Baby Pacman, correct flashes but no video?

scottmaggie

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Got a Bally 35 MPU to fix as a spare for my baby pacman. Typical acid damage on it. Cleaned it up, reflowed all pins, changed the 5101, added lithium battery & blocking diode.

I get the correct led flash sequence - 1 quick then 6 more (baby pac doesnt do the 7th flash). The playfield lights flash but the game won't play and no video at all.

For giggles I swapped 6800 and the 2 6820/6821. Didn't help. I am guessing that since the self tests pass I need to change the 2 connectors j2 & j3 and not something internal to the board.

What do you guys think?
 
Got a Bally 35 MPU to fix as a spare for my baby pacman. Typical acid damage on it. Cleaned it up, reflowed all pins, changed the 5101, added lithium battery & blocking diode.

I get the correct led flash sequence - 1 quick then 6 more (baby pac doesnt do the 7th flash). The playfield lights flash but the game won't play and no video at all.

For giggles I swapped 6800 and the 2 6820/6821. Didn't help. I am guessing that since the self tests pass I need to change the 2 connectors j2 & j3 and not something internal to the board.

What do you guys think?

I always start with the power supply and work from there. Measure the +5 voltage at the IC chips and should be +5 to +5.15 vdc. Then I look at any and all connections to the pcb and if any look damaged, worn, very old I replace them. Recheck all dip switch settings and look over the board for anything that may get moved or pushed from side to side.

The self test doesn't test every thing so it is possible to be a board problem.
 
Baby pac...

It's definitely on this mpu board. Also it's just a spare I am trying to get working. My baby pac works perfectly.

I'll replace the connectors on it next...
 
Baby Pac does NOT use a -35, it uses a -133 which is a -35 with a zero crossing circuit. In a nutshell a -35 will not work without the zero crossing circuit in a Baby Pac.
 
baby pac mpu

Everything I have read says only diff is a diode at r113... This nous has that and came out of a baby pac cab that was parted...
 
baby pac

Yes the vidiot is good. I have a 100% working baby pacman. This mpu we are discussing is a spare out of a parted baby pac. It is a 35 with the diode to make it a 133. Sorry I didn't specify earlier.

Did some testing last night and got correct voltages on all test points except #3 was jumping around between 4.3-4.7V. On my other 2 good mpu's it is a steady 4.8v.

What do you think?
 
Bally MPU 133 update...

Still not working but I know this much:

1. Getting correct flashes.

2. All socketed chips are tested good - pulled and installed on working board

3. Boots up but still no video. A quick flash on the screen then blank.

4. A TwoBits MPU tester shows no errors

5. Voltages are testing correctly at all test point, matching my working baby pac mpu.

5. It is not the rest of the cab. My baby pac is perfect, this is a spare board I am fixing and testing in my good known good working cabinet.

Any ideas guys?
 
update

Sorry, I actually ended up selling this as a spare to someone who bought a baby pacman from me.

On yours - I really do think it's the wiring or headers on the MPU since you get all the right flashes and the video test comes up.

You can send me any boards to test in my baby pacman if you like.
 
I got into the habit of replacing ALL the sockets on the mpu board and vidiot boards. I have seen on numerous occasions where the acid damage had got under the sockets and caused damage but none was apparent until the sockets were removed.
 
Baby Pac does NOT use a -35, it uses a -133 which is a -35 with a zero crossing circuit. In a nutshell a -35 will not work without the zero crossing circuit in a Baby Pac.

I was just about to mention this Dokert. I've repaired several baby-pac's. First thing I check is the cpu. Now the no video.. I would address the vidiot board. Not the CPU. the Vidoit board will product some video even when the cpu isn't booted.
 
Got a Bally 35 MPU to fix as a spare for my baby pacman. Typical acid damage on it. Cleaned it up, reflowed all pins, changed the 5101, added lithium battery & blocking diode.

I get the correct led flash sequence - 1 quick then 6 more (baby pac doesnt do the 7th flash). The playfield lights flash but the game won't play and no video at all.

For giggles I swapped 6800 and the 2 6820/6821. Didn't help. I am guessing that since the self tests pass I need to change the 2 connectors j2 & j3 and not something internal to the board.

What do you guys think?
Switch 16 on the pinball MPU must be off for the video to work
 
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