Wurlitzer P-10 Jukebox (1934)

Posted on March 27, 2017 by Randy

Symptom: Effects of time travel
Location: Denver, CO

The P10 was Wurlitzer’s first jukebox. The repeal of prohibition in December 1933 led to the opening of many public drinking places and live musicians and jukeboxes were the primary forms of entertainment. Wurlitzer and other jukebox manufacturers were quick to capitalize on the repeal.

Advertisement for the Wurlitzer P10 (click for larger).

This jukebox was found in the old Denver Hardware building that was slated for demolition. The owner was able to purchase it for approximately $100. The owner contacted me to determine what was needed to get it working.

Although the cabinet was a little rough, the amplifier and mechanism seemed to be largely untouched. It looked like once it stopped working, no one had tried to fix it and it just sat for decades. The internal counter says it played 40,000 records in its life.

Once I got the mechanism unfrozen and lubricated, I discovered the motor was burned-out. Many electric motors of the 1930s and 1940s didn’t have protection circuits to shut the motor down if stalled or stuck. I later discovered a 15 amp fuse in the 6 amp fuse holder.

Motor with rear casing removed. Note the inner layer of windings which are charred.

Close-up view

Quotes to rewind the motor were in the neighborhood of $700.00. I was able to find a motor on E-bay which came out of a Wurlitzer 412 for $80, so we decided to give that one a try first.

Motor purchased on E-bay was poorly packaged and arrived with broken wires and styrofoam pieces inside of the motor.

I had to take apart the motor I purchased on E-bay to repair it. I installed a fuse on the motor along with new wiring. Hopefully the fuse will protect the motor in case the jukebox mechanism jams.

Motor ready to be placed back into jukebox.

The next item was to check the amplifier. It was missing two 2A3 tubes, but fortunately they are still being made in Russia and China, and I was able to order a pair. The capacitors in the amplifier needed to be replaced.

Dry electrolytic capacitors in a cardboard box.

Once the amp and the motor were reinstalled (and the correct fuses installed), the jukebox fired up and played a record.

Jukebox playing one of the records that was found in it. Note the original needle.

The needle and sound system was kept original and it sounded good. Now the only thing it needs is a cabinet restoration, which I no longer do. But I know some cabinetry people who can do this.

Wurlitzer P10

West Slope Lubrication Tour

Posted on July 21, 2014 by Randy

Locations: Basalt, Colorado; Grand Junction, Colorado.

First stop was to work on a Wurlitzer jukebox model 1100 (1948). Like many 1940’s Wurlitzers I’ve worked on, the selector shaft and heart-shaped cam was not rotating due to lack of recent lubrication. This causes it to play one selection regardless of what was selected. Unfortunately, it’s not an easy thing to get freed up, and takes a lot of exercising and time.

The jukebox needed some other adjustments, such as the turntable height and the clutch. I replaced the line cord because it was in very dangerous condition. The color cylinder plastic sheets were also replaced. This was an original, un-restored 1100 in good condition.

Next stop was to work on two Williams electro-mechanical (EM) pinball machines, Grand Prix and Aztec (both 1976). The main problem with these machines were the stepper units were not freely ratcheting up and down. This is the number one problem with EM pinball machines. A quick disassembly, cleaning and lubrication fixes the problem. Occasionally the spring tension needs to be adjusted.

The Aztec was missing some electrical parts, which can’t be obtained unless someone is parting one out. But I got it working as best I could.

Next stop was an AMI jukebox, model A (1946), which is also known as the Mother of Plastic. The selection mechanism was frozen due to lack of recent lubrication. Like the 1100 above, it took a while to get it unfrozen and moving freely. The selection buttons needed some contact cleaning and lube (buttons would stick when pressed). The tonearm wire where it plugs into the amp needed to the resoldered. All in all, a great sounding jukebox.

It was satisfying to breathe some new life into these old machines.

Wurlitzer 2204 Jukebox, 532 Amp Rebuild

Posted on December 9, 2013 by Randy

Location: Denver, Colorado.
Symptoms: Amp rebuild.

When I listened to the amp, I didn’t really hear anything in particular that was wrong with it. But the owner was unhappy with it. Someone had previously done some work on it, replacing a few capacitors, including the main filter capacitor on the output of the 5U4 rectifier tube.

I brought the amp back and bench tested it. It failed.

Amplifier working normally at 50% volume.

Amplifier breaking down and oscillating at slightly higher volume.

Amplifier in bad shape at full volume.

The problem was primarily in the power supply as these waveforms were measured at the Aux Amp output, which is essentially the output of the preamp stage. The final output stage was loading the power supply and breaking into oscillation. Most often when an amplifier breaks into oscillation, there is a faulty capacitor someplace.

I decided to do my standard “re-cap” where I replace all of the electrolytic capacitors and some of the rolled capacitors of smaller values subjected to high voltages. I tested some of the old capacitors once they were out of the circuit (except in rare cases, capacitors can’t be tested while they are in the circuit). There are two large can capacitors that contain four capacitors each. All of the capacitors in one of the cans were dead (reading very low). All of the capacitors in the other can were better, but all were out of tolerance. Those cans probably were the culprits of the oscillation.

Unmatched 6L6 tubes, not even from the same era. The one on the left is military surplus. The one on the right might be original.

Both Wurlitzer and Seeburg amplifiers of this era use 6L6 tubes in the final stage of the amplifier. From a theoretical point, the two tubes should be gain-matched because one tube drives the upper half of the waveform, the other tube drives the lower half of the waveform (a.k.a. push-pull amplification). But these amplifiers seem to be pretty forgiving if the tubes are not matched. I once saw a Seeburg operating with one 6L6 tube missing.

The owner and I decided to go ahead and get new output tubes. The nice thing about 6L6 tubes is that they are still being made today due to their popularity for use in guitar amps.

After all the work was finished on the amp, it tests perfectly at all volume levels.

Wurlitzer 850 Jukebox (1942)

Posted on October 28, 2013 by Randy

Location: Bailey, CO
Symptoms: Needed adjusting and tuning, front door grill repair, broken bubble tube

This jukebox is a beauty, with a wonderful patina that I don’t see very often because it still had its original plastics and the original chrome has worn off most of the metal. Most jukeboxes of this vintage have had their plastics replaced and their metal re-chromed. My initial instinct was to replace the plastics and make it look like new. But the old plastics with their muted transparency really grew on me. Besides, it doesn’t look like anyone is still making reproduction plastics for this model.

Wurlitzer 850 Jukebox at night (Click for larger)

And because the German Wurlitzer company recently made reproductions, the patina sets this one apart.

Daytime view

On to the repairs…

There were a lot of small problems with the mechanism because it was gummed up. It looked like the mech was cleaned sometime in the 1990’s so there wasn’t a ton of old grease. It just needed some fresh lube. It also needed some adjustments as the turntable wasn’t lifting high enough and it wasn’t tripping correctly at the end of the records.

The amp didn’t sound good, but it turned out the needle wasn’t seated into the cartridge correctly.

Some of the wiring in the switch junction box wasn’t looking safe, so I rewired it. Some of it previously had been bypassed.

The left bubble tube was broken due to a blow to the lower grill castings of the jukebox, probably during moving. Unfortunately it broke the threaded anchor points for the screws in the castings. I removed the grill castings and used some metal epoxy to attach some new standoffs and reinforce one that was remaining.

Rear of front grill casting with new threaded standoff attached.

The speaker bushings were replaced with new ones, as the old rubber bushings were brittle and broken.

Everything was looking, sounding and working pretty well when it was done. The repairs were performed over the course of a couple of months.

Wurlitzer Model 3300 (1969)

Posted on March 31, 2013 by Randy

Location: Henderson, CO
Symptoms: Both record lifting arms jammed into the record carousel. The carousel was unable to rotate. Trip switch not working.

I spent a good half-hour trying to unjam the record arms from the carousel and realized there was no hope without total dis-assembly. Both tips were bent over facing the rear of the jukebox. I’m not sure how they got that way, possibly when the jukebox was moved to the basement. I’m surprised the plastic tips hadn’t broke. The only option was remove to the record playing mechanism from above the carousel, then remove the carousel. I advised the owner that this was going to take several hours. I got the go-ahead.

Once everything was disassembled, I noticed the three rollers that support the carousel were frozen. A generous dousing of WD-40 didn’t solve the problem. I finally took a pair of pliers and rocked the rollers back and forth sideways to break whatever corrosion or gunk kept them from turning. That worked. Then another dousing of WD-40. I followed up with regular oil and all three rollers were spinning freely again.

The tips on the record lift arms needed to rebuilt after being jammed. They are spring loaded and should open up as the arm rises into the carousel. I disassembled each tip, cleaned, readjusted, and lubricated with silicone.

I put the mechanism back together and did a couple of trial runs with no records installed. Everything seemed to be working great.

Once again, another bad trip switch. I encounter these a lot on later model Wurlitzers. As I have described here in this log before, I broke open the cover and flushed with contact cleaner. It’s pretty much all one can do, as you really can’t get to the contacts themselves with any kind of abrasive. I reassembled the trip switch, adjusted it, and played several records. Seemed to work okay after that. On the jukeboxes I have done this, they are still working after nearly two years. But still, it would be nice to find a replacement switch.

Wurlitzer 2104 jukebox (1957)

Posted on March 10, 2013 by Randy

Location: Lakewood, CO
Symptoms: Needle not contacting record, plays wrong selections.

We selected a record and the needle hovered about 1/8 inch above it. I moved the tone arm and felt it binding. I put some silicone lubricant on the tone arm pivots. I also noticed the tone arm audio cable seemed to be a little tight which added to the binding. I loosened the cable clamps and gave it another 1/4 inch of slack.

Usually when a Wurlitzer is not making the correct selections, the problem is either dirty switch contacts in the keyboard, or a lubrication issue with the pre-selection arm or disk at the bottom of the mechanism. Since this was probably the cleanest unrestored jukebox I’ve come across, I didn’t suspect dirty switch contacts.

On the ’04 models the pre-selection disk (I don’t know what Wurlitzer calls it) is used to differentiate the letter selections. I call it pre-selection because this disk the first thing that begins moving when making a selection. The disk rotates into position determined by a couple of solenoids, then fires one of the numbered solenoids visible around the edge of the mechanism. This disk rides on 3 nylon wheels, which often stop turning with age. I lubricated the nylon wheels and got them turning again. The jukebox now made the correct selections.

One additional item was that I cleaned the volume control with potentiometer cleaner.

Wurlitzer “One More Time” 1015-CD jukebox

Posted on January 8, 2013 by Randy

Location: Soda Fountain, Lyons, CO

Symptom: Arm that holds CD on spindle wouldn’t release properly causing CD to fling against the back of the cabinet.

I don’t normally work on CD jukeboxes, but I made an exception because Lyon’s Classic Pinball is located across the street and that would give me an excuse to go over and play some of Kevin’s 35 pinball machines from the 1960’s through present day.

Sometime after Wurlitzer stopped making jukeboxes in 1974, the remaining Wurlitzer company in Germany began making some nostalgic jukeboxes with modern CD players. In the past I’ve worked on the original 1015 from 1946 that plays 78 RPM records, so this was interesting.

I spent some time familiarizing myself with the mechanism. I looked at the lever that actuates the lift rod. Someone in the past had placed some rubber pieces at the bottom of the lift rod. Not having a service manual for this jukebox, I didn’t know how it was originally designed. It didn’t make sense how it was assembled. So I disassembled the bottom section of the lift rod and reassembled it. The lift rod and spindle arm worked correctly after that.

Examining the cam that actuates the lever, it appeared mushroomed in various places, which would have reduced the height of the lift rod, which probably prompted someone to put additional rubber pieces under the lifting rod. That cam will need to be replaced someday.

This post would make a lot more sense with either photos or some drawings. Maybe in the future I will update it.

Wurlitzer 2600 Jukebox (1961-1962)

Posted on January 8, 2013 by Randy

Location: Boulder, CO

Symptoms: Some selections not played, record arm jamming.

When I first arrived the mechanism motor wasn’t working. This was due to the Service Switch being off. This is used to turn off the motor when making adjustments to the mechanism. The normal operating position for the switch is on.

Once we got the mechanism running, the record lift arms were occasionally jamming against the sides of the record carousel. Both right and left record arms are designed to raise at the same time. If the carousel is aligned properly, one will glide into the record slot, while the other will stop against the record divider on the opposite side of the carousel. Some of the record dividers were bent which caused one of the arms to get caught and then free itself, launching the record across the room. Once I straightened the dividers, we didn’t see that problem again.

The jukebox played most records without problems, but some selections didn’t seem to work. I tested each letter and each number selection to make sure the solenoids and switches were working. There was no correlation between the non-working selections (i.e. there was letter group or number group that was not working). I had the owner make selections while I watched the selector mechanism. The rocker arms that release the selector pins were working but the pins were stuck. After some cleaning and light lubrication, the problems started going away. The owner is going to finish the cleaning and lubing on his own and will call back if he has any problems.

Wurlitzer 3500 “Zodiac” Jukebox

Posted on September 14, 2012 by Randy

Location: Longmont, CO

Symptoms: Would not return after playing record. Sound playing out of only one speaker (out of 4 speakers total).

As with other Wurlitzers of this era, the trip switch fails intermittently. I haven’t found a source for replacement switches, yet. But with past experience, opening the switch and spraying contact cleaner inside seems to solve the problem. The switch is glued together and to open it requires breaking it open. This is done by inserting an X-acto knife under the edge of the top cover at the opposite end from where the trip wire attaches. Usually about a half inch of the cover breaks away cleanly, allowing it to be re-glued or taped together again. The contacts are directly underneath where the cover is removed. I spray the contact cleaner on the contacts and cycle the switch dozens of times.

When playing records, I noticed the pair of top speakers (tweeters) were not working, and one woofer in the bottom was not working, leaving only one speaker that was working. No wonder it didn’t sound very good. Wurlitzer, instead of referring to the right and left channels, refers to them as “A” and “B”. I swapped the speaker leads and determined that channel “A” of the amplifier wasn’t working. At the same time, when moving the “A” speakers to the “B” channel, the tweeter of channel “A” worked fine. So there were two problems with the sound, channel “A” of the amp wasn’t working and the tweeter of channel “B” wasn’t working.

I decided to tackle the amp first. I swapped the input cables from the tonearm to make sure the problem was not the cartridge or the tonearm wiring. With my oscilloscope, I traced the signal from the input to the output of channel “A”. The signal was fine until it got to Q6 and Q8. Beyond that point, it was dead. I checked the bias voltage between the base and emitter of each transistor. Q8 was 0.05 volts, which is way below the 0.6V needed. Q6 was 1.2V, which was double the 0.6V that it should be.

At this point, since I knew I had a bad transistor and that it would have to cross-referenced and a replacement ordered, I decided to take the amp back to my shop for final repair.

Before I removed the amp from the jukebox, I wanted to find out what was wrong with the tweeter on channel “B”. After checking continuity of the speaker connections with the ohmmeter, and checking the coil resistance of the speaker, the only thing left was the 8 uF capacitor in series with speaker connection. I bypassed the capacitor with a jumper wire and it started working. The capacitor is used to block the bass frequencies from coming out of the tweeter. Somehow the capacitor had failed in an open condition. I added this to the list of parts to order.

With the amplifier at my home shop, I unsoldered both Q6 and Q8 from the printed circuit board to isolate them so I could test them individually. I checked the base-emitter junctions with the multimeter in “diode” mode. The junctions on silicon transistors should look like a diode, 0.6V one way, open circuit the other way. In the case of Q6, it was open both ways. Definitely bad. Q8 checked OK and didn’t have any shorts between any pins.

As usual, with Wurlitzer, it is difficult to cross reference transistors because they used their own part numbers on them. According to the service manual, Q6 is a 130537-5. Sometimes the first place I’ll go looking for a replacement semiconductor is NTE. In this case, I typed in the part number 130537-5 and got NTE289A. The basic specs seemed applicable to the circuit, so I was confident it was a good cross reference. Another source I’ll use sometimes is this page that shows some of the cross references for Wurlitzer transistors.

As I was working on this amp, I noticed some leakage on two of the capacitors.

: Capacitors (C19) on both channels are leaking electrolyte. Click for larger.

A lot of people advocate replacing all of the electrolytic capacitors in a solid state amp of this vintage. While electrolytic caps do have limited life, I prefer to wait until there are visible or audible symptoms. The gray caps in the center of the above photo look burnt, but that is just residue from burning dust on some power resistors not shown in the photo. Also, jukeboxes have spent most of their lives in establishments that had a lot of cigarette smoke, which leaves a residue.

The two leaky capacitors were replaced. Since the new caps were much smaller with shorter leads, I soldered them directly to the back of the circuit board. With the transistor replaced, the amp works fine.

Wurlitzer 3110, “Americana” Jukebox

Posted on September 13, 2012 by Randy

Location: Boulder, CO

Symptom: Sound in one channel stops working after 20 minutes of use.

I have worked on this jukebox in the past for other reasons; it gets a lot of daily use. When I first arrived, I couldn’t find anything wrong. I could hear sound coming out of each speaker. I checked all of the connections.

We were on the fourth or fifth record, and I was about ready to leave, when it stopped working. It started with static sounds, then after about a minute, the sound was totally gone. After further checking of connections, I learned it was sensitive to vibration. I could tap the final stage of the power amp with the handle of my screwdriver and the problem would change in severity, but wouldn’t begin working completely. My initial thought was there was a bad connection in the socket for one of the power transistors.

I brought the amp back to my home shop and removed each power transistor and replaced the mica insulators and cleaned the pin contacts. I also ordered and replaced the larger electrolytic capacitors in the power supply circuit and the final power amp circuit.

Electrolytic capacitors gradually lose their capacitance with age. I assume this is because the electrolyte paste eventually dries out. In some cases, especially in high voltage vacuum tube amps, the paste will leak out and the capacitor eventually shorts out. This amp is over 50 years old, and although the capacitors seemed fine, it’s just a matter of time.

However, after rebuilding the amp, the original problem still existed. I isolated the problem to Q15. This transistor drives the transformer that phases the final output stage drivers. As a double check, I swapped the channel “A” Q15 with the channel “B” Q15, and the problem moved to the other channel. I don’t know why it’s sensitive to vibration, but there must be a problem with an internal connection inside the transistor case. In any case, it needed to be replaced.

One of the difficulties working on solid state Wurlitzer amplifiers is that Wurlitzer used their own part numbers for transistors, probably even specifying to the manufacturer to print their part number on the case.

Power amplifier stage for channel "B" showing transistors with Wurlitzer part numbers. Note the 6648 number, which is the date code: manufactured the 48 week of 1966.

It’s difficult to figure out what the transistor is and to find a suitable replacement. Fortunately, with some help from Google and Bing, I found out this same transistor (Wurlitzer part number 125721) is also used in their electric organs. Somebody figured out it matches an NTE121, Germanium PNP Transistor, Audio Frequency Power Amplifier.

I was surprised to find that somebody was still making germanium transistors. (99.9% are made from silicon.) Keep in mind that the forward bias voltage on a germanium transistor is 0.1V, compared to silicon forward bias of 0.6V. This is something I had forgotten.

The replacement part was ordered and the amp is now working fabulously.

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Pinball Repair in Colorado, serving Denver to Fort Collins

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