Step 1 - The power supply
Warning: If you intend to resurrect old Bally/Stern pinball machines, you need to know how to solder. If you don't know how, you should learn or consider finding another hobby. There are several excellent videos on youtube that demonstrate proper soldering techniques. Do not be afraid.
Preamble: I find repairing pinball machines a lot of fun. There are, however, certain aspects of pin repair that are decidedly un-fun. Over the years I've determined that rebuilding Bally/Stern power supplies is one of those tasks that is basically zero fun. It's time consuming and a hassle because it involves *a lot* of desoldering and ensuring that the through-holes are good and clean. And when there are very nice and relatively inexpensive reproduction boards available through Rottendog and Great Plains Electronics, rebuilding these boards is pretty unnecessary. For the purposes of this task, however, and considering I want get this project up and running without spending a whole lot of cash, I figured I'd just rebuild the power supply that came with the game.
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Here it is as I found it (sorry for the crappy pics):
In the above pic, you probably can't see that J3 is broken in half and one of the wires is soldered directly to the header. All of the fuse clips are tarnished badly and a couple have rusted. The board isn't actually secured to the mouting plate, which means that heat transfer from the bridges isn't taking place at all, which means that if the game was working prior to now (which it wasn't) the bridges have a very short life ahead of them.
Tools and parts required for rebuilding a power supply include the following...
Tools:
- Soldering station
- Solder
- Desoldering pump or desoldering station
- A DMM
- A crimper
Parts:
- 3 x 400V, 35A, Bridge rectifiers w/ wire leads
- 12 x Tin plated beryllium copper, high current fuse clips
- 1 x 20 pin .156" header strip, 1 x 10 pin .156" header strip, 1 x 8 pin .156" header strip (Or just buy
THESE and cut them to size)*
- 1 x 20-pin .156" female housing, 1 x 10-pin .156" female housing and 1 x 8-pin .156" female housing*
- 4 x 1n4004 or 1n4007 diodes
- 1 x 600 ohm, 10 watt or 620 ohm, 15 watt resistor
- 1 x 25 ohm, 5 watt resistor
- At least 40 x .156" trifurcon terminals
- At least one heat sink appropriate for a 35A bridge rectifier and a machine screw/nut to attach the heat sink to the BR.
- Heat sink grease
*Bally's Future Spa, Kiss and Space Invaders use a slightly different power supply from the norm and have 9-pins on J1 instead of 8. If you're working on one of those games, bear that in mind when ordering the header strip and housing for that connector.
Also, the repro power supplies on the market, in order to accommodate the misfit games, *include* the 9-pins on J1 -- the 9th pin simply isn't used on the other games, so having it there doesn't hurt anything. As a result, if you're installing a repo power supply in your game, *make sure* you're pinning J1 properly and installing that connector properly. I have made this mistake and I know others who have as well.
I buy most of my electronic parts from
http://www.greatplainselectronics.com. The shipping costs are pretty reasonable (more-so than you would think) and all of the above parts are available there.
As for the tools, after putting up with the crappy Radio Shack-style soldering pencils for a while, a few years ago I bit the bullet and bought a super soldering station from
http://www.mcmelectronics.com. This is similar to what I have and it works great. It also goes on sale occasionally for about half price:
http://www.mcmelectronics.com/product/T ... 47-/21-147
Since then I've also purchased this one for when I do house calls and for working under playfields. It also works well and also goes on sale from time to time, but I see it's currently on backorder (read the comments -- Randy Fromm is complaining about how long it's been on backorder):
http://www.mcmelectronics.com/product/T ... 5-/21-7945
Both of the above have different types of tips that can be ordered separately. I use the micro point tip for intricate board work and the chisel tip for rebuilding power supplies and working under the playfield.
I use
THIS desoldering pump, but if you look at MCM there are several types available. The one I use is okay, but I find it gets clogged and needs to be cleaned out more often than I would like.
For solder, I use 60/40 rosin core solder in the thinnest guage I can find (.031" is good... .04"/1mm is alright, but the smaller the better). I see lead-based solder becoming more and more difficult to find, so it might be a good idea to stock up with a couple of 1lb spools before its NLA. Two or three 1 pound spools would probably last you for the rest of your life.
I've been using the
MASTERCRAFT AUTORANGING DMM for several years and find it to be more than acceptable for pinball purposes. Incidentally, as someone else on maaca pointed out a couple of days ago, that meter is currently on sale at Canadian Tire for $18. Now THAT is a smokin' deal no matter how you slice it.
Once I start repinning the female connectors, I'll need to use my crimper. The W-HT-1921 at Great Plains is excellent and works well for both .100" and .156" terminals, even though GPE sells a different crimper for the larger terminals. Princess Auto also sells a good yellow-handled crimper for about $18 that does the job nicely, but it's a bit more finicky than the GPE tool. Here:
http://www.princessauto.com/workshop/ha ... er-crimper
Still with me?
Okay, so first I removed the old bridge rectifiers, fuse clips and headers from the power supply. The bridges need to be desoldered *really well* or they simply won't come out. I've rebuilt a lot of these power supplies and determined that getting those bridges out can take some persuasion. Once the solder has been cleaned away as well as possible, I grab a small flat-head screwdriver to pry the bridges up:
Next, I move onto the fuse clips and remove them all. They're not as bad as the bridges to take up, especially when using a chisel tip on the soldering iron. Getting the new clips into place can be a challenge, since the "tabs" on the new clips are a bit thicker than the originals, but with clean holes, they can be made to fit.
Once those are out, I remove all of the header pins. Quite often these pins are burned or hacked to death and desoldering can be challenging. Once removed, the area should be cleaned up with steel wool or sandpaper so that the solder pads are shiney and provide a good surface area for adhesion of the new solder. This is also a good idea for the bridge and fuse clip areas as well.
Once all of that is done, whip out the DMM and check the resistance of R1, R2 and R3. If they are within spec, I see little reason to replace them. In the case of the power supply I'm working on here, all of the resistors are fine, so I left them alone.
Now you can start installing the new components.
Install the new header strips and remove the key pins. Make sure you don't create a solder bridge between adjacent pins where there isn't supposed to be a connection. Keep in mind that certain pins, like J1-1 and 2 and J3-1 to 4 are supposed to be connected. It's pretty obvious which ones are meant to be connected and which ones shouldn't be by looking at the traces on the board prior to soldering.
Install the new fuse clips -- make sure you put them in the right way. They have "brackets" that are designed to prevent the fuse from sliding out the end of the clip. If you install them the wrong way, the fuses won't fit properly.
Install the bridge rectifiers. Since the new bridges are quite a bit larger than the originals, they need to be installed on the front of the board instead of on the backside. It's worth noting that GPE sells the original size bridges, so if you want to go that route, you certainly can.
Bridges have a "+" lead and, assuming you're going with the large 35A bridges, this must be installed at the top left corner for each bridge. This is denoted by the cut-corner on some bridges or merely a "+" symbol on others. Generally, the positive side on all bridges can be identified by the "offset" lead -- the lead that is obviously in a different position than the other 3 is the positive one.
Bridge Rectifier 1 (BR1) requires a heat sink. Apply a little bit of heat sink grease between the BR and the sink and use a machine screw and nut to attach the two together. BR2 can also use a heat sink, but this is optional. I feel that if the game is going to be in home use for the rest of its days and considering the large 35A bridges dissipate heat a lot more effectively than the original BR's, you can get away without the 2nd sink. Even the repro manufacturers are split on this as Rottendog has a heat sink only on BR1 whereas GPE has a sink on BR1 and BR2. The choice is yours.
After everything is done, replace the four diodes at the left edge of the power supply with new 1n4004 or 1n4007 diodes. This section provides display high voltage and is often burned.
Finally, Clay recommends a couple of mods. Here:
From
http://www.pinrepair.com - Mod 1:
On the solder side of the rectifier board, add a jumper wire from J1 pin 5, to J3 pin 10. Note there are plated through holes in the circuit board that make this mod very easy. This adds additional area for the 7.3 vac general illumination lines.
From
http://www.pinrepair.com - Mod 2:
On the solder side, add a jumper from J1 pin 6, to J3 pin 9. Since there are no plated through holes here, solder the wire directly to the header pin and the circuit board trace. This adds additional area for the 43 vdc solenoid lines.
Mod 3:
Clay also talks about providing additional ground area for the GI and lamp driver grounds at J1, pins 1 & 2 and J3, pins 1 to 4. In order to perform this mod, simply scrape away some of the green solder mask from the large ground plane on the component side of the board to the left of J1 and J3 and solder two wires directly to the ground plane. Then run the wires around the edge of the board to the solder side and solder them directly to the header pin solder points. You can see this in the pic below.
Clay discusses drilling a couple of holes in the board and running the wires through the holes, but I've personally never seen the point of that.
Here's how I do it:
And here's the same basic mod shown at
http://www.pinrepair.com:
That's it! If everything went well, you should now have a sexy rebuilt power supply.
You can check your work on the bench using a two-prong power cable attached to pins 6 & 7 of J2. These are the AC input lines and will allow you to check the test points for proper voltage.
From
http://www.pinrepair.com:
Alternatively, you can just put the power supply back into the game and connect J2 only. This will also allow you to provide AC power to the rectifier without potentially damaging any other boards or playfield components if you've managed to really screw things up.
Voltage for *this board* should be as follows (stolen from
http://www.pinrepair.com):
- TP1 = 5.4 volts DC +/- .8 volts (4.6 to 6.2 volts). Fuse F1, bridge BR1. Used to power the "switched illumination" (feature lamps).
- TP2 = 230 volts DC, +/- 27 volts (203 to 257 volts). Fuse F2, diodes CR1 to CR4. Used to power the score displays.
- TP3 = 12 volts DC (11 to 16 volts). Fuse F3, bridge BR2. Used to create the regulated +5 volts DC for the game's logic circuits.
- TP4 = 7.3 volts AC, +/- 1.0 volts (6.3 to 8.3 volts). Fuse F5. Used to power the general illumination.
Make sure to set your DMM to **AC** when testing this one. All others are DC.
- TP5 = 43 volts DC, +/- 5.4 volts (47.6 to 48.4 volts). Fuse F4, bridge BR3. Used to power all the coils.
Without a load, these voltages may read a bit differently and that's usually just fine. Here's how my board read with just J2 installed and I'm quite happy with the results:
Test point 1:
Test point 2:
Test point 3:
Test point 4:
Test point 5:
The next task is repinning the connectors for the power supply, which is not a big deal, really. And then onto the driver board.
I'm pretty sure this thread and whatever video you're working on can co-exist peacefully. 
