Bally Old Chicago (Bally, 1976) weak flippers and pop bumpers

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sprig100

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old chicago(all i've got)
I recently did a flipper overhaul on my Old Chicago and they kicked A** afterwards. 2-3 weeks later they seem very "sluggish" and weak. Some of the pop bumpers have lost their umpf also. I changed the coil in the worst one but it made no difference. Any ideas? I'm far from an expert but everything looks ok to me. Where should I start looking?
 
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my guess is that the 2 hole kicker solenoids work fine. thats because they get their power from before the tilt relay and game over latch/trip relay. the dc thumper bumpers and the flipper coils get their power after those 2 relays. example if the ball goes into one of those holes during tilt it needs to be kicked out. so the switches that control the playfield power on those 2 relays and possibly the reset relay depending on machine need to be checked for pitted contacts and correct points gap. pitted contacts due to arcing can cause a voltage drop and lower the voltage to the coils. lightly file clean switches if needed. oxidized connections on the playfield jones plugs may also cause a voltage drop. transformer and solenoid fuse connections should also be checked.
 
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Hi
I havn't had time to get into it but some of the bumpers work fine, and I think the kickers are OK. Maybe slightly weak. I assume the relays you mentioned are located in the bottom of the cabinet? Luckily, after almost 40 years the machine still has all of the marking tags for the relays. Hopefully I have some time this weekend. Thanks
 
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how much voltage should I be seeing at the flipper and pop bumper coils? Can i check voltage at the pop bumper switch and the flipper button on the cabinet? I measured about 75 v at the pop bumper switches. Correct? Thanks
 
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with pitted contacts the proper voltage might be present but the availible current might be lower. each of the bumpers gets it power from the bridge rectifier, and it looks like each bumper gets it power from its spoon switch. each of the spoon switches should be filed clean. on newer bally ems a higher voltage was used to make coils stronger, so 75v might be correct. file clean the flipper button switches and the EOS switches and see if the flipper strength returns. the slingshot kickers also use the larger point switches and can be filed clean for proper strength. the hole kicker coils get their power from a relay and a switch on the score motor.
 
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Thanks. I'll check immediately. I don't have any special files. Of course I have an order from Pinball Resource on the way. Should have thought of that. What can I use? Tried cleaning flipper button switches With a business card but don't think it helped.EOS switches are New from PBR.
 
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i like using a metal points file or sometimes called a ignition points file. a business card or folded dollar is used for switches with gold points in solid state machines and will not remove any pitting.
 
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I used the file from a fingernail clipper. Maybe not the best Choice but seemed to clean them up Nice. No noticeable change in flippers or pops. I don't understand why if I have proper voltage, New coil, and newly cleaned contacts, that the bumpers and flippers won't work properly. Looks like a long term repair Project. The kids still enjoy playing anyway, but I'm frustrated and want it 100%. Thanks for Your help again Pinballdaveh.
 
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Try using a jumper across EOS contacts and see if there is any change in coil strength. I am curious about voltage levels when these coils are activated. Does it go real low?That 75 volts does sound a bit high but like 'DaveH' said may be normal. Is there a chance the bridge rectifier is allowing to much AC to pass. Do you still have some coils that seem strong? Shorting the end of stroke switch or winding in coil will force the coil to preform at maximum power and take contact questions out of equation for a test( it is safe but the coil would heat up after a bit) .
 
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Coil Smoke may be right about the bridge rectifier might be going bad or the filter cap after it might be bad and not filtering out the ripple. i dont have that schematic so i cant tell if both the flippers and bumpers are DC coils. the bridge and cap should not be expensive and should be changed.
 
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Hi guys. Done some checking under there. From the schematic it looks like the flippers come before the bridge so i'm not sure if they are connected to this. what kind of voltage should i be seeing at the bridge? i've checked the transformer and am getting all correct voltages out. 53.5,57.5, and 6.4. How do I short the coil to check strength? i tried to jump over to the switch and just blew the 5amp under the playfeild. But i think(hope) you guys might be on the right track With this. bridge looks "relatively New" but cap looks very old. thanks for all Your help. By the way, where should i be checking voltage at coils? i don,t understand how i'm getting 75 v when transformer doesn't put out more than 50v. but i'm not an electrician either.
 
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When your meter reads AC voltage it shows an R.M.S. value. The RMS is .770 of peak voltage. Rectified AC yields pulses of +DC and -DC. A filter capacitor across the + and - DC charges to the peak value of the applied waveform. 50 VDC divided by .770 = 61.5 VDC. 57 VDC divided by .770=74.025974025974025974025974025974 charges up to almost 75 volts and an interesting infinite repeating value.

About testing pinball coils with End Of Stroke switch. This sounds a bit complex at first. The genius of this protective circuit is how simple it actually is. This circuit allows a flipper to be held open(energized) without overheating. When the EOS switch is opened the current must travel the full length of both sections of the coil. The coil has two sections. A high power winding that pulls the solenoid in. A second winding in series with the first that drops coil power and just holds the solenoid at the end of it's stroke. Think of it as a center tap in the middle of a long winding. The EOS switch is normally closed and it shorts the low power winding of the coil. A jumper across the switch also shorts the low power coil. This causes all power to flow thru the high power winding in that coil. When the solenoid has reached the end of it's travel it pushes the EOS switch open. Now the power has to flow through both windings .
 
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so my Reading of 75 vdc is correct? that hasn't got me anywhere then.
 
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About testing pinball coils with End Of Stroke switch. This sounds a bit complex at first. The genius of this protective circuit is how simple it actually is. This circuit allows a flipper to be held open(energized) without overheating. When the EOS switch is opened the current must travel the full length of both sections of the coil. The coil has two sections. A high power winding that pulls the solenoid in. A second winding in series with the first that drops coil power and just holds the solenoid at the end of it's stroke. Think of it as a center tap in the middle of a long winding. The EOS switch is normally closed and it shorts the low power winding of the coil. A jumper across the switch also shorts the low power coil. This causes all power to flow thru the high power winding in that coil. When the solenoid has reached the end of it's travel it pushes the EOS switch open. Now the power has to flow through both windings .
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P>S> Simply put...The EOS switch is in parallel with the 'hold' winding. It bypasses that part of the coil until it opens.
The important thing is all coil pull in power goes through that switch so it has to make good connection. If it has any resistance= weak flipper...C_S
 
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the flipper coils aren't more than 6 weeks old. can they have gone bad already? or is it normal for them to "Level out" after a little time? Both flippers are weak, 3 maybe 4 of 5 pops are very weak and the kickers (except maybe the outhole" seem weak. yet i get the same voltage Readings on all the pops and brand New coils hardly fire.
 
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What voltages do you get when the coils fire? It is hard to proceed without schematics. Power must be lost somewhere common to all those coils. Like a bad ground or poor connection, solder joint, 'Jones' plug, bad fuse holder? ...
 
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here is some added info that might help. on the transformer the yellow wires are the common feed lines for the solenoids and the lights. the red-white wire is the solenoid return line. this red-white should be on the 53.5 tap , the tap next to it is the higher voltage tap and there shouldnt be any wires going to that. on the under-side of playfield the red wires going to the flipper coils are AC switched common return lines. the black wires are the AC un-switched common return lines. the orange wires are the DC common return lines. the yellow wires are the same as on the transformer. with the ball removed and the playfield stood up leaning on the head , slip a piece of paper in the spinning target switch , and start a game. use a alligator jumper from yellow feed and touch other end to orange-black wire on left flipper. does flipper pull in with full strength? remove jumper. on now the lower part of playfield there are 4 relays with red common going to 3 of them and a black common going to one of them. connect the jumper from the red to the black wires. do the flippers and bumpers now have full strength when operated? remove jumper
 
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hello again. i've tried Your suggestions. all pop bumpers show approx. 73.6 v at rest and 42.7 when fired (Orange wires). flippers Reading 53.3 ar rest(all wires) and .43 (Orange/red or blk/white), 16.1(grey) and 53 (red) when fired. I noticed no change in voltage or performance when jumping the common at the coils mentioned under the playfield. do these Readings make any sense to you? I still find it strange that 1 pop Works fine and the others work at varying Levels of poor. also no noticeable change in performance when jumping the yellow feed to the flippers.
 
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strange problems call for strange troubleshooting methods. with machine un-plugged remove both gen. illum. fuses, pop bumper fuse, and un-solder yellow feed to bridge rectifier. plug in machine start new game test flipper operation. replace gen. illum. fuses one at a time and check flippers. turn machine off resolder yellow wire to bridge, turn machine on reset game and check flipper operation. turn machine off replace bridge fuse and pull both gen. illum. fuses again. turn machine on and test replace each gen. illum. fuses and test. does all the coils in the head work properly? if you set all 4 players score reels to 1 does the reset work correctly? i think i see diodes across all or most of the pop bumper coils , are they all connected and with bands going in the same direction in reference to orange wires?
 
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I'm back again With a New problem. I think this machine is cursed. Player 1 gets 1 touch of the ball to a switch or pop bumper almost anything and everything Locks up. Pop bumpers fire but don't score, nothing happens With alternator switches, only drop targets, stand up targets and spinner Works and scores. Players 2,3, and 4 work fine though. I don't even know where to start. Fuses are ok. Hope one or some of you experts have an idea. Thanks
 
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thank you for the clues to make this problem easy to figure out. only happens on 1st player and some things still score points. it sounds like a 10 point and 10 point relay problem. when a 10 point playfield switch is hit the 10 point relay pulls in and stays pulled in thru its hold in switch and the EOS switches wired in series of all 4 players 10 point score reels. other switches on the 10 point relay will pulse the 10 point chime, 00-90 match unit( that controls the alternator), 90-100 carryover, and score reel solenoid thru the player up unit. so if the 1st player 10 point score reel isnt pulling in, or isnt pulling in far enough to open the EOS switch the 10 point relay will stay pulled in causing the other coils it operates to heat up. things to check out are 1st player score reel coil and connections,its EOS switch, the proper operation of the score reel, and any wires off or dirty wiper finger connections on the player up unit.
 
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when you say score reel, are you referring to the actual reels in the backbox and their respective mechanisms?
 
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hi again. finally got some parts after finding that the 00-90 (match) solenoid was completely burnt (probably Lucky it didn't burn the house Down). replaced the coil, turned on machine and started and scoring motor continued to spin round and round. upon investigation found that the player 1 10 pt. solenoid was melted inside the sleeve stopping the plunger from pulling in. "Stole" a coil from player 4 and replaced coil. score moter problem solved. Game will still not start. I have replaced the delay and reset relays (didn't look very good) but the game over interlock relay(trip) won't allow the game to reset. The Lock relay also looks quite burnt and seems like it is hot(always activated?) I don't however have a replacement for that one. can I substitute something else just to test. It is a G-33-2800. If it helps...I had a pop bumper bracket break and the coil "exploded" when it fired. could this have caused some kind of catastrophic failure to all of these systems? They are mostly what you have mentioned in the past. Hope you can help. Thanks
 
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