottom of the panel is too wide, this panel is the replacement panel from the 80s which has always fizzed and has always been of low output (why I started doing it first). This too wide strip goes low enough to touch were the holes are drilled and those holes were also drilled too close to the internal foil strip so the high voltage found itself a path through fizzing away shorting the panel. My fix was to slightly slot the holes down a bit and to with a craft knife cut moon shapes from the conductive strip near the bolt holes (not cutting the whole strip through of course) to increase the distance of the two parts of the circuit. There was yet another problem The central connector at the bottom were the stator is charged (external circuit) was riveted at least an inch lower than any of my other panels. The area around the rivet has no paint so you have uninsulated external circuit right next to the internal lower foil track. I painted the exposed metal and also painted into the holes to ensure there could be no leakage. Another error Quad made is on the older original panels they stuck insulating tape behind this point inside the panel a patch around an inch and a half square. On this panel the patch was maybe a one cm by two.
I hope that is all clear and I hope it prevents anyone else going through the headache I did over this. First make sure you panels inside are spotlessly clean with no smeres and second look for possible shorts, I had 3 that were cracking that turned out to be bits of rivet left in the holes, check check and check again.
Regards
CL

[cafe latte]

It seems I have found the distortion problem on the other speaker . I need to sleep on it and think what I might be able to do. In the last house in Aus one speaker was near a window and the sun did its worst especially as we were on the coast were it is very hot.


Not happy to say least .
I am thinking spliting the stator and clamping it down and hitting it with a heat gun on the not painted side. I dont have a lot to loose, any better ideas?
Ho hum
Regards
CL

[JoeE SP9]

It looks as if you have not disassembled that one.

[cafe latte]

It looks as if you have not disassembled that one.

Not yet that will be this afternoon. I had just refitted a panel to try on that speaker and and at first I could not understand what was buzzing so much, then I realised it was the tweeter. I knew this side had a buzz, but I thought it was a looose dust cover maybe. I cut the dust cover off and then I saw the shape of the thing.
It has been sugested and it is all I can really think of too is trying a heatgun with it clamped to a flat table. It cant be done like a warped record between glass in the oven for a couple of reasons, first the conductive coating is only paint so the hear may damage the paint. Also the connections for the grids and the diaphram are a special rivets that stick out and would be in the way when trying to clamp it.
It there were no soooooo many holes to drill I thought about making one using circuit boards and etching were you dont want the conductor.
Regards
Chris