(Topic ID: 74157)

bumper blowing fuses


By tinabanana

5 years ago



Topic Stats

  • 32 posts
  • 4 Pinsiders participating
  • Latest reply 5 years ago by tinabanana
  • Topic is favorited by 2 Pinsiders

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resistor.jpg
ISCSEMI-TIP102-pinout.jpg

#1 5 years ago

Hi. Im new at fixing pinballs so excuse my ignorance. I've already fixed a few things, easy things. but this one is starting to get me confused.

when i got the game, 2 of the 4 bumpers didnt work. so i ordered new coils for the 2, disconnected them, and didnt take any pics. so when time came to put them back together, i didnt know what side to put the wires. i guessed, and it didne work.

in an effort to troubleshoot, i inverted the wires on one of the other 2 working bumpers to see if my problem was wiring or something else. (yes that was very very stupid, i realize now). so no my other 2 bumpers quite working as well.

now i know the double wire has to go on the band side of the diode.
now that is connected properly, im still blowing the fuse for it.

so how to i find the problem?

i tested 2 of the diodes (they are accessible from the front) and they are both good. getting continuity one way but not the other

i tested the coils and im getting a reading higher then 4. so they are good as well

im not really sure what else to check. any tips? the machine is road king if that matters.

#2 5 years ago

You may want to post more prominently that the game is Road Kings (which is a Williams System 11.) I took the liberty of tagging your thread with the game.

I'm not well-versed in System 11 games, but I would say check transistors on the driver board.

I'm sure others can chime in who will be more helpful.

#3 5 years ago

thank you for the tip on posting info.

how do i know which transistor to test and how do you test them?

#4 5 years ago

Tinabanana - the first thing you need to do is get a schematic of your game. Follow this link for a schematic.

http://www.ipdb.org/search.pl?any=road+kings&search=Search+Database&searchtype=quick#1970

This will allow you to determine which transistor controls which solenoids. Look on the very first page and you will see that there is a table that shows the solenoid and which transistor controls it along with wire colors, connector identification, etc. etc.

Once you identify the transistor you can use your DMM to test it. Also, you can clip a wire to the tab of the transistor and then ground that wire. This should fire the transistor activating the corresponding coil.

Give this a try. Let us know how it goes. You can be sure you will get lots of help here. I have now repaired/restored four machines with the help of my fellow pinsiders! I am about to get started on my 5th machine in a couple of weeks. You will enjoy repairing your machine and get a great sense of accomplishment when it works and you did the repairs.

Al

#5 5 years ago

this is a good start, you guys are so helpful, thanks so much!

i have the book for road king, i just look at those diagrams and have no idea what im looking at.
but looking at that first page with the table, that was easy enough, i found the 4 transistors that control the bumpers.

had a look at the transistors and sure enough, one of the is allll bent and one leg is kinda sticking out. looks like maybe someone tried to fix it???
when i put the ddm on it, 3 of them got a reading between 009 and 010, the bent one got a reading of 001.
so its obviously different then the other ones but i thought if it was bad you would get 1 (infinity)

do you have to remove the board to replace a transistor?

while i was looking at that board, right next to the bent transistor, i found a bigger blueish box thing, says coil 6v dc on it that looks kinda melted. what is that and how do i test it?

can you explain to me in more details on how to get transistor to activate the coil? like is it going to physically move it? that sounds handy for testing out stuff.

#6 5 years ago

ISCSEMI-TIP102-pinout.jpg

Think of a transistor as a diode with three pins for testing purposes. On all transistors, the arrows on their data sheet will indicate that electricity should only flow in that direction, identical to a diode. With your meter in diode test mode, put the black probe on the base pin 1 (left) and the red probe on the emitter pin 3 (right). If you see zero resistance on the meter, the transistor has shorted. If that checks out okay, put the red probe on pin 2 (middle), and the black probe on pin 3 (right). Again, if you see zero resistance, it is shorted. You should see infinite resistance in both of those tests, just like a diode would if you try to go in the opposite direction.

That diagram may look a little confusing, to explain better, this particular transistor is called a Darlington pair. It is just two transistors sandwiched together in one little package.

Keep in mind those instructions are specific to testing TIP102/122/36 transistors. The pre-drivers and other transistors on your machine have a different pin-out, but the testing and information I gave you still applies.

The blue box thing is most likely a relay. Take a picture of the board and upload it so we can help you better.

#7 5 years ago

To replace the transistor, you'll definitely want to remove the board. Once you've got it out, it's easier to test transistors anyhow.

I would check any associated resistors as well. (On later games, diodes are on this board as well and should also be tested, but they should be on the coils on Road Kings.)

#8 5 years ago

i attached a pic here. you can see the transistor with the bent leg. i tested it and while i wasnt exactly sure which side was left or right, when i compared it to the one beside it they both registered the same results.

when doing both outer legs, i got a reading of around 600.
when i did center and one side, i got around 600
when i did center and the other side, i got around 10 or something like that

what is up with the leg out like that, did someone try to ghetto-ly fix it without removing the board?

resistor.jpg
#9 5 years ago

here is another thing that might or might not be related, when alot of lights are on, the machine buzzes quite loudly, when less lights are on, its not as bad

#10 5 years ago

What you are seeing there looks like there was PCB trace damage, so the person used the leg of the transistor to connect directly to that pre-driver transistor above it. Nothing really ghetto about that unless the underside of the board also has traces/connections that have been disconnected/neglected. Judging from the flux around that transistor though on the pads, it looks like a good candidate to replace anyway. I would test the pre-driver transistor that is just above it as well, these parts often fail together. When you desolder and replace that transistor, you can either bend the leg again and resolder it onto that trace, granted there are no traces on the opposite side of the board for that pin, or you can put the part through the original holes and run a jumper wire up to that pre-driver transistor. I prefer to run jumpers, but it is really personal preference.

The buzz is normal when lights turn on and off on all machines. It lessens when using LED bulbs as less current is being drawn.

#11 5 years ago

im not really sure what to do now. i checked the 2 parts right above the transistors and they seem to be ok, did the same kind of test as on the transistors, check left/right then middle/left middle/right and got some readings.

im hesitant to change out parts that are testing ok, i dont want to do more damage.

#12 5 years ago

the funny thing is that messed up transistor controls the left bumper, and that one always worked, until we switched the wires on the coil "to see what would happen".

i think my first step will be to replace all the diodes on the coils, even tho they tested fine.
from there, im not sure what else, id like to get a breaker so i dont keep on burning fuses, thats getting pretty irritating and a tad costly. but im in canada so shipping could take a while, so ill probably just get another box of fuses and hope for the best

my book says to use a 2.5a sb fuse for the selenoid, but in the cabinet, there is a replacement sticker over the original one that says to use a regular 2.5a. which do i trust?

do those blue relays pull out or are they soldered in?

#13 5 years ago

Above each of those TIP102/122's is the pre-driver transistor. If both test out okay and aren't shorted, and you are reluctant to try and remove them, perhaps you can ask someone else to help that is nearby.

If I were dealing with this issue of yours, I'd first make absolutely sure that I have my coil wiring done properly. Then I would just go ahead and replace all 6 of the TIP102s along with their pre-drivers. Why? Because $4 worth of parts and 10 minutes of board work is easier and less expensive than dealing with $2 fuses blowing each time I turn the machine on while trying to guess which parts are bad.

#14 5 years ago
Quoted from tinabanana:

there is a replacement sticker over the original one that says to use a regular 2.5a. which do i trust?
do those blue relays pull out or are they soldered in?

Use Slo-Blo everywhere would be my guess. I haven't come across a pin that used anything else.
The Relay is soldered in place. It is the flipper enable relay, it is probably working fine so I'd leave it alone.

#15 5 years ago
Quoted from thedefog:

Above each of those TIP102/122's is the pre-driver transistor. If both test out okay and aren't shorted, and you are reluctant to try and remove them, perhaps you can ask someone else to help that is nearby.
If I were dealing with this issue of yours, I'd first make absolutely sure that I have my coil wiring done properly. Then I would just go ahead and replace all 6 of the TIP102s along with their pre-drivers. Why? Because $4 worth of parts and 10 minutes of board work is easier and less expensive than dealing with $2 fuses blowing each time I turn the machine on while trying to guess which parts are bad.

I agree with this, assuming you have decent board work skills.

#16 5 years ago

Collin, nice collection. How do you like the Bad Cats? I've always wanted one.

#17 5 years ago
Quoted from thedefog:

Collin, nice collection. How do you like the Bad Cats? I've always wanted one.

Thanks! Some of my games are a bit rough; most of my more recent purchases have been projects to some degree.

Bad Cats is a lot of fun now that I've rebuilt the flippers. It definitely plays like an earlier game, without multiball or anything too complicated. It's a keeper for me because of the art... I would say the art package is an A+ and the gameplay is about a C.

#18 5 years ago

ok here is the plan. ill start with the diodes on the coils. if that doesnt do it, ill replace all those transistors as mentioned. never really done board work but my husband is good with a solder gun so i think we can manage.

thanks for the quick help guys.

#19 5 years ago

Sounds good! For that sort of work, it helps to have a desoldering gun (I recommend a Hakko 808) but if he's skilled with a soldering iron, I'm sure he can get it taken care of.

An actual solder gun probably doesn't have a fine enough tip for this sort of work; I've been there, tried that, and personally wouldn't use a solder gun for anything on a circuit board other than maybe a reasonably large cap.

#20 5 years ago

good advice. we looked up a few videos and will try to dig up one of the smaller iron instead of using the gun. if not will buy one.

#21 5 years ago
Quoted from tinabanana:

good advice. we looked up a few videos and will try to dig up one of the smaller iron instead of using the gun. if not will buy one.

Get something with an adjustable temperature or minimum 25 watts, otherwise you'll end up with cold solder joints and lifted traces. After a year of using a crappy radioshack iron (15-watt), my dad-in-law gave me his Weller WES51 station and I realized soldering wasn't so hard after all. Flash forward a decade and hundreds of projects later, and I'm still using that equipment.

Best advice I can give - For small solder pads and components, if you have to hold the iron down on the pad/component for more than 3 seconds to melt the solder, it is too cold. If it melts instantly or smokes a lot, it is way too hot. An adjustable iron comes in handy when you're working on large components (like these transistors), jacks and switches that require substantially more heat to melt solder properly. Even with the added heat, larger components will take longer to melt solder onto (sometimes several seconds before it starts flowing). No worries for switches and jacks though, as you can't really damage anything with heat. Always apply heat to the pad/component first for a second or two, then melt solder onto it. The end result should be mirror shiny, not dull or grey looking. If it isn't shiny, it is too cold. Also, don't put solder on the tip then place it on the area unless you are tinning a wire. Good luck!

#22 5 years ago

Tina, good advice from everyone. Just my $.02 worth get a good Hakko digital temperature controlled soldering iron like their FX-888D or FX-951. It will last forever in home use. Also, if you really get into repairing pinball machines you might want to get the Hakko 808 desolder tool that someone suggested. I have the Hakko 808 and one use (removing a forty pin display) made it worth its weight in gold. Got mine on Amazon but someone on Pinside was at one time offering them at a good discount. Don't know if that is still available.

A good way to practice and learn is to get some old junk PC boards and practice unsoldering components and then resolding them. You can probably get some from the electronic junk yard AKA electronic recycling center for free or check out a TV/Stereo repair shop.

It wont take long to develop the skill necessary to solder and desolder if you have good equipment. If you have cheap AKA poorly performing equipment it will make it a drag and you will not get good results and may even further damage something.

Let us know how things go with your Road Kings.

#23 5 years ago

i went out and found some diodes locally. as well as the bigger transistors, they didnt have the smaller ones.

so im doing the diodes tonight and if that doesnt fix it, ill go buy the other transistors tomorrow and give it a try.

i already did 2, and the way im holding the coil, the band was on the right for both, then i remove the 3rd one and the band is on the left. looking at all the other coils on the board, i see they are all to the right. is that a right way to point the diode? i know (now) the power/double wire has to go on the band side, but im not positive of the direction of the diode on the coil.

im searching on the net now to see if i can find an answer, but you guys are really fast on here.

#24 5 years ago

I looked and looked and finally found the answer on this forum

There is NO positive or negative side to a coil - you can put the diode on any way you like - when you fit the diode THEN you have to be careful which wires connect to which terminal.

It is the diode itself that makes the coil "polarity sensitive" - not the coil.

#25 5 years ago
Quoted from tinabanana:

I looked and looked and finally found the answer on this forum
There is NO positive or negative side to a coil - you can put the diode on any way you like - when you fit the diode THEN you have to be careful which wires connect to which terminal.
It is the diode itself that makes the coil "polarity sensitive" - not the coil.

That is correct for coils with a single diode, but it does matter for coils with two diodes.

#26 5 years ago

so i replaced the 6 transistors and 6 pre driver transisors. it didnt fix the bumper problem but it did fix the crazy loud buzzing. i also installed a breaker which gives me time to see what is happening. looks like two of the bumpers are getting stuck on as soon as i turn the machine on and the fuse pops. time to check out those 2 bumpers closer, will do some reading and see what needs fixed on them. i already took them all appart and they are not getting stuck in the sleeve, so not really sure at this point.

#27 5 years ago

Do bumpers work as a pair? If one has a problem, would it affect another?

#28 5 years ago

anyone have any ideas on what to try next?

#29 5 years ago

Can you manually push the bumper coil up and down with it out getting stuck? If you can't, you may need to replace the coils & sleeves for them. They should move freely with no friction.

I'd go to the schematics at this point. Both switches and coils are wired in a matrix. They go in chains and overlap each other. Switch matrix issues won't cause fuses to blow, but coil matrix issue could. You may have a bad diode in another area on the same line as the bumpers that is causing them to stay on. I don't know for sure because I didn't check, but it is likely both pop coils are on the same row or column of the matrix. Inspect the diodes on the other coils/test them in diode mode on a meter.

#30 5 years ago

the coils move freely, i don't think thats the problem.

i was reading on a site all about sys 11 machines. and it mentioned that a loud buzzing could be caused by missing screws on the cpu board. sure enough, our board is missing 2-3 screws. when we put it back in we moved some of the screws and i guess that fixed one of the ground issues that was causing it to hum so loud.

i wonder if this ground issue could be causing other problems. ill be replacing those as soon as i can.
as well as retest all the coils and transistors, regardless if they are the bumpers or not.

i had another look at the schematic, i still have a very hard time reading them, so ill have a closer look at that and do some more reading.

thanks for the help, i thought you guys had given up on me

#31 5 years ago

I had an issue somewhat similar to this on my JackBot. The issues were intermittent, and really frustrating to deal with. A friend taught me what I would call a last-resort method for diagnosing these issues:

First, disconnect the power wire from each coil that's powered through the fuse that keeps blowing. (make sure you protect exposed wire with electrical tape, and label which wire goes to which coil.) Power the game on and see if the fuse still blows; if it does, you've probably got a break in a wire somewhere that's allowing it to short out against something else. Assuming it doesn't blow go through this process: Power off, reconnect one coil. Power the game on and see if it blows. If it doesn't, power off, and reconnect another. Repeat until you've gone through this will all coils. You may well have multiples that're problematic.

It's a bit laborious, but it's how I finally diagnosed a problem that drove me mad for months.

#32 5 years ago

collin, thanks for posting that, that is the kind of testing i like to do. we did something a bit similar but we went too fast, i think going one by one is a great way to pin point the problem because at this point, im still not sure exactly which of the 3 is causing the problem. i only have one working right now, with the other 3 disconnected for right now.

road kind doesnt have a whole lot going on, without the bumper at the top is not a whole lot of fun

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