Well, I been meaning to post a follow up here for awhile, but busy with things and all. Anyways, I did decide to tear into my Dekabox, and I managed to repair the unit so I thought I would share the process.
Tools Used:
Flat blade screwdriver
1/4" Socket driver
1/16" Ball Allen (Used for dials, see image below)
Crescent Wrench
Solder Iron (set to 380C)
flux
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Being old, I found myself challenging my aging dexterity with this project, I had to finagle myself in strange positions to get my solder iron at just the right angle as to not inadvertently burn or melt the delicate fragile looking resistors set around the wafer switch assemblies.
First thing I did was to set all the dials to zero just to make things easier at the end. Using the Ball Allen I removed all the dials, then desoldered the two wires on the chassis banana jacks.
With the dials removed I used a wrench to remove the nuts securing the two resistor switch units to the chassis, and pulled the two resistor assemblies free of the mounting stand or whatever else you want to call it. I removed the housing of the broken resistor and had to un-solder one wire connecting the assemblies together:
Next step was to loosen the 1/4" nuts securing the whole switch assembly together. I discovered that the nuts were locktighted to the screw shafts, and as I turned the nut, the whole threaded shaft would work its way out. To overcome this, I threaded on a cap nut which allowed me to hold the threaded shaft in place while loosening the locking nut.
At this point I also had to desolder two wires attached the top wafer switch.
With the nuts and wires removed, it was easy enough to pull the top wafer free.
I then slipped out the damaged shaft assembly, the metal ball bearing and plastic indent had fallen out.
While I had the shaft out, I noticed the shaft was bent. This was not expected and I was not sure how to get it true again.
My vice just happened to have a groove in it that was just the right size, so using the vice I was able to get the shaft almost back to straight, not quite but almost and I hoped enough.
I then reinstalled the plastic indent piece and ball bearing.
And then I had to press fit the locking spring washer (or whatever it's called) on the other side. I used a deep well socket for this part and used my drill press to mash it in place.
Once this was done, I was ready to reassemble everything and test.
The reassemble was just a matter of reversing my process above. With everything back together, I measured the resistance with all the dials at 0. I got about 30 milliohms which is out of spec, so I will have to revisit that problem at a later time. I zeroed out the error just to check the resistors, they are still pretty spot on. 1
gave me ~.998
All the resistors check pretty spot on, and the dials rotate nicely now. One problem I am still having is that even fully tightened, the two
outer(i meant to say inner) knobs slip, not sure the best way to fix it.
That's about it, and maybe this post will help someone else who needs to perform a repair.