![]() "Randy is always very professional and extremely knowledgeable about the work that needs to be done."Randy just left here and after over 20 years I now have a jukebox that works." -Jeff, Aurora, CO.He was very professional and knowledgeable and I feel he has the ability to troubleshoot anything pinball or anything electronic for that matter." -Craig H., Broomfield, CO "Randy was there an hour and found the problem and also a couple other potential issues.Randy has worked on my three Williams machines (Taxi, T2, and Funhouse) and based on his previous work, I am confident he could solve any future issue." -Greg M., Louisville, CO He has always arrived promptly with all the tools and parts needed to efficiently complete the jobs. "Randy is a true professional with amazing knowledge of electrical wiring, programming, boards and mechanical workings.The Black Knight was ready for battle again! Next I solved some minor connection issues with the flippers and G.I. The switches all worked once IC16 was replaced. One of the switches in that row is the shooter lane, so the machine always thought there was already a ball there and wouldn’t deliver another to the shooter lane. The shorted switch row was the reason the multi-player bonus round was not working. The diagnostic still showed the switch row shorted to ground. To isolate whether the problem was in the machine wiring or with the driver board circuit, I unplugged 2J3. so it looked like they were shorted to ground someplace. They all share the same row (White/Green Row 5). It showed that switches 5, 13, 21, 29, 37, and 45 were all closed. I removed the balls from the machine and ran the switch diagnostics. Next, I noticed problems with other switches in the matrix. I found the screw in the coin box and reinstalled it. This turned out to be a missing screw that held part of the assembly together. A couple of the drop targets in the middle bank would pop up during reset, but would not stay there. Next, I decided to check the drop targets. I replaced the transistor, and for the first time in 5 years it made sound! I pulled it from the circuit and tested it with my meter and determined the transistor was bad (normally they short when failed, but this one was open). The transistor was acting like it wasn’t connected. From there it goes to a transistor (Q2) which acts as a current to voltage converter. With my oscilloscope, I could see the sound coming out of the digital to analog converter (IC13). This will send the analog sounds directly to the amplifier, bypassing the speech board. I disconnected the speech board and jumpered W1. Then the sound travels back to the main sound board for amplification and then to the speaker. On this era of Williams machine, the analog sounds leave the main sound board and go to the adjacent speech board, where the analog sound and speech are mixed together. ![]() I checked the connections to the speech board. ![]() ![]() ![]() When I started the game the speech was working fine, but the background sound effects were not there. Symptoms: Speech only, but no background sound Multi-player bonus round not working Some drop targets not resetting. Location: Fairplay, Colorado (home of South Park). In both cases, once the repair was complete, the Black Knight proclaimed “I will slay thee, knight!” Posted in Pinball, Repairs | Tagged Black Knight, Williams | Leave a reply Black Knight Pinball Machine (Williams, 1980) (Some Black Knights might have a different power board that uses a 2N6057 transistor with a separate regulator circuit.
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