|25th November 2004, 12:39 AM||#21|
Join Date: Apr 2002
I am on the road away from home in Ottawa at the moment.
The long blink rate on the defective speaker may be caused by getting too low a voltage on the multiplier board.
If one or more of your new diodes are leaking or not soldered properly then you may be getting less than 5K volts on the board.
This may result in a longer blink rate because the lower voltage does not leak off at the same rate. The circuit charges up to possibly 3K or less volts and does not have the same potential to leak off as easily because the discharge path may be less conductive at a lower voltage.
Lower voltage will translate into a lower volume.
You could try swapping the good multiplier board. If the blink rate goes back to approximately 1 second and the panels operate as expected then you should replace the diodes again.
If you still have the same problem then you know it is not the HV board.
You need a gold leaf meter to test the voltage a regular high voltage meter will bleed the charge off before it is measured.
Almost any HV diode will work O.K.
They should not cost more that about $1 CAN each.
I would not recommend cleaning the panels.
They are very very very very very delicate and can rip or tear at a touch.
I have rebuilt 4 HV boards over the years without any problems.
Let me know how you make out.
|25th November 2004, 05:56 PM||#22|
expert in tautology
The most usual cause of failure in a multiplier HV supply is one or more of the caps becoming leaky or shorted.
Replace the caps. The values only need to be close, not exact.
It's a multiplier and the tolerances are fairly large. So if it uses a 0.003 you could put in 0.005 or 0.002 and be just fine... etc.
or if it has 0.03 the same... about -50% to +200% is ok, all the same is best. But in a pinch to test, anything will do.
Higher voltage parts are preferred.
The idea of swapping the HV boards is fine.
In my experience, measuring before the HV supply runs through a large value (megohm) resistor out to the panels, you can use a normal HV probe on any meter and go right up the multiplier ladder and see if the voltages are correct. Of course a shorted cap or leaky cap will pull the whole thing down from the first leg up to the HV output side...
Assuming your HV is ok (and that has not been determined yet).
the next thing to check is the input transformer's step up ratio and make sure it hasn't been fried by amp failures (DC across the primary or parasitic oscillations.
Check the DCR of the good unit primary and secondary vs the bad unit... make sure the HV supply is BLED DOWN TO ZERO volts and or disconnect the secondary from the panels... you don't want to discharge the HV stored on the panels through your ohmeter! They should be quite identical.
You could always unwire the interfaces, mark the panels & interfaces and swap them too... that would tell you instantly where the problem is... but I'd try the above tests first.
Any HV diode will work fine.
1N4007s are fine general purpose HV diodes... higher voltage diodes will likely not break down over time in the event of various variations in component values or spikes... as noted there is nil current being drawn so that almost doesn't matter.
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
|26th November 2004, 11:42 AM||#23|
Join Date: Sep 2003
Be aware that the EHT board is fed with about 600vac from the mains transformer. The high voltage end is fizzy but safe, the low may give you a surprise. So take care.
An EHT probe into a normal DVM will suffice to measure the EHT, I have a 'Testec TT-HVP 40' which is good for 40kv and measures Quad ESL63 EHT boards to be roughly what is specified. http://www.testec.de/
There are probably many alternatives. I think you need to actually measure the EHT before moving on to other possible concerns.
|4th December 2004, 08:32 AM||#24|
Join Date: Dec 2004
Low eht voltage
I have 25 years experience on QUAD electrostatic speakers ESL (called today ESL57) ESL63 usual and ESL63 PRO.
First thing to do is to disconnect the speaker from main voltage, pull the socks down then delete the rear grill , check the EHT voltage with an EHT volmeter (you will find the address on the one thing audio site in UK "onethingaudio.com"
IF the voltage is not good enough (5,3 KV) discharge the EHT line (orange wire to ground it through a resistor) and then disconnect every element one by one (discharge between each step) and check the EHT voltage under this condition. If the value still the same,try with the next one following the same procedure, this way you will find wich one cause the EHT voltage goes down. If nothing change and voltage do no go to higher value this is coming from the eht board itself.
Repair this board is really easy and loose his time to check component is not necessary. Change diodes and caps in once and everything will be in order .
Feel free to contact me if you need it.
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