final 0.3 er audio repair kit - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th April 2008, 08:01 AM   #11
diyAudio Member
 
Join Date: Aug 2003
Location: Calgary on the Bow
Default Good suggestion Calvin...

a small neon bulb that is bypassed by a low uf value (but high voltage) capacitor in series with the HT supply connection. When the lamp is on the supply is delivering current to the diaphragm. This allows you to monitor the status of the static charge on the diaphragm. The lamp normally comes on only when charge is lost from the diaphragm that means if the lamp is on all the time you have a dead short. Do you have a high voltage probe? If not you should get one. You can use the probe to measure voltage on the diaphragm and a lot of other useful things. You need to be able to check what is working an what is not working so you can figure where the problem is. For example you can connect your high voltage suply to one of your stators and use a probe to look for leaks on the stators. Perhaps if you start at the beginning and provide some real information we might be able to sort your troubles out. As it stands we are guessing and there has been little to no real information provided by you. Sorry but you have us shooting in the dark. At this point Calvin is probably right in that you do not have enough tension on the diaphragms but it is difficult to say for sure. IF these speakers are older and well used what was the condition of the stock diaphragm? Did it have a lot of small pin holes in it? If that is the case then you may well have a lot of burnt holes in the stator wire insulation. This gets back to what I was saying about you having problems that may not go away. You cannot really fix those holes. Yes there are things that you could do but the work involved is about as much as building new and you will not have a new panel in the end. Are the panels ones you have owned since new or did you get them for a deal because they were cacked? We don't really have any idea what we are dealing with here. Your time and money may be better spent with a local ESL rebuilder. We are going round in circles.
__________________
moray james
  Reply With Quote
Old 12th April 2008, 09:35 AM   #12
diyAudio Member
 
brian t's Avatar
 
Join Date: Apr 2002
Location: england
guys, have done some more tests placed a straight edge across the film and its definately sagging in the middle panel size is 6"x47" thats the problem its to slack. have stripped panels again and tested the bostik 7432 superglue by sticking a small piece to the panel frame and its not holding in place. must admit never been a big fan of super glue. can anyone give me an alternative glue i can use . cheers
  Reply With Quote
Old 30th June 2008, 09:01 PM   #13
diyAudio Member
 
Join Date: Nov 2002
Location: UK
Brian,

You haven't mentioned the two strips running down the stator which divide the stator into three and keep the diaphragm centered. Have you replaced these? They, or something equivalent, need to be there!

Tim.
  Reply With Quote
Old 1st July 2008, 11:06 PM   #14
diyAudio Member
 
brian t's Avatar
 
Join Date: Apr 2002
Location: england
tim, hi yes have replaced those strips this was my 4th attempt at fitting new panels and am almost out of film and conductive coating this time i stretched the film much tighter before glueing in place to see if that made any difference, it didnt have even tried heating the film up to try and shrink it but no joy, would be grateful for any advice you can give me otherwise its back to moving coils for me!
  Reply With Quote
Old 2nd July 2008, 07:55 AM   #15
diyAudio Member
 
vitalstates's Avatar
 
Join Date: Jan 2006
Location: uk
Hi Brian

It does sound like maintaining tension is an issue here. Again, more information would help. What is the frame material you are bonding to?..Which film are you using? Did you get the glue from Rob with the kit, and if so did it have a bottle of primer with it.

IME bonding mylar to plastic(some plastics) works perfectly with a primer.

Ed
  Reply With Quote
Old 2nd July 2008, 09:16 AM   #16
diyAudio Member
 
Join Date: Nov 2002
Location: UK
Brian,

You could try some of MT Audio's ESL adhesive. I've used it on Quads and it works very well - an instant and strong bond. I've also used epoxy without problems.

I have a pair of Final 0.3s here which I am about to rebuild. The panels are already opened and as soon as I find some suitable replacement foam strip I shall finish the job. I'd prefer to use rows of plastic bolts/washers as this could probably result in a better panel, but I am thinking through the possible practical problems of doing this. For what it is worth I plan to use slow epoxy and gently stretch the diaphragm finger tight before it sets, then heat shrink. In my experience this results in a lasting tension. With my Quads I used a pneumatic stretching jig.

Check the perforated metal stator for flatness, mine are far from flat on close inspection, particularly after having been opened up.

A long shot, but if you happen live in the vicinity of Dorset I could have a look at yours and offer a second opinion.

Tim.
  Reply With Quote
Old 2nd July 2008, 09:50 AM   #17
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

somehow I get the impression, that you do something, but not what is recommended.

The final stators are simple flat metal pieces. Installing a membrane and tightening it is the easiest of all designs.

what you need:
- the right film: I assume that You got that.
- the right glue: epoxy works, some PU-glues and even some double sided carpet tapes. You should test the glue joint on its strength and stability before.
- the right tension: This seems to be the problematic point here. So do it this way:
- With a pen draw a first set of marking lines on a flat surface (rectangle). Now draw a second set of lines with >1% to <1.5% larger dimensions. Lay down a piece of diaphragm film on that surface. Fix it with some sticky tape (a strip every 1"-2") so that it is just straightened (no tension yet). Mark the film exactly at the same position as the ´first´ rectangle on the flat surface with a pen.
Now start tensioning the film by pulling at the tape strips.
Work always in a crossed way fashion. You will have to do this several times (don´t try to get the final tension just in one go), thereby increasing tension in small steps to the final value. You are finished when the markings on the film reach the ´second´ larger marking on the flat surface. And don´t be astonished....the pulling forces will be quite high! Keep an eye on the ´corners of the film. Here the stress on the diaphragm material is very high. I recommend to put some sticky tape over the edges to reinforce these joints.
Then glue the stator to the membrane (You need a lot of pressure when working with ´wet´ glues like epoxy).
If your stator allows for (metal sheets normally do) you might glue strips of double sided sticky tape on the ´outside´rim of the stator sheet (~1/2" wide) before glueing the stator onto the film. This is especially useful when you use double sided sticky tape throughout!
Tape may give in to the tension over time. By making the ´contact area´larger it resists the pulling forces much better.
When the glue has dried, peel off the tape strips in a way that slowly reduces the tension on the film (it may tear otherwise).
Now peel off the lining of the double sided sticky tape and glue the film onto it with a good pull. Then trim the film along the tape edge with a very sharp knife or razor blade (You must not cut into the insulating of the stator though).
If You haven´t already glued the spacers into the stator You can now press some silicone dots at the right places through the stator holes. Keep in mind the 1/70 to 1/100 rule!
When the silicone drops have dried, turn over the stator and control Your work. The membrane should be axactly flat and levelled.

Now use a heat gun and start the heat treatment.
Work in a zigzag fashion over the membrane area. You can come quite close to the diaphragm (1"-2") with the nozzle but You shouldn´t be too slow in your waving motion (1Hz zigzag) or even stop at any point. You´ll see the membrane relaxing and retightening. The tension will be lower than before, but the stresses within the membrane will be reduced and more even. The membrane will settle very close to the final working point. This way results are more predictable, stable and with closer tolerances (Fs can be within less than +-2Hz).
When You´re done with this you can coat the diaphragm and install diaphragm contacting strips.
Do a second heat treatment.
Test the coating on function by connecting the HV-supply to the stator and membrane. You should see the membrane bowing towards the stator, but it shouldn´t touch it. If You worked cleanly (sweaty fingerprints are a proven method of generating invisible leakage paths ) the tickling sounds (which every panel exhibits at least at first start-up) should vanish within a couple of seconds to minutes.
If they don´t and/or the mebrane is pulled into the stator then You have to add more spacers to reduce the freely vibrating distances. The membrane tension would be too small in this case, so that the membrane comes too close to the stator so that the field density becomes to large and saturated and lowlevel flashovers occur (You could lower the polarizing voltage, but this cure should rather be no option here!).
When the test passed succcessfully, switch off the HV and lay the second stator on the first. Run the test procedure again!

When the test passed you can glue the two stator halves together and let them dry. Install the membrane and stator contacts (if that hasn´t been done yet).
You could do a third heat treatment if you wish, but the mebrane should have settled to its final working point already.
Now you should hold a working panel in your hands.....wasn´t that easy?

jauu
Calvin
  Reply With Quote
Old 2nd July 2008, 08:39 PM   #18
Few is offline Few  United States
diyAudio Member
 
Join Date: Apr 2004
Location: Maine, USA
Nice set of instructions Calvin.

What problems have you encountered if you eliminate the heat shrinking step? Since it lowers the tension of a pre-stretched diaphragm it seems it would be nice just to avoid the heat shrinking unless doing so causes other problems.

Few
  Reply With Quote
Old 2nd July 2008, 10:02 PM   #19
diyAudio Member
 
brian t's Avatar
 
Join Date: Apr 2002
Location: england
thanks for info guys, tim i have some foam strip left over from the kit i had there is enough to do your speakers and i am in poole am happy to deliver it around to you sometime if that helps. cheers
  Reply With Quote
Old 2nd July 2008, 10:24 PM   #20
diyAudio Member
 
Join Date: Nov 2002
Location: UK
Brian,

It seems you're just down the road! I have sent you an email to arrange contact.

Tim.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
final 80 repair pschroth Planars & Exotics 13 30th July 2008 10:59 PM
the final attempt at audio buddhahood is finished... pics!! Audiophilenoob Multi-Way 77 14th September 2005 04:42 PM


New To Site? Need Help?

All times are GMT. The time now is 07:18 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2