Quad ESL 57 panel refurbish: DIY or not?

[Franz Gysi]

After about 23h hours of charging:

The formerly dead bass panel is playing again!

Boahhh, what a good luck!

Give me time to listen to music now

Franz

 

[Fabien Lefebvre]

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

Using a HT probe, I have same ratio but with a load which is much higher at 990+10MOhm.
This is not enough: I get between 4500 and 5000V iso 6000.
Just to give an idea.

 

[Franz Gysi]

As more as I am reading about the Nylon coating Quad used, the more I
ask myself what role the relative humidity is playing.

Could it be, that the coating from old panel could dry out completely?

Specially in winter season here in Europe, when the rooms are heated and have low relative humidity.

Nylon is very hygroscopic and this could influence the conductivity.

I could try one day the following, when one of the panels is getting low at soundlevel:

- completely discharge the panel
- open the dustcover
- put a tobacco humidifier for 24h into the panel (small can with holes, saturated with water inside)
- wait another 24 hours
- try again

What do you think about this thesis?

Franz

 

[lcsaszar]

I wouldn't open the dust cover. Humidity finds its way through the wooden frame that holds the dust cover, it is just a matter of time. I believed that higher humidity decreases sensitivity due to surface leakage shunt paths. Have you experienced the opposite?

 

[Franz Gysi]

Have you experienced the opposite?

No no, I was just thinking about my panels and about all this stuff I've read on the net in the last weeks.

I understand, humidity in the frame can produce undesired leakage current.

But some facts about Nylon:

- normally, it does not detoriate, exept when exposed to UV light (maybe a explanation, why the dustcovers are sprayed gray?)
- it is strongly and quickly hygroscopic

So, when you have optically perfect panels, like mine, and if they don't charge (mine do, actually), why not try this hypothesis?

Franz

 

[revinkevan]

Hi
I would like to have a pair of these built for me,and need to buy the various parts can anybody give me the exact spec's/part numbers for the parts ?
I went to maplins store with the standard EHT and they said they do not sell parts with that high voltage rating
I would also like to change all the resistors and caps is the transformers as well, but again I need to know what the the min voltage requirements are
could really do with some advise guys
thanks in advance

An externally hosted image should be here but it was not working when we last tested it.

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[/QUOTE]

 

[Franz Gysi]

Hello

I purchased the 10nF/3kV caps on eBay. Item-ID 140389963363

The diodes are simply 1N4007 and the resistors standard types.

The tranny does deliver between 600 to 650VAC.

Hope this helps!
Franz

 

[Fabien Lefebvre]

Hello

I purchased the 10nF/3kV caps on eBay. Item-ID 140389963363

The diodes are simply 1N4007 and the resistors standard types.

The tranny does deliver between 600 to 650VAC.

Hope this helps!
Franz

The 2.2MOhm can be chosen better than just standard. It has to withstand 750V DC continually.

 

[Franz Gysi]

The 2.2MOhm can be chosen better than just standard. It has to withstand 750V DC continually.

I agree.

But you could also use two 1.1MOhm in series, standard types in this case.

Franz

 

[revinkevan]

I've just emailed him to see if he has any more

 

[Franz Gysi]

Two years later, I feel very happy using this neon bulbs as indicator.

Last saturday, I found the neon bulbs constantly glowing!

I opened the backcover and found some dust bridges between the psu and the backcover (I did not mould the psu in wax, it is open).

After removing the dust (sorry, I should have made a picture), the bulbs are flashing now every two seconds.

The panels are beginning to leak. I will have a closer look at it soon. Maybe now it's time to refurbish the panels?

Franz

 

[Fabien Lefebvre]

Two years later, I feel very happy using this neon bulbs as indicator.

Last saturday, I found the neon bulbs constantly glowing!

I opened the backcover and found some dust bridges between the psu and the backcover (I did not mould the psu in wax, it is open).

After removing the dust (sorry, I should have made a picture), the bulbs are flashing now every two seconds.

The panels are beginning to leak. I will have a closer look at it soon. Maybe now it's time to refurbish the panels?

Franz

Before re-furbishing everything, if your only problem is some not-severe leakage, you can just remove the dust cover and re-insulate the outter part of the stator with serious tape (black 3M).

 

[Franz Gysi]

Thanks for this advice, Fabien

You recommended me the same procedure two years ago

I plan to do this during Christmas Holiday.

Franz

/Edit (add a Picture)

An externally hosted image should be here but it was not working when we last tested it.

 

[Fabien Lefebvre]

You mean you already did that 2 years ago and this happens again ?

 

[Franz Gysi]

No, I didn't

 

[Fabien Lefebvre]

No, I didn't

So maybe time to try it.
You will probably notice at that time that the current tape which is applied has aged.

 

[triode_al]

(black 3M).

Can you say more about the Black [magic] tape?
3M has hundreds, maybe thousands types of tape

albert

 

[Fabien Lefebvre]

Can you say more about the Black [magic] tape?
3M has hundreds, maybe thousands types of tape

albert

I am using one or two layer of the classical electric black tape (3M) + 2 layers of the thin transparent tape used for parcels.
The black tape covers the rivets themselves, not the sides.
Take care that if too thick, it will be harder to install back in the frame.

 

[Franz Gysi]

Fabien

I am a happy guy as I got an old spare bass panel some weeks ago. It has severe oxidations and the dustcover is damaged.

An externally hosted image should be here but it was not working when we last tested it.

I can use this panel to explore the construction in detail before I work on my other panels.

Franz

 

[Bazukaz]

Hi,

I have Quad 57's with serial numbers 21258 & 21253. I guess these should have clamping boards for treble units. I have disassembled one speaker for investigation & power plug replacement but cannot see a clamping board anywhere. Is it within transformer casing or its missing?

Regards,
Lukas.