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 Post subject: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Fri 18, 2017 10:58 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
I thought I would document my fix-up of a Wurlitzer jukebox I am doing for someone. That person isn't expecting a full "Like New" restore. The jukebox was made in 1959 and that is the first year Wurlitzer made a "stereo" version. It is a 104 play model, they also made 200 play (model 2300) and 100 play (model 2310) versions and each of these also came with monophonic audio systems. Two "plays" (sides) per record. This jukebox was in fair shape, some rust and corrosion on some of the chassis in the bottom. The owner discovered several blown fuses.
Attachment:
EdsPicE1.jpg
EdsPicE1.jpg [ 99.81 KiB | Viewed 1963 times ]

Attachment:
AmplifierTopE01.jpg
AmplifierTopE01.jpg [ 113.88 KiB | Viewed 1963 times ]

Attachment:
AmplifierSideE01.jpg
AmplifierSideE01.jpg [ 98.22 KiB | Viewed 1963 times ]

Attachment:
PowerSupE01.jpg
PowerSupE01.jpg [ 91.93 KiB | Viewed 1963 times ]

Attachment:
UpperFronInterE01.jpg
UpperFronInterE01.jpg [ 103.05 KiB | Viewed 1963 times ]

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UpperBackInterE01.jpg
UpperBackInterE01.jpg [ 103.59 KiB | Viewed 1963 times ]

The amplifier and power supply have been remove in this last photo.
Attachment:
LowerInteriorE01.jpg
LowerInteriorE01.jpg [ 110.44 KiB | Viewed 1963 times ]

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Fri 18, 2017 11:14 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
First off I noticed the crusty caps on the circuit board. I planned from the beginning to do a re-cap.
Attachment:
CrustyCapsE1.jpg
CrustyCapsE1.jpg [ 115.63 KiB | Viewed 1962 times ]


On the amplifier underside I found some seriously overheated wire-wound resistors.
Attachment:
FriedResisCircE1.jpg
FriedResisCircE1.jpg [ 105.09 KiB | Viewed 1962 times ]

These turned out to be cathode resistors (R65) on the amp output stage. Strangely they retained the correct resistance of 310 ohms.
Attachment:
SchemOutputE1.jpg
SchemOutputE1.jpg [ 104.17 KiB | Viewed 1962 times ]

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Tim
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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Fri 18, 2017 11:40 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
After cleaning up and partially re-painting the amplifier and power supply chassis, I started work on the power supply. The large selenium rectifier on top is used to provide DC current to some of the relays, solenoids and the carriage motor. I intend to replace it with a silicon bridge rectifier that I will place underneath. A 5U4GB is used to provide plate supply for the amplifier. One of the large transformers provide the power for the electromechanical systems and the other provides power for the amplifier.
The filament supply for the tubes of the amplifier is split between the two transformers. One transformer is always powered and provides 4.7 volts to the filaments, the other transformer only gets power after a record selection is made and adds 1.6 volts for 6.3 volts. So the tube filaments 'idle' when the amplifier isn't needed.
I was surprised to find that one (9K) section of the power resistor (R68B) was open.
Attachment:
SchemPowSupE1.jpg
SchemPowSupE1.jpg [ 99.39 KiB | Viewed 1958 times ]

I was disappointed to discover that T2, which provides the plate supply, had a short between the 5V winding and somewhere on the high voltage winding.
R68 is circled in this photo and T2 has been removed.
Attachment:
PSupT2CircE02.jpg
PSupT2CircE02.jpg [ 109.45 KiB | Viewed 1958 times ]

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Sat 19, 2017 5:58 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 1086
Location: 77001
Tim,
Thanks for posting the restoration ! These efforts are always
appreciated for the time, effort, and knowledge they impart.

Even if someone has a different juke, they will learn something as
to what it take to do a good restore.

Hotwax


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Sun 20, 2017 3:45 am 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
Here are a collection of links that have information and restoration stories that I found.

First one that clinched which model I was dealing with. The plate showing the model number was missing.
https://www.jukebox-world.de/Forum/Arch ... er2300.htm

A couple of restoration articles.
https://www.youtube.com/watch?v=XVnZiySb5ms

http://www.southtexasantiqueelectronics ... 2310S.html

Here is one that shows the mechanism working on one a year earlier.
https://www.youtube.com/watch?v=UHOsjOAHMUI

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Sun 20, 2017 4:05 am 
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Joined: May Thu 14, 2015 4:15 pm
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Location: Dallas, TX
I'm working on settling on replacement power transformers from Hammond. Neither Ebay or Victory Glass have the original transformer. None of the Hammond transformers have the same mounting hole spacing as the original, I will make an adapter plate or rails. One transformer possibility is a bit cheaper and smaller, easier to fit, it doesn't have enough 5V current for the 5U4 but I could change to silicon rectifiers. I would have to increase a resistor value to drop the voltage back down however. Another transformer choice would have enough current for the tube rectifier filament. The two section filament supply is the tricky part. I think I will use a small additional filament transformer that I will remove secondary turns from until I get it down to 1.6 V.
Meanwhile I have lots of caps to replace.

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Sun 20, 2017 7:23 pm 
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Joined: Feb Fri 13, 2009 5:09 am
Posts: 451
Location: Santa Clara, CA
I'm working on a similar resto of a 2310 for a friend. Is the top casting broken near the dome hinge on yours? It seems to be a very common failure in this model, due to the twisting strain imparted by the dome when it is propped in the upright position. I am working on an interior reinforcement made of steel to hold our broken casting back in the correct configuration. I'll have to snap some pictures.


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Sun 20, 2017 11:59 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
I have the amplifier and power supply chassis at my place but the rest of the machine is at the owners studio about a 30 minute drive away. I haven't investigated the mechanical aspects much yet, however I did take some pictures because I knew I will have to take care of some problems.
Yes, the cabinet casting near the hinge and latch has a crack in it. Someone previously made a repair.
I think the problem now is that the hinge rod is bent. Back when this machine was made, car hoods had a detent on the hinge and you simply pulled down on the hood and it would close. I wonder if people think this is how the glass 'hood' works on this jukebox. You need to reach in and lift the latch bar before the glass will lower.
Attachment:
CabCrackE01.jpg
CabCrackE01.jpg [ 90.04 KiB | Viewed 1881 times ]

Attachment:
CabHingeE01.jpg
CabHingeE01.jpg [ 101.08 KiB | Viewed 1881 times ]

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Mon 21, 2017 1:21 am 
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Joined: Feb Fri 13, 2009 5:09 am
Posts: 451
Location: Santa Clara, CA
Thank you for describing the two-transformer scheme for the filaments "warm idle" function. I was aware that Wurlitzer (and others) did that, but wasn't familiar with the details. I haven't started on the electronics on this one, but I don't think I'll have too much to do on it. It had already been recapped, and converted to a Seeburg(!) Magnetic stereo cartridge with a tidily-installed preamplifier behind the blue "scrim".


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Mon 21, 2017 4:46 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 8118
Location: Baltimore, MD
That's one of my favorite Wurlitzer cabinet designs. Unfortunately, broken castings seem to be common on these.

Looking forward to seeing the progress!

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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Mon 21, 2017 5:37 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12398
Location: Omak,wa,usa
Hello Tim,
wow you have your work cut out for you but it will be great to have up and running when you are done I have old Rock ola from the 50s .
my First thing to do is restore the wall box unit that bought this year off of ebay


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Wed 30, 2017 11:48 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
I had good luck and was able to find a NOS replacement transformer.
Attachment:
NewPowTransE1.jpg
NewPowTransE1.jpg [ 92.37 KiB | Viewed 1728 times ]


If I hadn't been able to find one, I would have used a Hammond 273BX and one of the Hammond 166 Series to provide the extra filament winding. The 166 series has primary and secondary wound on separate locations on the bobbin. I would have un-wound or re-wound the secondary to provide 1.6V at 4 amps. A bit of a science project, but I think it would have worked OK. The extra transformer would be a tight fit under the chassis though.
Attachment:
FilamentTransE1.jpg
FilamentTransE1.jpg [ 57.52 KiB | Viewed 1728 times ]

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Aug Thu 31, 2017 8:43 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
I was thinking about the pattern of failures and came up with a possible story. The 9K section of R68B opened up first. This caused the 295V supply to increase, this voltage is used as the output tube screen supply. I think this caused the output tubes to conduct more current which caused the cathode resistors to overheat. The increased current might of caused the 2 amp fuse in the primary of the power transformer T2 to open. I think a previous owner replaced the 2 A fuse with a 5 Amp. The amplifier might have continued to work for a little while, but the increase current overheated the transformer until it shorted!
On another subject, I replaced the selenium bridge rectifier with a silicon one. I don't know how much voltage the selenium rectifier dropped on this supply. The transformer winding is shown as 36V(RMS), however the rectifier output is labeled as -30V on one schematic and -28V on another. Also at least one relay coil on the parts list indicates 24V. This DC supply doesn't have filter capacitors to smooth the output. On a relay coil, solenoid or motor the important quantity is RMS voltage. The meter reading on this kind of waveform depends on the type of meter used. I've seem some people replace the selenium with silicon in this location without bothering with the different voltage drop. Long story short, I added a regulator circuit to adjust the output down to the RMS equivalent to 28V. (I edited this diagram because I realized the voltage wasn't quite high enough.)
Attachment:
ZenerRegE2.jpg
ZenerRegE2.jpg [ 27.74 KiB | Viewed 1053 times ]


Another thing I've done is make some decals to replace the damaged printing on the several chassis.
Attachment:
DecalLabelsE01.jpg
DecalLabelsE01.jpg [ 96.21 KiB | Viewed 1694 times ]

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


Last edited by Notimetolooz on Oct Thu 12, 2017 1:31 am, edited 2 times in total.

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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Sep Sun 03, 2017 6:57 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12398
Location: Omak,wa,usa
Hello Tim,
Yes I like your regulator circuit and I agree with you there are people out there that don't put much thought in to the added voltage from the new silicon diode


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Sep Tue 05, 2017 3:15 am 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
I'm hiding the new 9K resistor that subs for the open section of R68 under the unused selenium rectifier.
Attachment:
NewResistorE1.jpg
NewResistorE1.jpg [ 99.67 KiB | Viewed 1610 times ]


At this point I'm calling the power supply done.
Attachment:
PSDoneE1.jpg
PSDoneE1.jpg [ 101.52 KiB | Viewed 1610 times ]

Attachment:
PSDoneE2.jpg
PSDoneE2.jpg [ 90.17 KiB | Viewed 1610 times ]

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Sep Thu 07, 2017 2:32 am 
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Joined: May Thu 14, 2015 4:15 pm
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Location: Dallas, TX
Does anyone know how to remove the selector switch (keyboard) without taking the whole cabinet apart?
Attachment:
KeyboardInterE01.jpg
KeyboardInterE01.jpg [ 98.31 KiB | Viewed 1575 times ]

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Tim
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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Sep Thu 14, 2017 3:32 am 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
After removing a narrow long metal strip below the selector switches and a fluorescent tube and removing several screws, I managed to wrestle the selector switch assembly out.
Attachment:
ButtonsRemovedE1.jpg
ButtonsRemovedE1.jpg [ 97.01 KiB | Viewed 1471 times ]

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Tim
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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Sep Sun 24, 2017 10:56 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
I finished re-capping the amplifier. I also made replacements for the Sprague PEC (Packaged Electronic Component, aka. couplate) that are used for treble control. I probably didn't need to do this but the parts are hard to test and similar ones do go bad in TVs from that era. After I cut out pieces of PCB board material, I used chart tape to mark off the gaps between where the copper pads would be. I spray painted the boards with lacquer, then removed the tape. The boards were then etched and the paint removed. I drilled holes for the six leads that would attach them to the main PCB and soldered the leads on. The capacitors and resistors were attached without drilling holes. I used 1/4 W resistors and the smallest leaded capacitors I could find. Then the boards were covered with 30 minute epoxy.
Attachment:
PECBeforeE1.jpg
PECBeforeE1.jpg [ 89.37 KiB | Viewed 1332 times ]

Originally there was a resistor in placed that was inserted into the same holes as pin 1 and pin 4, so I added it to the assembly. This looked like it was an factory modification and it is on the schematic.
Attachment:
PECAfterE1.jpg
PECAfterE1.jpg [ 90.04 KiB | Viewed 1332 times ]

I added three wire stub test points at the top and covered them with black heat shrink.
I measure the resistors in the rest of the amplifier and found that the majority of them were out of tolerance, so those were replaced also.
I hooked the amp, power supply, some speakers and mp3 player and found that it worked fine, however I will now replace some of the tube sockets on the PCB. A slight tap will cause the sound to cut out.

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"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Sep Fri 29, 2017 1:37 am 
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Joined: Jan Sun 18, 2015 5:01 am
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Location: Waxahachie Texas
Nice Tim.

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 Post subject: Re: Reviving a Wurlitzer 2304 Stereo Jukebox
PostPosted: Oct Sat 07, 2017 12:12 am 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 542
Location: Dallas, TX
Some pictures of the finished amp, without tubes. I didn't re-do all the labels just the ones that were in poor shape or missing after removing the rust. One side of the amp chassis was badly rusted inside, I removed the rust with a wire brush, then I used a rust conversion coating then a red primer. I didn't bother with painting that area silver.
Attachment:
Wurl534AmpE01.jpg
Wurl534AmpE01.jpg [ 110.74 KiB | Viewed 1141 times ]

Attachment:
Wurl534AmpE02.jpg
Wurl534AmpE02.jpg [ 122.38 KiB | Viewed 1141 times ]

Attachment:
Wurl534AmpE03.jpg
Wurl534AmpE03.jpg [ 113.29 KiB | Viewed 1141 times ]

I have now gone through the rest of the electronics except the changer mechanism which is still in the cabinet at the owners place. Everything has been cleaned, lubed and adjusted. I hooked these pieces together and made sure they worked together. Aside from the sound system, the rest of everything counts the coins, then pops up the 'pins' corresponding to the song selected with the buttons in front. (I discovered that the coin sorter 'slug ejector' doesn't work.)
Once at least one pin pops up, the motor in the changer starts up and detects the pins. I'll have to get everything back in the cabinet to check the changer operation. I also need to clean up the button keys and install them. I'm putting together a small circuit that will simulate a coin drop when a additional button is pressed.
Attachment:
WurlitzerPartsE1.jpg
WurlitzerPartsE1.jpg [ 101.86 KiB | Viewed 1141 times ]

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Tim
"Excellent!" I cried. "Elementary," said he. - Sherlock Holmes


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