Symptom: No audio. It was reported that one day it was working fine, then it didn’t.
Checked the muting relay; okay. Checked the amp by playing a selection that had no record in it (to un-mute the amp) and injected an audio signal from an iPod. The amp worked fine. That left the wiring from the amp to the cartridge or the cartridge itself as the culprit.
The owner had re-soldered the connections to the cartridge socket, thinking that something had gone wrong there. If I understood correctly, the socket was unsoldered when he purchased the jukebox, so he or someone else had soldered the connections originally. So there is some question as to whether the connections have been made properly. The cartridge is a stereo Pickering 340-D and I could not find any documentation as to the connections. Assuming this is a ceramic cartridge based on the age of the jukebox, I should have easily been able to see some kind of signal on the oscilloscope as I touched the needle. I checked every possible connection arrangement. As a double check, we connected the cartridge directly to the amp using alligator clips, again trying every possible combination. The only conclusion was that the cartridge was bad.
In the past, I’ve seen some old crystal cartridges stop working. I’ve also seen a stereo ceramic stop working on a friend’s Grundig. Bad cartridges are nothing new, but it’s still surprising whenever I come across one. What’s interesting in both the case of the Grundig and the jukebox is that both channels stop working. I’d think that only one channel would fail, but I don’t know what is failing inside the cartridge. One of these days I’ll have to open one up and see why. Maybe they can be repaired, although I’ve never heard of it.
This jukebox is not fixed yet. The owner is going to obtain another cartridge. Unfortunately cartridges for jukeboxes are becoming extremely rare. I will update this post when the owner obtains another cartridge.
Something that doesn’t add up on the Jet: The cartridge is stereo, the wiring to the amp is stereo, the schematic claims the amp is stereo (but I didn’t actually verify that), and the wiring from the amp to the speakers is stereo. Inside the amp, right at the input it is factory wired to short both channels together. Maybe Seeburg had two versions of amps. Stereo was in its infancy in those days.
Update 4/4/2012: The owner obtained a new cartridge and it’s now working!
Location: Loveland, Colorado
Symptom: It would shoot two balls into the shooter lane.
At first look, the playfield switch in front of the plunger was badly bent and not reliably sensing a ball. I assumed this is why it was loading the shooter lane with two balls. As I tried to straighten out the switch wire, it broke. I repaired the switch with some piano wire (I guess it’s steel wire) that I obtained from McGuckin’s Hardware store, and epoxied the wire on to the switch lever.
As I investigated further, I discovered the reason the switch wire was bent was because the one-half of the fork was broken off the auto launch kicker (500-6091-00). When ever the auto launch mechanism shot the ball, it would jam the ball sideways.
Broken Auto-Launch Kicker
I found the broken piece down in the bottom of the cabinet. The owner took it to a nearby muffler shop and they welded it back together. With the switch replaced, and the arm welded back on, I fired up the machine to find it still deposited two balls into the shooter lane. The playfield switch was functioning correctly. After another 15 minutes, I realized there were 6 balls loaded into the machine, when there should only be 5 balls. It never is what you think. The other stuff needed repairing even though it wasn’t the original problem.
Replaced many bulbs.
Location: Superior, Colorado
Symptoms: Would not trip at end of record. When selecting B7, it would also play D7 and vice versa.
Checked the switch continuity with an ohm-meter and the switch was not reliable. Since the prospect of getting a duplicate switch was slim, I opted to open it up and clean the contacts. It solved that problem.
Observing the selector pins under the mechanism while the owner pressed the selector buttons on the front of the jukebox, I could see that two solenoids were activating at the same time. With an ohm-meter, I verified that the B and D solenoids were shorted together. I unplugged the front selector switches and the short was still present. I removed the selector mech and realized the box attached to the bottom of the selector mech was the stepper unit for remote boxes. I unplugged the stepper unit from the selector mech and the short between the solenoids went away. The problem was one of the stepper relays was gummed up with old grease and wasn’t resetting to zero. It was stuck between B and D, shorting them out. After consulting with the owner, I manually moved the stepper to the reset position, not repairing it and leaving it gummed up. The owner was never going to use the stepper unit, and I couldn’t simply leave the stepper unplugged because, according to the service manual, there needed to be a jumper plug installed.
I replaced the needle, which improved the sound substantially.
Location: Boulder, Colorado
Symptoms: Stuck flipper, flipper fuse blown, many lights not working.
The flipper circuit uses two voltages, one for pull-in (50V) and another for hold (8V). The transistor controlling the pull-in voltage (Q9) was shorted, leaving the high-power on to the coil, blowing the fuses. Replaced the transistor and the flippers worked.
I replaced many burned out lights. There are two rows of lights (in the 8×8 grid) not working. The transistors looked fried, and it looked like the board had also been hacked. Many GI lights on the backbox were not working too. Someone had re-wired some of the GI lighting bypassing one of the boards. Some of the ramp diverters are not working, so you never get the Hat Trick. The owner was not interested in fixing these issues! The machine needs to be “shopped”, but it is still being used in a bar.
Location: Denver, Colorado.
Symptoms: Turbo bumpers not working, blowing fuses. Broken wire under playfield, loose playfield components, stuck switch on left slingshot, lights not working.
Machine needs to be “shopped” as it’s not in good working condition. Found shorted transistor that drives solenoid for turbo bumper. Replaced it, but it immediately smoked. Took a closer look at both the input and output sides of the drive transistor (TIP122). On the output side, discovered a melted solenoid under the turbo bumper. Replaced the solenoid. The bumper switch was ok. Checked the input side of the drive transistor and found the 2N4401 was shorted as well as the 7402 NOR gate IC was blown. Replaced all the bad parts.
The stuck switch on the slingshot was because the entire slingshot assembly was ready to fall off the playfield. Tighten it, repaired the broken wire.
Replaced many burned out bulbs. Backbox lights not working. Owner didn’t want those fixed.
When playing a test game, right flipper was getting stuck. The flipper shaft bushing didn’t have any screws holding it to the playfield. Found enough screws lying in the bottom of the cabinet to fix it. Flipper was still sticking. Took it apart to find someone had greased the flipper solenoid. NEVER DO THIS. Went through and tried to clean up all of the grease. Flipper worked fine after that. Overall the game is working. It is in a bar. The owner doesn’t want anything else fixed.
Location: Denver, Colorado.