|Jungle Lord / Williams 7 Driver Board Update #2
|Posted by: AceBHound on Sep 4th, 2010 9:03 PM
|Still working on fixing the Jungle Lord Pinball. Apparently this machine had been sitting in the previous owner's basement for years. It came with a lot of gremlins, so I do wonder if the previous owner ever had it working 100% or bought it with some issues. Battery corrosion, wrong/bad MPU game & flipper roms, driver board blowing the solenoid fuse, the sound volume is barely audible. It shows a lot of use, so maybe it was purchased in partially working condition and played till it stopped working. Anyway on to the update --
I happened to find another solenoid driver board in my parts bin to swap into the machine and this time the solenoid fuse didn't blow. I was also able to go into the diagnostics menu and have it fire each of the coils in the game without an issue. The problem with this 2nd driver board was it wouldn't credit a coin for any of the 3 coin switches, so no way to start a game. I thought it was a 7406 hex chip (IC17 at the top right of the driver board) that is part of the switch column drive. Coin switches hook into IC17, so I tested it with the diode test on the multimeter (ground on pin7, then test all pins except 14 for about 0.5v). One or two pins tested lower the 0.5v so I removed the chip and replaced with machine pin sockets, then replaced the 7406 IC. Again used the diode test and with the chip in-circuit it was still reading low on a few pins. So, I tested where those pins hooked into the IC11 PIA (peripheral interface adapter) and then used diode test again to determine the PIA was most likely bad.
I still don't like blindly replacing a 40 pin PIA chip though, something with that many pins is never fun to unsolder and install a socket. So I used Leon's Test ROM and was able to verify the PIA was not pulsing a signal on pins 10-13. Also realized the 40 pin PIA was an NTE6821, not the stock Williams 6821, so looked like someone had already replaced it at one point. Not sure why they didn't put in a socket. The rule of thumb seems to be if you replace any ICs on a board that aren't already socketed you might as well install a socket in case it blows again. No sense not socketing it to find out that it was something under the playfield blowing the chip and then having to unsolder all over again.
Replaced the PIA and installed socket (as shown inside blue circle in the picture). Retested the board with Leon's test rom and pins 10-13 pulsed fine now. Installed the board & was able to add credits to the game and start the game! Yay!
Also used Leon's test rom to further isolate the 1st driver board that was blowing the solenoid fuse. Turns out a few of the special solenoids were locked on. Appears to be the IC8 7402 chip. Don't have any in stock so had to order some. Hoping that resolves the solenoid fuse blowing. If any solenoids are locked on via a shorted transistor or bad IC it'll blow the solenoid fuse (which is a good thing).
So, onto the next set of issues. I can start a game, it kicks the ball out, but lots of things don't seem to be working correctly. If I lose the ball out the middle it doesn't end the current ball. Drop targets seem to be gummed up, bunch of switches don't work, lots of lights out, very very low volume even with the volume knob turned all the way up, some of the displays are missing some digits. That's why I find it hard to believe even if this machine sat in a basement for a while that it would be in this much disrepair. Oh well, great for learning on anyway =)
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