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How To Read Pinball Schematics Repairing A 1975 Bally Em Pinball Machine! This COULD BE as a outcome of the MPU is sensitive to the exact voltage supplied and will not boot with a pc provide. If the board efficiently boots within the recreation, this might be the cause. Also, if the LED locks on immediately, strive doing a guide reset by briefly shorting collectively pins 39 and forty of the U9 CPU with a small screwdriver. This forces the pin 40 to go low and begin the boot course of. It is also attainable to short the junction of resistors R1 and R3, on the proper side of R1, to board GROUND with a jumper clip to accomplish the identical impact.  Likewise, the 6810 on the S&T board could be examined in a recognized working MPU board. Also, the 1st flash shall be computerized with simply the 6802 installed, so lengthy as jumper K is put in. Having U6 put in with a 6802 CPU chip put in does not harm anything, and both the L or K jumper can be installed, as long as the 6810 is sweet.  Pack Of 5 Kits  Next, place the plastic onto a bit of Lexan, and trace the proper aspect of the plastic's form onto the piece of Lexan. Make sure to use enough of the plastic to cover the 3 screw holes within the vicinity of the flipper. These 3 screw holes might be used to safe the Lexan. The edges could be smoothed with a file or sandpaper.  With the flat side of the half dealing with and the leads pointing down, the leads are from left to right, RESET, V (+5v), and Ground. Anode to anode of CR7, cathode to "left" hole of R140. The CR7 anode gap is massive sufficient to accommodate both diode leads without trouble. Illustrated picture of components to remove, maintain, and jumpers to add. The same image, however with the only jumper indicated , where to put in the DS1811 flat side dealing with left, and the added 1K resistor. With the board oriented as it might be in the game , set up a jumper from the top through-hole of where R139 was, to the bottom through-hole of the place R138 was.  R140 - Resistor 20k Ohm, 1/4w  The playfield was stripped and cleaned, numerous damaged components were replaced, and the flipper assemblies had been additionally rebuilt. However, there's nothing particularly thrilling about any of that. These fuses are all high quality Bussman/Cooper or Littelfuse fuses. Here is an alternate technique to keep from balls getting trapped on prime of the plastic behind the higher left flipper. First, take away the present large plastic behind the higher left flipper.  One very common concern with solenoids not performing on the playfield is a blown fuse beneath the playfield. This fuse, usually a 1 amp slo-blo, powers all the solenoids on the playfield, except the flippers. The symptom of a blown playfield fuse is when the flippers, knocker, coin lockout relay, and chimes perform in solenoid test, but no other solenoids will allow. While the LM323K is a dependable voltage regulator, periodically, they do fail. bally pinball machines 1970s, on replacing the LM323K may be discovered here. The spring power of the pins in these AUGAT sockets eroded over time.  The slight on/off and ensuing EMF pulse through the boot up on the fifth flash can cause the MPU to lock up. If all the shows have the same digit out, then the issue is most likely caused by a bad connector on the MPU. Check the connectors on the MPU and all of the displays. If all seem properly, then one-by-one, disconnect every display and see if the problem goes away. If it does, then there is a short or a bad connector drawback on the board you simply eliminated. Be sure to turn the ability off between swap-outs, and wait 10 seconds for the high voltage filter capacitor to discharge earlier than you take away any connectors.  These by way of holes are used to install an alternate block fashion Ni-Cad battery. The backside left via gap is for the battery's positive terminal. The higher left through hole is used solely to assist the battery (the pad does not go to any of the board's circuitry). After replacing any parts, check your work with solely the J2 cabinet connector put in. After/if the mpu board is booting, add the the rest of the connectors again in. When you add the playfield's connectors again in and energy up, listen for any solenoids locking on at power-up.  Repair of that swap would possibly require substitute, cleansing, or resoldering / repairing the wires. If it boots, you should affirm the voltages anyway. Typically fixing that is to switch the board AND the plug connectors. If changing the board, always substitute the plug connectors.  015" Header Pins  Send the BCD data to the display driver - This BCD knowledge is positioned on the BCD data bus and show #1 is strobed. This will trigger the display's decoder to latch onto the enter alerts . A small transformer in the cupboard bally pinball repair backside provides the voltage required for this board. That energy is fused by an "in-line" fuse at the small transformer. The transistor and "management sign" within the simplified drawing above can be changed with the precise circuit.  By turning the coils off simply after the zero crossing, the voltage spike caused by the collapsing subject can additionally be kept to a minimum. Two giant gauge yellow wires going to at least one lug (mostly two wires because the wire is "daisy chained" from coil to coil). The regulated voltage won't be mentioned right here, solely the solenoid drive part. Next, begin the two mounting screws that undergo the bridge rectifiers, however don't tighten them all the best way. Clicking on the thumbnail at left will open a .pdf file detailing the part location and full bill of supplies for Bally -35 and Stern MPU-200 MPU boards.  If it doesn't fireplace throughout this check, skip the swap matrix part. 6) Turn it on AND listen to insure not one of the solenoids lock on. If this occurs, you'll hear a ‘thud’ because the solenoid plunger will get pulled into the coil. TP3 – 21.5 V DC (18.8 – 24.2) – half the solenoid voltage. If TP3, TP6 and TP7 are low, you have a connector problem at J3 on this board. Note that the majority try to regulate this downward to one hundred seventy to 175 to make the displays last more.  They hear ‘replace the board’, ‘redo the connectors’, ‘rebuild the ability supply’, and so on. These are all good methods, when there's a cause to. But don’t do this till you have an thought of what's mistaken. This site is dedicated to those who personal, or wish to own pinball machines. Information from the fundamentals to advanced repair, maintenance and restoration.  The reset has to go low to 0 volts for just a moment while the +5 volts stablizes at power-on. Then U1 pin 6 ought to go excessive signaling an excellent reset. If this is not the case verify the elements above and/or substitute them.

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