Hello there!

I've been searching, reading and learnig along this forum about Sega large DMD pin problems, but I'm still fighting with mine.

I see there are many people with similar problems, so Im going to post all the test and fixes here for future reference, I hope it help other guys to keep Sega pins working

My Frankestein was having a DMD, Sound and game reset problems, sometimes DMD, sometimes Sound, and sometimes CPU were resetting during game.

What I already did:

At PowerSupply Board:
. Replaced x4 4700mdf capacitors at C11 to C14
. Reflow solder at CN1, CN2 and other connectors related, also cleaned pins with a fiberglass eraser.
. Replaced damaged/burnt pins and connectors
. Reflow the DB1 bridge rectifier (+5V, +12-12V unreg)

At the DMD
. Replaced pins and connector for the +5v and ground.
. Reflow solder at the +18V connector

After that I've been playing lots of games without a single problem for about 3 weeks, great DMD image, great sound, perfect play....

But today it is impossible to start and complete a single game, everytime you push START button, the game puts one ball at play and sound start to reset like crazy, also DMD, and finally the game completely resets.

*** TEST I'VE DONE ***
If I disconnect the Soundboard from the PS the game works correctly, DMD and game works without problems.
If during a game I reconnect the SoundBoard it immediately starts to reset, then the DMD fails and finally the game resets.

Test points at PowerSupply Board (spected voltage, min > max) with all connected (game in advert):
. +5V = +5V > +5.11V
. +12V = +12V > +12,20V
. -12V = -11.3V > -11.7V

Test points at Logic Board during a game:
. +5V = +4.92V > 5.04V (use to stay at 5.02V)

CNs at DMD board
. +5V = +4.92V > 5.04V (use to stay at 5.02V)
. +18V = +17.30V > 17.60V

CNs at Sound board
. +5V = still not tested
. -12V = still not tested
. +12V = still not tested

*********************

As you see I already have a low -12VUNREG at the PSBoard, but the +5V is very stable, rarely showing less than 5V.

I also have a low +18V at DMD, but since it works great and I think its not related with the resets problems, I will let it alone.

What do you think? DB1 bridge rectifier (+5V, +12-12V unreg) may be fatiged?
Sound board asking too much to the PS (connectors gaining resistance, bad caps...)?

Replaced the bridge, not an easy task, had yo fix 2 Broken traces....

Problem NOT FIXED.

PS VOLTAGES
+12V = 10.61
-12V = 14.28 (goes Up n down a lot)
+5v = 5.10v

CPU
+5V = 5.02

SOUND
+5V = 5.06
+12v = 10.72v
-12v = -14.25v

IMG_20180104_201740 (resized).jpg

I see a very low +12v and a too High -12v....

Any ideas?

I had the same issue on this particular machine... Im going to DoubleClick check

Mmm

Mmmm sound board.... Flash lights.... And?

Im starting to hate the pin hahahaha

If I disconect the +18v connector from the DMD, sound, dmd and Game keeps resetting.

If I disconect the small 2 wire connector, gnd and 5v from the DMD, I can Play a Game with sound perfectly.

So the problem is to have DMD and Soundb at the same time, with only one connected Game works great....

I already done all the connectors, fuses and double checked today

Found the same problem on mine, the ground string from the speaker was not attached, sadly didnt solve the problem.

Since the only stock condensers are C2,C3,C5 and C6 and they are unexpensive, and in someway related to 5V and 12V I'm going to replace them, or burn the machine and do a nice BBQ

Nope, pins and connector are in great shape.

I will also do a mod sugested here, I will wire directly (daisy chain) the 4 big capacitors to the bridge rectifier, in some cases the traces are not working properly anymore, and its an easy mod to do and undo.

I'm going to buy the condensers today and will post here the results.

Dont know... maybe looking to have low resistance on all the grounds? I will do a quick check

I have a Maverick buried somewhere in my garage hahahahaha, but I don't want to move all the other pins to reach that one

Already reflow solder on the 12pin connector, verified the pins, cleanead with fiberglass eraser....

Sadly until Monday I will not have the condensers needed, so I will let Frankenstein rest for a couple of days

Replaced all the PS capacitors... Still nothing.

If I disconect the Soundboard I can Play a complete Game, but DMD resets sometimes.

If I disconnect the DMD I can Play a complete Game and sound works perfect.

So.... Since I replaced the DMD connectors already, what do you think? DMD board??

Ive found a texto that Will point that my Soundboard is not resetting:

"Also, when both flippers are simutaneously used during a game, the dot matrix display can reset, (but the CPU may not!). This will display the display board ROM revision level and the initial power-on sound board tones/speech"

So, everytime DMD boots plays the Soundboard poweron speech :/

Next thing Im going to do...

Here!

http://techniek.flipperwinkel.nl/desega/index3.htm#dots

I believed I had a soundboard + DMD reset, but looks like only the DMD is having problems, thanks to that text I know that DMD boot secuence includes asking sb to do the callout "FRANKENSTEIN!"

Well, yesterday I got a little upset with this issue and I already have the pin on my van, ready to take it to a tech service....

But.... WTF I cant sleep, I started to check the Sega Bulletin 106, my DMD has the mod done, but the connector used is the "optional C5" instead of the recommended CN6, f*ck now I need to know if there is any difference...

Looking at the PS schematics I see that the 5V at CN5 and CN6 came from the same trace at the board, so, no difference here, BUT, BIG BUT:

. Ground used at CN5 is the same used at CN4 for LAMPS and SOLENOIDS.... and the ground from CN6 is used for LOGIC GROUND...

Since some of you suggested a ground problem... Im tempted to unload the pin and mod the connector to take +5V and Ground from CN6 instead and CN5 :/

Well... today I've got my MSF ready, and the problem was not on the boards...

You know that servo that moves the Franky head? well it was dead so I replaced it with a NEW one, it works nice and still does, but... the Motherf**** makes the game reset everytime it moves.

So finally the problem was solved by replacing AGAIN the servo, I hope it doesnt get bad again as the old one, worked well for months.

Sometimes you find the problem faaaar away the place you are searching at.

Yeah, replaced all the capacitors, verified traces and put a new rectifier Bridge...

Tried boards and DMD from another Sega pin and found the problem was not on the boards but on the cabinet....

Finally disconected the connector used for the Bill acceptor and servo... And voila!

NEVER, my pin only has the wires, but not an actual Bill acceptor, pin shares the wires with the servo

Nope, clear sound, and game runs perfect if I disconnect DMD or sound board.

Now with the new servo I can Play with all boards connected, and no problem, looks like the 3 months old servo is working but asking too much juice or doing some kind of shortcircuit....

I was focused on fixing the problem, using an external PS was not an option for me, that would be cheating hahahaha.

No magic involved, if you read my last 2 posts here, you will find that the motor that moves the monster head was the problem.

Looks like the motor sometimes was asking too much juice from the PS

Hi!

2 post before yours is the answer, a bad motor, the one that moves the monster head, with the new motor I ever had problems again, I just found the problem thanks to desperation hahahaha, disconnection everything that goes to the PS...