With the hundreds of ballasts ive installed and replaced over the years, of all shapes and sizes, I have never been so stumped on one until now. Here you see an electronic Tanning Bed Ballast that supposedly operates five 6-foot lamps. now as you can see there is no wiring diagram or any information at all on the ballast case.     A tanning salon here went out of business and was selling all the beds and equipment, when I got there the beds were all sold but they still had replacement ballasts and bulbs available. I picked up two of these ballasts. The person selling the equipment told me they drive 5 lamps as all of the beds they used contain 10 lamps and 2 of these ballasts to drive all 10. One drives the top (door) section of 5 lamps, and the other runs the 5 lamps in the bed (surface you lay on). Now with the output leads on the thing I cant for the life of me figure out how to wire it to 5 lamps. Consists of 12 leads, 2 brown, 2 red, 2 yellow, 2 gray, 2 orange, and 2 blue. If anyone has any clue on how to connect them up, or know what brand this might be, that would be awesome. I don't have a tanning bed, but still would like to use this ballast in some future project

Have you googled tanning bed ballasts?

Is it open-able ?

The black-white-green looks like the mains input (L-N-PE).
And then the other wires look like each wire color serves one lamp (assume IS)...
I assume all lamps are fed from one common inverter, just via separate ballasting coils and maybe DC blocking capacitors, so when measured by a DC continuity check, you will see one wire of each pair connected all together.
But be cautious, the connected one could be the "hot" one (via the ballasting coils), the cold one uses to have the series DC block capacitor (that arrangement makes the ballast a bit more likely to survive shorts to Neutral/ground)

A google search reveals nothing remotely close to this unmarked ballast, And I didn't ask the shop owner what brand of tanning beds they used. tonight I attempted wiring it to 6 lamps (as there is 12 leads, one lead for each lampholder, each lamp gets one lead of the same color at each end. Nothing happened except a faint glow (discharge) at one end of lamps connected to the brown and gray leads, the other 4 lamps showed nothing. I just can't understand how 12 output leads are supposed to connect to 5 lamps, it just makes no sense

If all lamps are series connected, the 12 wires would make sense: The lamp circuit you may imagine like series connected preheat, while instead of the starter there is a capacitor:
(copy following into some fixed character width editor, hope it will work)

|                                          -------       -------       -------       -------       -------     
|InverterOut ---BallastOutputInductor-----|       |-----|       |-----|       |-----|       |-----|       |------InverterReturn
|                                        -|       |-   -|       |-   -|       |-   -|       |-   -|       |- 
|                                       |  -------  | |  -------  | |  -------  | |  -------  | |  -------  |
|                                       |           | |           | |           | |           | |           |
|                                        -----||----   -----||----   -----||----   -----||----   -----||----

All except the lamps is inside of the ballast housing, interconnections between lamps are made directly without any lead into the ballast case, so you have 12 wires (5x2 for capacitors + 2 for the current feed).

But that means the ballast would have to be able to generate high enough voltage to feed 12 lamps in series, that sounds rather ridiculous. Do you have any idea what lamp types were there? I have no idea at all, what lamps are usually used with sun tanning beds in general...
For something like 50V arc lamps it could be feasible (250V total)
But with this circuit it is quite important to not "cross" the wires so, the capacitors are not each around just it's own lamp, so have wires in pairs of the same color looks rather strange.

Good thing, the ballast seems to be somehow alive.
But it would really help, if it would be possible to open the ballast and redraw the output circuit (or take some detailed photos)

@Medved, thanks for the possible internal diagram, however I still don't understand how to connect up 5 lamps (20 pins) with 12 output leads, and as you said the color coding matched leads are odd. The lamps they used were 72" T12 VHO and were 180w each, I didn't buy any lamps but remember they were all the same brand "SunMaster VHO-R 180w F73" and used Recessed double contact endcaps. This ballast also seems a bit small for 900w of lamps. I will attempt opening it, but im quite sure its filled with potting compound, plus ide like to still use it eventually for some bright VHO shoplights someday.

Open it only if it does not damage the ballast (I assumed rather "normal" construction of an electronic device, with just a board in a box).

Other option came to my mind was the middle sections (between the lamps) being connected parallel:
(again top see the "Ascii-art" schematic, copy into some fixed character width editor like Notepad or the reply editing box here)
|                                                                       
|                                        --------------------------------||---------------------------------
|                                       |                                  Resonant capacitor               |
|                                       |  -------       -------       -------       -------       -------  |   
|InverterOut ---BallastOutputInductor-o-o-|       |-o---|       |-o---|       |-o---|       |-o---|       |-o-o--InverterReturn
|                                     |  -|       |-+-o-|       |-+-o-|       |-+-o-|       |-+-o-|       |-  |
|                                     | |  -------  | |  -------  | |  -------  | |  -------  | |  -------  | |
|                                     | |           | |           | |           | |           | |           | |
|                                    Heater       Heater        Heater        Heater        Heater        Heater
|                                   winding 1    winding 2     winding 3     winding 4     winding 5     winding 6

Again it is 12 wires for 5 lamps...

Figured out your schematic medved, but to no avail on successfully wiring it up (probably my error). After some experimenting however, I have found that a lamp will light for about 5 seconds when one end (both pins) is connected to a single gray or brown lead, and the other end with one pin a random other color (blue) and the other pin another color (red). So one lamp has 3 leads (1 red, 1 blue on one endcap, and a single gray on both pins of the opposite endcap. The lamp started exactly like programmed start, with a second of preheating then full drive current. However the ballast shuts down when wired this way with only one lamp (an 8' 110w T12 HO) after about 5 seconds...but during those 5 seconds the lamp was stable and ran at about the intensity it normally would.

I have a feeling that those 2 pairs of brown and gray leads should somehow supply one end of all 5 lamps. They cause a partial ionization (glow) on the end of the lamps they are connected to, and only these 4 leads do this, the other 8 colored leads do not produce this glow in the lamp

The programmed start electronic ballasts usually contain a filament continuity check, enabling the ballast only when the lamp(s) presence is detected there. There are two aims: First restart the controller (and so clear the eventual fault flags) when the lamp is replaced without the need to cycle the power. The second reason is to make sure the ballast does not generate HV when the cold end of the lamp is not inserted properly in it's socket - because when the HV is generated with the lamp inserted only with the hot end, the lamp may ignite, become conductive and via the open pins (you can touch them, when they are not in the socket) of the cold end form a shock hazard.
With a ballast designed for so many lamps the second aspect could be waived (not needed with recessed pin lamps), so the continuity check could be only on the hot end.

That could be the reason, why you see the activity only when some leads are connected to the filaments. The reason why it lights and then shuts down could be, once you reconnect them, the controller gets reset and attempts to start the lamps. The one connec ted lights, but as the other outputs are open, after some time window (the 5s; normally designed to ensure the lamps run up properly without causing false fault detections) the protection shuts the ballast down (ignition failure detected on the unconnected outputs).

And yet one other connection way came to my mind (mainly because you have mentionned the lamps were some long types, so higher arc voltage):

One pair is the common "cold" return (with common filament supply output), then each remaining pair supplies the "hot" side of one lamp.
If you try some experiments assuming the parallel connection (well, first you would have to identify the common return pair) and you see only some lamps lit, it would be the series-parallel configuration - the lighted lamps would become split to few in series, with the "nonlighting" pairs feeding the filaments in the middle.

By the way do you have some sort of capacitance meter? That may help to identify at least the "cold return" wire pair
Connect mains input wires together, then short each pair and measure capacitance between the mains input and each pairs; the "cold return" would be the one with way higher capacitance than the others.


So the