Restoration- Wurlitzer 1600

Im not a big fan of deoxit, as it moves the contaminents around to settle else where.. More of a short term solution... But to get it working i guess...

The grease is the new name for the original which was also A lithium grease. The "soap" is the Lithium.

I traced the wire to the muting plug going to something like the c11 junction on the smaller close to edge tube... I do not have my noted infront of me.

I will have to clean up the resistor.... However it is NOT on the schematic. Was this an operator addition?

The orange caps look like they tried to bypass the can capacitors.


The operator also took out a lot of caps in the volume equalizer circuit and took out that tube as well. Namely c1/c2 and about 3 others in that circuit...


I am not sure how to test the dc filter can, so I guess it stays for the moment, i will check the parts list and see if it is listed and order a replacement, and I was considering changing the volume pot as well but may later.



Now on to tracing out the caps that are in the cans.

The cans section was modified, and will take some time.

A lot of caps were replaced with non original spec caps with different values, so it was difficult to figure out which were which.

I dif however by refering to the line schematics, and only replaced once I had traced it back 3 times. Triple checked my work.

So add an additional 4 hrs to the cap kit tally. And most likely another 5 for the can reroute.
 
Read the label (or imprinted) on the can. Each section has a symbol next to the terminals: circle, triangle, square, or no symbol. The label on the can will tell you what value of capacitor is connected to what terminal.
 
Read the label (or imprinted) on the can. Each section has a symbol next to the terminals: circle, triangle, square, or no symbol. The label on the can will tell you what value of capacitor is connected to what terminal.



I did not see them labled on the schematic.


Since therr are some odd operator mods cap wise... This is taking hours wherr it should have taken 2-3 max

So I know the values, just not which c# they are so I was going to trace them out... But there are not central grounds, hah so the rats nest takes a while to navigate.
 
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I'm an idiot.


I finally saw waaay down in the bakelite material next to the solder terminal the half circle, triangle, and square.

Good news is all the ones i traced ...which took hours.... Were correct. Bad news is..... It TOOK HOURS.


none of the additional info i needed was in the service manual or the schematic i got from tisdale... Which his copy is crappy.

Yep crappy. Its a bad coppy and he should rescan a new one.


This amp was heavily modified, and had a few wrong caps. Had this been original and un modified I could have been done in 3 hrs tops...



Plugged in the unit, and she works... Gets pretty loud too

I will need to replace the tone arm carts... And see how to modify the 518 amp to accomidate the modern cartridge heads.

This would include a preamp and modifying the tone arm...

So far this seems the way to advance.

The needles are not in good condition, and I do not feel it is worth saving.... Either of them.

So i will be replacing the tone arm wires, carts, modifying the amp i just recapped, and adding in a preamp, as well as replacing the origional balasts and floro lights. Eventually i will have a switch for floro or led.

I will also be rewiring the input power and placing a 4 gang box inside for additional led lights in the cab and a service outlet off the amp.

20170622_192846.md.jpg


I also need some rubber parts. I need to contact victory glass.. Again...

I need the rubber that is on the turntable and the rubber from the upper part that sandwich the 45.


45 r.p.m. drive wheel (55036) // 4-2408/$40 rubber part
Rubber Driver (52940) // 6-6773/$10
Sound cable assembly (54938)
Washer, record drive (53390)// 6-6772/$10 under pressure pad assembly

6-#'s are victory glass item numbers
 
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I would also like to point out, this amp was modified to not use the volume control circuit.

And it had a few missing caps as well.

C12 c8 c13 c1 c7 c5 c2

These are in mainly close to the input section.

I figured I would ask if these were needed.

Otherwise, I played black water by the doobie brothers.... And it was playing well enough to sing along.... But not good enough to play another record. Volume was adjustable nice and loud...


The sound is just garbled...like a tin-y long hallway. Treble , bass, and volume pots are functioning, and you can hear the difference.

But it sounds Like the needle is trashed


And for the cost of 160. (140 for 2 green cart cobra needles, and $20 shipping).

I would rather upgrade and modify the tone arms (since the last operator used epoxy and copper wire to hold the damned cart onto the tone arm.....

This juke is full of crap operator fixes.

I still need that resistor 1 watt to see if that allows the coin mech solenoid to function... If not


I need a way to manually coin up and skil all the anti cheat crap the mech has...


One of the main issues working on these old jukes is.... All the. Service people are either dead or are no longer in the game.... And it sucks.



Running tally:

24hrs of Service & $142 in Parts, Had the amplifier not been heavily modified, I would only have ~9 hrs in service thus far.
 
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I just read about repacking these cobra cartridges to get rid of the tin can sound.....

http://webreports.netlojix.com/pipermail/jukebox-list/2003-December/007737.html

"If you look at the needle, you will find that it is mounted on a twisted flat bit of metal. If you look where that metal enters the plastic, you will find that there is a small coil on one side. You should see some (white, when new--maybe black now on yours, because of "dirt") grease between that metal and the side of the coil."

They are repacking with silicon grease "heatsink grease".

Which most likely is dried up on mine...
 
Back to the amp for a moment.

So I read an article by a guy named Carl Haines http://www.carlhaines.com/jukebox/cobra.htm

About modding the wurlitzer 532 amplifier to accept the phono input.

Here is that circuit
ampMod.md.png



Now it seems he is jumping the volume control tube valve and putting the signal after the caps he pulled.

What I do not understand is the why. Are the caps acting as filters? The cobra needle apparatus seems to be refered to a frequency generator.

I do not understand the circuit, and I have not seen anything explaining it yet.


Here is the 518 amplifier partial schematic:

Screenshot_2017-06-24-07-17-26.md.png



Similar but different....


This is where I am at...


For postarity here is the rest of the instructions for modifying the 532 amp. Again Carl Haines.

"Modifying the 532 amplifier.
These instructions may work for the 530 amp too.
Schematic available here.
Remove C6
Remove C7 Just cutting the leads is sufficient to remove the components. If you leave enough of the leads from C6 behind, that will provide you with a place to attach the potentiometer later. Check the PCB layout for the location of C6 and C7.
Add the 250k ohm potentiometer to the ground side of C7. Use one of the non-wiper connections of the pot to make the connection. You will want to mount the potentiometer to the top of the PCB. Mounting it to the top will allow you to adjust the potentiometer while the amp is installed in the jukebox and will reduce the risk of you lifting or damaging a trace on the solder side of the PCB.
Connect the wiper of the 250k ohm potentiometer to the junction of C6, C7, R4, R5 (the other side of C7 should work).
Move the wire for the center conductor of the input RCA jack from its current location to the unconnected non-wiper connection on the potentiometer.
Set the potentiometer to pad the output of the preamp so that it falls within a reasonable range for the ALC circuit. Measure the ALC control voltage and adjust the potentiometer so that when you play your loudest record the voltage is no more than the voltage when the amplifier is on but muted. On the 532 amp, you can measure the voltage at pin 4 of the muting plug. This is a high impedance circuit and the meter will have an effect on the voltage. Take a measurement for only a moment at a time. How long depends on how quickly you meter can give a reading. After I adjusted the pot, it was set for about 200k ohms padding. Your results may vary."




Any help is appreciated, I am working and have not been able to really attack this problem.

Edit-
Apparently in haines got the idea from another on the jukebox listserv. That information is as follows:
"Re: [Jukebox-list] Wurlitzer 2304 Car...
From Sent On Attachments
Columbus Coin-Op Shop Apr 3, 2012 8:30 am
James Alexander Apr 3, 2012 9:09 am
Columbus Coin-Op Shop Apr 3, 2012 11:10 am
James Alexander Apr 3, 2012 2:14 pm
Jim & Laurie Dirksen Apr 3, 2012 2:15 pm
CCOS Apr 3, 2012 3:29 pm
Chan Gade Apr 3, 2012 4:06 pm
Ron Rich Apr 3, 2012 4:06 pm
Jay Hennigan Apr 3, 2012 5:17 pm
CCOS Apr 3, 2012 5:32 pm
Chan Gade Apr 3, 2012 6:59 pm
James Alexander Apr 3, 2012 9:02 pm
CCOS Apr 3, 2012 10:24 pm
CCOS Apr 3, 2012 10:26 pm
Chan Gade Apr 4, 2012 12:52 am
Ron Rich Apr 4, 2012 9:04 am
Jay Apr 4, 2012 9:23 am
Ron Rich Apr 4, 2012 9:43 am
Jay Apr 4, 2012 12:45 pm
James Alexander Apr 4, 2012 2:11 pm
Columbus Coin-Op Shop Apr 5, 2012 7:06 am
Carl Haines Apr 5, 2012 9:26 am
Jay Hennigan Apr 5, 2012 11:39 am
Columbus Coin-Op Shop Apr 5, 2012 12:49 pm
Carl Haines Apr 5, 2012 4:53 pm
James Alexander Apr 5, 2012 9:23 pm
Mauro Apr 6, 2012 3:29 am
Chan Gade Apr 6, 2012 5:47 pm
Jim & Laurie Dirksen Apr 7, 2012 7:42 am
Chan Gade Apr 7, 2012 1:00 pm
Subject: Re: [Jukebox-list] Wurlitzer 2304 Cartridge permalink
From: Mauro ([email protected])
Date: Apr 6, 2012 3:29:02 am
List: com.netlojix.lists.jukebox-list
Jim,
Thanks for putting this info altogether in one document. I'm printing it out and
including it into my 2304 manual.
(as you know) I am planning on doing 2 1950's Wurlitzer conversions in the
immediate future (2150 and 2304) this information will save me much trial and
error and frustration.
This has been great thread!
Thanks Jim and all,
Mauro

On Apr 6, 2012, at 12:23 AM, James Alexander <[email protected]> wrote:

Gentlemen:

RE: stereo magnetic cartridge conversion for a mono Wurlitzer 45-carousel
changer jukebox.

1. Original phono cartridge is the mono Zenith cobra cartridge. It's stiff
compliance, poor sound quality (judging by modern standards) and heavy tracking
are killers for stereo records. Most 45's pressed after 1965 are stereo
recordings. Some of the after market stylus makers have issued a
retro-designed .7 mil tip size cobra needles which helps the tracking issue, but
it's an engineering compromise. It's becoming more difficult to buy cobra
replacements (this translates into expensive) anymore.

2. The cobra cartridge is not a conventional voltage generating pickup,feeding
the grid input circuit of a tube amplifier stage. The cobra element modulates
a tuned RF circuit (oscillator and detector) where the resulting audio signal
is picked off and fed into the input stage of the first audio amp. A new
conversion cartridge with roughly .5 volt signal level needs to be connected
here,bypassing the RF tank circuit. Many ceramic element cartridges with their
stereo outputs "Y"-ed together can be plugged in at this stage. These (stereo)
jukes originally used Sonotone 8T, 9T and variations of Astatic 133 as original
equipment. If installing fresh ceramic cartridge, the Sonotone models are both
freshly replicated. The Pfanstiehl P-132D is being used as a universal
replacement for the others. There will be some minor fitment/arm
balancing issues to address when changing cartridge types. Mag element
cartridges can be used if a self powered phono preamp is inserted at this stage.

3. Pickering NP-AC ,EP-DJ cartridges and older style Stanton 500AL are
discontinued but NOS can still be found in the sales pipeline. Stanton 400V3
is the closest current physical/electrical match to the Pickering models. The
400V3 differs electrically in that it has a higher output level than the
Pickering originals did. The 400V3 has a contoured freq response (the ad lit.
promises a bigger bass response) that boosts lows and highs compared to other
Stanton cartridges. One of the Stanton 500 series cartridges has a flat-response
output. The newest Stanton cartridges use different-design stylii and don't
interchange with the needles for the older cartridges. There is some stylus
compatibility among NP-AC and older 500AL models.
All of these cartridges have the same physical footrprint that with a little
modification can be fit and glued into a cobra tone arm, which does not have the
standard 2-screw cartridge mounting setup. It is necessary to ream out the
rectangular hole in the tone arm to accept the larger-body magnetic
cartridge. On mono jukebox models 1900 thru 2400 salvaging a complete stereo
tone arm assy from a junked jukebox 2300S up through 3300 is a trouble-free way
to mount a stereo cartridge. As an aside there is an Audio Technica brand
cartridge (AT3482 possibly?) and a Sanyo-Fisher MG-29 that can fit this
application. The stylus needs to be a .7 mil conical type, tracking at about 4
to 5 grams to work properly. Don't select a cartridge using an elliptical shaped
stylus for this app. Jukebox models 1700 and 1800 have different style tone
arms,but are the same operationally, so these need to be modified to take the
new cartridge.

4. It will be necessary to add weight to the tailpiece of the tone arm as any
of the magnetic cartridges are heavier in actual weight than the stereo
ceramics used in this app. The ceramic carts are apparently lighter than the
cobra, requiring addt'l weight to be added to the tone arm at the cartridge end.

5. stereo outputs of either the ceramic or magnetic cartridge should be
parallelled together for best mono sound quality. Some of these cartridges have
ground straps at the terminals, bonding the LG terminal to the metal cartridge
body. This strap needs to be lifted. The cartridge's audio grounds should
connect to the amp input using the shells of the RCA input plugsand not touch
the steel changer ground potential.. A hum loop can be set up if this happens.
The improvement in audio resolution, lighter tracking,less record wear and
assurance that you can find replacement stylii at reasonable prices are the
reward that makes this conversion worth the effort. If this is the first time
you're doing this, some trial-and-error testing will be needed to get all the
settings at optimum. With practice the conversion process becomes easier to
accomplish.

Jim Alexander "


Additional reading:
https://www.thevoiceofmusic.com/cartridges_help_substitution.html
 
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hi
both jim and ron are highly respected ppl in this "rebuild" indurstry
the front stage u are looking at is a oscalitor
the cobra's did not work like a normal cartiage
they output a small rf signal
which is then mixed with the first stage "osc" u see in your schmeatic
the then "af" signal is then feed foward for riaa/bass treble/loudness/volume etc

now as far as repacking a cobra
ken/ron/jim are best to answer that 1
also u could try john at johns jukes. ring me if u need the www.
i know he has done a few
but as i explained to u a few pages back
we all ditch the cobra. there is not only $$ reasons for it
the 1's u get from fleabay are junk period
what u need to remeber is the 1600 was the last wurli model to use a cobra

ed
 
Yet where should the phono preamp be wired in....

I am sure someone has done this to a wurlitzer containing a 518 amplifier....

Haven't they?
 
right at the volume pot
or u could bypass and go right in behind the riaa circuit
i will d/l your schmeatic and show u

ed
 
do u see where the first stage coupler tube is ?
it is the 6an8
that is your first af amp (small) as it acts as a stripper
(osc signal removed here)
after that should be your avc then riaa or the other way around ? (ken chime in here)
on the second half of 6an8 u should beable to cap couple the audio from the preamp

ed
 
Cap couple the audio? Like with what a .1mfd cap ahead of the audio signal coming in?
 
From mr detrolia on antiqueradio website

"The Zenith Cobra cartridge used in some jukeboxes (and millions of post-war Zenith phonographs) is a small coil with a moving vane attached to the needle. To simplify the description of the circuit required to make this functional, let's just say that a tube serves as an oscillator, which is slightly detuned by movement of the needle in the record grooves, and it ends up creating an audio signal in an unconventional manner. In the 532 schematic, that oscillator is 1/2 of a 12AU7, and in the 518 it's the 6J5 (which are electrically identical to each other, just physically different).

A conventional cartridge whether magnetic or ceramic produces strictly an audio signal, and does not require the oscillator components or extra tube associated with a Zenith Cobra cartridge.

To eliminate the Cobra cartridge you also need to eliminate the oscillator circuit and other parts associated with it, and then connect your new conventional cartridge to the input of the amplifier's audio stage.

The steps listed in the modification seem reasonable, although each individual circuit may be slightly different. It looks like a good place to start. Note that in your model it looks like you will remove C6, C5, and probably C7. You can also remove the 6J5 tube as it won't be doing anything once those components are disconnected. Consider the free end of R5 as the audio input to the amplifier, but you need to add a control between there and the input jack, to adjust the level coming out of your preamp so it doesn't overload the input of the amplifier and create distortion.

A bigger issue is tracking........the Zenith Cobra cartridge and its socket are quite light in weight, and any magnetic cartridge you install will be considerably heavier, which can affect stylus pressure and record life, and possibly also the operation of the mechanism. You will need to find a way to get the tracking pressure back within the specified operating range for that tone arm used in your jukebox."
 
to start with
the cobra tracks at 5-7 grams
this is real heavy for a normal pressed record that is another reason we went mag.
3-5 grams vs 5-7
do the math

now that ^^^ post went the long way around telling u exactly what i stated in short form.
with mag u no longer need the first stage at all (this is the rf osc,stripper,first stage audio
pre amp (af))
as u stated u want to go mag (good move),u need the phono to line amp
alot of the times it will do the riaa for u (equlaition),with this in hand
yes u can go to the second stage (af) amp .1/.47/1mf bipolar (bp) 50 volt or better
cap is used to couple it in.
now if needed u can put a 10k-100k audio taper pot in to control the output of the preamp (phono to line),that shoulkd get u all the way there

ed
 
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