I slowly removed the two layers of epoxy and found the circuit board solder had broken and completely disconnected from the input jack sleeve. Only the green positive wire inside the tip of the jack remained intact and I was expecting that to break while I was handling it. Fortunately, it did not.
I managed to re-solder these areas...but not to a level needed as removing the old solder meant likely causing more damage on such an old fragile section. I re-soldered two wires on the board attaching to the ground and re-soldered the corner of the board where it meets the negative prong on the input jack. My meter verified I had continuity again throughout the unit and then came the test. Would it work?
I've only played it through bass thus far...but I'm happy to say the difference is nothing short of spectacular! These original units are from the late 70's to mid 80's and have the small adjustable impedance pot which adds a great deal of flexibility. The later reincarnation units have a fixed impedance and more features installed to eliminate electrical interference or short circuiting from sources such as static electricity. I also purchased one of these recently for comparison in sound as well as design. It's also encased in gray epoxy so the components are hidden there, too!
Once repaired, I was getting audible electrical interference from various sources. Which I totally expected without taking measures to isolate the circuitry. So I added a clear epoxy to the board to secure it to the wall and the jack housing to prevent any movement and also to cover the newly soldered areas. I then applied this pretty green crafters putty to isolate the circuitry and protect it from exterior sources and it worked perfectly! I guess some electrical surgery on the Izzy is a viable option with a bit of time and perseverance. I'm happy I could give more life to this great little unit from 50 years ago. Craig really made an amazing compact unit and it was such a loss to our small community when he passed away.
Dave
