Quoted from 27dnast:Where is the flipper relay located on classic Sterns?
The flipper enable relay is on the Solenoid Driver Board (SDB) in the backbox.
(picture courtesy of IPDB)
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Quoted from 27dnast:Where is the flipper relay located on classic Sterns?
The flipper enable relay is on the Solenoid Driver Board (SDB) in the backbox.
(picture courtesy of IPDB)
Quoted from Slogan1111:I ground pin 8 on j4 of the mpu and the relay clicks
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.
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.
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?
Quoted from EddiePi:Grounding R103 of the MPU engages the flipper relay.
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?
Quoted from EddiePi:R103 - 320 (is this within range at 320 ?)
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.
Quoted from EddiePi: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 ?
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.
Quoted from EddiePi: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.
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).
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