Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!hplabs!hpfcso!hplvec!reid
From: reid@hplvec.LVLD.HP.COM (Reid Trimble)
Newsgroups: sci.electronics
Subject: Re: At Your Table Jukebox Controller
Message-ID: <2610005@hplvec.LVLD.HP.COM>
Date: 9 Apr 91 21:10:16 GMT
References: <1921@camex.COM>
Organization: Hewlett-Packard Co., Loveland, CO
Lines: 54

In sci.electronics, kent@sunfs3.Camex.COM (Kent Borg) writes:

>   (If someone knows what kind of volts this thing takes, I might figure
>   out a lot experimentally.)

You can probably figure this out by looking at the light bulbs it uses.
I'd guess it's about 24 VAC.

>   General question: Does anyone out there have experience hacking these
>   contraptions?  

I've never played around with AMI wallboxes, but I have worked on a few
Seeburg's of the same vintage.  With that in mind, I'll guess at some
answers to your other questions:

>   Some specific questions: What information was sent to the jukebox by
>   this box?  When?  Who counted whether the four selections for the 25
>   cents had all been choosen?  Who buffers the selections?  How does the
>   "data link" between the two boxes work?  What unexpected warnings
>   should I have before applying power to it?

Since you only have a few connections, it's obvious the data link is
serial.  Seeburg's only have 3 wires: 24 VAC, common and data.  The data
stream is a series of pulses, like a rotary dial telephone would generate.
The data line is either floating (actually, it's pulled up at the jukebox,
sort of a "wired-or" configuration) or connected to common.
In the Seeburgs, you get two "packets", separated by a few milliseconds of
dead time.  The jukebox decodes the data stream by applying it to two
stepping relays (it knows to switch from one relay to the other during the
dead time.)  After that, it's "parallel loaded" into the selector matrix
just as if you had hit "A" "5" at the jukebox itself.  

The data is sent from the wallbox between the time you press the final 
key of the selection sequence and when the button pops back out.

The wallbox counts selections.  Remember, with a box at each booth the
next table over could use up your money if the jukebox kept track of
selections used.

The jukebox "buffers" the selections by setting a mechanical "flip/flop".
If you watch the old jukeboxes select records, you notice they don't 
necessarily play in the order selected - just the order they happened
across a selection during their scan cycle.  Also, you can't select the
same record 4 times.  Once the flip/flop is set, it's set and won't
be cleared until the mechanism picks up that record.

I think you'd be surprised how simple the thing really is if you pull it
apart.  Most of it is the coin separator (slug rejector) and keyboard.

You can get a service manual for it from AMR Publishing Co.  Call them
at 206-659-6434.  You'll need the model number or a good description
(like number of selections).  Probably cost you about $25.

Have fun,  Reid