Arcade Collecting > Pinball
My First Pin - Flight 2000 (Pics)
Neverending Project:
OK, so I am able to narrow it down to connector J5 on the SDU. If I unplug J5 and power the game on, it goes into attract mode, and the rest of the connected coils will fire in the self-test mode. While it's in attract mode if I plug in J5 I hear a coil immediately fire - so I unplug it immediately.
I disconnected the coil that was firing (13), and try again. This time another coil fires immediately. I think it was 12. I could disconnect this one too and repeat, but isn't this telling me there is something wrong with the wiring, not necessarily a coil?
Neverending Project:
Next up I need to check the solenoid driver board. I tested +46V at pins 3, 7 and 8 of J5 on the SDB, and it is my understanding that there should be to voltage on these pins.
From what I understand, when the MPU tells a solenoid to turn on (momentarily) it sends a signal which gets decoded, and the corresponding solenoid driver transistor turns on. The solenoid lug (connected to the non-banded side of the coil diode) is connected to this driver transistor, and hence gets connected to ground when the driver transistor turns on - thus energizing the coil. My point is that there shouldn't be +46V on this part of the SDB. I'll check for shorts or other funky stuff.
Neverending Project:
OK, I think I was wrong in my last post. Every solenoid pin on the SDU should be +46V until it is fired, which will bring it low, and energize the coil.
So next I unplugged all the playfield connectors and checked the outputs of the transistor array chips (U1, U3 and U4 which are CA3081 chips) with a logic probe. Their Base and Collectors are labeled in the silkscreen on the SDU. They should all be high, but they're not. Some don't even register on the logic probe. Something funny is going on here. Next up will be to double-check these pins, and either check their traces or just replace them with new socketed chips.
But it's late, and I have had at least one cocktail. So I'd better sleep on it and double-check my work tomorrow.
Neverending Project:
OK, I just checked with the game on and in attract mode and solenoids disconnected from the SDU. Each of the 16 pins of the decoder chip tested high, which is good. But some of the transistor array pins were not testing high, which is bad. These should all be high so their corresponding driver transistors are low (off).
So I powered off the game and tested each of the pins of U1/U3/U4 with the DMM on diode setting. Sure enough four of the transistors on U3 tested bad. I double checked every other pin on the three chips, and these are the only four that are bad. And I think it makes sense - if these transistors can't turn on, then their corresponding driver transistors would be on, and hence the solenoid would be stuck on.
So I will order some new CA3081 chips and solder in some sockets. If they're cheap enough I may replace all three. I guess next report will be in a week or so.
Neverending Project:
The parts came quick (thanks Ed!) and I installed the new socket and CA3081 and re-checked that everything looked good with the DMM. I reconnected the coil leads, turned on the game and plugged in the SDU connectors one at a time making sure no coils were energized, and they weren't. So the locked-on coil problem is fixed.
Next up, flickering displays. I am suspecting bad 5101 chips on the MPU, but I will try to get a quick video posted soon so maybe someone else can give me clues.
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