Hi, this is my first post to this site.
I'm looking for help repairing my Williams System 7 Jungle Lord.
I got this pin from a friend of my dad, who got it from another guy who I'm afraid ruined the poor thing.
It didn't work when I first received it, and it still doesn't work to this day, with basically the exact same symptoms regardless of the work I've put into it. When powered on, the general illumination comes one and stays on. No coils lock on (last I checked, before replacing some chips). It does nothing else. I can do a sound board check and it cycles through all of the sounds correctly.
Here are all of the repairs and modifications I've done to the machine since receiving it: I have replaced all of the lights (except playfield) with new bulbs. I have replaced a 9-pin connector on the power supply board because it had a burned spot on it (The connector next to the 6.3VAC GI in, don't know the label on it offhand.). I replaced a section of the 40-pin interconnect because it had a dodgy connection (all other pins have continuity. I don't have the parts to replace them on hand and it's on the bottom of the totem pole atm.) I have replaced all of the capacitors on the power supply board and sound board (because I had read it's a must-do due to them deteriorating with age). I have replaced the AA battery holder on the CPU/MPU board (is it called cpu or mpu here? I've heard both...) because the old one corroded, and luckily didn't cause any noticeable board damage. I have replaced the solenoid and lighting bridge rectifiers (because the solenoid voltage on the power supply board wasn't correct), and I made a modification to put a 8A slow-blow fuse on one AC line going to each rectifier for safety. I have completely redone the coin door (in the images you can see my frankendoor that I have brought to life.) A prior owner cut out the wiring harness and gutted the coin door. All I was able to get a hold of was a Bally door, so I managed to rewire the entire coin door, replace the mechs, troughs, switches, reject solenoid, light sockets, etc. I haven't been able to properly test it, due to, you know, dead game. But I'm pretty proud of the repairs and am fairly confident they will work.
Even after all of this, the cpu board still won't boot. It won't do a self-check, nothing on the LED light, and nothing on the 9-digit light. I have even disconnected every connector to the cpu board except power, and everything from the driver board. I just wanted to see the LED on the cpu board flash, or something to show me that it's even trying to boot. Still nothing.
I replaced all the ROM chips (both flipper ROMs and the game ROMs) on the board. I also replaced the CPU chip, and both of the PIA chips. I have no proof that they're bad, but I suspect a prior owner might have crossed the black and white connectors, frying the logic. I know the CPU and PIA chips are complicated chips, and I figured it would be easier to proactively replace them then trying to trace the logic with them potentially having issues. Even then, putting power to only the cpu board, it still won't even try to boot.
I tried tracing the power coming from the transformer, and right now with the lines I have checked, I have a solid 6.3 VAC going to the general illumination into the power supply board. Right now my + line from the lamp rectifier is 19.7 VDC, and the + line from the solenoid rectifier is about 47-48 VDC. I'm not sure these are right, and it worries me. Does this mean that my main transformer is bad? I'm hoping that's not the case, as that will probably run $100+ and I've already dropped enough money into this thing...
The schematics for the solenoid rectifier says it should be 25.5 VAC in. It is currently reading 30VAC. The schematics for the lamp rectifier says it should be 13.5 VAC in. It is currently reading 15 VAC. Is this within the allowable range, or does it mean, again, that my transformer needs replaced?
The last check I did was to put the CPU board and Driver boards back in and tried testing the CPU with the new chips installed. The only connections are the 40-pin interconnect, and the power connector into the CPU board. Still nothing. I have a good +5V DC into the board, at Test Point 9, and at pins 8 and 35 on the CPU chip.
I know the easy thing would be to just send this thing out to get repaired at this point, but I would really like to try to fix it myself, so I can learn/know how to do it, and to feel like I fixed it. I would like to try and turn this into a long-term hobby, but this first machine of mine is really taking it to me. Again, any help is appreciated.
So far I've kind of had the feeling of 'Now I should do this.... okay now I should do this.... okay how about this?.... this?... etc. etc. etc. But right now I feel pretty stuck.
I'm trying to get a hold of a computer power supply so that I can bench-test the logic on the cpu board, because I still suspect fried logic chips. I have all the schematics that I can find online, even though the logic schematics are archaic at best. I think I can manage, but it's pretty tough.
I'm really sorry about the wall of text, but I wanted to be thorough. I hope I can get some help from you guys. Thanks for looking.
Here's some photos of my machine as is (8-19-15):
In addition, I just want it clear that I know this is a difficult and very technical project and problem. I know I'm asking a lot to be shown "what to do". I'm just basically to the point where if someone knows what I should do next, I'm going to try it. New transformer? Alright, I'll fork out the $100 and replace it. Oh, I should start tracing the logic starting with the CPU chip? Alright, I'll try it. I should go bury a pinball in the back left of my backyard at midnight and say an incantation? Sounds like a plan! I just am looking for a little more confirmation and direction. I've been working on this machine nearly day by day for about a month now, and while I feel like I've made a lot of progress, and everything I've done probably needed done, I just don't feel any closer to having it fixed.
I'm really to the point of considering just dropping $300 on a Rottendog MPU/Driver combo board. I just don't want to go to that extreme if this seems like something potentially simple that you guys could help me with.