Hi,
I have a Bobby Orr's Power Play which is at a friend's house. I ordered Big Daddy's MPU rebuild kit, and installed it, but for some reason it doesn't include sockets for U2 and U6.
On my board these are the worst kind: old ugly brown ones.

I'd like to order replacements but I don't have the machine with me. I found this picture: http://pinwiki.com/wiki/images/d/d0/Bally_MPU_Sockets_Orange.JPG
I know they're 24 pins, but I don't know the spacing. Also, which material should I get? Tin?

I'm hoping this is going to fix the reboot issues. Game boots up fine most every time, but 1 or 2 games in it just blanks out (doesn't actually reboot though).

Thank you sir.
Exactly what I wanted to know.

I'll get them from Digikey.ca though, since I'm in Canada.

Cheers!
Phil

Another question...
since I don't have replacement for those chips unlike the other ones... should I clean the pins? Maybe with alcohol or something?

Right, I'm still going to change the sockets.
I want to know if there's anything I should do with the chips themselves to help them out a bit.

Thanks
Phil

I have no idea how to modify ROM contents. Pretty sure the info's out there but for now I'll start with replacing the sockets and hope that solves that...

I'm still curious to understand what it does and why it helps.

For the record, here's the mod:

Single 2732 U2 on a Bally -17 or Stern M-100 MPU board.
This modification combines the two original 9316 ROMs at U2 and U6 into one single 2732 EPROM at location U2. This works only for the early 1977 to 1979 games.
To combine the original 9316 (or 2716) U2 and U6 ROM computer files into a single 2732 U2 ROM file, use this DOS command:

COPY /B U2ROM.716 + U6ROM.716 U2COMBO.732
Make sure you use the "/B" option in the copy command, as shown above. This binary copy command will combine the two files into one.

In addition to the jumpers listed above (6-7, 8-10), you must also make the following cuts and jumps to use this configuration.

Make sure jumpers E6-E7 and E8-E10 are in place.
Remove any jumpers at E3-E4, and E1-E2.
On the solder side of the -17 board, find U18 pin 4. Follow this trace to the via ("trace thru dot"). Cut the trace near the via.
On the soider side of the -17 board, run a jumper from the via ("trace thru dot") that was seen above to U18 pin 5. It's easiest to run the wire from U18 pin 5 to the via ("trace thru dot") that connects to this trace. This connects U18 pin 5 to U2 pin 18.
On the componet side of the -17 board, find U2 pin 13 (top right hand corner). Slightly higher and to the right is a via ("trace thru dot") with a trace going straight down. Cut this trace to separate the via from this trace.
On the component side of the -17 board, run a jumper from the above via ("trace thru dot") to jumper pad E4. This connects jumper pad E4 to U2 pin 21.
On the component side of the -17 board, notice the large GND trace that runs to the right of the ROM sockets. To the right of the U2 ROM socket, scrape the green solder mask from this large GND trace and jump a wire from this GND trace to the jumper pad E3. This connects U2 pin 20 to ground.

Ok I understand... less moving parts, less points of failure.

I don't own a ROM writer (if that's what it's called)... That MPU is beaten to hell but I like trying to fix it one step at a time and learn some stuff along the way. If the socket replacements don't do the job as well as I like I guess that's going to be my next step.

Hey,
how about contact cleaner for the chip legs? I know you shouldn't use it in an EM since it's flammable, but I guess it would be appropriate for that kind of use?

If not, I'm kind of stumped on what the use is for that product altogether.

Ok,
I understand for the EMs.

I want to do the fix today after work and I have some contact cleaner handy. I was wondering whether it was a good idea to use it on the ROM legs of my Bally MPU...

If not I have 99% alcohol as well.

Oh man...
sloppy, sloppy work on my part and now I get the dreaded "always on" LED. I'm not sure if it's my work on U2 and U6 that did it either as I replaced all the other ones too and maybe just touching them made something that was barely touching go out or vice-versa.
I tried shorting pins 39 and 40 on the U9 but that didn't do the trick.

I have this logic probe thing (only with a light, not a little screen) that I haven't tried out yet.
I guess it's time to check the board signals?

From http://techniek.flipperwinkel.nl/ballyss/rep/index2.htm#flash :
"LED Still Locked On: MPU Board Signals.
If having play problems with an otherwise working MPU, check all the chip's signals with a logic probe, and cross reference them to this chart. If a signal is other than shown below, check the schematic. If it's an input line to the chip, the device that feeds that pin is probably bad. If it's an output line from the chip, the chip itself is probably bad.
All the following signals are with the MPU board in "attract" mode, and a MPU -35 loaded with Kiss 2732 EPROM's at U2 and U6. Because these signals are with the game in attract mode, this chart won't help much if your MPU is in some other state."

If my MPU is stuck with the green light on, I guess I'm not really in attract mode though, right?

I did check the continuity and it looks like everything is good.
It's harder to check for shorts, though but I'll get on that as well.

I don't understand what you mean by "compare address or data lines and see if one is drastically different than the rest (short)."

How would I go about doing that?

Thanks,
Phil

Ok thank you,
yes I did check for shorts that way and I'm all good in that regard.
I understand what you mean with the pattern, I'll check that out too (although I'm not sure what you mean about address and data lines - are all pins either address or data or is there any other kind?)

Thanks a lot!
At first glance it looks as scary as the EM schematics when I first looked at them but that turned out pretty good, so hopefully I'll be able to say the same about these.

Wow, great idea!
I actually cut the plastic that holds the 2 sides together so I could see what was going on under there. I didn't know these were available, I'll get them next time.

Nice, thanks for the diagram, that's what I'd been looking for.

Have you done it yourself?

BOOM!
Got it working again!

Thanks Barak, your diagram really helped me troubleshoot the issue. I tried to match up every data and address pins, and found that the D2 wasn't making contact between U2 and U6.
I also had a pin which needed pressure to make contact on U7 (which might have to do with some of my intermittent issues).

One thing I'm not sure about is that I have continuity between U2 and U6 at pin 18, and no ground there. Maybe it has something to do with the jumper settings?
Also, I have continuity between U7-10 and U6-21, but since U7-10 is supposed to be A9 and U6-21 A14 I'm not sure how that works. If I follow the path of traces, this is where I get too so it doesn't look like anything is shorted. Jumper settings again?

I've only tested with a computer power supply, I'll go put the board back in the machine at my friend's place and we'll see about the reliability.

One thing I'm having a bit of a hard time with to try and do cleaner work is unsoldering the pins where there's no trace in the back, and just a bit of copper around the hole. I'm getting better at it, but I'm still lifting about 1 out of 4 or 5... any tricks?

Many thanks again, hopefully it's fixed for good and I can move on to a TFTC I have that's been sitting idle for some time...

ARRRRGH!
This thing's gonna drive me nuts. Fired it up this morning, only get 3 flashes.

I'll do another round of continuity testing, with all chips in this time.

Ok thanks guys, I'll check it out next week, I'm out of town right now.
As for desoldering, I just use my regular soldering tool with the plastic "push in-pop out" vacuum thing.

Alright,
I finally figured it out. I went and soldered all the contacts that have traces running on the upside of the board directly on that side, I pulled out the U2 and U6 and gave them a good cleaning with contact cleaner: still random flashes. Either nothing, always on, 2 flashes, 3 flashes, 6 flashes.
Double checked all the continuity using your diagram, all good.
Finally... I triple check them, found out I had discontinuity somewhere. This is where I used a wire on the backside to repair a trace I had broken. The cold solder had broken, and the wire was making contact, but not all the time.

Repaired that, and I had 6 flashes last 30-40 times I tried. I still need to put it back in the machine, but so far so good.

A LOT of time spent on this but I think it gave me good practice, my soldering was looking much better towards the end.

Installed back on the machine at my buddy's place, he played many games yesterday without any issues.

Thanks to all for your help!

Phil

Well it looks like it's not going to be easy with this one...
My friend played the machine intensively for a 3 weeks, then 1 week ago he tells me it stopped working. I bring the board home and plug on my test fixture and get solid green LED.

I push on the chips, restart it and get the 6 flashes. I try it about 30 times and get 6 flashes each time. When I get around to restoring that machine I'll get a brand new MPU but for now I figured I'd just tell my friend to try pushing on the chips if he has problems. (I know, I know...)

I get back to his place, plug the board back in - still get 7 flashes but the game won't start. I get weird random behavior instead of that (garbage on the displays, no startup chimes, etc. etc.).
As I'm typing this I'm wondering if I didn't simply plug a connector backwards.

Any ideas?

Thanks
Phil