Wurlitzer 3700

[Brian]

Hi all,

I hope what I'm about to ask isn't something that folks in this forum will take offense to.  I recently got a broken down Wurlitzer 3700, it's in pretty bad shape.  My goal is to repair the unit cosmetically, rip all the guts out of it, and install a Raspberry Pi and some aftermarket speakers.  My issue is, I'd like to get the button selections to work correctly (to be held down, etc) as if it were fully functioning.  I don't care if the amp works, record player, or anything else...I only need/want to get the selection buttons to hold down like they are supposed to until the Raspberry Pi releases them.

As it sits today, there was already a jumper from pin 2 to 6.  I added test leads to pin 7 and 8 and tied them all together.  I tried to attached pictures, but it says the forum is out of space??  The buttons still will not stay down (and don't hear anything trying to keep them down either).  Like it's still not getting power.  Could this be the tiac problem I've been reading about?  Is there a way to apply power directly to the switch assembly and bypass the control unit all together?

Any pointers on where to start would be greatly appreciated.

Thanks.  Brian

[jukenorman]

Hi Brian,
I think you just need to concentrate on the button bank and forget about the other electronics in your jukebox. Once you figure out the I/O interface to the Raspberry Pi, just install (build?) a small power supply to service the I/O and to energise the latch solenoid which will now be controlled by the Pi. You could use power from jukebox but I suspect that would be more trouble than it's worth - although I haven't checked the manual.

[Brian]

I guess, that's where I felt I needed help. I agree, at the end of the day, I don't want anything original in this juke other than the buttons/latch mechanism. Having said that, I don't understand how the buttons are supposed to work in conjunction with the control box. If all I have to do is apply power (or trace the leads back in the harness to make it look nice) to the solenoid and not even use the control box, then you're right...I'm good. I'm already looking for a 12v version of that solenoid so I only need one new power supply (one I'm looking at will supply 12v, 5v, and 3v). I was trying to at least fix that part so I understood how it worked. Maybe you can confirm my thoughts so I don't have to study a working unit...

Power needs to be supplied to the solenoid. Now, a user can press a letter (hitting the reset button disrupts power to the solenoid - releasing the reset button restores power to the solenoid) which gets locked in place (because power is already at the solenoid) to then allow selection of a number. The number would be held down along with the letter until the power is disrupted to the solenoid. Would this be accurate? If so, this might be easier than I thought...

Thanks again. Brian

[jukenorman]

Hi Brian,
The process will be covered in the sticky "how a jukebox works" but in simple terms - when you have credit, the latch solenoid will be energised. When the first button is pressed, it latches; when the second button is pressed, it also latches. A secondary circuit that recognises that both a letter and number are depressed triggers the selection process. The selection process removes one (normally) credit, the action of which de-energises the latch solenoid releasing the buttons. If further credit is available, the latch solenoid will re-energise.

I don't have any 3700 literature but I will message you a bit of 3800 info which might help you.

Norman.