Indianapolis 500 - Target Assy rebuild project
While taking care of a Bally Indianapolis 500 (1995) for a friend, I had the pleasure of rebuilding a full target assembly for this particular table. As I found this project quite interesting, I would like to share it with you.
Firstly, by inspecting the playfield and pinball’s guts, I missed the modification done by a previous owner. Not knowing this model, I didn’t realize that those two yellow targets were not originals, butI did find funny the double white posts on the playfield and the two rubber rings behind them.
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Playfield pictures from IPDB
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Current shape of the playfield of the machine I have.
Next, by looking underneath the PF, I understood how far this modification went. There were wires cut from connectors and soldered directly to the yellow targets switches, screws had damaged the playfield bottom as it is not meant to be so close to the edge. By searching a bit on IPDB, I realized how bad it was and what I needed to put everything back to its original state.
The target assembly in the back of PF is still intact and fully functional, that will be my model of the complete assy. By checking the cabinet, I found a broken target, I could fix it and perhaps use it in the game so I needed to produce at least one complete target and two circuit boards (they are also missing from the game!).
Hypothesis : The clear part of the target, which masks the IR signal of the opto, seems to break easily in this game, making the target useless. I think a previous owner couldn’t change the part, because of a time or money issue, or just wanted to change the target with a less fragile one. So he ended up putting two standup targets and getting the switch contact to the connector by cutting the wire and soldering it directly to the blades.
I do understand the idea, it gives the game its full functionality back. But I am truly shocked to see a playfield tortured like this : a double post screwed through the wood on a painted area, rubbers added on one side, but missing on the other...
Issues : First, we lose the 4 led displays behind the targets according to the game missions. Second, yellow targets wear off the playfield edge as they are screwed too close to the hole. Third, since those standup targets are more bendable than the original ones, the spring effect makes the ball jump up after hitting it, and sometimes lands in the opposite ramp, next to the F1 car, or more often knocks the playfield glass.
I start by looking for a full genuine assembly on the websites in my knowledge. First problem, the parts are sold out almost everywhere, and quite costly. Around 20$ for the clear part, and more like 30$ for the black housing. I did not find the circuit board for the Led display and opto. Total cost for two targets : ≈100$ without PCBs and shipping costs. It is quite a lot for plastics.
I needed another solution. I came up with an idea less costly but way more time-consuming : modelize the original targets in the most precise wayin CAD drawing to print them on a 3d printer. For PCBs, I would like to draw the electric diagram and wire it like the original one.
I started to work as my brain was overheating. After a few long nights staring at my computer screen drawing the target, geared with my slide gauge, I’m scaling, extruding and piercing.
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The result is okay, looking like the original one I’m holding in my hand. Let’ss try it out in my dlp 3d printer and compare.
Of course the first batches turn out to be a waste of resin, I’m having some problems with support design.
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Original target on the right
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During the (quite long) printing time, I developed the circuit board and wire it so I can try it up in the machine.
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Prototype wired with leftover componnents
The board is working when powered on. I still need to design and print the guide that brings the target into the opto switch. And also a metal part to screw the board with the target.
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As it is an almost handmade work, it is not as perfect as a NOS one but I’m happy with the result. Still need to fix those connectors and touch up the playfield to hide the double post scar on it.
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On the front : Two newly made targets assy, The original one still in the back
I also used the CAD drawing to print up some target fixes for the clear part. I found one on Thingiverse but couldn’t use it as it wasn’t on scale (don’t know why). So I am now ready for any breaking situations on those bloody targets !
Thank you for reading, I'll test the target in game and see if it is tough enough to endure the ball hits few games. I'll post more infos later.
Houston, TX
