OK, it's been several weeks since my last update... thought I might share the completion of this project
After months of searching, I was FINALLY able to find someone who had not 1, but 2 spare 4-channel indicator 'scope' assemblies that he was willing to part with! (and at a quite reasonable price, too)... so, I purchased and received the 2 donor scopes. Unfortunately (or maybe not, since I ended up learning some stuff) neither one was 100% operational. Both had 3 good operational channels; and 1 channel with a failed aperture motor. SO... guess what I got to try?
I removed 1 bad motor from one of the donor pieces and replaced it with one good motor from the other donor part. Honestly, that wasn't as bad as I thought it might be. The motors are held in place by 1 tiny screw; and yes, that was a real PITA to remove. Otherwise, it was a simple matter of heating / removing the old solder from the motor terminals, removing the old wires and sliding the motor out of the plastic housing. New motor went in as easy as the old one came out. Then after the screw had been reinstalled, it was time to 'transplant' the repaired donor scope into the receiver.
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Here's where it got a little more interesting. The 'scope' has a total of (14) wires connected to it: (4) leads for the 4 - channel indicator motors; (1) lead for the indicator lamps; (4) grounds for each of the 4 - channel indicator motors; (1) ground for the indicator lamps; and then inexplicably (2) additional leads for the receiver front panel lamp circuits and (2) grounds for those same lamp circuits (!)... basically, the receiver lighting circuitry wiring passes
through the scope assembly - instead of simply having a single lead and ground come off the circuit harness to the indicator bulb board. Way more complexity than it needed to have.
Anyway, I had some luck in that (3) of the (4) indicator motor ground wires were still attached to the original 3 'good' motor terminals; so I only had (11) wires to connect, LOL. The main difficulty was that the wires inside the receiver are very short, and the space behind the installed scope assembly is very small - so there was no way my man-sized hands were going to be able to reconnect / resolder all those wires inside the receiver cavity. My solution was to cut some 3-ish inch long wires to use as 'extensions' between the receiver wiring and the scope assembly. This way I could do all the connecting / soldering outside of the receiver, and then carefully push everything back inside the scope assembly opening and (hopefully) it will all fit without breaking any connections or shorting anything out. I also used heat shrink tubing over every solder joint to help prevent accidental shorting of any connections, should those extension wires contact each other inside the receiver cavity...
Here I am using jumpers to test everything out before final installation - it works!!!
(Also note that the "FM" light is out, and the tuner dial pointer doesn't light up... more about those later)
Several of the 11 jumpers I had to install to make sure everything was 100% operational.
You can see how little space there is behind the opening for the scope assembly
Once I had all the extension wires soldered in place, I was able to put the scope assembly back into the receiver cavity. It was a good thing that I used the shrink tubing, as all that extra wiring ended up being butted up against each other in the little bit of space behind the scope assembly.
While I was inside the receiver, I took care of the only other issues I had with the unit. I replaced the "FM" indicator lamp as it was blown; and I replaced the tuning dial pointer since the original apparently had broken off years ago, and the previous owner seems to have replaced the lighted OEM part with a non - lighted pointer from some other model. Luckily he had not removed the tuner lamp wiring (he just taped it off...) I was able to find a lighted pointer off eBay that looked like it would fit the QX-949A, and it did.
About 2 hours later, she was all bolted back together and ready to rock! I took the opportunity to clean and oil the cabinet since it was off the unit anyway.
Here is the finished project. Everything works 100% - and I would give the cosmetics overall about an 8.5 out of 10.
The sound is rich, full, and everything I expected from a quality vintage Pioneer unit. Looking forward to years of excellent listening!