Help fixing the electronics in a electronic game (Ideal Speedball).

Discussion in 'The Projects Forum' started by Trike007, Jan 26, 2012.

  1. Trike007

    Thread Starter New Member

    Jan 26, 2012
    10
    0
    *Sorry for the long post, I just wanted to be as detailed as possible*

    Hi,

    I recently purchased a toy game called Ideal Speedball. It's a mini version of skee ball. The electronic scoring was faulty from the very beginning with fresh batteries. After reading reviews on amazon, it appears to be a common problem and people who have exchanged it for a new one still experience the problem. I figured even If I exchanged it, I would most likely have the same problem. So I want to fix it. It'll give me some more electronics experience and it'll be fun troubleshooting it.

    The Problem: When the ball is shot into the scoring holes, the electronics would randomly reset or turn off completely requiring the game to be power cycled. If I dropped the balls in by hand, it appeared to keep score correctly.

    Details and troubleshooting: I took it apart to see how it works. The contact switches is just a piece of thin flexible metal tab. When the ball drops in, it pushes the thin metal tab down making contact with the bottom tab.

    I figured this was a case of bad switch debounce filtering or lack thereof. Since If I drop the ball in by hand, it seemed to work fine. If shot with the launcher, the amount of force and the ball spinning in the hole could be causing multiple bounces and crashing the processor.

    Before I use a RC circuit or PIC to filter the multiple bounces, I would start with the simple stuff. The game runs on 3 C batteries (4.5v). Since most electronics run on 5v, I fed it 5v from a 7805 regulator. What do you know, everything seems to be working just great now. I played with it for about 30mins shooting balls back to back and it never crashed, I had a few balls where it failed to register, but that's probably because of the switches.

    So it appears that the electronics can't handle running on 4.5v reliably, voltage could be sagging when the switch is bouncing and causing it to crash. Maybe it runs on TTL and the voltage was in the between area (.8 - 2v) and causing weird side effects?

    Solutions?: The easy solution would be to hard wire it to a 5v power adapter. But I would like to keep the portability and retain the batteries. I'm not sure if I should attempt to fix the underlying problem by filtering the multiple bounces or band aid it by providing it 5v.

    If I attempt to filter it, An RC circuit would probably work, but I would have to build the circuit for each switch. Just seems inefficient to me and not sure how it would affect battery life. I have a PIC16F688 that I could use to filter the 5 switches as well.

    If I wanted to feed it a fixed 5v, I would have to power it externally or add a battery pack and regulate it. I have some 2s lithium packs I could regulate and use.

    What about adding a buckboost switching regulator to the existing circuit? could it step up the voltage reliably and efficiently from the 4.5v (3 C batteries) to 5v?

    I think feeding it 5v would be easier than filtering the switch bounces. I'm just not sure what the best method is while retaining the 3 C batteries.

    This is where I'm at now, any comments/suggestions?

    If you managed to read this far, Thanks! I'm just a hobbyist trying to learn more. The speedball game is pretty fun when it does work.

    Thanks
    WG
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If it is actually TTL, then operating it on 4.5v is a poor idea. Using a boost circuit would help, but no boost circuit is 100% efficient. It would help a great deal to know what your current draw is at 5v; peak and average.

    You'd really be better off to just use a regulated "wall-wart" type 5v plug supply. They're cheap and available almost everywhere.

    Unless you can come up with maximum and average current draws on the supply, it'll be tough to recommend a suitable circuit.
     
  3. Trike007

    Thread Starter New Member

    Jan 26, 2012
    10
    0
    I'm not entirely sure if it's TTL or not. It was just a guess. But it seems there's a design flaw somewhere in the electronics or software.

    I'll get a avg/peak current draw when I get home from work. If anything I'll be curious to see what circuit options there are.

    Thanks! Much appreciated.
     
  4. Trike007

    Thread Starter New Member

    Jan 26, 2012
    10
    0
    I got some measurements for current draw. Measured with my fluke on the 300ma port.

    Power on: 84ma
    Peak in 2 player mode: 108ma
    Avg. in 2 player mode while idling: 44ma

    This is lower than I expected. Curious what you guys think would work.

    Thanks
     
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