Picked us a black pyramid and put the mpu on the bench. Missing flashes, replaced the 6800p and ended up with a full 6 flashes. Next rebuild rectifier board, turned on and F3 blew. Disconnected Soundboard, replaced fuse and MPU shows only 3 flashes. Pulled MPU and back on bench gets 6 flashes. Put the mpu back in the back box, powered up... 3 flashes. Checked test points on MPU and found 5v spot on, and 12v was actually 14vdc. Any ideas what’s going on here?
Any help is appreciated.
14v on 12v is normal.
no 4th flash means the CPU can't control all the ports of U10. If it works off the bench you may have a connector hooked up wrong. I think you can do MPU J1 and one of the lamp connectors but double check all the plugs. If that is not a mixed up connector it unplug all the displays, lamp driver, solenoid driver j4, sound board and see if you get all 7 flashes. If so hook up the boards one at a time until you find the one with a problem.
super helpful, thank you. Isolated the problem down to MPU J1. Removed that connector, everything else connected (except cheap squeak as it’s blowing F3 fuse on 2518-54) and I am now getting all of the led flashes. Next step, disconnect both lamp driver and display boards and connect one by one?
Quoted from DynamoHumm:super helpful, thank you. Isolated the problem down to MPU J1. Removed that connector, everything else connected (except cheap squeak as it’s blowing F3 fuse on 2518-54) and I am now getting all of the led flashes. Next step, disconnect both lamp driver and display boards and connect one by one?
sounds logical approach to me.
plug in one at time until you find the naughty board.
Your cheap squeak board has bad tantalum capacitors. Pretty much guarantee as they always are... Be lucky the fuse is blowing otherwise tho little bastards go up into a fireball. The tantalum caps, at least the two on the 12v supply, replace with 10uF 25v(or more) electrolytic capacitors.
Awesome, thanks! Can all tantalum get replaced with equivalent (or greater in terms of voltage) electrolytic?
Quoted from DynamoHumm:Awesome, thanks! Can all tantalum get replaced with equivalent (or greater in terms of voltage) electrolytic?
Close enough here it's OK. Electro caps don't normally explode into flames when they fail too.
Thank you.
Okay, so I disconnected the lamp driver board (removed all 4 connectors on the lamp), disconnected each of the connectors from the score displays and disconnected the Aux Lamp Board. Reconnected J1 back into the MPU and back to just 3 flashes.
Looking at the schematics again, I see that J1 on the MPU connects to following list below, all of which I disconnected, but nothing. So, I decide to follow the wires and I noticed that some go from MPU J1 to apparently Solenoid Driver J5... Not seeing this in the schematic? But why not, right? I pull the J5 connector and Bam! all flashes. Reconnect all of the below items and I am getting all flashes again with some decent activity on the pin. Score displays are working, GI is working, playfield lights are working, right flipper is working (not left), moving target is working, coin mechs are working... pretty good so far. But why the Solenoid Driver? I guess the next step is to pull the Solenoid Driver and check for shorts? Bad IC's? Any help appreciated.
A1J1 -Score Display?
A9J1 - Aux Lamp Driver
A5J4 - Lamp Driver
1A1J1 - Score display P1
2A1J1 - Score display P2
3A1J1 - Score display P3
4A1J1 - Score display P4
5A1J1 - Score display Credit
MPU_j1 (resized).pngfull schematic (resized).pngWent back to the Soundboard tonight. Checked for shorts and found c10 to be shorter in the 12v section, also replaced c22 and c27 on the 5v rail with 50v electrolytic replacements. Pulled squeak board in and no fuse blown and even better beautiful sounds!! On to the solenoid board. Any ideas on what could be up with J5 on the solenoid board?
Quoted from DynamoHumm:So, I decide to follow the wires and I noticed that some go from MPU J1 to apparently Solenoid Driver J5...
Which wires are you seeing going from MPU J1 to SDB J5? J5 is just coil drive outputs and there should be no connection between the two connectors.
aux lamp j1 would and driver j5 both 15 pin plugs with a key at p6. aux j1 would be going back to MPU. sounds like these two might be mixed up.
Spot on guys. I checked all transistors and resistors on the SDB last night before seeing this posted. All checked out. Then saw this, and checked and confirmed that J1 and J5 are keyed exactly the same, swapped and we're golden. Amazing.
To recap, rectifier board fixed, mpu cpu replaced and fixed, cheap squeak caps replaced and fixed F3 from blowing, wiring corrected!
Now it looks like I have two things left to do.
1. Left flipper is dead. Not seeing any burn marks, but will remove and check the backside. I noticed that the green ground and two thick purple wires going to the solenoid were disconnected, reconnected, no dice. Time to read up on flippers.
2. Display boards are showing some ghost numbers - for example 7th digit is showing all the way on the left.
Quoted from DynamoHumm:Spot on guys. I checked all transistors and resistors on the SDB last night before seeing this posted. All checked out. Then saw this, and checked and confirmed that J1 and J5 are keyed exactly the same, swapped and we're golden. Amazing.
To recap, rectifier board fixed, mpu cpu replaced and fixed, cheap squeak caps replaced and fixed F3 from blowing, wiring corrected!
Now it looks like I have two things left to do.
1. Left flipper is dead. Not seeing any burn marks, but will remove and check the backside. I noticed that the green ground and two thick purple wires going to the solenoid were disconnected, reconnected, no dice. Time to read up on flippers.
2. Display boards are showing some ghost numbers - for example 7th digit is showing all the way on the left.
1. flipper should be wired like the other one is. Relevant plugs are the two on the left side of the driver board. Check there for connector problems like busted solder. Make sure the EOS is adjusted right.
2. Every time the backbox door swing the wiring harness flexes on all the displays. The displays are also single sided PCBs with no plated holes. This makes the solder joints crack on the male header pins of all the displays. Pull them off and reflow connector solder joints at the least.
To add to Barakandl - check the MPU J1 connector for any signs of corrosion on the pins. Don't know the history of the original MPU - if there was battery leakage, it can affect the pins in the connectors. Flow the connector solder joints first - most likely cause.
Quoted from DynamoHumm:1. Left flipper is dead. Not seeing any burn marks, but will remove and check the backside. I noticed that the green ground and two thick purple wires going to the solenoid were disconnected, reconnected, no dice. Time to read up on flippers.
Can you confirm you have voltage at the coil? Be worth ohming the coil out to check resistance but its not the most likely root cause of your issue. Coils rarely go bad unless they have been locked on or over heated too long. However the coil being disconnected is interesting...
On two occasions ive had to deal with a dead flipper. In both cases it was a bad contact on the EOS switch. The contact literally fell out so it wasnt operating on the high current side at all. These were normally closed switches so looked good from far but far from good lol. Moral of the story is take a good close look at the switch contacts to make sure the are intact and not pitted and worn away.
With regard to the score displays, I reflowed the pins and also realized that the credit connector was connected to P4 display, changed that and the issue was resolved.
With regard to the solenoid, connectors to SDB look good. Switch for end of stroke looks good. Tried connecting the left terminal green wire (opposite side is the double wired switch) of the bad left flipper to the left terminal orange wire of the good flipper. When I hit the left switch, the right flipper moves. I guess that rules out an issue with the push button switch. But not yet the voltage or resistance of the solenoid. Going to test using the below thread: https://pinside.com/pinball/forum/topic/testing-flipper-coils-ballys-star-trek
Quoted from DynamoHumm:43vdc on all lug except green wire/ left lug, which shows 0. Apparently it’s “open”?? Not sure what this means.
[quoted image]
sounds like the coil has busted winding. Inspect the thin winding wire near the lugs. Sometimes its broken right at the lug and you can fix it by taking one turn off. Scraping off the enamel of winding, and solder down.
Thanks all. Order placed for the new parts. Almost ready for game time! Thanks for all of the help everyone.
Big thanks to barakandl, couldn’t have done it without your help.
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