That's great. Do you have a manual? Do you have a DMM and a logic probe?

This kind of damage has done damage to the CPU board for sure. I would also bet that the fuses are not the correct value, when getting a used machine you must check all fuses before you even plug it in.

You need to test first before randomly replacing parts. There is a limited number of times that you can replace a TIP before you damage the board.

Let me know when you have the tools and I will assist you in fixing these minor repairs.

That is perfect!

Yes this is wired incorrectly. For future repairs you always replace diodes when you replace coils. Also the silver band on the diode always faces the power wire. You can tell which wire is the power wire by a number of ways. It's listed in the manual, the wire is a larger gauge wire then the other and sometimes there are two wires. In this case all 3 are there to let you know that the red/ white wires are the power wires. Now that there has been a dead short you need to replace the driver, predriver, the coil diode and check the coil for the correct resistance. Now when you replace the driver you can upgrade to a TIP102 instead of a TIP122 as they are 60% stronger. As for the diode I upgrade to a 1n4007, these can be used for any 1n400x diodes in the game.

You can test ZR-3 thru ZR-8 for being shorted. But your other issues require the board to be installed in the machine for further testing.

Also when you install the CPU board you need to leave 1J19 connector off the board until you are sure that there is no issues with the pop.

This couldn't happen if the connector was off. This is a must so that you can power on the game to do the final testing.

You can leave it in a do testing before replacing the predriver and driver.

There is two ways to active the special solenoids, the cpu can activate the coil in solenoid test and the game can activate the coil by a switch closing on the play field which applies a ground to the 1J18 connector which will go to U-45 or U-50. The zener diode which is in between the 1J18 connector and U-45 or U-50 chip is tied to ground. If the zener shorts it's the same as the switch being stuck closed, which will lock the coil on and melt it.

On Pinbot it is hard to hear a locked coil because the visor motor goes into the limit switch test as soon as you turn it on.

This happens often, its an easy test, with 1J18 disconnected set DMM to ohms and place leads on zener, note reading then reverse leads and note readings. If it is shorted it will have a low reading both directions. Since your issue is special solenoid 6 you need to test ZR7. This is on page 59 of the manual. You also need to test if the pop skirt switch is stuck closed which will also lock on a coil, you can do this by checking ohms from the ground braid to the connector 1J18 pin 9. This should be infinity until you press the skirt then it should drop to zero ohms.

Are you sure it was 5.5 ohms or was it 5.5k ohms?

So then test the other zeners to see what they read.

This mean they are all bad or your meter is not showing the k ohms. Normally when I test them on board I read 5k ohms both directions.

I was under the understanding that the top was bad and the other 2 pops were ok.

Did you separate the 2 red wires when you removed them? If so you can wire nut the 2 red wires back together but leave them off the coil.

No but the power goes from one coil to the next and so on. If you separated the red wires then the power stops right there and any coil down the line will not work.

4.8 k ohms is fine, but ZR-7 is testing funny, so cut it off the board. The board will work with out the zener diodes until you have a replacement. Also there is another way to test the zener diodes if the board is installed in the game.

There are so many DMM available and they all react a bit different, it does add a bit of frustration when helping people. For me I need to use a meter every day at work so I count on my Fluke 77 meter for over 25 years now. ZR-7 can also be open which will give an infinity reading.

Right now is the board in the game?

With j-19 disconnected and j-18 connected, turn on the power. Take your logic probe and connect it to the five volt and ground test points on the cpu board. Then probe the j-18 connector, all pins should be a high except for 1,6 and 7 as they are not connected. If this is good then probe pin 2 which is SS #3 and then press the left pop bumper skirt, the high should go low each time you press the skirt. Then repeat this for all 3 pops and both slings.

The ground is near the upper left of the battery. The five volt is between U-21 and U-22.

It is a poor quality copy of a ohm symbol not a n mark.

Cut this off the board and retest 1J-18 pin 9 for a high with your probe and then drop to a low when you push on the pop skirt.

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Check the adjustment of the switch and see if it is not closing.

Yea this is a problem and must be fixed first before any board repair work.

This is possible, you can disconnect the orange/blue wire and see if it goes high now.

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Also in the pic you will see that there is resistor and cap connected to the solenoid switch, if these are also on your switch the cap may have gone bad causing the switch to be shorted. You can cut one lead of the cap to see if the short is fixed.

The cap and resistor together make an RC network to extend the switch close pulse so that a light tap of the skirt from the ball will give a strong hit from the coil. They will not come on a new switch. Since most people just transfer these parts from one switch to another its likely they are original parts. Some people don't transfer the cap and resistor or just cut them off when they are having issues, that's why I asked if your pin has them or not.

Ok, look for SR20 resistor pack. It looks like the pic I posted. You will see a white dot on the board, this is pin one. Inside there are 9 resistors which are pins 2-10. Pin 1 is 5 volts and is tied to one side of all the resistors. These packs can crack internally and sever the 5 volts from the resistor. You can test them with an ohm meter with the power off. You check for ohms from pin 1 to 2 then from pin 1 to pin 3 and so on, you should see 4700 ohms or 4.7k ohms.

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Sure sounds like it. Is this something you can replace?

Off the top of my head....
1. TIP102
2. 2n4401
3. 1n5234
4. RESISTOR SIP 10 PIN 4.7K 9R 10 5%
5. 1n4007

You are not doing anything wrong, but sometimes the damage is more severe then first thought. U-50 is most likely shorted out. You can cut U-50 pin 5 to see if the switch input line raises to 5 volts as it should be. If it doesn't raise then it can be U-49 or the pia chip that is bad. You will need a very small anvil cutter to do this. Something like this.

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In this particular case you're testing the zener not as a diode but more like a resistor. By using ohms instead of diode test, a working circuit will read @ 5 k ohms. If you are reading 1 ohm then you know that you may have a bad zener diode. When you get a low ohm reading then you are sure something is wrong you can lift a lead of the zener and retest it to know if it's the zener or something in the rest of the circuit causing the low ohm reading. Now if U-50 is the problem and you cut pin 5 and separate the lead in half. This will remove the short and allow this circuit to rise back up to 5 volts. If there is no change then U-50 isn't the problem and you need to test further up stream to U-49 and so on until you have removed the short. When there is a short on a circuit like you have there is no way to separate the components from the short without removing them from the circuit either by removing the part completely or by cutting a pin. A piece like SR -20, you can't cut a lead so it must be removed from the board and once it has been removed you may as well replace it. Now for U-50, if you cut the lead carefully it can be repaired without replacing the chip. Also if you do not power up the coil until all your testing and repairs are completed you will not damage them. Some people get in a bit of a hurry and power the coil on as a test, this will cause them a lot of frustration, money and time. Test with your meter and probe and when is works correctly with them you will be confident that it is repaired the first time.

Your meter will always read the component with the least amount of resistance. So if U-50 is shorted and ZR-7 is good and they electrically connected the meter will beep because of U-50.

Yes I was under the assumption that it was soldered directly to the board.

These 4 components rarely go bad. Its best to keep testing until you find the short, then order parts and replace them, followed by a final function test. robertmee is correct in saying you can carefully bend the lead out a bit and then reinsert the chip in the socket for testing.

Have you soldered SR-20 in place yet or is it just a friction fit still?

Yep. The second chip is a "LS" Low power schottky. I don't think this chip can pass as much current as the STD TTL chip.

Do not connect this until all testing and repairs are completed. This is what causes most people's frustration when repairing.

Did you check all 6 special solenoid switch inputs, all should be high until you close the switch then they will go low. After all inputs are checked and working, then you need to check the outputs of U-45 (pin 1,4,10 and 13)and U-50(pins 1,and 4). In attract mode all 6 outputs should be low. Then start a game and recheck the same pins and there should be no change.

So check both inputs for this section of the U-45 chip. In attract mode both inputs (pin 11 and 12) should be high.

Attract mode is when the machine is on but a game has not been started.

Do you have the connector J-18 connected to the cpu board? If yes then disconnect j-18 and retest the header pins on the cpu. This will tell you if its on the play field or on the cpu board.

This happen from time to time. Could just be a coincidence. First check the ohms of ZR4. Looking for @ 5k ohms. Double check your soldering of SR-20 pin #8.

Now the inputs are good, lets check the outputs one more time. Keep J-19 off of the cpu, J-18 on the cpu, power on and start and game. Now check the outputs of U-45 (pin 1,4,10 and 13)and U-50(pins 1,and 4). All 6 should be low. If this is good then test the base (pic below) of all 6 drivers (Q-69,Q-71,Q-73,Q-75,Q-77 and Q-79) They should all be low. If this is good then set DMM meter to ohms and check the resistance from ground to the collector of each of the 6 drivers, you should see a reading of .600 meg to .900 meg ohms. If you get a low reading, then the driver transistor is bad. If all 6 test good then plug in J-19 while listening for a coil activating. Unplug immediately if you hear a coil lock on.

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Check the 2 inputs for each output. Check input pins 11 and 12 for the output pin 13. Check input pins 8 and 9 for output pin 10.

Has u-45 been socketed?

Does it look like someone has replaced it? Could there be a damaged trace? If everything looks ok then I would replace it with a socket and new chip. Then start all over with the testing.

Are you saying no reading on pins 1, 2 and 3? Or do you mean pins 2, 3 and 4? Pin 1 is a key ans will not have a reading.

Do you mean the CPU controlled lamps? The next time this happens you should for voltage at both sides of F-3 fuse. The fuse maybe going bad, the fuse clips maybe loose or corroded. The bridge rectifier that supplies power for the lamps maybe going bad.

I got to ask if you are confident on the soldering of the socket. If so then you may have a bad chip.

There is a time during attract mode that the game goes thru the instructions and turns on a off lights and gives a description on the displays of the rules. Could this be what your seeing?

Try a new chip at U-45.

If you start a game and it acts normal instantly, nothing wrong.

https://www.greatplainselectronics.com/proddetail.asp?prod=7402

He sells good stuff.

You have 4 pins that are basically system 11s so I would keep on hand some,
10 TIP102
10 2n4401
4 Nor chip
4 And chip
2 Nand chip
50 1n4007 diodes
2 Header pins
2 IDC connectors
An assortment of fuses
4 flipper coil sleeves
10 std coil sleeves.
An assortment of some #6,#8 and #10 nuts, washers and screws
2 EOS switches
This should cover most repairs on your older 4 pins.

Since it worked at start up but later went bad after warm up, can be a poor solder joint or a bad chip. You may need to look at the chip upstream U-49 as the cause of the trouble. U-49 is a buffer amplifier chip so a high in = a high out and low in =a low out. So when U-45 test bad at pin 2, then test pin 5 and 6 of U-49.

Pin 14 is 5 volt power input. You get no reading?

Is this with or without the connector installed? The cap on the skirt switch maybe dragging down the voltage.

So your the guy with all the fuse ads on CL.

There are a couple of via connections in between U-49 and U-45. They maybe cracked and lose connection after the board warms up. A via is a solder connection from one side of the board to the other. Reflow these and retest.

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Each chip has a small green filter cap by the notch in the chip labeled "B". Try snipping off the cap for U-49 and see if that helps.

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Snipping off a part and removing each lead separately is much easier then trying to remove the part whole. This will save you from causing unnecessary trace damage. This is a filter cap that is connected across the power and ground for each chip on the board and if it is going bad it could be dragging down the 5 volt signal. At this point in the troubleshooting you are going to have try the less commen part failures to fix your problem.

So with the cap removed the power on pin 14 is stable at 5 volts?
Did you install a socket for U-49? If so then remove the chip and power on the machine and test all 14 pins again.

These are still issues, can you remove U-45 also and then retest at U-49 socket again.

This is a problem, now that you have U-45 and U-49 removed from the board (1J-18 disconnected) there is only 3 components left that can cause this. C-72, SR-20 and ZR-5. You have replaced SR-20 already so its most likely good. That only leaves ZR-5 and C-72 as the problem. Pick one and cut it off and retest pin 10 on U-49. This needs to be a high.

This is definitely not a run of the mill problem.

Yep.

I know the feeling as it has happened a number of times to me also. It's no big deal, all part of the learning curve.

Yep.

This is a second issue to work on after pin 10 is corrected.

Well then cut the cap off and retest.

Yep.

You do have j-18 disconnected while testing?

Lets recap, U-49 not installed. U-45 not installed. 1J18 not installed. Zr-5 and C-72 are removed. So the only component left connected is SR-20 which is just a resistor, the resistor supplies the 5 volts. I suppose if the resistor is heating up and then going open causing the blink, then cooling off and reconnecting and showing a high again. There is nothing left in the circuit to cause it. You just wouldn't think that a new part would act up right away. I have seen resistor packs short and open up but never seen one act like this before.

This is very strange for sure, do you think these are tied together in any way. There shouldn't be any connection with the chip removed.

The 5 volts for SR -20 can't be the source of the pulsing as it would have showed itself on the other switch inputs, but I am with you on your assessment of this problem. Maybe time for a good pic of the front and back of the board so a bunch of eyes can look it over and see something he has over looked.

Yea after I watched the video I too doubt that the resistor is going open and closed (way to fast). I'm betting something under one of the 2 sockets.

It is used for the enable signal to turn on the flippers and special solenoids, but I don't see how there can be a connection to your issue of the pulsing signal. But again this is a strange issue that your experiencing on your board.

Pull all 8 Led bulbs and replace them with incandescent bulbs Do they work correctly now?

Check these diodes.

There also maybe a shorted led in one of the 8 bulbs.

Next would be to disconnect the play field from the cpu by removing J-6 and J-7. Make a test rig from a lamp socket and diode, a pair of wires. Put game in single lamp test and stop on 2X bonus. Verify if 2X bonus lamp is working by connecting test rig to J-6 pin 1 and J-7 pin 2. Now move the test rig to J-6 pin 1 and J-7 pin 8, does the bulb flash now?

Exactly like this except clips on both wires. Now you don't connect to the lamp bus. You connect to the pins on the CPU board.

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Try this, the 2x lamp should be working but the left outlane bulb should not light. If the left outlane lamp is on then the CPU board has a problem, if its off the there is a play field problem.

Check U-52 pin 11 for a pulsing output with a logic probe. Test Q-53 and 54 with DMM. Check the 3 resistors for the correct ohms. Check R-83 for cracked solder joints.

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Did you get pulses on pin 11 of U-52 in attract mode? You can compare with pin 6 of U-52. If not then cut the middle lead of Q-53 and recheck for pulses on pin 11 of U-52.

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Since it is stuck low, either the resistor or the transistor is bad. Cut the base of the transistor to remove it from acting upon U-52. If it pulses then the transistor is bad, if not the resistor pack is bad.

Doesn't matter.

Very likely, but you have to have hope that new parts are good. Even China makes some that work.

In attract mode the game is pulsing the lamps in different patterns so the outputs will be slightly different.
U-52 is working now. If its was me, I would replace both the predriver(Q-53) and the driver transistor(Q-54) as a pair.

So this sounds as if the resistor pack SR-17 is working with no load, but stops working when there is a load. Or the new Q-53 is bad just as the old one was. You can test the resistor pack with an ohm meter. Check from pin 1 to 2, from pin 1 to 3 and so on. Pin 1 has a white dot for marking. Each of the 8 resistors in the pack should read 4.7k ohms. These don't go bad very often, but sometimes they fracture internally causing intermittent problems.

I have only seen this a couple times. Tested fine in circuit, looked fine too. Fell apart in pieces after removing the solder.

If you meter was showing a k behind these numbers then its testing fine. But it can still be bad.
You have changed 2 of the 3 parts that can cause this issue. Sometimes you just have to replace a part to be sure.

Do an ohm test on SR-16.