(Topic ID: 309343)

SEGA/Data East Power Supply (12 Volts Low)

By DanMarino

1 year ago


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  • 28 posts
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  • Latest reply 1 year ago by DanMarino
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    #1 1 year ago

    I posted this in the Maverick thread, but didn't get any response yet. So I figured I'd try again here.

    I'm having some sound and DMD issues on my Maverick and it usually happens during multi-ball when a lot of stuff is happening all at once. It also seems like the pop bumpers stop on occasion, but I'm not sure it is related. It's kinda like the voltage drops during the game and the sound and DMD will re-set with the Lauren Belle steam whistle sounding and the DMD display resetting briefly.

    I opened the back box and it looks like the the power supply board is having some low 12 volts measured at the test point.

    5 volt test point = 5.03 volts.
    +12 volt test point = +8.25 volts.
    -12 volt test point = -12.3 volts.

    I pulled the board, cleaned the pins, and reflowed solder to everything on the back side. The +12 volts is now up to about 9.9 volts. The game is resetting during multi-balls, but is working slightly better.

    Any tips for what to dig into first on the power supply board? Could I possibly need to replace the DB1 bridge rectifier, or else the 4 capacitors that are 4700 micro farad/25 volts?

    I'm not real familiar with how the board generates the +12 volts.

    Thanks,

    Tom

    #2 1 year ago

    I'd recommend modifying the 5vdc wiring to the DMD (Stern/Sega service bulletin 106) if you have not yet done this.

    Additionally, the +5/+12 volt bridge rectifier (DB1) on the power supply board may need to be replaced. If this bridge becomes "leaky" (less efficient), it may not be able to supply the robust +5 volts needed on the display board. So if the above modification does not work, replace bridge DB1 next. When replacing DB1 on the power supply board, also solder an 18 guage wire from the "+" lead of bridge DB1 to the "+" lead of capacitor C4. Solder another 18 gauge wire from the "-" lead of the bridge DB1 (the lead diagonal to the bridge's "+" lead) to the "-" lead of capacitor C1. Do this on the solder side of the power supply board. These added wires will help prevent future cracked solder joints on the power supply board.

    #3 1 year ago

    Awesome!!!! Thanks for the tips Wayout440. I'll look for the service bulletin. I did already install new pins and a molex connector that connects to the DMD. I'll give all of that a try and report how things progress.

    #4 1 year ago

    Cool. I printed out the SEGA service bulletin and will check that out this weekend. I'll pull the board and test the bridge rectifier. I'll also take a look at the wire harness situation for the large DMD. I have already put on new pins and a molex connector on the DMD side. Bridge rectifiers are cheap, so I'll go ahead and order one of those too.

    #5 1 year ago

    Yes sir. There could be something else, but you gotta start somewhere and these are pretty important items to address for this series of games. Good luck, please let us know the outcome.

    #6 1 year ago

    I did the Service Bulletin modification today. I created my own wire harness from the DMD with new connectors and molex plugs. I also did a new Molex plug and connectors on the other end to the power supply board.

    The machine is still having the same problems, but the reset seems more like it is only impacting the sound.

    A new bridge rectifier is on the way in the mail, so I’ll install that on the power supply board this week.

    #7 1 year ago
    Quoted from DanMarino:

    I did the Service Bulletin modification today. I created my own wire harness from the DMD with new connectors and molex plugs. I also did a new Molex plug and connectors on the other end to the power supply board.
    The machine is still having the same problems, but the reset seems more like it is only impacting the sound.
    A new bridge rectifier is on the way in the mail, so I’ll install that on the power supply board this week.

    You check the diodes in the bridge with a DMM. My baywatch bridge blew out just one side of the rectifier so it was running on half phase. It kind of worked but the sound/display would reset when you flipped both sides together.

    I am not sure which connectors you did but the AC power input connector on the power board could cause this kind of problem.

    The crappy fuse clips DE/Sega used are notorious for causing problems too.

    #8 1 year ago

    I converted the CN6 connector plug on the power supply board over to a molex connector. The ground wire to the DMD is connected to pin #1 on the CN6 plug and the +5 volts wire connected to pin #10.

    #9 1 year ago

    Good thing I have a new power rectifier on the way in the mail. I pulled the power supply board on my Maverick this afternoon and did a test of the power rectifier. One of the legs from the positive leg of the rectifier was shorted. Hopefully that addresses the problem.

    Anybody have tips for unsoldering the old power rectifier from the circuit board without tearing anything up? haha.

    #10 1 year ago

    The new bridge rectifier came in the mail yesterday so I installed it last night. I had a little difficulty removing the original bridge rectifier, but the solder sucker helped a lot. I got the power supply board installed back in the machine and the voltages seem better.

    5 volt test point = 5.03 volts.
    +12 volt test point = +13volts.
    -12 volt test point = -13 volts.

    The game still lost the background music during a 4 ball multi-ball, so I'm not quite sure what to do next. I might remove the sound board from the machine and take a look at re-flow the header pins and pop out the sound rom chips.

    #11 1 year ago

    Reseat the sound board ribbon cable at the sound board and the MPU board.

    #12 1 year ago

    I just played a game and the multi-ball seemed fine and it didn't lose background music. So that's good. I must have lost a ball in the Lauren Belle someplace, because the 4 ball multi-ball only had 3 balls. haha. I'll reseat the ribbon cable and see if that helps.

    Sometimes the pop bumpers don't seem to work. So I guess I'll have to take a look at them and see if the switches need adjusting or cleaning.

    #13 1 year ago

    I played a few games at lunchtime and all seems to be working fine. @wayout44 PinballManiac40 and barakandl thank you for the help.
    It's pretty neat that the bridge rectifier was causing the issue. The sense of accomplishment from troubleshooting the machine and replacing a component on the power supply board and getting it up and running again is lots of fun.

    #14 1 year ago
    Quoted from DanMarino:

    I played a few games at lunchtime and all seems to be working fine. @wayout44 PinballManiac40 and barakandl thank you for the help.
    It's pretty neat that the bridge rectifier was causing the issue. The sense of accomplishment from troubleshooting the machine and replacing a component on the power supply board and getting it up and running again is lots of fun.

    Fun, as a hobby. Stay out of electronics as a profession, lol.

    #15 1 year ago
    Quoted from PinballManiac40:

    Reseat the sound board ribbon cable at the sound board and the MPU board.

    I reseated the ribbon cable on both the sound board and MPU. Something flakes out during 4 ball multi ball sometimes and it loses the background music, but switch sounds still work. Then everything is fine with the next ball.

    I did a switch and solenoid test of the pop bumpers in the diagnostics tests and they were fine. I flipped the playfield up and cleaned the pop bumper switches and they are working much better now.

    #16 1 year ago

    My power supply board repair didn’t last long. Now that the bridge rectifier has been replaced, the +12 volts is now putting out only +8.13 volts.

    Any ideas what to work on next?

    #17 1 year ago
    Quoted from DanMarino:

    Any ideas what to work on next?

    Reseat CN1. Has no burnt pins? Capacitors are likely next.

    #18 1 year ago

    Thanks. CN1 is beautiful. Just measured +8.31 volts.

    #19 1 year ago

    Check CN1X12 pin 10 and 11 as the 12V AC comes in there. My baywatch burned up the connector pins there and caused a reset problem. I think you are either missing half the wave or the caps are bad.

    Set your DMM low AC volts and check across the 12vdc and ground. This will measure the amount of ripple. If its more than a half volt the filter cap is probably bad.

    #20 1 year ago

    Thanks guys. All of the CN1 pins and the connector plug look beautiful. Tight fit and nothing burned looking.

    The voltage test you are talking about is from the power supply board test points for the 12 volts ripple? I'll take a look at that this evening.

    I went ahead and just ordered a set of new capacitors for the power supply board.

    #21 1 year ago
    Quoted from DanMarino:

    Thanks guys. All of the CN1 pins and the connector plug look beautiful. Tight fit and nothing burned looking.

    That is nice it looks good, but check the AC coming in. Check the AC on each wire and past the connector. 8vdc past the bridge is high sus there is an AC input problem or massive ripple from blown caps.... i'd wager on missing half the ac wave though as i have seen it a couple times in these sega games including my baywatch... same symptoms. There are usually four redundant 12v bulk filters.

    #22 1 year ago

    Check ac volts bottom of both these two 12vac fuses. I would guess one is missing.

    20220215_124806 (resized).jpg

    #23 1 year ago

    Thanks barakandl, that helps tremendously. I'll report out what the readings are later tonight.

    #24 1 year ago

    Barakandl, you are right. The left fuse measured 8.4 volts and the right fuse measured zero.

    On the CN1 connector, pin 11 has 10 volts ac. Pin 10 has 8.7 volts ac.

    #25 1 year ago

    The one that is missing trace back to the connector .

    Fuse clips themselves are often the problem.

    Transformer -> Connector -> fuse(travels from top to bottom) -> rectification diodes

    #26 1 year ago

    Thanks for all the help Barakandl. Fuse 2 on the power supply board was the one having the problem. I removed the fuse and checked the continuity and it was blown! I happened to have another fuse and popped it in there and the game seems to be fully functional.

    When a bridge rectifier goes bad, can it cause a fuse to blow? My bridge rectifier was definitely bad since 1 leg was blown.
    I'll play the machine tonight for an hour and see how it goes.

    #27 1 year ago

    When bridge rectifier shorts from either of the 2 AC inputs across to either + or - output, that is when a fuse will blow.

    2 weeks later
    #28 1 year ago

    This item is resolved. The Maverick is playing perfectly. Here is the summary of the problem and resolution.
    Problem. Game would play, but during multi-ball, the DMD and music would re-set.
    Resolution.
    1. Tested the voltage test points on the power supply board and found +12 volts to be low.
    2. Tested the power supply bridge rectifier and found one leg shorted.
    3. Removed the bridge rectifier and installed a new one.
    4. Game still had same problem with multi-ball causing the DMD and music to re-set.
    5. Fuse #2 on the power supply board was blown when the bridge rectifier failed. Replaced Fuse #2 and full voltage restored and the machine plays perfectly again.

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