I found the following using google from a 1985 article. The trick
seems to be to melt it:
"To make sidetone adjustable, remove R4 (R5 in European
networks) and replace it with R11 (for European networks use
Given that there is no standard European netowrk, I am not sure quite
wwhat this is saying.
R12). The Western Electric Network comes
and sealed in a can; the other networks are mounted on PCBs. To
I think I have 4 American telepghones.
A WE/Bell 500 (rotary dail, with this potted network block)
A WE/Bell 564 (rotary dial, 5 line select buttons, again with the
network block. No I don't have a relay set for it)
A AE/GTE rotary dial telephone/ There's a PCB in the bottom carrying the
hybrid netowrk components and the hookswitch.
A 2500 DTMF set made by one of the ITT-related companies. This has a
smaller PCB (about the size of the network block in a WE phone) carrying
the hybrid network componetns/ The hookswtich is separately mounted to
the baseplate. This one has the rather odd 'chuttling ball' ringer. Alas
it ahs the modern DTMF dialer with an IC on it (it's a 5089 or similar, I
Needless to say the PCBs don;t pose any real problems.
Incidentally, if anoy needs information on such telephoens, I've found
the sties http://www.telephonecollectors.info/
are worth looking at.
remove R4 from the Western Electric network, the can
has to be
opened by bending the holding tabs. Don't be surprised to find
that the network has been potted in a very sticky, odious paste
that has the texture of hot chewing gum and the odor of unwashed
Tha'ts the stuff alright ;-(. I fon't remember any smell though.
shirts. (This material - alleged to be manufactured
a secret formula - will not wash off with soap and water. The
Yes, I gound out that soap and water was no good when I got it all over
I am suprised the formula was so secret, given that the scheamtics, etc
phone company has a solvent for it, but because one of
ingredients is said to be beeswax, ordinary beeswax solvents such
as gum turpentine, mineral turpentine (paint thinner or white
spirit) and kerosene will work.) To remove the bulk of the
Interesting. I am suprised the solvents I tried didn't appear to have
much effect. However, I may well try putting the module and can in some
white spirit (about the cheapest of those solvents) and leaving it.
potting compound, heat the opened can for 30 minutes
in a 300
degree F (148 degree C) oven, or apply heat from a hot hairdryer
or heatgun. You can also put the can out in the hot sun under a
sheet of glass. Don't use too much heat because the plastic
terminal strip may melt. Even with a film of compound remaining
Yes, I discovereth that the hard way ;-)
on it, the network can be worked on."
Hmm, I've made similarly sticky stuff using beeswax and lanolin and a
bit of varnish.
Old-timey potting compounds are nasty.
I think some of the mdoern ones are even hardter to remove without
damaing the internals...