Another ESL 57 restauration

I will soon get my hands on a pair of ESL 57 restauration objects. I have now read alot of information about restauration. All seems quite straight forward. But my concern is about material for diaphragm and dustcovers. And it’s right I don’t know if it’s going to be necessary at all but I want to know the options. I have seen several sites to order from but all pretty far away from Sweden.
Electrostatic Loudspeakers By ER Audio seems to be the one with most/best materials.
Seems also possible to order diaphragm/dustcover material direct on Ebay Electrostatic Speaker Membrane Dupont Mylar C 2um 20M | eBay Reasonable price too.
From Onething England you can buy "powered Graphite" to rub in to make the elements slightly conductive. ESL57 Powdered Graphite 50g

And what glue to use?

But to get a clear picture of this part of the process is not easy. Can someone help me? Or guide me where to look. I have red Sheldons book and have build all my HIFi part smyself. Also Sheldons DAC 😊
 
Some pics from the restauration.
 

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legopart

Member
2016-10-19 1:13 pm
good work!
thanks for sharing.

I wanted too measured the the EHT but I have only a regular voltmetter 2 * 1Gohm and 1* 22Mohm 1* 10Mohm resistors.


this old resistors could have something like +-20% mistake
crossover capacitor have +-20%
in room temprature
If you can measure them then they still ok

IEZlgBT.jpg
 
This makes 10*(1500+10)/10=1500V and 35*(1500+10)/10=5285V ?
Good enough in that case.

Thanks Fabien you are right. I had some bad resistors at the EHT-board and I changed them and now the boards measures the same. 10 and 35Volts with 150Mohm + 10Mohm gives around 10V at 1,5Kv tap and around 35V at the 6KV tap. And due to load it dosent measure 40V at the 6KV tap.
All ok now :)

Nice site Fabien about ESL57. Really liked the part list. Thanks.
 
Thanks Fabien you are right. I had some bad resistors at the EHT-board and I changed them and now the boards measures the same. 10 and 35Volts with 150Mohm + 10Mohm gives around 10V at 1,5Kv tap and around 35V at the 6KV tap. And due to load it dosent measure 40V at the 6KV tap.
All ok now :)

Nice site Fabien about ESL57. Really liked the part list. Thanks.

With load, I can measure up to 5.6kV in max position:
see here

Thanks for comments about my site. I will make its promotion: there are some rare information on how to replace neon bulb, and how to make own clipping board that fits inside transformer.
 

legopart

Member
2016-10-19 1:13 pm
I tried to do some measurments too and got some bad resolts on both of EHT
6000v
used 20Mohm1% build in, for test I use: 1000Mohm5% :: 20Mohm1%
its somethin like 1040::20 == 52::1

1500v
used 40Mohm1% build in, for test I use: 1000Mohm5% :: 20Mohm1%
its somethin like 1060::20 == 53::1


resived voltages:
6000v is 31.4 *51= 1600v
1500v is 8.6v *52=450v

got some voltages of 1600v and 450v
why ? :(

CMdK6vs.jpg
 
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legopart

Member
2016-10-19 1:13 pm
*my mistake, using divider of 1G::20M on 20M without calculate the internal resistance of the voltmetter

I searched a lot and do not find another solution
*the measurment is in Mohms
hJUnrpy.jpg


its means that I measure the 20||10Mohm==6.67Mohm

so on the formulla I have to replace the 20Mohm with 6.67Mohm so the resolts will X3 highger.
so it means that they ok

I really want to buy some good Fluk with documentation

dont want to do the test again, I estimate the values:
1350v and 4835v

can't use this shitty metters even for home usage :(
 
I have done some new things. Replaced the resistors at the audio transformer. They were out of spec. Measured higher values all of them.
I go with the old caps sins they seems to be fine.

VR68 I presume. Good to see that you could get some.
Note: numbering (1234) does not respect 'official' documentation.

ESL57_audio_transformer_ser2.jpeg
 
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