Intermittent switch indication

(Topic ID: 233627)

Intermittent switch indication


By newbieinKC

11 days ago



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  • 6 posts
  • 3 Pinsiders participating
  • Latest reply 10 days ago by frunch
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#1 11 days ago

I have one switch that is clearly open visually and tests open until the game has been played for a while and warms up. After about 20 minutes of playing, the switch starts scoring over and over intermittently. When this happens, I can immediately test it and it shows "half closed" if that makes sense. The 6803 control board test mode 94 (switches) will indicate two switches if one is closed. When this one is acting up it flashes 0, 13, 0, 13 etc. until you hold the rollover down and actually close the switch, then it flashes 13, 13, 13, 13. What the heck does that mean?

I assume I should start with a check of the pin on the control board associated with the right rollover target, but has anyone experienced something like this?

#2 11 days ago

If that switch has a disk capacitor on it (dunno if they were still doing that on this game) replace it.

#3 11 days ago
Quoted from cody_chunn:

If that switch has a disk capacitor on it (dunno if they were still doing that on this game) replace it.

Thanks. There are many disk capacitors on the 6803 control board, so the switch probably has one. Now I just need to trace it... I have the wiring diagram, but the 30+ year old wires are getting a bit dingy. I have a DMM, so I am sure I can figure it out.

Is this a sign that I can expect frequent failures? There are 106 capacitors on my 34-year old 6803 control board.

#4 11 days ago

The cap he's talking about is on the switch itself. After doing a bit of digging through the manual, i found out switch 13 is the right rollover button that scores Special.

436212838.png

If you cut the capacitor off that switch, you'll hopefully find the problem goes away. You'll want to replace it eventually, but it should work ok for the most part without it. The cap allows shorter, quicker switch closures to still register properly. You'll only see caps on certain switches, the schematic shows which ones will have them. The blue arrow is pointing at the cap on the switch for the right rollover button (the one you want to remove for now).

180634805.png

Note that not all switches have caps. For instance, the C-H-A-M-P lanes don't, but the E-I-G-H-T targets do. Here's the replacement cap at GPE: https://www.greatplainselectronics.com/proddetail.asp?prod=CCD-0.047uF-100V&cat=27

When these caps go bad they can sometimes cause weird, intermittent problems.

#5 11 days ago

Got it. That makes me feel better than something wrong on the control board.

I cut out the cap and the switch still works, kinda. It shows up in test mode, but only scores rollovers about 1/3 of the time. Like you said, frunch, it doesn't score quick hits well.

Thanks for the part lookup. I see in the manual that the OEM cap is .05 uF 12/16V and the one you linked is .047 uF 100V. I want to confirm my understanding of capacitors that you want to get pretty close to the capacitance level and it is ok to use something rated at much higher voltage but not 1 volt lower than what your circuit is running, correct?

Now, here is the real newbie question. This switch is in a very inconvenient place to get to when my playfield is tilted up. It seems like the wiring harnesses in this game are pretty tight so I would unhook them before lifting the playfield past vertical to rest on the backbox, but is that the way to do it or just pull the playfield all the way out? I have a bit more soldering to do on the playfield, so I would like to not be standing on my head for all of it.

#6 10 days ago
Quoted from newbieinKC:

I cut out the cap and the switch still works, kinda.

You'll want to make sure the switch is clean (a business card, crisp hundred-dollar bill, or clean piece of paper should suffice, just don't file the contacts) and make sure the switch is gapped properly too, you may need to close the gap a bit if it's not registering consistently. Even without the cap it should be registering most hits.

Quoted from newbieinKC:

I see in the manual that the OEM cap is .05 uF 12/16V and the one you linked is .047 uF 100V

Typically if you're within 10% of the capacitance, you'll probably be ok. Depends on application. In this case, it's such a close difference it doesn't matter. Voltage rating has to be at least the same or greater than the cap you're replacing though.

You may want to pull the playfield out to do the work. More of a judgement call, but you have a good idea what your up against. If it'll save you some awkward bending etc, it may be worth the effort.

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