Patrick's Seeburg HF100G Restoration Blog

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At this point, the jukebox was working pretty well most of the time, but some components had not yet been restored so there were some interesting intermittent behaviors. The most serious of these had to do with the old gummy lubrication of the mechanism. Sometimes when the mechanism picked up a record, it would reject as soon as the needle touched down on the record. In other words, as soon as the needle touched down, the mechanism would lift the needle again and put the record back. Sometimes the mechanism would put a record back, then immediately pick it up and start playing it again. At times these effects would cancel each other out; the mechanism would pick up the record, reject it, pick it up again, reject it, pick it up again and finally start playing it. I knew I had to completely clean and apply fresh lubrication to the mechanism, but I had been afraid to tackle it. The Seeburg mechanism is downright intimidating. It is a very complex looking set of gears, wires, switches, cams, and levers with loads of tiny adjustment screws. Since I am not particularly mechanically inclined, I didn’t know if I would have had the guts to try taking something this complicated apart and clean it if it were not for Ron Rich’s Seeburg Mechanism Guide. Being the geek I am I had actually purchased this book before I bought the jukebox! I wanted to learn as much as I could about this fascinating mechanism. So without further ado:

The Mechanism Take II

After reading Ron Rich’s Seeburg Mechanism Guide about 300 times, I felt about as ready to tackle the mechanism as I would ever be. I reluctantly removed all the records from the jukebox then removed the mechanism. Taking out the mechanism is relatively easy; just remove some trim pieces, unplug a few cables, remove two pins, and slide the thing off of the rails it sits on. I will skip quite a few steps here so I will not bore everyone with the details, but I first removed the tone arm assembly for cleaning separately.

I knew from my symptoms of the record rejecting and replaying that I likely had issues with the clutch assembly, so I removed and thoroughly cleaned/lubricated it as well.

The next time consuming task was to mark the wires going to the motor and remove it. I also needed to remove the trip solenoid. The trip solenoid is the magical connection between the jukebox electronics and mechanics. When the mechanism is scanning along and gets to a selected record slot, the electronics fires the trip solenoid and this causes the mechanism to stop scanning, transfer the record to the turn table and start playing it. When the record is over and the needle enters the lead out groove, a micro switch driven off a lever from the tone arm activates the trip solenoid again. This time, the trip solenoid causes the mechanism to leave play mode, transfer the record back to the record magazine and start scanning again.

With the tone arm assembly, motor, and trip solenoid removed, it was time to wash the mechanism. Wash!? Yep, Ron Rich sprays degreaser on the whole mechanism and then washes it with warm water so I did the same. After washing the mechanism and removing stubborn spots with a toothbrush, it was time to apply new lubrication. During this process I learned some interesting things. First, the problems I was having with the jukebox rejecting/replaying were due to the levers that control the clutch rather than the clutch itself (though it may have contributed). After cleaning and while lubing, I noticed the release lever (lifted by the trip solenoid) was quite gummed up and did not move freely at all even with all the springs, etc. removed. I decided to remove all the levers (for all you Seeburg people that would be the release lever, reset lever, and clutch shifting lever) and clean them and the posts they ride on.

The second thing I learned was far more insidious. One of the rollers on a cam follower was seized. This is very serious because if not caught in time, the roller would eventually develop a flat spot and both the follower and camshaft would be ruined. Good thing I decided to take the mechanism apart! Unfortunately the seized roller was on the detent cam follower buried deep inside the mechanism. The detent cam (and related parts) aligns the mechanism with a record slot and locks it in place for playing a record. It also operates the safety plunger (a whole other conversation). I tried freeing the roller with my finger at first, but it was futile. Next up was Liquid Wrench penetrating oil. Even after 24 hours+ the roller was as seized as ever. Access to the roller is difficult because of how deep inside the mechanism it is so removal was the only option. The bad news is that the detent lever shares its shaft with the record lift arm cam follower. The record is lifted to the turn table via a spring relaxing. Problem is that the record lifts several inches, but the spring is near the pivot point of the cam follower and stretches less than an inch or so. Therefore this is a very strong spring. I decided to manually rotate the camshaft to the play position to reduce the tension on the spring to a minimum and slide the shaft out in the direction of the lift arm, but only enough to remove the detent lever. There were some brass spacers between the two levers I had to keep track of, but I managed to remove the detent lever without incident. Now that I had the detent lever out, I was free to attack the seized roller. Penetrating oil and solvents did zilch. I finally heated the roller with a small butane torch and got it moving. After that I was able to add penetrating oil followed by solvents to clean out the old gunk. I then applied proper lubrication and reinstalled the detent lever – not forgetting the brass spacers of course!

The rest of the reassembly was time consuming but I eventually had the whole thing put together again. I tested the mechanism at first by turning the motor coupling by hand and when confident everything was working right, I hooked it back up to the jukebox electronics and tried it out. I was amazed and how much more quietly and smoothly the mechanism operated. Also the intermittent replay/reject problems were completely gone.

Nit-picky problems

At this point my confidence in the jukebox working correctly was around 90% per selection. There were a few small problems that came up. Here they are briefly:

Problem	Solution
Sometimes a selection would not cancel and the jukebox would play it again (For example: Select A7 once and it would play 2 times)	Fixed by re-adjusting the ’IC’ switch contacts on the mechanism
The cartridge was running into the needle cleaning brushes when playing B record sides	Adjusted the brush positions
The cartridge slammed into the needle cleaning brush when the tone arm was returning to its resting position at the end of record play	The pickup lifting adjustment was way off on the B side. Probably because the setscrew was loose!
Sometimes the needle would land a few tracks into the record; most of the time it would land in the correct place	The trip switch pressure adjustment was off.
One time, the jukebox abruptly rejected a record in the middle of a song	Probably same cause as above
Sometimes the jukebox popped loudly (through the speakers) when the record tripped at the end of play	The pretensioner for one of the ‘MA’ switch contacts on the mechanism was misadjusted. Fixing this quieted the ‘pop’, but it is still there. Don’t know if this is normal or not.
On rare occasions one would make a selection, but the jukebox didn’t play it.	Fixed by adjusting switch contacts operated by the cancel solenoid.

Putting them in a table as above gives the impression they were easy to fix, but some of them required lots of troubleshooting and consulting with Seeburg experts in the yahoo group seeburgjukeboxinformationclub.

In the course of fixing these little problems, my confidence in the jukebox rose to nearly 100%. I am not aware of any intermittent problems at the time of writing this.

Project PC-o-matic

Being a computer nerd (and not yet owning a Seeburg wallbox), I thought it would be fun to hook my laptop up to the jukebox so I could use it to make selections. For those who don’t know, the Seeburg wall-o-matic wallboxes connect to the jukebox using 3 wires. The three wires are ground, power (25 VAC), and signal. The signaling is done via a loop disconnect circuit – like the old pulse telephones. Thankfully, the service manual details the protocol and in particular the pulse timing. With this information I was able to write a computer program (called “PC-o-matic”) to send the pulses to the serial port by turning the DTR line on and off. The only thing remaining was to make the hardware connection between the serial port and the jukebox.

My first idea was to use an opto-isolator. After I finally got the component, I discovered it didn’t work for this application. Either the voltage on the signal line was too low, or the serial port did not have enough current to drive it. Anyway, when the DTR went on, the resistance of the opto-isolator dropped, but not enough to trigger the thyratron tube in the wired selection receiver.

My second attempt was to try out a transfer relay from an old thermostat I was no longer using. Normally a serial port does not put out sufficient current to operate a relay, but since a thermostat is designed to run on batteries for a long time and hence use little power, I figured it just might work. I hooked it to the serial port and toggled the DTR line and … the relay made an audible click! - A very good sign. I then hooked the other end to the jukebox and made a selection from my PC-o-matic program. Wonder of wonders, the wired selection receiver decoded the message and the jukebox mechanism took off scanning and amazingly picked up and started playing the selection I keyed in! I was ecstatic. As I calmed down listening to the jukebox rock away I thought to myself “yep, I’m a geek.”