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Some hints for DIY repair of QUADs 63    

Working for our repair customers, we are stretching the Quad panels with a special engineered multi-purpose jig, which also can be arranged for stretching curved panels (Shackman, B+W DM70)or for winding foil on rolls.
For stretching the foil for repair, the foil is not cut but  instead stretched "from the roll", as it has been originally done by Quad. Usually an amateur does not have such a tool or any equivalent one, or it is not very much economic to build it for only one or two panel repairs.
For these amateurs we will try to give a short description of  how to achieve the  correct stretching procedure without a jig. But we once again say, that this will not give that much precise results, only a rough, but nevertheless sufficient result.  

Customers for our repair materials will get all the following informations on video.

Preparations: Peel off the old film and clean the contact borders  thoroughly by sanding  (P100 dry) and cleaning with cleaning alcohol.

As work bench you need a plane, clean surface of at least 1m x 0,4m. This plane must be stable and fix, so that you can use rotating forces without seeing the table move. We use insulation window double glass. Lay a panel on the plate and draw the outer dimensions of it to the surface with a cd pen righ tinto the middle of the plate.  Not necessarily very precise. It is only an orientation for later positioning of the tapes and the panel to be glued.

Materials: PU-Adhesive (eg. PMU-2020), Special Silver tape (TP-2048)and  normal Scotch tape, cutter, scissor, wooden weight plate(19mm), at least 30kg  additional weight, 2-way coating liquid (PMMA 2.5), clean cotton cloth.

Remarks: Do not use normal sticky tape (colour usually silver grey or black). Its non-gluing side is normally not appropriate for gluing on it. In the opposite, it is explicitly made non-gluing  for not attracting paints or other glue. This kind of tape will not constantly withstand the force of the stretching tension. The whole process would be unsuccessful.

1. Cut or better tear a piece of  ~90cm x ~60cm. Lay the foil on the surface and loosely fix it by Scotch tape near the four corners without any stretching forces. The only goal of this step is to fix the foil to the surface for the next steps.

2. Take the special sticky tape and cut it into correct length for the short border (~40cm). Put the tape along the drawn outline of the panels shape with a distance of  2-3 cm. Do that  in a way that the tape is completely glued to the foil (not on the plate).  Do so with the other end and then continue with he long borders.  Now you have a loose foil surrounded with tape TP-2048.

3. Cut the tape (including the glued foil under it) off in a way that 3/4 of the tape remains on the foil and put off the cut away rest. Again start with the short ends, Than fix that remaining tape/foil laminate again very loosely with thin Scotch tape. Continue as before  with the opposite end and than the side borders.  Fine. Now you have a foil square on the plate surrounded by special tape. It is fixed loosely to the plate by the 4 office tapes.

   

4.  Fine. Next we have the stretching process.  Start at one end again, right in the middle. Glue the end of the tape roll to the surrounding silver tape. Cut to appropriate length with a scissor and glue it down after having umgeklappt the outer end of the tape strip. That is for more easily being able to lift off the tape for later re-stretching.

   

5. to be edited and continued

Below you see a well done repair by a pro company, although again  with un-sufficient stretching. The mechanical diaphragm tension shows only half the value (left) than the original panel (right, black coating). That will result in  too low a resonance frequency. In this case the resonance frequency is half as low as it should be. The sound becomes  duller, less crispy and more distorted. But actually most important is the danger of  flapping and finally a "gluing" diaphragm during charging process . On the other hand, the sometimes recommended 2kg per strip tension is way too high. That will end up in too high a resonance frequency.

The image below shows a wrong coating of the same panel. It has the appropriate conductivity, but one can see very well defined borders of highly concentrated coating liquid. That are areas of higher conductivity which lets the charge keep moving  on the diaphragm . So the liquid has to be better distributed in order to provide constant and stable charge to the whole diaphragm area.  Not doing so will result in a kind of buzzing and an  unbalanced frequency response.

Trust in our experience. You will be satisfied.

Prices depend on time spent. No costs for checking. Best lasting results guarantied.

It will pay.

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