Motordome Repair Log - 100% complete!

bimm25i

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Just Scored a Bally 6803 MotorDome from a pinsider. Game is in OK shape but was VERY dirty. Cleaned it up and have played a couple games, its pretty fun but the music is trash.


Issues that need fixin'

CRAZY UPPER FLIPPER (FIXED!!!): the left upper flipper goes into machine gun mode when the button is held...haven't researched yet.
Attempt 1 - can see that the thinner wire coming from one of the pins going into the coil wrapping is damaged, tried soldering it back together, worked for like 2 flips then broke again, going to replace the solenoid ( AQ-25-500 34-5050 )
Attempt 2: Replaced coil with new one, WORKS!!!!

DISPLAY VOLTAGE LOW (FIXED!!!) : Sitting around 135 VDC, adjusted the POT up, checked the supply 230VDC and its also around 140-150....
Attempt 1 - going to replace the filter Cap ( 160uf / 350V )
Attempt 2 - replaced filter cap, voltage very high, adjusted down with POT to 170, flicker fixed!

MISSING FLASHERS (FIXED!!): The Flashers behind the "turbo booster" sign work, but the flashers behind the goggles/and lightning bolts do not work :(
Attempt 1 : replaced all flash bulbs with known working flashers - the left lightning bolt and the "Turbo Booster" flashers work but the goggles and right Lightning bolt still don't work will try replacing the transistors next (need part #)
Attempt 2 - unlit GI light was actually a flasher socket with wrong bulb installed, replaced with flash bulb, now left AND right flashers working, only remaining failing flasher is Visor. The flashers are all wired up in 3 bulb series, if one bulb goes out the entire flasher will not work!!
Attempt 3 : Pulled Main board, Q20 Transistor was burnt up and physically damaged, removed, replaced with TIP 122 transistor, installed backwards :( blew 8A fuse
Attempt 4: replaced tip122 transistor and diode, now flasher is stuck ON...not sure how to proceed.
Attempt 5: replaced IC @ U20, flasher still stuck on, unsure how to proceed.
Attempt 5: checking diode @ Q20 - In attempt 4 I mistakenly used a 1n4001 diode, needs to be 1N4004 or higher value. replaced, WORKS!!

BAD PLAYFIELD LIGHTS(FIXED!!#): One set of lights off, one set stuck on - these games use a multiplexed light driver, the lights that match (lightning bolt 1, spinner 1) are stuck ON, and OFF (Lightning bolt 4 and spinner 4). I am planning on replacing the transistors that drive these two sets of lights. Weird issue though, when I remove the bulb from spinner 1, the lightning bolt 1 light operates normally, but when the bulb is inserted it and its partner become stuck on. Thinking i'm gonna change the resistor (diode?) on the socket as well just in case.
Attempt 1 - replaced SCRs at Q51 and Q27, lit/spin 5 is working 100%, light 5 is aame, will replace diode on socket next
Attempt 2 - replaced diodes on light sockets, works!


ONE GI IS OUT (FIXED!!!): not sure why just one, socket looks OK,
Attempt 1: tried a couple different bulbs but none of them work in that spot (bulbs are tested good, and other GI's are on).
Attempt 2 - this is actaully a FLASHER socket, replaced with flasher bulb, tested, works!!!



those are the fixes, once i get them down I'm going to change the music to mode 2 (sounds but no BGM) and use a WAV trigger to inject some 8 bit metal. This game gets a bad rap but so far Im digging it. Too bad there's no multiball.
 
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Feeling a little more confident that the center flasher is going to need a new transistor (Q20)

Had one spare TIP 122 on hand but installed it backwards!!!?!?!?!?!?!

Whenever you feel smart, always remember to wait like 2 minutes.... :(
 

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check the diode on the flasher also.

and HTF did you install it backwards? there all going the same direction... $h!t happens..
 
check the diode on the flasher also.

and HTF did you install it backwards? there all going the same direction... $h!t happens..

Haha yeah I have no idea how I screwed it up, I'm such a dingus sometimes:D
 
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Not sure why the flasher is stuck on now after replacing the transistor, could it be the driver IC?
 
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time to buy a $20 logic probe and some tip102's.
 
Check the diode on the flasher.....

I did replace the flasher's diode on the MPU, there are no diodes on the flasher sockets.

Logic probe.... ugh, but i guess, i've been waiting to get my feet wet with one of these though
 
I know on my strange science pin (same 6803 series boards) all the flashers have a 1n4004 diode on the socket. I had a stuck flasher and it was a shorted diode on the socket. just for S&G check to see if there is a board or something that the flasher connects to with a bunch of diodes or something. And since you put the drive transistor in backwards did you verify the 2n4401 pre driver
 
I know on my strange science pin (same 6803 series boards) all the flashers have a 1n4004 diode on the socket. I had a stuck flasher and it was a shorted diode on the socket. just for S&G check to see if there is a board or something that the flasher connects to with a bunch of diodes or something. And since you put the drive transistor in backwards did you verify the 2n4401 pre driver

I just looked it up, they don't have diodes and are arranged in groups of three in series like he was mentioning... looks like you need to check Q20 (you replaced), U20 (chip that drives it) and diode d33 (hard to read, might be off... it's the diode right behind q20)
 
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Replaced the transistor @q20 and the diode there as well. Just ordered a CA3081 IC to replace U20. Will post results
 
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Ugh I replaced the CA3081 IC at U20 and the flasher is STILL stuck on. I'm not sure what to do next, but I'm thinking I'm going to replace the IC above U20 once I identify it.


Driver IC is U14, 74LS154N (de-multiplexer) , ordered replacement, will post results.
Manual schematic INCORRECTLY lists part as 75LS154N


The only thing Im confused about is How a de-multiplexer, that sends a LOW to the result pin, and then goes through a NPN logic IC (which must be passing a LOW signal right?), THEN triggers a NPN transistor to drive the flasher, I am still learning this stuff but to me it seems the TIP102 should be a PNP transistor, not an NPN
 
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So I replaced the 74LS154N (de multiplexer) that drives U20 which drives q20 but that dang flasher is STILL stuck on!!


I'm gonna check the schematic and find out whats driving U14


:(


man I was really hoping that was gonna fix it
 
So I have a bally special force and it has the same ICs as motordome, I swapped the chips at U7,U8,and U1 and both games still behave exactly the same (SF is 100% and MD is having 1 flasher stick on). I have seen that sometimes there are jumpers installed for specific games, it a bad idea to change roms and completely swap MPU boards between the two games to test?
 
I believe that they are both the same size eprom. Just look at the eprom (under the label) I want to say they should be 2732 or 2764's I haven't worked on a 6803 series game in a while.
 
Switched mpus with special force, the game is working 100% . special force now has stuck flasher issue, I'm going to re-replace the diode on q20 and the 330 and 240 ohm resistors there
 
Got it, I (stupidly) replaced the N4004 diode at Q20 with a N4001 - diode was zapped, replaced with correct diode, works!!
 
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