Some final notes:
1. I forgot to mention, you must remove the two long standoff bars at the bottom side of the unit to dismantle the boards. These are the standoffs that have the white clamps and screws. I use a good set of vice grips and lightly clamp onto the standoff, then loosen it. Same to tighten.
2. I smear a small bead of silicone onto the bottom of the heads of the four screws that go in the battery box. These have little orange o-rings from the factory but they do not hold up to being disassembled, they tend to split and break. A good dab of silicone to cover the screw heads after tightening is good insurance.
3. A good little bead of silicone around the headphone wire, then tighten up the strain relief. This is factory procedure.
4. There is no silicone sealing the xxxheadphonexxx cable (correction, I meant the coil cable) the grommet does the work. Putting a small bead of silicone around the coil wire and grommet prior to putting on the strain relief nut is good insurance.
5. Use extreme caution at all times to not damage or contact any components on the boards. I wrap them in soft cloths while working. One slip and kaput.
6. I count 12 little yellow trim pots on the top board. That's a lot of crap to trim out.
7. The bottom board has five or six white trim pots.
8. The top board comes completely free of the unit, no wires attached.
9. The bottom board has four ground wires soldered to it from the switch board. I leave it all together to cut down on soldering, plus there is no need to separate the bottom board. I unsoldered the sens pot wires at the sens pot. It is very difficult to solder the sens pot wires directly to the switch board, not much room. I simply soldered the new switch wires to the old wires where I disconnected from the bad pot, which was much easier. Use shrink wrap everywhere.
10. The bottom board plugs into the faceplate board with a 15 or 20 pin/socket plug. Use caution when aligning all those pins with all those holes.
11. The top board connects to the bottom board with two 6-pin connectors, one at both sides. ***correction there is a third set of pins that engage the upward pins on the switch board******** see pics. Use caution when aligning.
12. Once all the pin/socket connections are started, CAREFULLY press the boards together until all the pins are firmly seated in the sockets. Take your time when pulling apart and pressing together the board pin connections.
13. tywrap the coil wire and headphone to the two short board standoffs as seen in pics to give some good mechanical pinning of the cables.
14. Take care when stuffing the grommet for the coil wire into the strain relief, its difficult and you will need soapy water. Fully seat the grommet. Do not damage the grommet. Take your time and work it in with a butter knife or screwdriver.
15. Use a bit of blue loctite on the board clamp screws. They have been known to get jingling.
16. Make sure you use insulation or shrink wrap on the two coil shield wires. You can see this in the pics, they used clear tubing.
17. Now, stuffing it all back together, this is more difficult than pulling apart. Put the desiccant pack on in original position. When stuffing the guts back into the housing, be patient, keep pushing everything in while lightly pulling the coil and headphone wires out, until the faceplate is up against the gasket. Make sure the paper clip is firmly on the shield paper. Keep your eyes on any wires that get in the area of the gasket, keep them tucked in. If the faceplate does not want to go all the way, do not force it, its the power wire getting pinched at the back end of the unit. Try to pull the power wire up and out toward the face plate and keep working, it will go together very freely if everything is in the right spot with no pinching or binding of wires. You will know when its okay, it goes all the way home very easily.
18. There is no need to remove the switch knobs to tear down, I did just to clean and inspect. Beware that sometimes the knobs will be very difficult to remove, they tend to be stuck on the switch shafts real tight. If you have to remove a knob and it wont come of, do not force it. Cut it off with a dremel and order a new one. I ream out the knob holes with emery cloth so they never get stuck.
19. The headphones can be separated with a butter knife and some patience, they snap together, but it's tricky.
20. The CZ21 upgrade is not for me. Too expensive. But that's just me.
.....Jim
