5th ball trip relay not working
|Case Study Summary|
|Games Applicable To||3 card|
|Problem Reported||5th Ball relay not tripping|
No payout occurring on a Bally Beauty. The problem was traced to the 5th ball relay not tripping when the 5th ball was raised.
The solution to this problem should be fairly easy as there are only 2 switches and the Timer Unit in the circuit to energize the relay. However, as it is with these wonderful old machines, this was far from straight forward and did have me puzzling for a little while !
Inspection Debug Procedure
As usual, I prefer to start checking the circuits using a continuity tester. It's just what I prefer, as the circuits are tested with the machine switched off, so there's no likelihood of any mishaps.
The first switch is on the ball lifter cam and comes directly from the 30 wire, so I assumed this was ok as all the other 50v circuits were functioning correctly. All the switches had previously been cleaned, so all I had to do was check the continuity across the blades - OK.
Next in line was trough switch #4. With the previous switch open, continuity was checked to the trough switch and across the blades - OK.
Finally was the Timer Unit. Unfortunately, on these older machines, there is not a great deal of information about wiring numbers in the manual, but it didn't take long to work out what wires went where. One pair of wiper fingers on the unit contacted onto rivets on the 4th step of the Timer Unit, meaning that when the 5th ball was raised to the playfield, the Ball Lifter cam switch would complete the circuit and energize the trip relay.
The circuit through the Timer Unit was continuity tested and again found to be OK. With the whole circuit tested, it really only left one option - the trip relay coil was burned out or faulty.
Rather than take it out and change it, the best option was to test the resistance through the coil, which is easily done with a multimeter. The resistance was spot on, so I knew the coil was OK. With everything seeming to be alright, I powered on the machine and tried it, but yet again, the relay still didn't trip !
Voltmeter Debug Procedure
What I had to do next was get the voltmeter out and see what was breaking down in the circuit.
With the machine powered up, one end of the voltmeter was attached to the trip relay coil and the other end to the 30 wire on the Ball Lifter cam switch. The reading came back as 50v (actually 48.6v if you want to get really picky). The probe was then placed on the Trough switch and the Ball Lifter cam switch closed. This too came back with a reading of 50v. Next the probe was put on the 51-10 wire entering the Timer Unit. This also showed 50v.
The Timer unit was stepped up to the 4th position and the probe placed on the 61-10 wire leaving the Timer Unit - Nothing.
This showed that the problem was located somewhere in the Timer Unit.
The obvious fault was that the wipers were not contacting the rivets properly, but I had already check this out and they were fine.
I switched the machine off and went back to the continuity tester.
With the Timer in the 4th position, continuity was tested between the 51-10 and the 61-10 wires and this time there was no continuity, although I'm sure there was when I tested it before ! I stripped the Timer unit and checked all the wiring to the rivets and did continuity tests to check them. All seemed ok. The only thing left was the pair of wiper fingers.
I continuity tested between the ends of both wipers and again everything seemed fine, but still no continuity between the 51-10 and 61-10 wires. I tried the wipers for continuity again and although it was ok, it wasn't consistent. So I decided to take the wiper unit apart and clean everything. It was reassembled and tested again and this time continuity was much better. I was so confident that I had found the solution, that I put everything back together, turned on the machine and tested it. Still no 5th ball relay tripping !!!!.
In desperation, I put a jumper wire between the 51-10 and the 61-10 wires, fired up the machine and Bingo - so to speak. The relay tripped, proving that the fault had to be in the pair of wipers. I had (obviously) already checked that the wipers were contacting the rivets. so there had to be another problem. I started with the Timer Unit in the reset position and tested the continuity through the wipers - OK. Each time I stepped the Timer Unit I tested them again - each time OK, until I came to the 4th step and then I got the inconsistency that I had before.
By probing around with the continuity tester, I found that if I gently touched one end right onto the contact on one of the wipers, I would get no continuity from anywhere else on the wipers. It appeared that the contact on one of the wipers was maybe very slightly loose, but not noticeably so. Perhaps some dirt had just got under it, but when it touched the rivet, it was pushed away from the wiper blade enough to lose the contact.
So, all I had to do was put a little solder on the back of the wiper blade, over the contact, and then test everything again. This time, everything worked perfectly - and still does !!! But it just goes to show how silly little faults, that you wouldn't dream of looking for, can sometimes take hours and hours to find !!