1959 Wurlitzer 2310S Restoration

I bought this in March 2012 as part of a load of Seeburgs I bought from a fellow in San Antonio. It looked pretty rough but I loved the styling so I bought it. Most people would consider it a parts machine at best but I like fixing up stuff that I call "a diamond in the rough". The 2310S was built in 1959, played 100 selections and had stereo sound (the "S" designation in the model number). Other models in 1959 included the 2300 and 2304. The nice thing about the 2310 is that some of record magazine is still visible. For some reason, the juke manufacturers were starting to hide the mechanisms. Here is a picture prior to restoration:

Poor, poor Wurly! Who would put vine wallpaper on the sides? Maybe to hide a blemished original finish, but vines?

This picture shows the broken dome hinge panel. Not a good design and apparently many of this model suffered the same fate.

Dome Hinge Panel Repair:

I looked for a replacement on eBay for two years with no luck before deciding to try some form of repair. In the following picture, I removed the hinge panel and top to get a better idea what I was facing. I built a bracket out of 1/2" flat plate. I fastened this at the end bosses of the casting. I then attached the broken hinge bar to this, as well as the unbroken section.

And here's a picture of the repair with the hinge panel re-installed. The cracks will always be visible but the dome hinge is now solid. I'll probably fill the cracks with a silver JB type resin eventually, as this all has to come apart again down the road.

Now that the hinge bar has been successfully repaired, I need to put this project on hold while I take care of other projects. Up to now I have accumulated parts such as the speakers, new side glass, the "Wurlitzer" glass pane in the dome hinge panel, and chrome side pieces that are in better shape. The project once I get back into it will include:

Well it's July 2014 and time to get back to this beast. Here is a picture of the backside...not pretty! Closer examination and some more homework indicates I am missing the turn table motor and mechanism motor. I'm sure eBay will come through. With the heat of the Texas summer upon us, now is a good time to rebuild some of the components in the comfort of the air conditioned radio repair room.

Amp Rebuild/Restoration:

This is the "534" stereo amp, utilizing 7025, 12AU7, 12AX7 and 6973 tubes, the latter being a relatively uncommon audio output tube. The amp is in rough shape and of course, missing the tubes. The only tubes that gave me a concern were those 6973's, and some research indicates the 6CZ5 will sub. I happen to have 3 NOS in inventory, I just need one more. It's a lot of work but I decided to strip down the chassis and paint it and the transformers, followed by capacitor replacement. The following two pictures show the top and underside.

Closer examination indicated fine sand/silt deposits...not good! Unfortunately the amp and who knows what other parts of the juke spent some not-so-quality time partially submerged in water. After labeling all the leads, I removed the output transformers (OPT's) and did an ohm check on the windings. On one, there was good resistance on one half of the primary (around 300 ohms) but unusually high on the other half (over 4 k ohms). It was worse on the other OPT...one half of the primary looked good but the other half was open. I removed the bell cover of one to discover lots of silt deposits, as indicated in the next picture.

Both OPT's now need to be replaced. This could be a big problem finding something exact as there are many leads on the secondary for numerous speaker options. However, my speaker options are one...I plan on using the 12" speakers that belong to this juke (missing of course upon arrival but replacements bought on good ole eBay). That makes OPT replacement a lot easier. Reviewing the 6973 datasheets and amp design operating conditions, I determined I needed something with about 6,600 ohms impedance on the primary class AB1 with cathode bias) and at least 100 mA capacity. The Hammond 1620 appears to fit the bill although I will likely have to re-drill the mounting holes. And shell out some cash...they're gonna run about $90 each. Instead of finding 6973's, I decided to go with 6CZ5's.

Power Supply Rebuild/Restoration:

The power supply (PS) for the 534 amp is supposed to use a 5U4 full wave rectifier and a selenium rectifier. The amp that came with the juke had neither. Great...I have some oddball amp that doesn't belong to the juke. Some quick research though indicated it was likely the amp for the 2400, utilizing only discrete diodes for all rectification plus a voltage doubler circuit. Like the PS that is supposed to be there, two transformers are used: one for B+ and a portion of the amp filament supply and the other transformer had a 40 vac CT winding, two 26 vac windings and the rest of the filament supply winding. Wurlitzer wired these two filament windings in series to provide the desired 6.3 vac but why? Condition-wise, it was rougher than the amp as the following two pictures show. And since it looked rougher than the amp, I was even more concerned the transformers were bad and if so, they wouldn't be as easy to replace.

Upon removal of the transformers, I did an ohm check and everything appeared to be OK! Whew! To be on the safe side, I applied 120 vac to the primaries and then did voltage checks on the secondary windings. Things continued to look OK. I left them powered up for about 15 minutes and felt them to see if they were getting warm...no temperature increase! That was a good sign but the true test will be when they're under load.

Here is a picture of the unit before and after sandblasting, painting, and re-assembly. I still need to install a few diodes and procure some missing fuse holders.

Coin Registration Unit Rebuild/Restoration:

This was Wurlitzer's fancy name for the credit unit. It has two credit modes: 5/10/25 and 10/25/50 cents, determined by a slide switch on the back. The number of credits can be set for dimes and quarters in the 5/10/25 cent mode and quarters and half dollars in the 10/25/50 cent mode. Nickels (and dimes in the 10/25/50 cent mode) produce only one credit. There was also a "dual pricing unit" but this juke uses the conventional credit unit.

Here is a picture of the credit unit. It seems the components are getting uglier and uglier.

This one had even more silt in it than previous components and I decided at this point to name the juke "Katrina". I compared it with the credit unit from my other (complete) 2310S to discover parts had also been cannibalized. I quickly decided it was eBay time again and one was listed at $50 BIN plus shipping. I slept on it and then thought maybe I could rebuild this one. I first checked the condition of the two relays (pulse relay, timing relay #1) and determined they were OK but needed serious cleaning up. The missing parts included two "coin coils", the bracket they were mounted on, some springs, and the cancel solenoid. Looking at the good unit, the coin coils looked like simple electromagnets and relatively easy to fabricate. I ohmed the two coils and got .3 ohms and 4.4 ohms. Something wasn't right here and I figured the .3 ohm coil was bad as it did show signs of heating. The wire looked like #30 gauge so that is what I used. When I was done winding, I had about 6.6 ohms each. Using Ohm's Law and a supply voltage of 24 vac, I came up with a current of 4 amps; way too high for #30 AWG. However, these coils are powered only for a fraction of a second as a coin paddle completes the circuit when a coin is inserted. And the manual did mention something about using a slo-blo fuse and that the fuse would blow if excess current occurred for more than 3 seconds. A stuck coin paddle and the wrong fuse and poof...these coils will burn out! I was going to put in some dropping resistors but I will wait and see how they perform. Here are two pictures of the mechanical portion. The first one is with the missing coin coils, the second one shows the new coin coils and new springs.

Next up was the missing cancel solenoid. I was going to fab one from scratch but remembered the Seeburg Selectomatic mechanism used a solenoid called the trip solenoid. Could it possibly work? I had a spare mech so I pulled the coil out. The plunger diameter was about the same length but slightly larger in diameter. The Seeburg uses 25 vac to energize this coil and the Wurlitzer uses 24 vac to energize the cancel coil so that was a good match. I drilled and tapped some new holes in the mounting brackets, found a suitable link pin in my supply of hardware, found a spring to retract the plunger and voila...the Seeburg coil works! Here are some pictures: the first is a side-by-side with the complete unit showing what was missing and the second shows the installed Seeburg coil.

The inside of the credit unit looked very cruddy so I completely removed all remaining components, sandblasted the inside and bottom, painted with silver Krylon and re-assembled everything. The two plugs were repaired and reconditioned and the unit is ready to go. Here are pictures of the painted housing/bracket and everything re-assembled.