Well, it's "done" for now, at least as much as I'm going to do to it for the time being.
This means I took the best of the guts and cosmetics from the three machines and made one "good" one.
The latest one I purchased (the $30 one that came with the RC-71) was overall in the best operational and cosmetic shape, so that became the focus and the other two donors to address issues such as:
• some less than desirable cosmetic flaws
• a bent pitch control pot shaft
• a broken output level pot shaft
• a wobbly capstan pulley
• a bad channel on the mic input board
• a burned out VU meter lamp
Other things I did included replacing the belts and the pinch roller.
Here's that tweaked pitch control pot shaft...it's nice having lots of spares...just swapped in the one good pitch
control assembly from another machine to fix that problem:
And the busted output level pot shaft...same tactic here...I just grabbed the entire I/O control/counter assembly from one of the other machines:
Dishes are done!
the best of the best cosmetics scrubbed and ready for reassembly:
New pinch roller and belts installed on the transport assembly...and the capstan motor pulley was wobbly so I just traded out the entire motor and bracket with one that was true:
And back in it goes along with shiny transport control and cassette bay cover:
After flushing the pots, cleaning out the cabinet interior as best I could and putting everything back together it looked like this:
Did a full functional test of every feature and it's 100%. Later I cleaned up
the remote and, since I have multiples of everything decided to experiment on one of the mic input boards...recapped 2 channels and replaced the 4558 opamp with a socketed 2134. Going back and forth I can hear a difference. It's subtle considering it's basically one amp stage out of everything the signal goes through to get to the headphones, and nothing else has been recapped or anything including the power supply, but the modified mic inputs sound more present and clear...maybe a little more "alive". Again, subtle, but worth the 30 minutes to find the parts and swap them out.
Toying with the idea of recapping at least the power supply, and maybe trying my hand at some of the calibration procedures though I don't have a test tape. I've always wondered what would happen with a full recap and some additional select opamp changes...don't know if I'll ever do that. It works you know? And as far as I'm concerned the 234 is the bomb of 4-track cassette multitrack machines. Simple signal path, but can be used standalone with the onboard 4 x 2 cue mixer. Handy. And sounds really nice.