The flipper relay is controlled by one of the transistors along the bottom edge of the solenoid driver board. Take one end of an alligator clip and clip it to the ground braid. Touch the other end to the tab on each of the transistors. When you find the right one you should hear the relay click.

Then you can clip onto the transistor tab to keep it active while you test the flippers. If the flippers work then most likely the transistor or the pre driver IC is bad. If the flippers don't work then either the relay contacts are bad (unlikely) or the connectors on the right side of the board need work (more likely).

Where is the flipper relay located on classic Sterns?

The flipper relay is tested during the soleniod test part of self test. It is listed as K1 flipper enable. You can hear it click during the test. It is located on the left side of the SDB in both Bally and stern.

The flipper relay can also be bypassed entirely by jumpering the leads going in and out of the board. But it's easy enough to test the relay in solenoid test and just testing continuity across the headers.

The flipper circuit basically just comes into the SDB.. and heads right back out... just passing through the relay purely so the game can disable the flippers via software. Listen for the click, and test with continuity if needed.

Normally though it's other connectors that are the problem or the EOS. Unlike modern games, bally/stern flippers are purely switch driven except for the loop through the SDB/flipper relay.

SBD?

The flipper enable relay is on the Solenoid Driver Board (SDB) in the backbox.
(picture courtesy of IPDB)

Lectronamo_SDB1.jpg

Can anybody elaborate or help me with a flipper issue? I've tried everything in this thread. Both my flippers do not work on my Dolly Parton. Here's what I've done or checked. Brand new Alltek mpu. All voltages are within spec. Bypass the relay and can work the flippers if I send voltage directly to the transistor on the sdb. Replaced relay, transistor, & diode on Q15. Repinned connectors to the mpu. Finally put in a known working rottendog sdb from another machine, still no flipper action. I'm a little stumped at what could be bad here? Or where the problem lies? If the flippers work by bypassing the relay, but the relay clicks, where or what is the missing link?
Thanks,
Scott

Do you have voltage present at the flipper coils? Are the EOS Switches making good contact. You can test the flippers like any other coil if the voltage is present. Ground the center tab on the coil momentarily to see if the plunger pulls in. The correct tab to ground is the one with only a single wire going to the EOS switch.

How are the connectors on the rectifier board? All power originates and returns here. Anything wrong here will keep something from working

Yes, I can pop the coils by using the metal rail. I'm guessing I need to repin the connectors on the sdb? I will double check the eos switches. Another clue is, the flippers would stop working now & then, but they would come back to life. This one is tricky. Like you mentioned all power goes through the rect board. And the flippers are pretty much a direct route from that, through the sdb. BTW the connectors have been redone on the rect board.

Next thing I would test is continuity from the relay pins 8 & 9 to pins 2 & 1 on connector J2 on the driver board and relay pins 4 & 3 to pins 8 & 9 on connector J1. This is the path of the flipper power but would not prevent the relay from operating.

If you pull the SDB you'll see the traces near the relay. They're pretty straightforward. If this is an issue it's probably cracked solder joints.

p.s did you check the eos's? If they are not connected the hold coil doesn't have enough pull to pull in the flipper plunger. you can temporarily jumper across the switch to eliminate it as a problem. Don't leave the jumper though or you will melt the flipper coil quickly

never forget bad wires... even if they seem intact in the insulation. Wires can break inside. Intermitant behaviors are connectivity.. so find where it's intermitant by checking continuity in the fail cases.

When someone 'redid the connectors' make sure it's both pin and connector... and check for broken wires. You can always test by grounding pins at the board end to check continuity.

Ok. Thank much Cheddar & Flynn. I will post back with some good news, hopefully. Once I get home from work & check a few of these things!
Have a good one.. Scott

This is a very simple circuit. Originally we tried driving the flippers with transistors as any other coil. But that was too hard on the transistors so the relay was used to enable the flippers.

The circuit is simple. The brown wire side of the coils should have have constant 43v. Ground is applied on the other side of the flipper coil to operate it. The ground arrives via the following path: Leave J2-9 on the Rectifier board, through the flipper buttons in the cabinet, arrive SD board J2-1&2, through the relay then leave the SD board to the playfield and arrive at the flipper coils.
Since neither flipper works I would first confirm there is 43v present at the coils. Then investigate the first part of the citciut starting at the A2 rectifier board at J2-9. Try manually grounding the wire along the path to the flipper buttons. Connections on the rectifier board are notorius for failing over time.

Still pulling my hair out on this one. If i by pass the sdb the flippers work. J2 1 to j1 9, etc.
If i put in a different, known working sdb, i get then same results. Flippers do not work.
I have an alltek mpu board. Tried a different rectifier board as well. All voltages on all boards measure in spec. Yet the overvoltage red light is on on the mpu. Not sure if that is effecting anything? What component or issue could be causing then flippers to not work? Thanks in advance for anymore input.
Scott

If you put in a good SDB and it doesn't work.. but bypassing the relay works... then you should look at what is driving the relay.

Depending on how you tested J2 to J1 your connections could still be a factor.

The flipper disable signal comes from the MPU into the SDB on J4 pin 8. Which comes from J4 on the MPU and is fed by the PIA at U11.

So the problem can still be your J4 wiring... connectors.. or the PIA on the MPU.

I'd always start with checking the connectors tho.

I once had a similar “pull my hair out” issue with my Lost World - I bought it with no boards and rebuilt it. It was also lighting the Altek “over voltage” led.

Finally I figured that one of the connectors (from memory on the MPU) was wired wrong. Looked fine - maybe the wires/connector had pulled out of the molex and they’d just pushed them back into an empty hole. From memory, 2-3 of them were in the wrong holes.

Maybe pull the manual, and check all wire colours are going where they should be.

Long shot - but worth a double check.

rd

I took a wire from j2 1 from the molex to j1 9. Turned on and the flipper worked. Same for the other flipper. I will double check the mpu connectors. Thanks friends. I'll report back.

Well, the rest of my hair has been pulled out. Lol.
I haved ruled out all possible bad board theories. Went to the schematics and repinned all wires that had a connection involving the flipper reset and relay. Still no flipper action. When the machine boots the relay doesn't click. Nor does it click during self coil test. One decent clue I have is, I ground pin 8 on j4 of the mpu and the relay clicks, flippers also work when holding ground to pin 8. The connector is plugged into the board when i do this. Does this tell me voltage is not getting from sdb to mpu?
On a good note, the high voltage led on the mpu board has disappeared. Thanks.

That might be your problem. Pin 7 of J4 at the MPU board is for the flipper enable relay, not pin 8. Someone may have crossed some wires on that MPU J4 connector.
So MPU J4 pin 7 is supposed to be a blue-white wire. It goes to the Solenoid Driver Board at J4 pin 8 which ultimately switches driver transistor Q15 for the flipper enable relay.

Good lessons learned here. How to track down the issues & how to connect the schematics to the machine. Its finally fixed. Now to grow my hair back.
Long story short. Connections. Totally redid every single one. Also, the reset relay ended up going bad through all this. Thanks all for your valuable inputs.
Scott

Hi All. I need some help. I am having the issue raised by the OP, my flippers are dead.

I believe I was hit by a power spike. The varistar blew but as noted in other threads, early ballys will continue to run unlike modern sterns which will blow the fuse until the varistar is replaced. The surge issue has since been resolved.

So the flippers are dead. I grounded the tab on q15 to the braid, the flipper relay clicks and the flippers fire. Based on the 2nd issue in this post, I did some continuity testing. However I don't believe there is a pin 9 on the flipper relay as posted by Cheddar.

If the flippers fire when grounding the q15 tab, what am I missing ? Thanks.

Eddie

Grounding the transistor doesn't actually test the transistor itself, though in this case it's telling you the relay is good and the flippers are ok otherwise. You can use the diode test on your dmm to check the transistor, compare readings with other known good ones nearby. If transistor is good, I'd suspect the chip that drives the transistor.

Frunch...thanks for the reply. I'm going to take some time to jump into this tomorrow. I am assuming I should be looking in the area of the Q15, a SE9302. It sounds like this circuit comes into the board and then just leaves. Possibility a dumb question, but is there a chip driving this circuit ?

Mati Hari (resized).JPG

Yep, looks like the chip driving Q15 is at U4. 2136913.png

I'd check the transistor at Q15 and the diode at CR15 as well. If they both check good, I'd suspect U4. You can also ground the metal tab on Q15 to see if the flipper relay activates. If the relay clicks/activates, you should be able to try the flippers while it's activated.

Note that grounding Q15 doesn't test the transistor itself, you'll still need to check the transistor using the diode test on your dmm.

Frunch thanks for the above and Cheddar thanks for the link below regarding testing the 3081's.

https://pinside.com/pinball/forum/topic/game-plan-mpu-repair-a-shotgun-guide-w-pix/page/2#post-2049837

I finally got around to really getting into this machine, picked up some parts but still can't get the flipper relay to engage during bootup and game play. As before, when grounded to the Q15 tab, the relay engages and the flipper fires.

Tested Q15 (SE9302) and replaced it with a TIP102. Tested each of the transistors in U4 (3081). Based upon the link above, they should each have readings between .65-.75. The following tested good - 16/1; 8/7 and 6/4. 13/14, 11/12, 10/9 and 3/2 (flippers) tested bad. I also compared the results with U3.

Acquired a socket and a new 3081. Put the DMM to the 3081 before installing it and obtained correct readings. After socketing the 3081 and before putting the board into the machine, the readings are still off. The 2nd reading is to pin 15. Again, they are all based on testing per the link above.

Red/Black - Readings
16/1 - .729 and .729
13/14 - .233 and .511
11/12 - .233 and .511
10/9 - .233 and .511
8/7 - .732 and .732 (Right Drop Target Bank)
6/4 - .729 and .729
3/2 - .233 and .509 (Flipper)

Is there a different way I should be testing these ? All readings from U3 are in the .720 to .730 range.

During testing, I had a slight issue with the right drop target bank (Mata Hari), so I replaced all of the transistors, caps and diodes. The bank works. So my install of the socket and chip appears to be successful. Additionally, based on Mata Hari's schematics, 8/7 for the Right Drop Target Bank is the only other used in U4.

All components in the circuit were tested, except for the diode at CR17 which reads the same as others but as I understand needs to be tested out of circuit. I was getting strange readings from CR20 at the flipper relay, so replaced it. There was no change in the readings after replacement. I also tested continuity across the circuit from J4 8 to J3 5.

What am I missing ? Why are my readings off on U4 when I insert the chip ?

I could really use your assistance at this point.

Eddie

If you pull the 3081 and test it do the readings go back to normal?

Also I'm no expert but it looks to me like you can test the flipper relay by applying ground to J4 pin 8. That would test the whole circuit

Test point TP6 on the SDB is specifically there to help you manually test the driver transistors. Hook up a jumper lead to TP6 and very *briefly* touch the other end on the base leg of the transistor - since the base leg is hard to get to, easier access is to touch the banded side (lower leg) of the associated diode which is CR15 in this case. If the respective solenoid/coil/relay activates, the transistor should be good.

If that works, the next step upstream is to briefly ground the base leg of the transistor array that's associated with the driver transistor. In this case it's pin 3 of U4. This will test the transistor inside the transistor array live in the game. If this works, you've got a connection issue of the flipper enable signal between the MPU board and the solenoid driver board that's not activating the transistor array. See the previous post by Cheddar but instead you need to ground pin 8 of J4, not connect it to 5V.
If the previous transistor array check didn't work, then a diode check on CR15 will tell you if it's bad or good. If good, likely the problem is the transistor array. You can still check the transistor array live in circuit with your multi-meter set on voltage.

These things can all be done before you even pull the SDB out of the machine.

Corrected, thanks for catching that!

Thank you both again....I'm on it and will report back.

Cheddar Quench

Cheddar and Quench. I completed the tests, with success.

1. TP6 to Diode CR15. Flipper relay pulled in.
2. Ground to U4 3. Flipper relay pulled in.
3. Ground to J4 - 8. Flipper relay pulled in.

I now assume the SDB is operating correctly.

I will check the wire connector at J4 8 of the SDB then on to the MPU at J4 7 to look for bent connectors on the wires. I'll also look for continuity.

It looks like the J4 7 on the MPU is for "continuous solenoid data" and connects to a a 330 resister.

Sound about right ? Any help with whats next would be appreciated as always.

Eddie

It looks like the disable line goes from mpu j4-7 to sdb j4-8 and the color of the wire is blue white

Ok...so I have continuity across the wires. It's an mpu issue?

I did have a surge which took out the main power varistor. Thought I would throw that in there.

Assuming you have a Bally mpu and not an altek, swap the 2 Pia's and see what it does

Hi all, been a little backed up, so I put this on the secondary list. Back at it and hoping to get the flipper issue resolved. @cheddar, per your suggestion, I swapped U10 and U11, no change.

Just to eliminate the possibility of connectors, I again checked continuity from J4 8 of the SDB and J4 7 of the MPU. Took it one step further and tested between R37 of the SDB and R103 of the MPU which are both a little further down line from the connectors. All is well.

Flipper relay still pulls in when grounding tab Q105. I 'assume' this tells me the power side of the circuit, the flipper relay and everything through the flipper coils are working.

What is my next step ??

Eddie

When you ground the side of resistor R103 on the MPU board (the side of the resistor R103 that connects to the SDB), does the flipper enable relay click on?

Quench

Thanks...yes.

Grounding R103 of the MPU engages the flipper relay. Flippers fire when flipper buttons are pushed.

Eddie

So on the MPU board, either R103 (330 ohm resistor) is open circuit, there's an open circuit between pin 16 of the U11 PIA and the other leg of R103, or pin 16 of U11 has a short to some other signal that's normally high. Does it look like the U11 PIA socket been changed at any point?
Has this MPU board got any battery corrosion? Can you post some clear high res pictures?

@quench OK...so here is what I have.

R103 - 320 (is this within range at 320 ?)

I have continuity between the other leg and pin 16 of U11.

Yes...the U11 socket has been changed and yes there is battery corrosion. I bought the machine about 5 years ago. It had no batteries so I added the 5101. The corrosion was there when I got it, but never really noticed how bad it was, I believe it has somewhat expanded as corrosion does. I'm learning how these boards work and had no issues in recently repairing WPC that had similar corrosion. One thing I am not as familiar with as I would like to be is the inner workings of the PIA's ie what does Pin 16 do once it gets in there ?

I see the issues below U11. The test light CR8 works and blinks as it should on startup. Here are 2 pics. Let me know if you can see them clearly.

P_20190923_132005 (resized).jpg

P_20190923_132027 (resized).jpg

Yep, 320 ohms is in range. The tolerance colored band on that resistor is gold which specifies a tolerance of 5% so anywhere between 314 to 346 ohms is in spec.

PIA pin 16 is just a signal that can be used as an input or output. In this game architecture that pin is configured as one of many outputs and in this case it controls the flipper enable relay. When the game wants to enable the flippers, pin 16 gets programmed logic low to zero volts. When the game wants to disable the flippers, pin 16 gets programmed logic high to 5 volts.

What voltage do you measure at pin 16 of U11 when the machine is in:
game over (attract) mode
game mode

Pin 15 of U11 controls the coin lockout coil on the front door. So long as you don't have maximum credits, you should measure the same voltage on pin 15 as pin 16 when the machine is in game mode.

Another thing to check:
With the machine off, set your multi-meter to resistance mode. Measure the resistance between pin 16 of U11 and ground (test point TP4 on the MPU board is a ground point) and also measure the resistance of pin 16 of U11 to the 5V supply trace - use TP5. Compare it to the resistances of pins 14, 15 and 17. You can even do this with the board on the bench. If pin 16 measures different resistance to the other pins it'll give us an idea if it's shorted.

The corrosion was superficially cleaned at some point but not neutralised and it's returned. What's the corrosion on the back of the board look like? (post pics).

I want to thank everyone for their input on this, but it was time to give up and get the thing running. I bought the Alltek Ultimate MPU for Bally/Stern, set it to Mata Hari, set the features and it fired right up and cleared up the flippers, flickering displays and a few other things. After an attempt to clean the board, it was acting even worse. The corrosion finally beat it.

While I was at it, I picked up the LED flicker eliminator adapter kit. It was basically plug and play. Replaced the pop bumper skirts, added LED's and it plays fast and looks great.

While frustrating, along with the fact I really wanted to fix it, I learned a lot in this process. My takeaway is once I cleared the SDB, that I needed to go further downstream. The tests that Quench mentioned weren't testing out correctly and it was time to pull the plug.

Thank you all so much for all the info… this thread has been super helpful so far. So I have a Stern Stars and it’s running a new NVRAM WEEBLY MPU board. Everything works except it seems the board is not sending a signal to activate the flipper relay on the SDB. I’ve gotten to this point of grounding the R103 but this does not activate the relay. What would be my next step? As a side note I have done everything leading up to this point and it all checks out. Thank you in advance.

IMG_0929 (resized).jpeg

with the game on, using a jumper lead ground the metal tab of transistor Q15, do you hear the relay pull in/click?

Yes

Figured it out, bad connection on SDB J4 pin 8. It threw me for a loop because I just re pinned that connection and I had continuity with the other side but apparently the pin wasn’t making a good enough connection.