KLH Model Nine, how do I depot the wax cans?


I have a pair of klh 9's and one has lower gain with some distortion in the tweeter as well. On the recommendation of David Janszen I swapped supplies and both problems follow the supply (tweeter distortion and low gain). I had also cleaned all contact assemblies on the power supply connectors and tweeters.

I want to rebuild the weak supply and looking at it I see lots of wax. I was wondering how I would depot the cans (melt out or chip out the wax). If anyone has any ideas it would be appreciated

Andy
andy_p
You have to put the power supply in an oven and SLOWLY advance the temp until the wax melts. Before you do, make sure you make a template so the female jacks in the power supply line up properly with the male plugs on the speaker itself.
Thanks Gmuffley, I had contacted David Janszen again and he gave some additional instrutions (he said to drill a small hole in the bottom of the can and put it in the oven with a pan underneath, he was guessing 200 deg F), with as you say the connector position secured with a jig of some sort. He said only the diodes would need to be replaced. I quote:

"Wire three 1N4007 in series as a replacement for each diode. Maintain polarity.

Check the voltages. The woofer bias should be about -5700VDC and the tweeter
bias -1100VDC. You need an electrostatic meter for this; any other type will
load down the supply and you will have no idea by what amount. These will
probably be about 10% higher with the silicon diodes, which is too much and
will cause a sizzling sound from ionization of the air gap and a reduction
in SPL. If so, experiment with adding series resistance to the AC line going
to the AC step up transformer. I think about 5kΩ is right. I think you
should use a 1W or 2W resistor. If you don't have a meter, just add the
resistor and test using the panel with clip leads, but BE CAREFUL.

Melt the original wax. Drive a screw into the hole you had drilled. Pour the
wax back in several stages/layers, with the thinnest one last, allowing it
to cool fully each time, so it all fits and is smooth when it cools. "
A lot of organic solvents such as lacquer thinner would work as well- don't use heat with them though as they will ignite very easily. Be careful with the too. If it is too high, it will burn the wax and make a mess of things as it will leave carbon which is conductive. I do not know if he warned you, but those voltages are near the limit before it arcs through air, hence the wax potting. Often special high voltage probes are used. Not just for a the aforementioned reasons, but for safety as well.
Thanks 4est, I was trying to figure out how may of the selenium rectifiers were in the supply (so I could order an appropiate number of diodes, they are only 15 cents each so I could order a bunch of them but maybe there are a lot of the selenium rectifier?). I think I would like to replace the resistors as well but unless I can get a schematic I will have to wait until I can see everthing.

Thanks for the warning about the voltages, will use a lot of caution.
It should have said "Be careful with the HEAT too. If it is too high, it will burn the wax and make a mess of things as it will leave carbon which is conductive."