Firepower
Williams, 1980Quoted from fattdirk:My suspicion was correct! Right flipper coil had a bad diode. Measured it and it was open. I replaced it with an new 1n4001 and now the sound is perfect.
Sweet!
Did you typo the diode you used? 1N4001 will not last long, if at all on a flipper coil.
Quoted from Schwaggs:Sweet!
Did you typo the diode you used? 1N4001 will not last long, if at all on a flipper coil.
What should I have used? I did use the 1N4001 because that's the first one I saw in my parts bin. I don't know that I've ever had a problem with one of these on a coil in the past. They're rated for 50V @ 1 Amp. It's just shunting the EMF.
I think general consensus is to use 1N4004 or stronger. I have some 1N4007 that I use on coils but I think that is overkill. The diode does not need to suppress a ton of current but it does have to suppress relatively high voltage.
Quoted from Schwaggs:I think general consensus is to use 1N4004 or stronger. I have some 1N4007 that I use on coils but I think that is overkill. The diode does not need to suppress a ton of current but it does have to suppress relatively high voltage.
Ordered some 1N4007. I'll throw it in there when it comes. I didn't think about the high voltage.
Quoted from Geocab:It's really cool reading threads like this. Great job on resurrecting another dead pin.
How do you like the game?
Thanks, the game is wicked. I really like it. I rerubbered it and threw a bunch of wax on it. The new flippers really get the ball moving. Unfortunately when my wife and I were play testing the game and it started having a bunch of phantom switch hits. So back to the bench with the board for further troubleshooting. Whoever ends up getting this game eventually is going to have a rock solid machine!! 
I hope I have the parts to repair the switch matrix. This is really cutting it close for the party as I need to bring the machine over Friday to set it up.
It would be interesting to look at the EMF feedback with a scope. I would imagine you want a 1n4004+ diode though.
Quoted from barakandl:It would be interesting to look at the EMF feedback with a scope. I would imagine you want a 1n4004+ diode though.
It's pretty interesting that the EMF was triggering the sounds.
I probed the switch circuit and the SN7406 at IC18 is bad. I think I'm going to go ahead and replace the one at IC17 also just for good measure. I don't typically do that, but I've had a few of these system 6 games that I've worked on and every time I blow a 7406 I need to replace the other one not too long after.
While I wait for my chips to come, it gives me a chance to soak the legs in evaporust.
So, I started reading up on your use of the logic probe and decided to practice my Mandarin Chinese instead.
Quoted from fattdirk:It's pretty interesting that the EMF was triggering the sounds.
I probed the switch circuit and the SN7406 at IC18 is bad. I think I'm going to go ahead and replace the one at IC17 also just for good measure. I don't typically do that, but I've had a few of these system 6 games that I've worked on and every time I blow a 7406 I need to replace the other one not too long after.
While I wait for my chips to come, it gives me a chance to soak the legs in evaporust.
You can test the 4049 and 7406 in game conditions and figure out exactly what is bad. The other side is i am really handy at soldering and can socket and replace all four of the switch matrix chips in less time than a thorough logical testing of switches. A lot of time i do some testing with known good boards to rule out a driver board problem and then just replace the associated components. I can't recommend that approach for everyone though. Once you fix so many of these boards you get a good instinct for whats wrong.
You did a great job of logically working through everything. I like posts like this. A+. Have fun =D.
Andrew
Congratulations and nice work from here Argentina!!! Let me tell you that the last week I bought my FIREPOWER (of course it doesn't work) and I´m learning a lot from your post.
Quoted from fattdirk:Ordered some 1N4007. I'll throw it in there when it comes. I didn't think about the high voltage.
Did you ever end up swapping the diode?
Quoted from mrm_4:Did you ever end up swapping the diode?
Nope. Sold the game to the host of the party. It still works to this day. Played it at Thanksgiving.
Quoted from fattdirk:Nope. Sold the game to the host of the party. It still works to this day. Played it at Thanksgiving.
That’s awesome
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Cleveland, OH
