Hello everyone,
I've just joined this forum after weeks of reading different post on here about baby PAC man isssues. This is the first arcade I've restored. When I got it nothing would power up at all. So I've worked through several issues over the last few weeks. Thanks to all the great information here.
I am now at the point where I have seven flashes on my vidiot start up light ( occasionally I will only get one but I can retry the start and get seven again ) ,and one flicker with 6 flashes on my mpu . And all the lights and relays test seem to be working as designed.
Now ,according to the manual the eighth flash that I can't get is supposed to be a test of the PIA at U7 (MC6821P) . Since the mpu is booting fine and it has two PIAs the same part numbers I swapped with one of those With no change in light sequences on either board. Then I tested the socket at u7 with the pia plugged in I had continuity from each pia pin to the back side of board on all forty pins. I am at a loss as to what else to try.

Things I have repaired.
-removed/relocated battery pack
-repaired acid damage (two bad traces)on mpu
-cleaned and tested pins on mpu
-replaced 5 bad sockets on vidiot
-cleaned and tested rest of sockets
-cleaned and tested pins on vidiot
-replaced three bad pots
-tested(looked) for bad or damaged traces on vidiot

Machine statis on start up.
Powers up speaker buzz on start then quiet.sound test does nothing.

Screen lights up different shades of blue /green /red depending on how I move pots on vidiot. Screen test does nothing .

Play field lights up in attract mode .
Light test works
Relay solenoid test works

I did notice there appears to be a socket added to the harness at the cabinet hinge.?? Seems to be a joint all the wires twisted and tapped no solder. I would like to remove it and clean it up. But I'm not sure if it's needed?? Any help would be appreciated. Thank you.

After reading back through some old post I realized that the vidiot board flashes don't quit flashing when they get a bad test . So now watching the sequence of test on you tube and comparing to mine. I am confident I am missing flashes 1,2,and10. I am starting out ordering a new 6803 to take care of 1 and 2 . and a few ram chips to hopefully correct 10 .

Yes I have verified the the voltages at all the test points. And at one point checked voltages on the reset lines before I was gettting any flashes , they are good also.
Since I have tried swapping the PIA with the same working mc6821p from the mpu board, is it possible that the 6809 at u8 is having an issue even though it was used for the 5 test previous?

There is about a three second pause after power up before any flash. And when I press the sound test buttton the only result is a slight static sound at the speaker. No lights.

Thank you all for the interest and the help.

Yes , the pin repair page has been a big help. Mine is definatly delayed before I get a flash. And I don't get a pause and flash before the last. So I'm hoping the 6803 and the ram chips fix the last of the issues.

Quick question on replacing those chips. Do I need to worry about installing any type of program to them? Or do they have a predetermined function?

5volt line seemed good every where I could check it. Good idea on capacitors. I will look at them specifically . And get some new ones they are cheap . Thanks.

Grounding tp4 does reset the chips and starts the flash sequence over still only getting 7 flashes.

I still had the delay. I should have the new chip tomorrow. I will see how that affects the operation.

I installed the new 6803 tonight. It had no affect. Still have the delay before the flash. And only getting the seven flashes. I tried the reset again (tp4 to ground ) with the same result . I double checked the sockets and the traces. All good. I'm curious about the EPROMs.how often they go bad and how to diagnose if that's the issue??

This board did have corrosion damage I did replace 5 sockets. With u27 being one that was replaced. I did not find any bad traces on the vidiot.

I do not have a logic probe.

But when testing my repairs and existing sockets I did a continuity test from each exposed pin with the chip plugged in. To the back solder joint then also to the next exposed trace joint.

I do not own a programmer bit I have been looking at some on eBay. Just very reluctant to buy a cheap one and have it be junk.

I'm going to try to get my hands on a logic probe to see if I can do some better testing to verify the clock circuit.

I have the rom files downloaded . Do you guys have a recommendation for a good programmer that's cost effective?

I found a logic probe locally so I'm going to get that today in town. I will be able to eliminate more potential issues tonight.
Thank you.

I'm trying to figure out what I need to be looking for with this logic probe. Do I need to be looking at specific pin on the u27 and u29 chips ?

I ended up ordering a logic probe lp-560 .. just got it today. I'm trying to run the test on u27. It appeares that 8-20 do not pulse the only reading I get on those is
8- high volt
9- low volt
10-20 nothing
Then the other side I everything reads right except for 34 which does not pulse just reads solid low volt.

U32- I have no communication on either side except my high on pin 14 and low on pin 7

U32 is the digital to analog converter soldered to the board no socket. Looking at the schematic it connects to the u27 on pins 13-20

Pin 40 is pulsing
And you are correct with pins 1-3 being low and pins 6and7 being high
I am getting the same signals on back of board

All of my pins on u-29 had either a high or low or a pulse. U27 was one socket that I replaced and I have double checked it several times front to back of board.

So basically u27 is sending a signal to the dac on pins13-20
So it would not necessarily be an issue with no pulse there if there is no sound commands ??

U27 pins 10-11-12 are connected to u7 and I have no signal on those three either...