Can you post a picture of your MPU board at the U54 location. I believe that is 1 of the 2 chips right below the battery. Possible old corrosion or if someone socketed that chip maybe u bumped it and it needs reseated

Actually just looked it up theat chip is to right of batteries but I read that if the diode in you battery holder came loose that it may be causing your error. Are you using a remote battery holder? Or are your batteries still on your board? Google search pinwiki systems 9-11 MPU boot issues

Take that ribbon cable off so there's a clear view of the battery holder area and shoot another picture or two (make sure you select "original size" from the dropdown menu when dragging the pictures onto the post)

Did you try re-seating the game roms (and sound ROMS too?) to clear possible oxidation on their pins?

Not sure what System 7 error codes have to do with a System 11 MPU.

Hmmm, middle of the day post, so I can't really come up with why I would have crossed that wire...

I still say reseat the ROMS though.

Also, a picture of the BACK of the board in the area where the battery holder is on the other side would be helpful.

I have made a few middle of the day posts in other threads and I can say I was not thinking too clearly.

The procedure for checking the U54 PIA from the repair guide, using only a multimeter:

Check the 6821 PIA Chips.
Now check the six 40 pin 6821 PIA chips at U10, U38, U41, U42, U51, U54. The easiest way to do this is to remove the PIA chips (with the game off), one at a time, and put them in a working CPU board (in the same chip position). This way you can see if putting in the questionable PIA chip causes the otherwise working board to fail.

If you don't have a working CPU board to use as a text fixture, you can also test these chips with your DMM. With the game off, set your DMM to the "diode" setting, and put the red lead on ground (pin 1). Then put the black lead on pins 2-9 (PA0-PA7) and pins 10-17 (PB0-PB7), one by one. You should get a reading between .4 and .6 volts. If you get a short (zero) reading, replace that PIA. Note it's best to perform this test with the chip removed from the CPU board.

You had me for a minute by changing the orientation of the closeup of the PIA (it's upside down). Pins are fine. The PIA one is pretty ugly with flux and could benefit from a cleanup with rubbing alcohol and a tooth brush.

did you acquire this game with this problem? or was it working and then this issue started? did you touch up the solder joints or was it like that? the flux is ugly, but cleaning it up wont really have any effect on the function of the chip.

Yeah, my OCD kicking in. Ugly flux has to go.

Did you reseat the game roms?

I'd look at the +5v being slightly under power at boot (then stablizing when it's too late) then. According to the repair guide, this can result in the 7 flashes you are seeing (incorrectly indicating a PIA bad). I'd try the test clip test first and work down from there:

"To "go around" the POR section of the board, you can do a simple test. After attempting to boot the CPU board, ground the /RESET line on the CPU chip (pin 40 of U15) momentarily with a test clip. If the board boots up consistently without a problem (correct flashes or "0" in the LED), then the POR section is definately at fault.

The POR section's job is to look at the +5 and +12 volts, and make sure they have stablized, as determined by zener diodes ZR1 (1N5996A, 6.8 volts .5 watt) and ZR2 (1N5990, 3.9 volts .5 watt) before starting the CPU. This is done by transistors Q34, Q36 and Q38, but before these three transistors can work, capacitor C30 and resistors R55 and R56 provide a delay to allow the voltage to stabilize. Only then the /RESET line can be released.

Any of these POR components could be bad, and not causing the CPU board to boot properely. If the board boots inconsistently, first look at capacitor C30 (a 22 mfd 10 volt electrolytic). If you don't have any way to test the capacitor, just clip another 22 mfd electrolytic cap across the leads of the existing C30 cap (positive to positive, negative to negative, a parallel connection). If the board now boots up consistently, you have found your problem! If not, check resistors R55 (4.7k 1/4 watt) and R56 (10 ohm 1/4 watt), and transistors Q34, Q36, Q38 (2N4401)."

Definitely, replacing C30 would be my next step.

Edit...on the CPU board

What is the 5v actually reading at TP2 to TP4? On the main board, not the Power supply.

I don't think it matters once the game has booted because the problem occurs AS it's booting. The 5v is slow to come up to a stable level and it messes with the diagnostics.

I disagree, These things will run just fine a tad under 5V, At the main board. But what do I know, Im a Newb.

PIA is bad. Remove the chip and install a new socket and new 6821.

Sounds like you did it right. The PIA might just be bad. I'd just spend the $4 and get it over with. When you unsolder the chip, though, cut off all the legs and unsolder one by one to minimize the chance of pulling pads off.

I also recommend using these kind of sockets:

pins (resized).jpg

Boosman, if you aren't comfortable desoldering and installing a 40 pin chip, I have done 50-60 of these on a system 11 boards. Pm me if you want the help.

I see a bunch on Ebay spain, but you have to be careful of counterfeits (and prices are a LOT more expensive than here in the US). Any decent electronics supply store should have it.

I would test out all the traces from the IC pins of U54 (not the back of the board) to where they all go to. It is possible since it had an IC socket installed previously, could be a damaged trace under it.

Also get a new C30 22uf 16v or 25v axial electrolytic capacitor. I seen old ones sometimes cause false PIA failures. This is why I had suggested the C30 previously.

Yes, add a wire. Retest with the original PIA that was in the board to see what happens.

Bummer. I thought the socket was installed by someone else.

Where did you purchase the PIA from?

sounds like the Blanking Circuit and/or the Clock circuit

Where did you purchase the PIA from? There have been quite a few fakes being sold at many places.

I would retest all the traces to and from the U54. Also check adjacent pins of the IC socket so that there is no short between pins? Do you have a logic probe?

So the middle (diagnostic) nor the blanking LED or LED at all?

So your problem now is worse than last reported, which the diagnostic LED was blinking to give you the U54 error code. So either the jumper you added is in the wrong place or the PIA is in backwards.