The board was retested in the machine and everything was fine. I then placed a new ULN2804 into the socket. I replaced U20 with a socket because this is a common problem with these Williams MPU boards. I then checked the input to U20 to make sure the upstream chip was functioning correctly. The 12 volts on the pullup resistor was fine. I checked that there was 12 volts on the pullup resistors to make sure the PCB wasn’t damaged from leaky RAM batteries. Instead of seeing a signal pulsing from 12 volts to ground, I saw a signal pulsing from about 2 volts to ground. To be sure, I checked the column outputs with my oscilloscope.
ROWE AMI CD JUKEBOX MAKE LIGHTS BLINK DRIVER
This pointed to the column driver chip U20 (ULN2804). I repeated with a few of the other rows and got the same result. Instead of seeing a single switch closure, the entire Row 1 lit up as being closed. With the pinball machine in the Switch Edges test routine, I took a couple of jumper leads and a diode and connected a Row 1 with Column 1. I disconnected all of the switch connectors from the MPU. Lower portion of the Williams MPU board (click for larger), U20 is just left of center. Posted in Jukebox, Repairs | Tagged M100, Seeburg | Leave a reply Bram Stoker’s Dracula Pinball Machine (Williams 1993) This is great if you have small kids around who might be randomly pressing buttons and then walking away. The advantage to this solenoid protector over the solutions provided from various internet sites (where the latch solenoid is wired to the hold relay), is that if a letter is selected without a number or vice versa, the solenoid eventually times out and releases after about 30 seconds.
ROWE AMI CD JUKEBOX MAKE LIGHTS BLINK FREE
It has a small switch on it that selects between coin operation and free play. Victory Glass sells a solenoid protector that is plugged in between the Wired Selection Receiver and the selector keyboard. Eventually the latch solenoid overheated and shorted. It was being used at a party and someone probably pushed the button a number of times establishing the maximum number of credits, then the person didn’t follow through and use all of the credits. In this case, the jukebox had a small pushbutton switch on the rear that gave three credits every time it was pressed. That process probably takes no more than 30 seconds. Under normal circumstances, a person deposits coins, the solenoid energizes, the person makes selections until their credits are used up, then the solenoid is de-energized. The solenoid isn’t designed for continuous use. All seemed normal.Īfter a while, smoke did appear and it was coming from the latch solenoid behind the selector switches. The jukebox was in the middle of playing a record when it was shut down, so it continued playing the record when I powered it up. I visually checked the latch solenoid, but I didn’t notice anything wrong. This could have been the mechanism or the selector switches, or even something from down below. The owner said the smoke was visible at the front of the jukebox. Symptom: Visible smoke coming from jukebox.