pcb – Zitt's Blog

February 16, 2018February 16, 2018

Data East: Chase rope for Star Trek and Hook – Part 1

The Data East Chase rope lights used in two Data East Pinball machines (Star Trek: 25th) and Hook) are a huge problem on the game. So much so; that my Ebay-purchased game came with no rope lights at all. 🙁 This blog series walks thru my intention of recreating the chase rope lights – but made out of LEDs so they use less current, generate less heat, and can be used for decades without any issues.

First, some credit – Patofnaud on Pinside wrote a great tutorial on repairing these chase lights. I used this pinside thread almost exclusively for this blog series and if you happen to have the original rope lights; please take a look at his tutorial.

My game has no chase lights to repair; so I’m going to have to replicate the chase lights. I decided that I didn’t want to try and re-configure a standard off the shelf rope light because they likely don’t support doing a +12VDC common with three ground leads as discussed in Patofnaud’s post #1. Additionally; I don’t have exact specs of the rope light w/ regards to light spacing, diameter of the rope, ect. Since I’m going to have to recreate the lamps; I have decided to do a conversion to LEDs… specifically, using some “fairy light LEDs” which have recently become available on the market. I started by going to Hobby Lobby and buying a set of their battery operated lights using a 40% off coupon. Amazon has a whole bunch of alternate versions of this product… so you might be better off looking at Amazon if you don’t have a Hobby Lobby near you. B072NH2FQ1 seems to be a nearly identical match to what I got from Hobby Lobby.

These strings appear to be made of discreet 603 Warm White LEDs soldered to a common anode and common cathode. The LEDs are encased in a hot-glue like product to protect the LEDs from mechanical stress and help with water proofing. The fact that all LEDs are in parallel might end up being an issue because you can’t control the current into each LED. LEDs wired this way means that any variance in forward voltage drop (Vf) between the diodes in a series may mean that LEDs with low Vf would get more current that LEDs with higher Vf and could lead to premature failure of those leds. We’ll see long term if this becomes an issue with this project.

Taking apart the battery pack of the fairy LED light uncovered what I thought… A power switch and a 1/4W series current resistor of 15ohms. 3AA batteries supply 4.5V which is current limited by that 15ohm resistor. I did some quick measurements of the entire string and IIRC; the whole string took around 113mA with the 15ohm current limiter. I don’t recall what the series Vf was for the whole string.

Because the LEDs are powered with a 4.5V source; it becomes rather obvious that I can’t use these as a drop in for the 12V incandescent rope light originally in the machine. I’m going to need a conditioning circuit which will drop the 12V down to ~4.5V and provide some current limiting. I started by measuring my machine’s ramp to determine the approximate length of the chase lights. I measured with a piece of string to be about 15inches. The fairy LED lights have spacing of about 3inches which means that my largest segment would be about 15/3 = 6 leds, max. These 6 will become important for the series resistor calculations in the future.

Before I got to far into designing a voltage level shifter and current limiter; I looked at my machine. I couldn’t find the chase light connector shown in post #6 of pat’s thread. I couldn’t find it because the previous owner connected the left and right .156 connectors together with a Z-connector. That may mean there is now an issue with the chase light board (DE #520-5054-00 or #520-5054-01) in my backbox but I’m thinking connecting them together did no future damage since they are wired together in a OR configuration in the schematic manual. Meaning OUT1A is tied to OUT2A via the Orange/Black wire in the cabinet (See post #7, picture 1). I decided that Zconnector is a good place to put my Incandescent to LED converter circuit. My plan is to replace the Zconnector with a board which does the conditioning.

I decided I was going to abuse a LM1117 style +5V regulator to voltage shift the +12V common down to +5V common then use a series resistor to current limit for the LEDs. Since +12V is the common; I’d need to do a wired-OR configuration with a set of fast Recovery SCHOTTKY diodes to the OUT connections on the chase light board. I have no idea if the LM1117 vreg can operate properly with a v+ common connection; but I suspect it will have no issue given the frequency a which the lamps operate. Additionally, given the previous incandescent lamps had issues blowing the NPN Darlington arrays on the lamp chase board; I figured putting in a PTC resettable fuse would be a nice addition. My circuit took shape in eaglecad using Digikey as a part reference.

Here’s my original Fab A circuit, keeping in mind this is untested – but I retain all rights to this circuit for the moment:

Chase Light to LED — DE Chase LED conditioner

Some theory of operation:
D1&D2 provide some polarity protection – for paranoia. D3-D8 are the Schottky diodes which provide wired-OR back from the ground of the +5V regulator (U1) back to the chase light board’s OUT* connections.
C1, C2, C3 provide some filtering for the +5Vreg to help it maintain stability with the wired-OR configuration. D9 provides some additional protection for the Vreg – probably not needed; but extra insurance. R2 – R7 provide the series current-limiting resistors for the various LED strings. Why the different values of 13.3 vs 16.9? Well; my quick napkin calculations shows that there may be 5 or 6LEDs on the longest string and then one less on the shorter strings. I plan on connecting the longest string on the 1A & 1B lines while the shorter strings (with the higher resistors) will be on the others. F1-F6 are the resettable PTC fuses. The bidirectional LEDs at the bottom are monitoring the output of the chase light board to give me an indication the chase board is working properly. They will chase green if working properly. I basically created a small “Z-connector” board to condition these LEDs but also added some small connector boards to help me interface from the LED strings to a simple 4 pin 0.1″ pitch latchable connector. The idea is these smaller connector boards would be fixed to the end of the “rope lights” and allow for a quick connection.

A little background on the Series resistor calculations. Basically; Vf isn’t known for the parallel LED strings. You can’t measure Vf with the diode setting of a Digital volt meter which btw; my favorite is a Fluke 87 series meter. Vf according to my DVM is around 2.4V and we know that no current white leds operate at 2.4V for 20mA. Since I don’t know which LED the chinese put in these strips; I had to make an educated guess. To do this I went to digikey.com and drilled down on warm white 603 LEDs, downloaded the table (using the button near the bottom of the page) and then imported the data into excel so I could get an average of the Voltage – Forward (Vf) (Typ) column. I calculated Vf ~= 3.23V. Armed with Vf, and the knowledge I wanted to operate the LEDs near their 20mA operational current so they would be their brightest I was able to calculate a theoretical series resistor. Here are the “knowns”:
Vf = 3.23.
Each LED should operate at ~18mA.
With the ground diode in the Vreg path… assume Vfdiode = 0.4V. This would cause Vout of Vreg to be 5+0.4V, or 5.4V.
“ground” will be thru the UL2003A darlington on the chase driver board. VCEsat = 0.9 min.
Assume 5 leds needed for longest string and solve using Ohms Law. R=V/I.
V = 5.4 – Vfled – VCEsat
I = 18mA * numOfLEDs in string or 18mA * 5
R = (5.4 – 3.23 – 0.9) / (5 * 18mA ) = 14.11 ohms
Subtract off typical Fuse resistance of 0.9ohms and you arrive at ~13.3ohms. Repeat the calculation for a 4 led string and you arrive at ~16.9ohms.

The only “gotcha” with this theoretical calculation is that what happens to the LED if we are drawing near 18mA? There’s no real ground plane or PCB to draw heat away from the LED. The only “heat sink” is the hot glue used to encase the LED and the wire LEDs connecting the LEDs. I’m hoping the low duty cycle of the LEDs will help keep thermal runaway in check. This is something I’ll have to watch in the final assembly. If LEDs start dying… we’ll know it’s either getting too hot… or the parallel LED VF vs current is a problem.

Here’s the Fab A boards as committed to OSHPark. This is their render of the boards as I don’t have them back from fabrication yet:

I’ll post more on the circuit boards in Part 2 when I get them back from OSH Park and have them built. We’ll see if my little experiment bears fruit.

Now onto the actual chase lights themselves. I thought about using polyurethane blue tubing from Granger.com as I posted in Pat’s Pinside thread on post #19. But honestly, I don’t really feel like the blue rope light fits the ST:25th theme very well. To me; it looks like some attention getting feature to draw in the eyes of a would be quarter-dropper in an Arcade. Not that is a bad thing; I just figure since I’m not going to an have original rope light assembly with the proper Light spacing… I might as well try to make it fit the theme a little better. If not blue, then what? Well Clear is definitely an option… but it won’t really hide the led wiring very well. I had a lot of extra 1/2″OD, 1/4″ID rigid Acrylic tubing left over from the guide plastics from Star Trek: The Mirror Universe custom pinball project. I was thinking of doing that with some custom Acrylic etches on the tubing. The problem is that Techshop.ws failed due to piss-poor-Management so I can’t really go there to use their rotary attachment on the Tortec. My new-to-me Epilog Laser doesn’t have a rotary Attachment, yet. Not sure what I’m going to do about that yet… Even if I get a Rotary… what would I put on the Tubing? Then there’s the issue of bending it properly… which shouldn’t be too hard given the Youtube videos for Hard Tubing in water cooled case tutorials.

Then I stumbled across ENT Corp on Ebay who seems to have colored versions of this rigid tubing available in cut-to-order. I went ahead and ordered 6 pieces of the smoke acrylic tubing custom cut to 15.25inches. After I experiment with the etching and try my hand at the clear tube bending… I’ll proably finalize the chase lights using the smoke tubing on the final machine.

That’s it for Part 1 of this blog series… I’ll start Part 2 when I get some tubing experiments done and/or when I get the PCBs back from OSHPark. For now, Peace and Long life…

July 8, 2017July 8, 2017

Announce: Star Rollover LED boards

We are pleased to make a delayed announcement of a product which we’ve had in stock for almost a year. This Star Rollover LED board fits on the underside of your Playfield under a Star rollover assembly and will bathe the Star Insert is lower power LED light. With this product you can replace the inefficient horizontal lamp socket and incandescent light bulb with this board:

Each board provides 4 natural white LEDs in a non-polarized light from either a 6.3V source. Because the board has a built-in rectifier bridge; you can supply power from both a 6.3VAC GI circuit or ~6.3VDC controlled insert. You can even control the brightness via a microcontroller PWM signal or from one of the new DIY control systems such as the PROC or its PD-LED driver board.

The design also features a brightness resistor at R5 to allow you to dial the brightness to your desired level. A hole in the center of our PCB allows the actuator to work from the insert to a standard Leaf switch typically under the insert.

A typical installation may require a set of #6-32 x 0.25 inch wood screws so you can bolt it to the back of the playfield under the star rollover insert. Electrical installation is super simple; simply solder the GI connection from the old horizontal lamp socket to the JGI connection, or jump to the nearest GI socket as we did in our machine below. Here is an example installation we did on our Star Trek: The Mirror Universe custom pinball machine.

Source: My Star Trek: The Mirror Universe custom machine

This populated PCB is available for immediate shipping in Our Online store @ http://pinball-mods.com/oscom/modifications-do-it-yourself-star-rollover-led-p-17.html

August 23, 2016August 23, 2016

Announce: Stern Star Trek Nebula Mod

We are pleased to announce the official launch and immediate availability of our Nebula Backbox lighting kit for the Stern Star Trek Pinball Machines. While the product has been available on our site for almost a month; we just completed our detailed step-by-step instructions to aid you in installing it in any Stern Star Trek Pinball machine – enabling us to make the product official with this announcement.

This kit comes with a set of three Printed circuit Board Assemblies (PBAs) which you snap apart and install behind the stock nebula plastics on a Pro, Premium, or Limited Edition pinball machine’s Back board. Like our Kelvin product; it is 100% compatible with the PWM circuitry on our GI Dimmer so the customer can dim or control the Nebula lighting for both Normal and Klingon MultiBall modes.

This kit is a Do-It-Yourself mod requiring assembly using the attached step-by-step instructions:
Stern Star Trek: Nebula Backboard Upgrade
and may take a couple of hours to complete.

Here’s the stock, unlit Nebula backboard on the Author’s machine:

Here’s the Nebula backboard with our DIY Nebula kit installed:

For More information; please visit our online store’s product page for more detail and an order link:
http://pinball-mods.com/oscom/game-specific-products-stern-star-trek-star-trek-nebula-p-15.html

September 1, 2014July 14, 2021

Chicago Dynamic Industries Sound Card (EM Gun Games)

A fellow Arcade collector sent me this Private Message a few months ago on the KLOV forums:

I’ve got an old EM Chicago Coin “Shoot Out” gun game. Works great, but came without the sound PCB that generates the gunshot sound. They also made a “Coney Island” game that used the same sound PCB, but I’ve been searching for ~5 to 6 years for a used board with no success.

The problem with the soundcard is it used older End-Of-Lifed (EOL) transistors that can’t be easily found. I offered to help him design a PCB and BOM which would duplicate the sound and provide a “modernized” BOM which could be ordered off Digikey.com. He reported back that after some rework to the pinout; the card worked as expected. As a result; I’ve incorporated the rework (ie corrected the design)… and have provided the materials here for the public to duplicate and use for any older machines which are missing (or has a non-functional board) the EM Gun Soundcard used in these games.

The major changes to this board vs the original are as follows:

The PCB is double sided with large ground plans to aid in noise reduction.
Additional caps are placed on IC1 (LM380) and the Zener diode regulators to help improve the immunity of the circuit to noise. CIC1, C22, C23 – all .01uf.
PCB’s has both a top and bottom silk screen:
1. Top has values and reference designators to aid in assembly and debug.
2. Bottom has used edge fingers labeled as well as the legs of the transistors; again for debug.
All transistors were replaced with 2N3904 NPN transistors which are very much still in use today. The single PNP was replaced with the 2N3906.
Test points for the 18V, 12V, 9.1V, and ground rails are provided for easily troubleshooting the voltages on the sound board.
LEDs provided for the 12VAC and 30VAC lines coming into the sound card. Again quick glance that there is at least some voltage going into the sound board.
Although not needed in a real game; two mounting screw holes are needed if you have a non-standard installation.

I’ve decided release this design to the public under the TAPR Non-Commercial Open Hardware License which indicates:

You may make products based upon this design, provided you do not make more than ten units in any twelve month period for your personal use.

If you agree with the license terms; Schematics and BOM lists are posted here under TAPR/NCL license:
Rifle 444-310 Soundboard Package

Ordering should be easy: https://oshpark.com/shared_projects/6GKvZu4s
The boards are $67-ish for a set of 3 PCBs… and they are high quality. Gold plated fingers, two layer, silkscreen on both sides. It’s the cost of doing prototypes. OSHPark usually get the PCBs back to you in about 2 weeks.

BOM Cost from Digikey came to a WHOPPING $17 for one board. My advice is to take the BOM and multiply it by 3 in Excel or some other spreadsheet app. It’s usually cheaper to by 50 or so of the resistors. IE in one qty; they are 8cents… in 50s they are > 3cents. I usually buy 50-100 of each; just so I have them around when I prototype on breadboards and such.

The PCB is very compact; it was done this way to save on the prototype PCB sq inches cost. If you find some of your components are tight; you might try laying them similar to this:
http://pcb.bastl.sk/?page_id=50

Here’s a picture of the assembled board:

Hope this helps the EM Gun collectors out there. If it does… please drop me a comment letting me know it’s done some good!

April 12, 2014August 14, 2016

EagleCAD Tutorial: Custom shaped PCBs

As seen in the Worklogs for the Star Trek: Mirror Universe Pinball project; Making custom shaped PCBs in EagleCad isn’t all that difficult. With a CAD file; one can make some pretty unique shapes to fit the project you’re working on. This tutorial aims to show just how easy it to create the perfect shaped PCB. The Author used this technique to create custom LED boards in the Mirror Universe project which replaced all the Switched Illumination sockets on the underside of the Playfield.

Pre-Requisites:

EagleCad 5.11 or higher (tutorial written for 5.11).
DXF2SCR from micromagic systems. (It’s Free and Awesome)
A DXF file to convert. Scroll down for a .ZIP file containing files used in this Tutorial.
About 10 minutes to do your first PCB outline.

Making the PCB shape

Please click the pictures below to be taken to a higher rez screen capture/picture.

1) The toughest part of this tutorial is creating the CAD file (DXF) which will serve as an input to the DXF2SCR tool. The author uses the Free GPLed version of QCAD to create DXF files. Teaching QCAD is beyond the scope of this document; but the basic principle is that you want to create the outline of the PCB in CAD via a series of curves or lines. Make sure you put in any mounting holes you want … and maybe even some documentation layers; like a center line or critical component locations. This allows your PCB to be “exact” without having to move holes, lines, or arcs in EagleCad.

Once you have the CAD (DXF) file; you can proceed to covert the file using the DXF2SCR tool. Start by opening the tool and selecting the input DXF file and the output .scr file. The SCR file is used later to “draw” on a blank PCB canvas. More on that in a bit. Make sure you match the units in which you created the DXF file. In my case; I almost always use inches. At this point I basically leave everything else at defaults of 1mil (0.001 inches) line widths and no offset. I leave the line with at 1mil because I can change the width in eaglecad based upon whatever I’m trying to accomplish. For much of the file; it’ll be an outline – and most people recommend you leave the outline as a “hairline” so the fab house doesn’t “charge” you for the additional 8mil width of the outline. Once you have the setup complete; click the Convert button on the left.

If the conversion is successful; you should see the number of lines, arcs, circles, converted along with a Complete message. If you get that, you can move on to the next step.

2) I start by opening EagleCad and Selecting File/New/Board… This gives me a blank canvas to create the outline on. I’m fairly sure I’ve done this on an already created board; you just have to be careful how you move the outlines and such with components are in the way. By far tho; it’s easiest that you either create the Schematic after the PCB outline, or at least make sure you don’t place parts “inside” the normal rectangle when creating the PCB from schematic.
You need to run the script created in step 1 above. This is done from the File / Script… dialog. Select the SCR you created in step 1 (or in our case rollover2k.scr) and hit open.

3)At this point EagleCad should begin executing the script drawing your arcs/lines/circles on the Dimension layer (layer 20).

At this point you should begin to move the documentation shapes to either tDoc or bDoc and then later move them to tSilk / bSilk if necessary. You want to leave the outline and any mounting holes as 20 Dimension Layer… as that is what the gerber generator uses to generate the .oln file when you commit this design to the PCB Fab houses like OSHPark.

If you do transfer some of the lines to a silkscreen layer or even a copper layer; you should remember to change it’s width to the minimum tolerance allowed by your FAB house. In the case of a 2layer OSHPark file… it’s probably 8mils (0.008 inch).

With the steps outline above; you can basically use the CAD file as an input to even align LEDs on a evenly spaced spoke pattern or really any desirable orientation.

I’m providing the input files here for you to follow along with the steps above. Download it here:
Shaped PCB Tutorial Files

This PCB outline was used in the Star Trek: Mirror Universe as the GI lighting for the Star Rollovers. The star plunger fits inside the center hole and the two holes on the side provide mounting to the underside of the playfield. These PCBs light the Rollover from the underside with Red LEDs.

Hope this tutorial helps!
John

October 18, 2012

Modernized Williams Serial Kit

For the last couple of months; I’ve been working on a redesign of the willams printer kit for my Star Trek: The Next Generation pinball. Much of the work as been in the Complex Programmable Logic Device (CPLD) which is in 256BGA form. Why a CPLD? Long term I intend to replace the Intel 8251A USART (which is becoming increasingly difficult to find and expensive) with a “soft IP” core. The only pseudo-free 8251A core I could find was by ALTERA. They allow free use of that IP; but only as long as you put it in an Altera device. I’m ok with that; but to be honest, I really do not like the company. My first tech-support request was “refused” because I wouldn’t provide them with a company or university name. I’m a hobbyist for crying out loud; support your damn products or bite me. If I had any other choice I’d go with another CPLD/FPGA company for this reason alone. But I digress…

This is a 1mm pitch BGA – needed it because the whole design requires logic blocks which only come in bga form factors. 🙁
I was forced to go to a 4 layer PCB to get the smaller 13mil drill sizes for “escape routing” the bga signals. I designed the pinout of the BGA to mainly use the outside peripheral pins of the bga. Pinouts were made to make for easier routing to U3 (Ti’s 74LVCH16T245), U2 (Ti’s 74LVC4245A), and U6 (FTDI’s FT232RQ) chips.

The design used the Ti 245s to translate between the MaxV’s VCCIO of 3.3V and the WPC/USARTs system voltage of 5Vs. Linear 1.8V and 3.3V LDOs from Ti drive the MaxV VCCINT (1.8V) and VCCIO (3.3V) pins. 3.3V also drives the other support chips; the UART->USB (FT232RQ) and the RS232 charge pump (U5/MAX3242UI). Logic in the CPLD controls “enables” to the MAX3243 from the USB chip; so that if a laptop/computer is plugged into the usb (J710U); the rs232 port at J710 is “off”.

This leaves a question; Why have the i8251A device onboard. This is a debug feature. Given I’ve never done a CPLD or FPGA design before; I’m thinking it may not work “right out of the shoot”… so I’m providing myself with a short term verification feature; where I can prove a real 8251 works … but there is a bug in the IP core (or my implementation of it). Long term; my goal is to de-pop U1 and U2 to reduce bom costs once the design is proven functional.

The FabA schematics and FPGA high level schematic is posted in the PDF below:
Williams Serial Printer Kit (pre-debug)
I retain all rights to the implementation and schematics.

The top layer board will look something like this:

When installing in the pinball machine; one would disconnect the main cpu ribbon cable and plug it into J701B. The connect a short “jumper” ribbon cable from the cpu board to this board via J710A.

I got to be honest; the bga on the board is very scary. $20 a piece… and BGAs aren’t really known for their ease in the DIY workshop. But; it’ll be fun to see how pcb assembly goes.

I hope to order the PCB shortly… then be “waiting” for the batch pcb service to pool with others. I may quote with PCBFabExpress.com as they seem to have very reasonably priced 4 layer boards with a quick (compared to batchpcb, 5 day turn).

Next step after ordering boards and BOM for assembly; is to get back to the visual pinmame source code in order to begin “simulating” the printer kit from a software prospective. Long term; I want to test the ROM hacks to dump the high scores via serial port and the Serial kit. Once I’ve tested the roms in pinmame; then I can commit them to the real machine. I did have some success compiling pinmame from source; but for some reason I get an assertion about filetypes when running the compiled images.

I’d also like a benchtop WMS debug system… thought about using a P-Roc – but not sure if close enough to the original WMS board to be compatible with the WMS printer kit.

January 5, 2012January 6, 2012

FreePlay 555 Coin Circuit

My Sega Star Trek Captain’s Chair is destined to be present at the 2012 Texas Pinball Festival. As a result; the game needs to have a FreePlay feature (IE a way for the public to play the game without needing quarters). I know Sega Star Trek has a freeplay rom hack available; however, at this moment, VectorLabs isn’t supplying freeplay roms with their devices. I haven’t spent enough time with the multi-vector boardset to determine how easy/hard it would be to convert to Freeplay. As a result; I wanted a simple inexpensive way to credit up the machine when the user pressed the Start button (1UP).

I toyed with the idea of using a cheap 8pin ATMEL microcontroller; but decided a simple 555 timer could be developed to do most of the heavy lifting. In the end I decided to go with a dual 555 timer (NE556) in a cascaded mono-stable configuration. The circuit features:

PowerOn Reset to “credit up” a single credit when power is applied to the machine. Jumpered feature.
Ability to drive COIN_NO signals
Ability to “interrupt” COIN_NC
Can be alternatively stuffed for AC power supplies (6.3VAC GI circuits in Pinball Coindoors).
Jumper configuration to “disable” circuit.
Barrier Diodes to help prevent “installation error”.

I have decided to release this design under to the public under the TAPR Non-Commercial Open Hardware License which indicates:

You may make products based upon this design, provided you do not make more than ten units in any twelve month period for your personal use.

Schematics :

Click to view FreePlay 555 Schematics in PDF

The first timer conditions the active low switch connected to J2-3 (1P [aka the start button]). On the Sega vector hardware; this signal is tied high to 5V via a 2.2K pullup resistor. The start button connects momentary grounds at this signal. The Trigger on the 555 timer is also triggered when the voltage at pin 6 transitions below 1/3VCC. D4 protects the cpu board by preventing current from flowing back into the cpu board. This timer “de-bounces” the switch which sends a single long pulse via OUT1 (pin 5). This timing is created by TA = C6*R4 or ~242mS. I’ll explain the function of R5, JP3, D1, and C7 later.

OUT1 drives the “armed” LED to notify the user/debugger that a “start” pulse was received. OUT1 is coupled to Timer2 via C4 and R6. The purpose of these components is to provide a “negative” trigger pulse at the falling edge of Output. Timer2 then drives based upon TB = R1*C1 or ~60mS. This is the coinup signal which is sent to the coin circuit of the arcade machine. 60mS was derived from measurements of my acutal Star Trek Captain’s Chair by dropping a quarter into the slot via an Oscope.

OUT2 (pin9) drives Q2 and Q1 respectively. When not processing “start/coin up signals” Q1 is “active” providing conduction between the CPU Board and the Switch (PNP active when base is low). On the sega star trek; I found that I had to interrupt the NC signal of the switch in the coin door to get the cpu to “detect” a coin from our COIN_NO (J2-4) – Q1 provides this interruption. Speaking of NO, Q2 goes active when OUT2 outputs a high… which drives a “low” to the COIN_NO. In the Vector machine; COIN_NO is pulled high thru another 2.2k resistor and drives the !Set signal of a Set/Reset Latch made out of NAND gates. Incidentally; the NC signal drives the !Reset signal. The Q output of the NAND gate drives the clock of a D latch which drives the interrupt pin to the cpu board.

I promised to talk about the R5/C7 combo. These components control the “poweron” coin up timing. TpwrCoin is a function of U2’s timing and R5*C7 which is basically ~1.2seconds. U2 is a ActiveLow microprocessor supervisor IC. It monitors the 5V powersupply and holds !RST low for about 150mS. This allows the top of R5 high thru a 5.5k internal pullup resistor when the device is non-active. Meaning U2 will drive RST high on each timer after 150ms once the 5V rail is at least within 15% of the 5V target (4.25V). This effectively provides a “credit” signal to the game about 1.2seconds after the power button is pressed (for initial credits). In theory; this circuit can be disabled by removing JP3’s shunt.

JP1 provides a mechanism to “disable” the freeplay circuit. IE virtually removing the circuit from your game. Use this in position [2-3] to disconnect the timers from the bases of the transistors which should return the game to normal operation. IE if you want to start charging people money. I plan to use it to enable money when I take it for charity work.

Please be aware; this circuit still allows the coin shutes to work… even if the circuit is enabled. This was intentional.

The PCB is designed as a two layer PCB with through-hole parts on the top layer to enable those less skilled with a soldering iron to build the circuit.

FreePlay 555 Fab A Top Layer w/ Silkscreen

FreePlay 555 Fab A Bottom w/ Silkscreen

For those without PCB layout tools; a bare PCB is available from the batchpcb service for under $14. You can purchase the boards from this link:
http://batchpcb.com/index.php/Products/75967

The Bill Of Materials (BOM) of the board is available from Digikey for $9.02 (as of the time of this post). A bom is included with the schematics PDF above, but An XLS file with the digikey part numbers with the complete package of the materials above as a single download: FreePlay555_pkg

The author’s prototype was built from mostly RadioShack parts he had in his parts bin including the breadboard. He intends to replace this with a PCB from batchpcb in a few months.

Installation note: You need to make sure this circuit used the same voltage rail of your cpu board. The authors’ G08 wiring harnesses did not follow either the Cockpit (which is correct) schematics or the Upright harness (which is incorrect). The J4/P5/p12 harness shows that the cockpit connects the coindoor lamps to the +5V rail at P5 pin6 and pin8. However, The author’s harness had it connected to the -5V rail which is BAD and will prevent the circuit from working properly (and possibly damaging your machine). The upright schematic shows that +5 and -5V goes to the lamps for 10V… also bad.
Either wire up a new +5V signal to this board; or correct your wiring harness to be like the schematics of the cockpit. Seriously – go double check it.

I wired in this circuit into the coin door harness so the board can be bolted to the inside the door. You’ll need to “cut” the NC wire of one of your coin switchs and put this circuit between it at J2-5 and J2-6. Then wire in the NO signal at J2-4. The Start Button goes to J2-3, the +5V rail to J2-1, and Ground to J2-2.

The circuit works as expected in my machine…. providing an inital “Free” credit upon powerup and then providing additional credits each time the start button is pressed (after the game starts). If you want more than one credit; the circuit can be redesigned; or you can press start multiple times during your “inital” game. 😉

I’m fairly sure this circuit can be adapted to any arcade machine. I provided a bridge rectifier stuffing option at B1 to enable “AC” voltage inputs from 6.3V AC. Or Jp2 can be “bridged” with solder to enable 5V to via the D3 shottkey diode. I plan to test this circuit on my Bally Star Trek Pin once I get the PCBs back.

Enjoy… I’ll post more pictures when I get the PCBs back from batchpcb.

October 16, 2011February 7, 2020

Star Trek Red Alert Audio Trigger

For those following my Sega Star Trek Captain’s Chair restoration; I replaced all the bronze plexiglass with some newer Transparent Grey Acrylic which did not have scratches. One of these peices was featured in the Restoration Worklogs at AustinModders.com or KLOV.com where I custom laser etched schematics of the Klingon D7 crusier and the Nomad Probe:

At the time; I predicted that the etch would not show up well once it was installed in the chair:

Sadly; that prediction came true. As a result; I decided I wanted to find a way to lite the etch with LEDs. SeaWolf on KLOV mentioned to me that he planned on lighting his Chair with some red lights to give it a “battle stations” feel while playing… I told him at the time; I’d proably steal his idea … which is the update your reading about now.

To light the Etch; I decided to create a Red Light bar under the custom Black Corner piece I created when I destroyed mine. But before we go there; I had to decide HOW to create the light. I decided I wanted mine to “activate” when a new game was started and then automatically turn off when the game was finished. I don’t have access to the Star Trek source code; so a software hack seemed problematic. Hummm… What’s the next best thing? Audio! With the exception of attract speech from Scotty and Spock; the instructional videos are silent. So I decided I wanted my machine to go into “Red Alert” Mode when real game play audio starts.

The Red Alert Audio circuit was born. 😉 I spent several nights running spice simulations and came up with this circuit which I’m donating to the public under the TAPR Non-Commercial Open Hardware License which indicates:

You may make products based upon this design, provided you do not make more than ten units in any twelve month period for your personal use.

Schematics :

Click to view Red Alert Audio Schematics in PDF

The only IC in the circuit is U1, a dual JFET opamp – TL062P which operates from a single supply at ~12VDC. U1A makes up a 13.5x amplifier to amplify the ~100mV speaker signal from J1-1. The amplifier operates in non-inverting mode; so the gain is derived from 1+R9/R7. R6 is a series resistor intending to limit the loading of the audio amplifier (prevent distorition) and impedance match closer to the that of the 8 ohm speakers present in the upright version of the Sega Star Trek. D1 and D2 provide over/under voltage protection for U1A; limiting pin3 to 12+0.7V and ground (-0.7V) – a real possiblity given the audio amp is powered from a split supply @+/-24V. C2 is a DC blocking cap to prevent our single supply opamps’ bias voltage from loading the sega’s audio amps. R10 provides a high resistance path to our bias voltage of ~6VDC.

The second opamp (U1B) operates in comparator mode; comparing to the voltage divider made up of R4 and R5. V+U1B is (R5*Vcc/2)/(R5 + R4) or 100k*6V/(110k) or 5.46V. If we have no input audio; Pin1 floats above our bias of 6V; forcing the comparator to drive low providing no voltage to the remaining circuitry… effectively an off. Once the amplified input exceeds (6V-5.46V) 546mV; charging current is sent to D3. For those paying attention; 546mV /13.5V/V… means the input voltage at J1-1 must exceed 40mV regularly to charge the capacitor at C1. Empircal evidence on my Chair indicates that “Thrust” alone generates ~100mV at Pin3 of the U1A. Ofcourse your mileage may vary depending on a number of factors including your current volume level.

Once Pin7 of U1B begins to provide a voltage it is channeled to the RC circuit made up of R2&C1. Since the comparator swings between ground and ~+12VDC; it take nearly zero time for the capacitor C1 to charge to full capacity ~R3*C2 or 3.5mS. D3 provides blocking to prevent U1B from loading the RC circuit and R3 provides load resistance to prevent “shorting” the opamp to ground while C1 charges. Once U1B turns off; the RC circuit becomes a voltage source for M3. R2 slowly drains C1 meaning Toff = R2*C1 or ~8.6seconds. This time delay is necessary to ensure the red alert bar doesn’t go off in the middle of a game… IE between Sectors.

R1, Q2, and Q2 make up a BJT Current Mirror with M3 becomming the “on/off” switch for said mirror. When the gate exceeds approx 3.3VDC; M3 turns on conducting R1 to the top of Q1. Since we tied V+ (J2-1) to the 12VDC PSU in the sega G08 Card Cage; We can calculate the reference current into Q1. Iref is (V+ – Q1_VEB)/(R1 + M3_Rds); assume Q1_VEB=0.7V and M3_Rds from datasheet is 5ohm max. Iref is (12-0.7)/(681+5) or 16.5mA. Given Q1=Q2; ILED @ Q2 (J2-2) is 16.5mA; meaning we now have the means to pull 16mA thru up to 5 LEDs. Given my planned use is ~2V super bright Red LEDs; we can fit at most 5 LEDs in the leg of the current mirror before we run out of voltage. Q4 is a secondary Current Mirror “channel” to allow me to drive another 5LEDs… so I now have a means to drive 10 LEDs in the Red Alert Lightbar.

The powersupply for the circuit is made up of D4, C4, and C5. D4 provides a blocking diode incase I screwed up the wiring. C4/C5 provide filtering given the 12VDC source is about 12feet away. D5, R11, and Q3 make up a simple linear regulator to derive the 6VDC (VCC/2) biasing voltage to U1.

Whew! – clear as Mudd? There was some detail there; hope some of it made sense. 🙂

The PCB is designed as a two layer PCB with through-hole parts on the top layer to enable those less skilled with a soldering iron to build the circuit.

Red Alert Audio Fab B Top Layer w/ Silkscreen

Red Alert Audio Bottom w/ Silkscreen

For those without PCB layout tools; a bare PCB is available from the batchpcb service for under $15. You can purchase the boards from this link:
http://batchpcb.com/index.php/Products/70379

The Bill Of Materials (BOM) of the board is available from Digikey for under $6 (as of the time of this post). A CSV file with the digikey part numbers is here: RedAlertAudio_FabB_bom.csv

Here’s a package of the materials above as a single download: RedAlertAudio.zip

Here is the the prototype assembled:

Now I needed to find a way to mount the 10LEDs under the black corner piece. This was done by laying out a 1inch strip of Red Acrylic in Corel Draw and laser cutting said peice:

I decided the LEDs would be wired as a “circuit” on the Red Acrylic. My LEDs are 5mm in size; so these would edge light the 1/4inch red acrylic. I put in 40mil traces in the design which are etched on the laser cutter to give us groves to put the LED leads in:

5 of the LEDs were placed on the right side with the Cathode of LED1 at the far left side end. LED2’s cathode is wired to LED1’s Anode repeating until the LED 5’s Anode which is then wired back to the left hand side. When the LEDs touch; they are soldered in place. When they don’t touch a piece of Adhesive red rework wire is soldered between the leads:

The Anode is wired back to the left side by the red rework wire. The Anode of the second 5 LEDs is then tied to the Anode of the first 5LEDs and the cycle repeats in reverse until the cathode of LED1 is at the right most side. It is then tied with a peice of Black adhesive rework wire back to the left hand side. This provides a “single” connection side for all the LEDs.

Here’s the finished Circuit on Acrylic:

I twisted about 12feet of yellow and black wire together and wired it into the connector on the G08 PSU at the +12VDC lines; it terminates on pin 1 of J1. The LED connections also terminate on J1. I drilled a couple of 7/16″ holes on the right side of the chair near the speaker using the circuit board as a template; making sure not to go all the way thru the side wood – just deep enough for the hex standoff threads. I then tapped these holes with a #6-32 tap; and placed a set of #6-32 hex standoffs in the holes. A couple of #6-32 screws and the board is now mounted at the top of the chair:

I found that I didn’t need to wire the speaker ground from the PCB to the speaker; instead only wired from the + side of J1-1 to the + side of the speaker. A small 7/16″ hole was drilled thru the wood to allow the 3 rework wires to come thru to the PCB. Given rework wire is fragile, small, and solid core; I put about 3″ of stranded 26 gauge wire before the crimp style connector. All of the excess wire was tye-wrap anchored to side of the wood -leaving plenty of “service loops” to enable future changes.

So… was it a success?

Does it Activate as expected?

While the circuit works as expected; it fails to deliver the intended effect of lighting the Window etch properly. Still a cool effect; one I’ll keep… but I’ll need to give the etch lighting some more thought. I’m also going to try and increase the current thru the LEDs by adjusting the R1 reference resistor. The LEDs should be able to handle close to 20mA (package says 24mA max); so the increase in current should brighten them up a bit.

November 3, 2010September 9, 2011

Gottlieb Open Source PopBumper Driver Board?

I just successfully; built my prototype Gottileb PBDB design and have tested them in my Black Hole Pinball project at AustinModders.com. I have decided to release this design under to the public under the TAPR Non-Commercial Open Hardware License which indicates:

You may make products based upon this design, provided you do not make more than ten units in any twelve month period for your personal use.

The design include the recommended fixes from marvins u-fix it site including both Power and Fire LEDs. It also features protection circuitry including a barrier diode and a resettable fuse to try an prevent damage to other devices in your machine. The Logic on this board is Low-Voltage tolerant; so it should operate in situations where +5V is low.

The design uses the more readily available and cheaper TIP120 transistor for driving the popbumper coils.

Schematics :

A8_PBDB_Bsch — Click to view GTB PBDB FabB Schematics in PDF

The PCB is designed as a pair; IE you get two boards in the same foot print as the original. I designed it this way to minimize PCB cost, aid in building multiple units, and enabling the boards to be snapped apart after assembly. The board is a two layer PCB with mostly surface mount parts on the top layer to minimize PCB real estate. The TIP120 driver transistor is mounted on the bottom layer again to keep the board size low.

PBDB_B_Top — PBDB Fab B Top Layer w/ Silkscreen

PBDB_B_Bottom — PBDB Bottom w/ Silkscreen

For those without PCB layout tools; a set of two bare PCBs are available from the batchpcb service for under $28. You can purchase the boards from this link:
http://batchpcb.com/index.php/Products/44762

The Bill Of Materials (BOM) of a pair of boards is available from Digikey for $10.70 (as of the time of this post). A CSV file with the digikey part numbers is here: A8_PBDB.bom.csv

Here’s a package of the materials above as a single download: GTB_A8_PBDB_pkg.zip

Here are some pictures of the prototypes assembled and installed:

Edit jzitt 11/4/2010 to add batchpcb order link