Wurlitzer 2800 Jukebox Repair Journal and Photos
by Chad Hauris, Retro
Electronics and Audio Lab, Midland, TX. 7/10/06, Updated 1/6/07
This Wurlitzer 2800 appeared to be in pretty decent shape when it
arrived...but it turned out to need the most work out of any we have
worked on! Please click the pictures for larger views.
We noticed that the amp had all the capacitors replaced on the circuit
board and these looked O.K. so we left them alone. We replaced the
power supply capacitors as some of them appeared to be salvaged from
other units or old stock and we wanted to install new fresh caps for
best performance. This unit appeared to have been repaired in about
1989 but appeared to be a so-so job so we also repaired some bad solder
joints in the amp, the power line fuseholder, and the power cord.
This Wurlitzer had a 6CZ5 subbed in for a 6973 in the late 80's.The
late 80's and the 90's were kind of the dark ages for replacement tubes
as the old manufacturers had shut down and newly made tubes were rare.
Luckily in the early 2000's Electro-Harmonix began selling newly made
Russian tubes of types used in jukeboxes such as 6973's and 7868's.
We installed 2 new Electro-Harmonix 6973's to replace the 6CZ5 and the
other 6973 in that pair.
Here is the amp and old ballast before repairs.
The old ballast was replaced with 3 new ones and the wiring to the
ballast sockets was repaired with heat shrink tubing for safety. We
still need to replace some of the lamp cords as they had been repaired
with black tape. A new power cord and fuse for the ballasts was
installed.
New ballasts on ballast rail.
Ballast rail mounted. The lighting cords have been replaced
with new ones.
We installed a Pickering NP/AC magnetic cartridge to replace the old
Astatic and noticed that the tonearm was sliding across the record when
tested. The problem, we noticed, was that the weight of the Pickering
was different and this was upsetting the tone arm balance. Initially we
placed some coins on top of the back of the tonearm and this
counterbalanced it to where it would play good. We melted out some of
the lead that was in the bottom of the tonearm to help lighten up the
opposite end, and installed some washers for weight on the back of the
tonearm top to help counteract the tendency of the tonearm to skid
down. Even warped records play fine with this arrangement. A phono
preamp was installed for the new cartridge.
Here is a test with a record...you can see the coin counterweight.
The mechanism seemed kind of sluggish when tested and we found a lot of
gummy grease in it. We cleaned and relubricated it. We removed the
carousel and found the roller bearings were stuck, so we soaked these
overnight in varsol, and then followed up with Gumout spray. We used a
pin to remove old hardened grease in
the bearings and relubricated them with Hammond organ generator oil.
It turned out, however, that this treatment did not last, and the
bearings began to seize up again. So, we had to replace the bearings!
We went to Roll-Tex Bearing down the street and found some that would
work (a KYK R6 2RS SRI2).
In order to attach the new bearings, we had to drill out the old rivets
and install new ones along with washers.
Here we are using the rivet tool to rebuild the bearings.
Here you may be able to see some of the old grease in the mechanism.
With the machine re-assembled, we noticed that the record was being
pushed up to the turntable with excessive force...sometimes the record
would overshoot the turntable and end up jamming the mechanism. This
problem can be caused by binding in the mechanism as the record is
pushed up, resulting in the spring force not being released smoothly.
We removed the entire mechanism from the jukebox and took it to the
bench for cleaning. First, the carousel and upper part of the mechanism
containing the turntable had to be removed. Then, the selection memory
unit had to be removed from the bottom of the mechanism.
The mechanism motor was removed, and all parts were thoroughly cleaned
and re-lubricated. When we re-assembled, it turned out that the tapped
holes for the mechanism motor had stripped out, causing the motor to
push itself away from the mechanism. We had to replace the bolts with
new bolts and nuts:
New bolt on mechanism motor.
Also, we replaced the turntable motor mounts.
The control box had a loose relay socket which we epoxied back in
place, and we replaced the old capacitors in there.
Here is the control box before repairs:
After repairs:
Testing the machine with lid closed:
After we got basic functionality of the mechanism, amplifier, and
tonearm, we turned to the credit and keyboard system. This system had
been pretty messed up but was rigged up in a way that it would still
function after a fashion. You could enter a selection by holding down
and keeping a letter and number button depressed till you heard the
selection coil buzz and then releasing the buttons. We wanted it to
work like it ought!
First we noticed that the keyboard latch solenoid was not latching in.
This was kind of odd, since selections could be entered by holding down
keys. Normally the machine will not accept any selection until it
recognizes there are credits present. We first turned to the Playrak
(credit unit) to see what was going on there.
It turned out that a circuit breaker had been installed to replace the
coin fuse, and it was open. We hooked up a test fuse in place of the
circuit breaker but still could not get credit.
We noticed the keyboard had some bad wiring on it so we removed it for
repairs. Here is the keyboard before repairs:
Repairing the solenoid wiring. More photos of completed keyboard to
come.
We repaired all of the trouble spots, including re-insulating the
solenoid leads with heat shrink tubing, and re-wiring the counter. The
resistor terminal strip had burned apart and was replaced.
We then found one of the relays had burned wiring in it (this is the
leftmost white relay at the rear of the control box, looking from the
rear.) We repaired the relay by soldering a new wire to replace the one
that had burned open.
With the relay reinstalled, the latch solenoid attempted to engage but
there was arcing at a switch contact. This was fixed with some De-oxit
gel and a contact burnishing tool on the contacts. The latch solenoid
would then latch in O.K. but the credit system was still not
decrementing credits.
It turned out someone had bent the contacts in the Playrak so that it
never ran out of credits. We re-formed the contacts so the credit wheel
would activate them properly. The machine then gave proper credits when
a coin was dropped and decremented properly.
Now, we almost had it working right, but not quite. When a number
button was pressed by itself, the selection motor would run. We tracked
this down to another set of contacts that needed to be adjusted on the
keyboard, to activate the second solenoid.
This keyboard mechanism is different than the most common type, in that
it has 2 solenoids. The first is the usual one, to activate the
keyboard latch mechanism when credit is established. The second one on
the 2800 only activates momentarily when the second keystroke of the
letter-number pair is pressed. When this solenoid activates, the
circuit is completed to the selection system. In most models, 2 leaf
switches in series, one for the letters and one for the numbers, are
used.
Now, the credit and keyboard system was operating functionally. We will
add in a free credit switch if the client desires. We recommend NOT
modifying credit systems to never run out of credits, as someone had
done here. The resistors and solenoids in the keyboard can cause or
suffer heat damage from always being on. In one 2600 model we had that
did not have a slug rejector, we used a timer circuit that is activated
by a button press to deactivate the keyboard after a certain period of
time.
More information to come!
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