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Old 25th October 2010, 09:48 AM   #11
oshifis is offline oshifis  Hungary
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Quote:
Originally Posted by Franz Gysi View Post
Yes, I also plan to install blinkers to control leakage.

My intention was to use the same circuit as used in the ESL 63: a bulb with a cap in parallel and inserting a protection resistor.

What type of neon bulbs do you use?

I agree: it is hard to believe, that the bass panel failed.

I will investigate further.

One bass panel of this speaker is playing on low level, the other is silent.

Franz
Franz,

I used NE-2 type bulbs without any resistor or capacitor, same as depicted here:

Neon lamp - Wikipedia, the free encyclopedia

Did you try swapping the HT block from the working to the non-working unit? You wrote that you replaced the diodes (why was it necessary?), so you never know...

I have one other idea. Since the stator of the bass panels is metallized outside (unlike the mid/treble panel that is metallized inside), you can test the continuity from the left/right binding posts and the front/back surface of the stator. You just need to remove the dust cover and scratch the grey paint a bit. Or you can puncture the dust cover with a needle at the top corner, easy to undo. The metallization is on "islands", it is missing where the HT goes to the diaphragm (from the red wire on the middle binding post).

BTW the dust covers in my original units were painted grey. Since it is transparent on your units, could it be that yours have been already repaired? This could explain the small washer. Anyway, you are lucky if the mid/treble panels are OK, since they are much more difficult to repair than the bass panels.
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Old 25th October 2010, 01:48 PM   #12
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Quote:
I have one other idea. Since the stator of the bass panels is metallized outside (unlike the mid/treble panel that is metallized inside), you can test the continuity from the left/right binding posts and the front/back surface of the stator. You just need to remove the dust cover and scratch the grey paint a bit. Or you can puncture the dust cover with a needle at the top corner, easy to undo. The metallization is on "islands", it is missing where the HT goes to the diaphragm (from the red wire on the middle binding post).
Many thanks for this explanation!

Now, I understand how the stators are built. What material are they made from?

I changed the diodes in both speakers I own and it is the planned next step to take out the HT supply from the working speaker and test it on the faulty one.

After that, I will examine the faulty panel in more detail.

No, I dont think they are repaired before, as it seems that the front cover was never removed.

Franz
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Old 25th October 2010, 02:57 PM   #13
oshifis is offline oshifis  Hungary
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I found some interesting photos explaining the interiors:

Quad ESL-57 repair by Hey You
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Old 25th October 2010, 05:35 PM   #14
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Thanks, very informative link!

I can imagine a contact problem with the rivets connecting the signal/polarizing voltage to the stators.

Specially when I know now, the stator panels are made from some kind of thermoplast.

Could the UFO be a part from this rivet/contact assembly?

Next weekend, when I have free time, I will first move the HT supply from the working speaker to the faulty one. Before I punch the dustcovers.

And when this does not cure the problem, I will check the stator connections as you described, punching the dustcovers with a needle.

Kind regards
Franz

/Edit
do you think, it is better to make the needle hot to melt a hole?

Last edited by Franz Gysi; 25th October 2010 at 06:00 PM.
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Old 26th October 2010, 08:33 AM   #15
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Quote:
Originally Posted by oshifis View Post
Franz,

I used NE-2 type bulbs without any resistor or capacitor, same as depicted here:

Neon lamp - Wikipedia, the free encyclopedia

Did you try swapping the HT block from the working to the non-working unit? You wrote that you replaced the diodes (why was it necessary?), so you never know...

I have one other idea. Since the stator of the bass panels is metallized outside (unlike the mid/treble panel that is metallized inside), you can test the continuity from the left/right binding posts and the front/back surface of the stator. You just need to remove the dust cover and scratch the grey paint a bit. Or you can puncture the dust cover with a needle at the top corner, easy to undo. The metallization is on "islands", it is missing where the HT goes to the diaphragm (from the red wire on the middle binding post).

BTW the dust covers in my original units were painted grey. Since it is transparent on your units, could it be that yours have been already repaired? This could explain the small washer. Anyway, you are lucky if the mid/treble panels are OK, since they are much more difficult to repair than the bass panels.
I confirm that bonding between metallized zones can fail. This happened to s.o. I know.

What do you mean by much more difficult to repair a treble than a bass panel ?
Indeed it requires more weights. And some heat setting can be applied as an option. But basically it is the same process isn't it ?
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Old 26th October 2010, 06:28 PM   #16
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Quote:
Quad fan !
I subscribe immediately this statement.

When I come back tired from work and other things

I switch on my ESL's and relax.

Even with one bass panel not working but the very low level supported by the JBL sub (yes, the soundstage is not perfect, yet, but I dont sit in the sweet spot anyway).

Such a clearness and without any coloration, absolutely no listening fatigue.

Relaxing and reactivating long forgotten emotions...

And my cat: she never turned the ears to my old speakers so many times as with the Quad's. Specially human voices are always attracting her (she worries about unkown people in the flat as she is very very shy).

Franz
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Old 26th October 2010, 06:34 PM   #17
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Quote:
I confirm that bonding between metallized zones can fail. This happened to s.o. I know.
I will examine the panel. Thanks for sharing your experience!

Franz
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Old 13th November 2010, 05:14 PM   #18
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Today, I had time to work with the faulty basspanel.

I've built a completely new high tension supply (covered with bees wax later):

Click the image to open in full size.

This supply includes neon bulbs, one for the treble panel and for each bass panel one separately.

Immediately after switching on the first time, I have seen the two bass panel bulbs flashing several times with decreasing frequency.

After one or two minutes, no more flashes could be observed.

I turned on music. In the first moment, I thougth having solved the problem: both bass panels where playing at very low level, while the treble panel still was silent.

After 10 to 15 minutes, it was obviously not having solved the problem as the left bass panels gots louder and louder while the other one remaines at very low level.

The treble panel is still charging with a the bulb flashing about once per minute and is playing now at good level.

I give it time to charge till tomorrow. Should the problem with one bass panel not be solved then I will start to investigate the panel and possibly perforate the dust cover to do some measurements.

Franz

Last edited by Franz Gysi; 13th November 2010 at 05:21 PM.
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Old 13th November 2010, 05:29 PM   #19
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BTW:

I measured the originial (but revised) power supply and compared it to the new build.

To do the measurements, I made a voltage divider 99Meg / 1 Meg and I fed the circuit by 6VAC instead of about 600VAC.

Both measurements showed about the same results:

0,14VDC for the treble panel and 0.32VDC for the bass panels.

I think this is in the green area, with the voltage divider 1:100 (to be exactly, 1:99).

The Cockroft Walton cascade is to heavy loaded and therefore showing the voltage drop in the higher voltage output of the psu.

Franz

Last edited by Franz Gysi; 13th November 2010 at 05:33 PM.
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Old 13th November 2010, 08:04 PM   #20
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Use a digital VOM and measure the drive voltage to the panels. Set the amplifier to 1VRMS. You should measure approximately 280VAC across the bass stators. If this voltage is low, disconnect 1 wire from the stator and remeasure. If the voltage is normal, the stator has a problem...perhaps the conductive coating has failed. Otherwise the problem is the transformer or a series resistor.
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