One Thing Audio panel from March 2019 is quiet and lack high frequencies. I have installed this panel in place of good panel to check if it's not EHT. Sounds same.
Can I measure capacitance of both panels and compare before sending to OTA?
Any other additional test without tearing down faulty panel?
OTA charges 50 pounds for diaphragm change and when I open panel then they will ask more for repair. Coating bad maybe?
Can I measure capacitance of both panels and compare before sending to OTA?
Any other additional test without tearing down faulty panel?
OTA charges 50 pounds for diaphragm change and when I open panel then they will ask more for repair. Coating bad maybe?
Open the panel up. Look if the coating seems good all the way towards the edge and is in contact with the aluminium stripe. You can coat the membrane with conductive coating so that the current can go from the aluminium strip and trough your extra conductive coating and out to the dissipative coating.
Hope this helps.
Pictures is a good help also.
Hope this helps.
Pictures is a good help also.
Not sure how OTA does their rebuilds, but there is a very real possibility that you will damage the diaphragm splitting the panel open. And then OTA may not take it back. I am VERY wary of working on panels that others have worked on.
If you accept the risk that you may damage the panel further, and may not be able to send it in for service, here's a quick description of how to open it.
Remove the four nut and bolt assemblies with the felt washers that hold the dust cover in place and damp it.
Carefully cut around the perimeter of the dust cover frame at the sides, being careful to slide your blade between the wooden frame and panel edge. It can be helpful to do this cut on both sides of the panel to free up the front and back dust covers.
You are now looking at the panel. Look through the holes in the stator for obvious burn marks. Check both front and back. You want to concentrate on the center section (based on your described issue). If you see a burn mark, you need a new diaphragm and the stators repaired. Nothing short of that will bring the panel back to life.
Remove any insulating tape around the perimeter of the panel if there is any (not sure on OTA's materials and methods)
It appears that OTA uses nylon nuts and bolts in place of the rivets. You will need to remove all of them. It also appears that they use them on the perimeter as well.
After all the nuts and bolts are removed, you should be able to split the front and back stators apart. The diaphragm should be glued to the rear stator. There is a real danger that the adhesive from the original tape inside will stick to the diaphragm and cause it to tear when you split the stators. So don't be surprised if the splitting ruins the panel. Happens all the time.
Now you have it apart and can do whatever you think might fix it.
Frankly, OTA should stand behind their work and take a look at the panel and only charge you if there is damage. But we each offer different levels of customer support.
Sheldon
If you accept the risk that you may damage the panel further, and may not be able to send it in for service, here's a quick description of how to open it.
Remove the four nut and bolt assemblies with the felt washers that hold the dust cover in place and damp it.
Carefully cut around the perimeter of the dust cover frame at the sides, being careful to slide your blade between the wooden frame and panel edge. It can be helpful to do this cut on both sides of the panel to free up the front and back dust covers.
You are now looking at the panel. Look through the holes in the stator for obvious burn marks. Check both front and back. You want to concentrate on the center section (based on your described issue). If you see a burn mark, you need a new diaphragm and the stators repaired. Nothing short of that will bring the panel back to life.
Remove any insulating tape around the perimeter of the panel if there is any (not sure on OTA's materials and methods)
It appears that OTA uses nylon nuts and bolts in place of the rivets. You will need to remove all of them. It also appears that they use them on the perimeter as well.
After all the nuts and bolts are removed, you should be able to split the front and back stators apart. The diaphragm should be glued to the rear stator. There is a real danger that the adhesive from the original tape inside will stick to the diaphragm and cause it to tear when you split the stators. So don't be surprised if the splitting ruins the panel. Happens all the time.
Now you have it apart and can do whatever you think might fix it.
Frankly, OTA should stand behind their work and take a look at the panel and only charge you if there is damage. But we each offer different levels of customer support.
Sheldon
Do you mean you installed the suspect OTA panel in another ESL that had a good panel, and it does not work in that other ESL (even after waiting a couple of hours)?
I can't speak to OTA's coating, but the original Quad coating only took a few minutes to charge when it was new. My coating only takes a couple minutes to charge as well. So if OTA follows that same charge time constant, then you shouldn't have to wait hours, minutes or seconds should tell the story.
Sheldon
Sheldon
You can test the correct repair of your ESL panels by measuring the capacity. E.g. an ESL57 MHT panel should have a plate to plate capacity of about 50pF. The capacity plate to diaphragm is about 30pF.
Source: Shackman-international-esl-services
yes, very normal. If it was flat, you'd have to bend it to that shape to install it in the frames. When rebuilding original panels, the wooden dust cover frames and the plastic stator panels themselves have typically taken a set after decades bent to that shape in the frames. So rather than fight it, I rebuild them such that when bolted back together, they have that same slight arc. The dust covers don't fight you when finishing off the panels that way as well.
hope that helps,
Sheldon
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