The person I bought my Avenger from replaced the fluorescent tube lighting with LED lighting which provides bright, even lighting of the backglass but also lots of glare in addition to the stock DMD. I installed a DMD glare filter from PBL which works great for that part but the backglass glare was intense. I usually left the LEDs unplugged so I could see the PF.

My final solution was to build a module that switches off the 12V power to the LED backglass mod when the right flipper button is pressed. About 30 seconds after the last flipper button press, the LED lighting gradually comes back on to full brightness over several seconds. The module optically isolates the 5V flipper button circuit from the 12V LED lighting circuit to protect your driver board circuity. I have been testing this module for about a month now and it has worked flawlessly during that time.

The result is a perfectly clear view of the PF while playing a game. It looks like there is no glass installed on the machine if you are playing in a dark room (and your glass is clean ).

Installation is a snap and is completely reversible. Simply plug the module into the Power Source Connector under the right flipper button, plug you LED backglass power cord into the module and clip an alligator clip onto the non-ground leg of the right flipper button (the side with only one wire solders onto it). The only drawback is that each time you first turn the machine on, the backlight will take around 30 seconds to come on (pretty minor if you ask me).

Each module will be hand made and tested by me. They are not hard to make, but the molex connectors, soldering, shrink wrapping and testing does take some time. I figure I can make them for around $25 each plus whatever USPS costs.

Is anyone interested in purchasing these? (remember this will only work on machines with LED backglass lighting mod, NOT with the stock Stern fluorescent light installed)

If I were to publish the schematic, how many people would want to make their own?

Thanks for feedback so far guys. My solution is fairly simple and therefore limited on the number of machines it will work with. From dkpinball's PM, it sounds like his idea is much more sophisticated and may be able to solve more problems than my idea.

My idea WILL NOT work on machines with CPU driven backglass lighting like WPC era games. It would be possible to modify the circuit to work with 80s era, non CPU controlled lighting but the flipper switch connection on those machines would need to be worked out as they are high voltage and the modern Stern machines use logic level voltage. Additionally, for WPC era machines that Herg's GI OCD solution supports, a better solution would be to talk to him about adding a blanking function to optionally turn off the backglass circuits while a game is underway.

I created a 1 minute video so you can see the effects... pretty dramatic difference eliminating the backglass glare makes!

[attachment=1628551,]

Hey guys, I will post up the schematic later this week. It's been working flawlessly on my machine for months now and am comfortable sharing it now.

Sorry I'm so late in posting the schematic. I need to find time.

Herg, can I drive incandescent bulbs with the GI OCD board or do I have to run all LEDs? If so, you sir have made a couple sales!

Alright DIY'er, I finally got around to writing up the schematic and scanning it in. Sorry it took so long...

Basic operation is:

The open flipper button does not provide a path to ground for the opto LED. While the opto LED is off, the opto coupled transistor does not conduct which acts like a very high resistor. This allows C1 to slowly charge through R2. As it charges, the Gate voltage of Q1 rises to the point of saturation in about 30 seconds, turning the LED backlight on.

When the flipper button is pressed, the opto LED is lit up, the opto transistor conducts. The transistor in the opto acts like a short to ground, rapidly discharging C1 to near zero volts turning off Q1.

Hope this helps!

On-Delay Circuit.jpg

This circuit is SOOO simple, you do not need a circuit board. I was able to solder the components to each other with shrink wrap tubing on the joints, zip ties on the leads and a large piece of shrink wrap around the whole thing. The ground wire is a pass through so you zip tie the other leads to it to prevent pulling leads out of the circuit. I would advise you to use the 2N35 as the leads on it are a bit more beefy than the leads on the 2N25 and a radial capacitor and you should be able to solder the whole thing together without a board.

Total parts cost is around $5 and that includes the connectors.

You are welcome, have fun with it!