Thank you Ron.
I have worked on this jukebox all day today. I got the selector unit all together, adjusted and put back into the machine and did some general cleaning.
This is followed by placing the negative end of a standard battery (AA-C-D) against the chassis and touching the tip of the pulse map's RCA plug to the positive end a few times. This will flip all Toroids to the "selected" state. Place the RCA plug back in the P.A. and start the mech scanning -make sure the service sw is in the "normal" or "play" position. The mechanism should trip at the first slot it finds. Press reject and see that it will trip at at least a few others in succession.
If this fails to happen first make sure there is a readout pulse of minus approx 300 vdc at the plungers that ride under the Tormat. the rear plunger is for the "A" sides the center ones are ground return and the one closest to the front of the mech is for "B" sides.
My new 2050 tubes came in today and I used a fresh new "D" battery to flip the memory. The mech still failed to pick up any records. I checked for -300V at the plungers. Nope, nothing. The memory controller's
TP-G is the line feeding the detent switch. I got about -450 on the TP-G... and on one side of the detent switch. But the -450 would not make it through the switch, even at the top of the cam.
So I removed the switch. Not very much contacts are remaining there, I assume most of them have burned away. The mech's frame under the detent switch has black burnt specs dropped on it which aparrently came from the contacts. Anyway I cleaned the remaining contacts and adjusted the detent switch as per the service manual. After I fixed the detent switch, I got -450v through it at the top of the cam lobe.
I put the svc switch back to play and flipped the memory unit with the "D" battery and made a selection. The mech scans twice and stops. Still didn't pick up a record. Hmm.
I checked for voltage at the plungers while scanning. Nope. Nothing.
Turned out the "A" and "B" plunger wires were broken off. I couldn't really tell until I tugged on them.
I removed the plunger block from the machine. Someone had put oil on the block, gumming it up pretty bad so I disassembled and cleaned it out. I also cleaned the bottom of the memory unit. It seems someone had covered it with grease. The silver tops of the plungers have worn very thin and some brass is showing through. Now the plungers in the block moves very well and all the contacts are very clean.
I put it all together, making a quick estimate of the plunger block adjustments. I again used a "D" battery to flip the memory unit but it still refuses to pick up any record at all. The "A" and "B" plungers were arching to the next memory unit contacts as it scanned across with popping sounds from the speakers, so I carefully did the plunger block and memory unit position adjustments per the svc manual. It is not arching anymore but still won't trigger to pick up a record. The voltage on the plungers vary between -450 and -150 depending if the detent switch is closed or not, apparently loaded by the memory unit. TP-G on the controller reflects the same figures.
If I am supposed to see -300v on the plungers with a closed detent switch then I probably have a bad resistor(s) in the controller unit.I have a BNC to RCA adapter on my scope. I can flip the memory unit with a "D" battery then make a selection in "Play" mode with the RCA jack plugged directly into my scope. The carriage scans twice but I see no reaction at all in my scope through the RCA jack. Flat line no matter how sensitive I put the scope input. I did a resistance measurement on the RCA jack tip to gnd and get about 2 ohms. The jack is wired so the shield and red wire are soldered to gnd and the green wire to the tip.
I made a video of this:
http://youtu.be/B2slj9coMNs* The 1st part shows how I set the mech into position to adjust the plunger block. (I tied off the tonearm to keep things quiet... it's 2:30am... also I had to walk around to switch the machine off).
* The 2nd part shows where I have the plungers adjusted when the mech is in the playing position.
* The 3rd part shows how I am flipping the memory unit with my battery and checking the output.
If the memory unit requires -300v to reset the cores then it's only getting about half of what it needs and I will need to investigate the power supply in the controller unit. Does that sound right?
I will recap the whole thing and replace any resistor out-of-specification, but I can't do the whole thing right now. For now I can only fix what's causing problems.