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.
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.
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
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 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
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
Yes, here:
http://www.diyaudio.com/forums/plan...57-panel-refurbish-diy-not-2.html#post2343083
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:
An externally hosted image should be here but it was not working when we last tested it.
Franz
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.
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
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
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.
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.
The treble panel is now re-built, using Elvamide. And a new sheet of mylar stretched with more than 50kg.
No hum any more...
I still have some leakage but not that much and localized on a bass panel, near one metal support. If I push the bass panel this disappears. Some simple insulation and it will be gone.
I read somewhere "you don't imagine what can conduct at 6kV". This is indeed truth !
My advice for this: take your multimeter and check voltage at these locations. You might be surprised. One precision:I am using high voltage probe thus with input load > 1000MOhm. This might be important. I did not check with standard probe (10MOhm).
No hum any more...
I still have some leakage but not that much and localized on a bass panel, near one metal support. If I push the bass panel this disappears. Some simple insulation and it will be gone.
I read somewhere "you don't imagine what can conduct at 6kV". This is indeed truth !
My advice for this: take your multimeter and check voltage at these locations. You might be surprised. One precision:I am using high voltage probe thus with input load > 1000MOhm. This might be important. I did not check with standard probe (10MOhm).
Indeed I read that some people had issues with Elvamide.
My experience is completely different: I am using Elvamide with Ethanol (widely available in drug store) and this works great !
Difference is certainly in preparation: I am using a hot stirring plate each time.
I wash the mylar with acetone as well before applying Elvamide.
Finally adherence is really good. For example when I want to remove it from
outside of the panel or because I fell I did not put enough, it's not that easy even with acetone.
I am using as well a precise scale for preparation but I do not think this is key.
Note that even with a hot stirring plate preparation can be as long as one hour for perfect dillution. But not a problem as the device is making the job for you. Thus I imagine that some people lack patience if doing it by hand.
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