I originally wrote this "informal review" of Herg's LED OCD and posted it on Pinside.com.

Informal Review


Altan's LED OCD Informal Review
Revision 1.03

Over the past few years many pinball owners have decided to "go LED". This is likely encouraged by the ever increasing number of LED sources, recent pins by Jersey Jack Pinball and Stern using LEDs, owners wanting to bling out their machines, reduced power needs and heat, and because many pinball owners want to tweak their own machines to perfection.

But Bally/Williams WPC machines were designed to use incandescent lamps and may not take kindly to LEDs. At a very high level, it's important to understand that LEDs and incandescent lamps have very different characteristics. For example, LEDs can almost instantly turn on and achieve full brightness while incandescent lamps have a longer "ramp up" time. The WPC software was designed to control lamps with incandescent characteristics, not those of LEDs.

This mismatch causes at least 3 problems: ghosting, strobing and the loss of fading effects. Ghosting occurs when a lamp should be turned off but instead it flickers on and off dimly. Strobing occurs when the lamp should be "on" for a period of time but rather than being continuously on for this period, the lamp very quickly cycles between on and off. Some may call this flicking when the on/off is further apart. Finally, loss of fading effects occurs because the pattern of electricity that makes an incandescent bulb ramp from off to full brightness in a period of time will typically cause an LED to stay off for a bit and then strobe.

Note that WPC games control the General Illumination differently than the lamps in the Lamp Matrix. While the lamp matrix can experience at least the 3 problems listed above, the G.I. is typically troubled only by strobing and loss of fading effects. Ghosting isn't a problem.

The LED OCD product is designed to solve the problems that occur when a WPC is controlling LEDs in the lamp matrix (it does not address problems with the G.I.). In addition to the problems mentioned above, the LED OCD product offers unique control over each lamp in the matrix. The LED OCD also has the very nice ability to concurrently drive both incandescent and LED lamps.

LED OCD has 3 main parts:

1) The main LED OCD board
2) A jumper/breakout board (which is unique to the WPC version of LED OCD)
3) Various cables

I was initially surprised by what seemed to be a significant number of cables provided in the package. However, after closer inspection, I realized there are not a large number of cables but rather 2 large cables and a USB cable. The two large cables are special cables for LED OCD that have a single large connector on one end and two smaller connectors on the other.

The first picture below shows the main LED OCD board. It is slightly larger than a WPC instruction card. The second picture shows the jumper/breakout board.

Installation should be straightforward for anyone that has experience pulling connectors from inside the backbox. The large number of steps included in the detailed instructions may make the process appear harder than it actually is. Installing LED OCD requires no permanent changes to your pinball machine.

The installation involves:

1) Mounting the LED OCD board in the backbox
2) Mounting the jumper/breakout board in the backbox
3) Disconnecting the lamp matrix cables from the WPC driver board
4) Connecting these same cables to the jumper/breakout board
5) Using one of the supplied cables, connect the WPC driver board's output to the LED OCD board
6) Using the other supplier cable, connect the LED OCD board to the jumper/breakout board
7) Using a Z-connector, have power go to the LED OCD board

Originally the WPC driver connected directly to the lamps. With the LED OCD board installed, the connection is

WPC driver board -> LED OCD board -> jumper/breakout board -> lamps

As can be seen from the sequence above, the LED OCD board is installed between the WPC driver board and the lamps. At this location the LED OCD board is able to look at the signals being generated by the WPC driver (which were designed to control incandescent lamps) and convert them into an appropriate signal to drive LEDs (or incandescent).

Installation took me about 30 minutes. The majority of this time was taken by mounting the boards in the backbox and simply being careful. I had a little trouble mounting the LED OCB board itself using the supplied adhesive mounts. Even after cleaning the backbox area with isopropyl alcohol, the top right mount didn't want to stick well. Also, there was a sticker on my backbox where one of the adhesive mounts ended up. I think these could have easily been resolved with a little more prep work on my part. For anyone doing the install, I recommend:

1) Use the screw mounts rather than the adhesive mounts
2) Look carefully where you want to mount the LED OCD board and ensure there is no metal or other object in the way
3) Keep in mind there is a USB connector on the LED OCD board and you want to ensure the mounting position allows access! Be very mindful of this! I suggest connecting the USB cable when determining where to place the board.

Now that I've done the install once, I expect another installation would take 15 minutes.

Before talking about LED OCD's behavior in the real world, let's set a baseline. I was playing around with LEDs in my Twilight Zone (with home ROM 9.4h). I replaced a few lamps in the lamp matrix with LEDs to see how they compared to traditional lamps. I was very unimpressed with the LED experience. This was the same poor experience that I have had with other WPC games that have LEDs in the lamp matrix. To me, there was terrible strobing when playing the game. The effect was most obvious when the ball rolled over an insert. Also, with LEDs installed, the fade effects were destroyed. Wham! It's on. STROBE. STROBE. STROBE. Wham! It's off. And so on.

Note that I didn't have any ghosting problems because ROM 9.4h includes the Williams change avoids ghosting.

For this experiment with LEDs in my Twilight Zone, I installed just a few LEDs in the following inserts:

1) GUM insert
2) BALL insert
3) "Lock 2" insert
4) Bottom pop bumper

The LEDs I used are Pinball Life's "Ablaze 3-LED #555 Wedge Base Lamp" with "Warm White" color.

I took a video to show this terrible strobing. A slow motion camera is required to capture these LED behaviors because the cycle times exceed the regular 24, 30 or 60 frames per second offered by normal cameras.

With the LED OCD board installed, the change in behavior is nothing less than amazing. The strobing is gone. The LEDs fade correctly. In short, the LEDs look fantastic. With LED OCD, you can take advantage of the various colors, diffusions, and brightness offered by the LED vendors and have none of the traditional LED ill effects. The slow motion video shows how great the LEDs look with the LED OCD board installed.

The following side-by-side video shows the standard WPC behavior on the left and the LED OCD behavior on the right.

The default behavior of the LED OCD is to drive all the lamps in the lamp matrix as LEDs using what is referred to as the 85% profile. However, each lamp can be individually configured to use 1 of 8 profiles. A profile allows for an 8-step brightness transition and delay that effects how quickly the 8 steps occur. The default 8 profiles are named:

1) Incandes (for traditional bulbs)
2) LED 25% (max brightness is 25%)
3) LED 35%
4) LED 45%
5) LED 55%
6) LED 70%
7) LED 85% (generally recommended brightness)
8) LED 100% (maximum brightness)

I learned that 100% isn't the default because it may cause ghosting. With this setting, the LED is enabled for as long as the lamp matrix allows. However, at the electronic level the various components (transistors, etc.) are analog and require a certain amount of time to engage or disengage. Because the LED 100% profile doesn't account for this, you may see ghosting in the lamp that is in the same row but the next column. The LED 85% profile plays it safe to ensure this never occurs.

To make these "OCD" level adjustments, you connect the LED OCD board to a computer using the provided USB cable. The software requires a Windows machine to run, so Mac users (like me), Linux users, or any non-Windows person will need to borrow a Windows machine or attempt to use a virtualization solution. The software isn't completely self-contained, requiring other packages to be installed (example, ".net" and a USB to RS232 driver).

I grabbed an older laptop with Windows 7 and gave it a shot. It didn't go smoothly and took about an hour to get working. First, the USB cable provided with the LED OCD is quite long and didn't interact well with my laptop. I switched to a much smaller one I had and started making some progress. Second, I had trouble installing the USB driver. After a couple of attempts and a few reboots, it started working. The LED OCD site has a good troubleshooting section that was quite helpful.

The LED OCD software is simple but effective. It comes with a set of data files that associate the lamp row/column number with the friendly name. If your game isn't listed, it's easy to enter the friendly names yourself. Alternately, you can use a generic data file where the friendly name is simply the same as the row/column lamp number.

With the WPC version of LED OCD, the software supports a "Pass-through" feature. With the press of a button, the LED OCD board effectively disables itself (although the signals still pass though the LED OCD board). This feature is useful to perform an A/B comparison of the original behavior against what your current masterpiece in progress offers.

Another nice feature is the ability to send a new configuration to the LED OCD board without storing it permanently. You can try out various combinations knowing that you can always go back to the original just by turning the game off and back on. When you have found something you like, you can permanently save it to the LED OCD board. Of course you can always save configurations to your local storage and retrieve them later.

I was pleased to find the LED OCD board saves configurations in an easy to figure out XML format. In my (unusual case) where most lamps are incandescent, I opened the XML file in an editor and did a search and replace to change all profile 7 (LED 85%) entries to profile 1 (incandes). That was much faster than manually selecting each lamp and then selecting profile 1. Instead, I only needed to manually change 4 entries (lower pop bumper, GUM, BALL, and "Lock 2"). Note: the video above was taken before I made this switch, meaning all lamps are being driven with the 85% profile.

I've played around 30 games of Twilight Zone with the LED OCD board installed. The strobing is gone, the fading is back. When I went back to the non LED OCD setting, I was amazed how terrible it looked. I can confidently assert that I would never think about doing a partial or fully decked out WPC LED game without the LED OCD board. It solves the inherent problems which occur when putting LEDs into a game designed for incandescent lamps and, in the process, removes the need to purchase any of the expensive anti-ghosting LEDs.

Hope this has been helpful.

More information about LED OCD, including purchase information, can be found at http://ledocd.comuv.com. Also, Herg is the inventor of LED OCD and is an active pinside member.

... Altan

Revision 1.01: Clarified purpose of Jumper/Breakout board
Revision 1.02: Added side-by-side video (and removed individual videos)
Revision 1.03: Moved to this web page. Added a few pictures and did slight reformatting.