Quad ESL 57: hum on one treble panel - diyAudio
Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th November 2010, 09:34 PM   #1
diyAudio Member
 
Join Date: Feb 2004
Location: Caen - France
Default Quad ESL 57: hum on one treble panel

Hello,
I have completed refurbishing a pair of ESL57, which means all panels except one: a treble panel, which appeared to be good and besides already refurbished (don't know when).
This treble panel makes some background noise, some kind of hum. If un-connected from power supply, this noise disappears. But output power reduces significantly almost immediately and more and more as time passes (timescale in seconds). I changed power supply (the full EHT block) but no improvement.
On the treble panel I refurbished, this is not the case: no hum and even after removing power supply connection, output power still stays high for a long time.
Any idea ? I have one but I would like to get confirmation.

I tried this: add a layer of insulating tape on the outside of the stators (I had to remove the dust cover for this). But I did not test yet if it improves behaviour.

Thank you.
__________________
Quad fan ! One hobby: re-build ESL 57
  Reply With Quote
Old 16th November 2010, 10:38 AM   #2
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

sounds like a seriously leaking panel, that draws too much current from the HV-supply. Try to measure the current or test on leakage with a blinker circuit.
If it prooves to be leaky, inspect the panel closely and try to find out if there´s some dust, humid grease or a particle at or within the panel that may cause the leakage.

jauu
Calvin
  Reply With Quote
Old 16th November 2010, 04:05 PM   #3
diyAudio Member
 
Franz Gysi's Avatar
 
Join Date: Oct 2007
I think, it is very important to avoid leakage current not to destroy the HT-psu tranny.

My local dealer warned me, that he has seen a lot of burned trannies. His conclusion was, that the trannies are made for 220VAC and not 230VAC.

I think, this conclusion is not correct.

The tranny is marked with 0.5mA (at about 610VAC). And the fuse is a 100mA type.

So, every leakage current could imho be dangerous for the tranny, specially when feeded with 230VAC.

I strongly recommend the blinking neon bulbs to control leakage.

Franz
  Reply With Quote
Old 16th November 2010, 04:18 PM   #4
diyAudio Member
 
Join Date: Feb 2004
Location: Caen - France
Quote:
Originally Posted by Franz Gysi View Post
I strongly recommend the blinking neon bulbs to control leakage.

Franz
Any reference for this blinking neon bulb to suggest ?
__________________
Quad fan ! One hobby: re-build ESL 57
  Reply With Quote
Old 16th November 2010, 04:38 PM   #5
diyAudio Member
 
Franz Gysi's Avatar
 
Join Date: Oct 2007
Quote:
Any reference for this blinking neon bulb to suggest ?
Yes, here:

Quad ESL 57 panel refurbish: DIY or not?

I used very "normal" NE-2 bulbs.

100V types without series resistor.

And I connected them simply in the HT-line. One for each bass panel and one for the treble panel.

Here you can see the bulbs:

Click the image to open in full size.

Franz
  Reply With Quote
Old 16th November 2010, 08:17 PM   #6
diyAudio Member
 
Join Date: Feb 2004
Location: Caen - France
Quote:
Originally Posted by Calvin View Post
Hi,

sounds like a seriously leaking panel, that draws too much current from the HV-supply. Try to measure the current or test on leakage with a blinker circuit.
If it prooves to be leaky, inspect the panel closely and try to find out if there´s some dust, humid grease or a particle at or within the panel that may cause the leakage.

jauu
Calvin
I removed dust covers to re-insulate the external side of the stators.
No improvement: the panel is certainly leaking. Knowing that there is no rivet at the peripheral (fixed by some strong tape) there remains one option from what I read on the net: coating is too conductive and might be in fact graphite based.
It looks like I have to re-build this panel completely. Anyway I will open it and see if I find some dust inside.
__________________
Quad fan ! One hobby: re-build ESL 57
  Reply With Quote
Old 17th November 2010, 06:29 AM   #7
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

the blinker consists of a small neon flash bulb, in parallel with a small film cap and a high ohmic resistor in connected in series to the bulb||cap.
The bulb may have a flashover treshold of less than 100V, the cap may be 100nF and >100V, the resistor may be 10MOhm. If the HV-supply already features a high ohmic resistor You may use that one instead.
Since the bulb is rather a shortcut when flashing You shouldn´t omit with the resistor in any case, because it reduces the current to a small and safe value and reduces the stress on the HV-supplies components. The small cap then supplies for the charging current through the bulb and it guarantees a clearly visible flash.

jauu
Calvin
  Reply With Quote
Old 18th November 2010, 09:24 PM   #8
diyAudio Member
 
Join Date: Feb 2004
Location: Caen - France
I opened the panel. No obvious sign of dust or whatever could create some leakage.

The coating itself is rather dark; it looks like graphite. I measured its conductivity: 1e7 Ohm/square, which is much lower than what can be achieved with original coating, soluble nylon: from 2 x 10^9 to 1 x 10^12 ohms per unit square according to quadesl.org.

See here.

This panel is really noisy, in the sense this hum is audible at a distance of 1m. In my opinion this is due to the chosen coating.
__________________
Quad fan ! One hobby: re-build ESL 57
  Reply With Quote
Old 19th November 2010, 08:38 AM   #9
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

this could be the case indeed. AFAIR the caps in the HV-supply are of rather low value (<<100nF) and a low ohmic coating might be a too heavy load for this.

jauu
Calvin
  Reply With Quote
Old 19th November 2010, 09:14 AM   #10
diyAudio Member
 
Join Date: Feb 2004
Location: Caen - France
Quote:
Originally Posted by Calvin View Post
Hi,

this could be the case indeed. AFAIR the caps in the HV-supply are of rather low value (<<100nF) and a low ohmic coating might be a too heavy load for this.

jauu
Calvin
The caps I use are 10nF (ceramic, 3kV).
__________________
Quad fan ! One hobby: re-build ESL 57
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Quad ESL 57 panel refurbish: DIY or not? Franz Gysi Planars & Exotics 50 4th February 2013 07:20 PM
WTB: Quad ESL-63 Treble Panel jeffx Swap Meet 2 6th September 2010 10:39 PM
How is Quad 57 Treble Diaphragm Charged? markzb Planars & Exotics 8 16th May 2009 06:02 PM
QuAD ESL 57 Stators/panel - German ?? dude007 Planars & Exotics 7 16th January 2008 02:00 PM
Quad ESL-57 (pair) TimA Swap Meet 2 14th November 2005 11:34 AM


New To Site? Need Help?

All times are GMT. The time now is 02:49 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2