Back to the Future: The Pinball
Data East, 1990Hello,
I have a pop bumper on my BTTF that I noticed had one of the wires intentionally cut. I re-soldered it and and it fires without stop and buzzes. I have disconnected it for now. I checked the boards for any black marks and there are none.
Also, none of the bulbs will light on any of the 3 pop bumpers.
Let me know what I need to do.
Thanks,
Jeremy
Since it was cut, I doubt this is the issue, but first make sure the pop bumper switch is not stuck closed. Check the manual and you should be able to get the driver transistor number. Check it with a DMM using the following procedure.
If you can't find the transistor number just let us know which bumper it is and someone can respond.
It's the left bumper. I have the manual but page 41 doesn't make any sense to me.
With the DMM should I power on the machine and connect the black to ground and the red to each transistor? The transistors are the black squares with the silver part coming out of the top with the hole in it right?
The transistor you need to check is Q11 on the CPU board. Should be very close to connector CN19. The article I previously referenced will provide a more thorough explanation of testing transistors than I can cover here.
But in any case you will do the tests with the power off.
Quoted from treibj:The transistors are the black squares with the silver part coming out of the top with the hole in it right?
Yes
Black lead on tab (ground) red on top leg, then red on bottom lead (colector, emiter) .4 to .6 on both legs should be seen. Anything less, transistor is bad. Doubt the transistor is bad, however, because your bumper coil is still firing. If the transistor blew "open", it would not do anything. Sounds like a mis-adjusted switch like terryb said. PLEASE REPORT BACK WITH YOUR FIX AS THIS HELPS EVERYONE!
Quoted from smokey_789:Black lead on tab (ground) red on top leg, then red on bottom lead (colector, emiter) .4 to .6 on both legs should be seen. Anything less, transistor is bad. Doubt the transistor is bad, however, because your bumper coil is still firing. If the transistor blew "open", it would not do anything. Sounds like a mis-adjusted switch like terryb said. PLEASE REPORT BACK WITH YOUR FIX AS THIS HELPS EVERYONE!
I would have thought the most likely problem would be that the transistor is shorted and thus the coil fires on all the time.
Quoted from DCFAN:I would have thought the most likely problem would be that the transistor is shorted and thus the coil fires on all the time.
That is a possibility. thanks.
Quoted from smokey_789:Black lead on tab (ground) red on top leg, then red on bottom lead (colector, emiter) .4 to .6 on both legs should be seen. Anything less, transistor is bad. Doubt the transistor is bad, however, because your bumper coil is still firing. If the transistor blew "open", it would not do anything. Sounds like a mis-adjusted switch like terryb said. PLEASE REPORT BACK WITH YOUR FIX AS THIS HELPS EVERYONE!
DMM in diode test setting.
Quoted from terryb:Since it was cut, I doubt this is the issue, but first make sure the pop bumper switch is not stuck closed. Check the manual and you should be able to get the driver transistor number. Check it with a DMM using the following procedure.
If you can't find the transistor number just let us know which bumper it is and someone can respond.
http://pinballrehab.com/1-articles/solid-state-repair/tutorials-and-techniques/120-electronics-tutorial-2-transistors
Terry, you're the man! These articles you wrote are worth their weight in gold. You've helped me out in the past and I always see you somewhere on this forum helping others. Just wanted to throw you a shout out! Thanks!
Mike
Quoted from papazit1963:These articles you wrote are worth their weight in gold.
Not to be a smart ass....but to be a smart ass, those articles are digital files that weigh nothing. 
Seriously though, I also have learned quite a bit from the pinballrehab articles. Thanks!!
I tested all of the transistors on that side. All of them read at .4 except for Q10 and Q13 which were 0.
The other 2 pop bumpers work fine except that none of them light up.
I REALLY appreciate all of your posts. Let me know what I should do next.
Quoted from Pafasa:Not to be a smart ass....but to be a smart ass, those articles are digital files that weigh nothing.
Nonsense! Electrons piled onto a magnetic disk to create a charge weigh something. Google it, electrons weigh approximately .00000000000000000000000000000091kg. Now whether or not the billions of electrons weigh as much as an atom of gold, that's possible. Since an atom of gold weighs .0000000000000000000032706kg, and a bit on the server disk takes so many millions of electrons, it is certainly worth its weight in gold!
Quoted from treibj:I tested all of the transistors on that side. All of them read at .4 except for Q10 and Q13 which were 0.
The other 2 pop bumpers work fine except that none of them light up.
I REALLY appreciate all of your posts. Let me know what I should do next.
Zero as in ohms? If so it sounds like the transistors need to be replaced.
I am not sure how you are testing.
Quoted from DCFAN:Zero as in ohms? If so it sounds like the transistors need to be replaced.
I am not sure how you are testing.
I have my DMM on DCV 20 and it gives a .4 reading for all transistors in that row except Q10 and Q13. Where can I order some transistors if that is the issue?
Quoted from treibj:I have my DMM on DCV 20 and it gives a .4 reading for all transistors in that row except Q10 and Q13. Where can I order some transistors if that is the issue?
In the manual Q10 is a slingshot and I don't see what Q13 is. Both of my slingshots work fine.
Quoted from treibj:I have my DMM on DCV 20 and it gives a .4 reading for all transistors in that row except Q10 and Q13.
Game should be off and DMM in diode/continuity mode.
Quoted from Patofnaud:Exactly 180 degrees from where the knob is in the picture is diode mode.
Thank you!
Q11 comes up as 038 while all others in that row are 1. Q11 is the problem bumper. Should I replace the transistor? Where would I get one online (locally we have a Radio Shack)?
Seeing I just happen to have Back to The Future manual open.....
That would be a TIP122, Rat Shack 'may' have those, most online place will have those but shipping will cost you 20x the price of the part. It's a fairly common part. Maybe a local Pinsider has a stash, otherwise Ed from Great Plains has them..
http://www.greatplainselectronics.com/search.asp?pg=1&stext=tip122&sprice=&stype=&scat=
Quoted from Patofnaud:Seeing I just happen to have Back to the Future manual open.....
That would be a TIP122, Rat Shack 'may' have those, most online place will have those but shipping will cost you 20x the price of the part. It's a fairly common part. Maybe a local Pinsider has a stash, otherwise Ed from Great Plains has them..
http://www.greatplainselectronics.com/search.asp?pg=1&stext=tip122&sprice=&stype=&scat=
Will a TIP120 work? Radio Shack has them in stock locally for $1.99. If not I'll order the TIP122 from greatplains.
If you look at the Great Plains link,,, 'Replaces TIP120 and TIP121' so yes, but 122's are rated at 100V, 120's only 60V. Sol power in a DE is +32/+50V depending on specific coil so your not leaving a lot of wiggle room. It won't be as reliable.
Quoted from Patofnaud:If you look at the Great Plains link,,, 'Replaces TIP120 and TIP121' so yes, but 122's are rated at 100V, 120's only 60V. Sol power in a DE is +32/+50V depending on specific coil so your not leaving a lot of wiggle room. It won't be as reliable.
I'm not in a rush. I'll order from Great Plains. Thanks again for the help (everyone). I'll update this thread when the TIP122 comes in.
Quoted from Crash:Nonsense! Electrons piled onto a magnetic disk to create a charge weigh something. Google it, electrons weigh approximately .00000000000000000000000000000091kg. Now whether or not the billions of electrons weigh as much as an atom of gold, that's possible. Since an atom of gold weighs .0000000000000000000032706kg, and a bit on the server disk takes so many millions of electrons, it is certainly worth its weight in gold!
I hadn't thought of it that way! 
Quoted from treibj:I'm not in a rush. I'll order from Great Plains. Thanks again for the help (everyone). I'll update this thread when the TIP122 comes in.
May as well order a few. Also grab a few other common parts like 1N4004 diodes.
Quoted from Crash:Nonsense! Electrons piled onto a magnetic disk to create a charge weigh something. Google it, electrons weigh approximately .00000000000000000000000000000091kg. Now whether or not the billions of electrons weigh as much as an atom of gold, that's possible. Since an atom of gold weighs .0000000000000000000032706kg, and a bit on the server disk takes so many millions of electrons, it is certainly worth its weight in gold!
Thank you Crash...took the words right out of my mouth.... 
Mike
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Missoula, MT