(Topic ID: 163252)

1977 Bobby Orr Power Play: No MPU LED flash


By SkyKing2301

3 years ago



Topic Stats

  • 12 posts
  • 6 Pinsiders participating
  • Latest reply 2 years ago by SkyKing2301
  • Topic is favorited by 1 Pinsider

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#1 3 years ago

EDIT -- RESOLUTION: Verified Rectifier Board Connector J3 Pin 8 was providing 11.9V, verified wire (when connected) at Pin 8 was showing the voltage too. Followed wire to other end -- a connector on the SDB, and found the end of that wire was fraying/broken and coming loose from the connector pin. I popped it out and re-pinned it, and now it works fine!

_______ORIGINAL POST BELOW________
My original problem child has reared its ugly head again. It figures, as I have out-of-town guests coming in tomorrow, and a party/tournament coming up on the 23rd.

Anyway, went to play a game on each of my pins tonight to verify all's well ... everything was going great until I got to my Bobby Orr Power Play. GI comes on, but didn't appear to boot up. I opened up the backbox, wondering which error the MPU's LED was going to show me this time.

Well, the LED showed me nothing. Nothing at all. No flicker, no flashing.

I checked all the fuses on the rectifier board; they're good. I disconnected / reconnected all the connectors. No help.
I flipped through the troubleshooting guide I'd printed out, and it mentioned to check the voltage at the MPU's TP2 -- which should apparently be 12V. I'm getting about 1.3 volts, so this seems like a good clue.

It's very late, and I'm overly tired ... maybe I'm missing something simple, but I can't see straight anymore. I won't have much time to work on it tomorrow, as I have to prep the house for guests ... but I thought I'd just throw this out here for some quick troubleshooting assistance, in case I have a few moments to look at it.

(One of these days I'm just going to have to bite the bullet and get an new MPU. This MPU had a fair amount of corrosion damage but I've had it working fine for quite some time now. In fact, I played it as recently as Monday with no problem.)

Anyway, thanks in advance for your help / recommendations...

#2 3 years ago
Quoted from SkyKing2301:

This MPU had a fair amount of corrosion damage but I've had it working fine for quite some time now.

Was the corrosion addressed and the affected components replaced? Or has it been left untreated?

#3 3 years ago
Quoted from ForceFlow:

Was the corrosion addressed and the affected components replaced? Or has it been left untreated?

I removed & cleaned up what I could after I first got it, and that was able to bring it back to life. Periodically, though, it'd go down again, so I'd do a little more cleanup (maybe some areas I'd missed or couldn't get to) and then it'd come back to life again. In all these iterations, though, even when apparently knocked out, the LED would still always get into the flicker/flash sequence. This is the first time I've ever had it not even get to the first flicker. That's why I'm wondering if there's something else that could be affecting it.

#4 3 years ago

Without 12V the LED has no power, and no flashes. If there's no 12V to the SDB there won't be regulated 5V to power the MPU.

I would check voltages on the test points on the rectifier, SDB and MPU. Could simply be a blown fuse F3 or a break in the power chain somewhere. If you have 5V on MPU TP5, then maybe the corrosion finally claimed your MPU.

#5 3 years ago

Yeah, check the easy/obvious things 1st.

1 week later
#6 3 years ago
Quoted from dothedoo:

I would check voltages on the test points on the rectifier, SDB and MPU. Could simply be a blown fuse F3 or a break in the power chain somewhere. If you have 5V on MPU TP5, then maybe the corrosion finally claimed your MPU.

Thanks, sorry it took me so long to get to this.

Firstly: Fuse F3 is good. Swapped it out with a brand new one to be sure.

Next: I don't have 5V on MPU TP5. See below for voltages at test points.

Here are my voltages on Rectifier, SDB, and MPU. Note: I'm comparing to the values found at http://techniek.flipperwinkel.nl/ballyss/rep/index1.htm#tp ... "s/b" = Should Be.

Rectifier TP1: s/b 5.4 ... is 6
Rectifier TP2: s/b 235 ... is 230
Rectifier TP3: s/b 11 ... is 11.9
Rectifier TP4: s/b 6AC ... is 7.3AC
Rectifier TP5: s/b 45 ... is 43

SDB TP1: s/b 5 ... is 0.34 ***
SDB TP2: s/b 190 ... is 187
SDB TP3: s/b 5 ... is 0.35 ***
SDB TP4: s/b 230 ... is 236
SDB TP5: s/b 11.9 ... is 1.3 ***

MPU TP1: s/b 5 ... is 0.35 ***
MPU TP2: s/b 11.9 ... is 1.3 ***
MPU TP3: s/b 21.5 ... is 21.8
MPU TP5: s/b 5 ... is 0.35 ***

As you can see, rectifier voltages appear nominal, but the 5V and 11.9V test points on the SDB and MPU are coming back way low. Please advise. Thanks in advance!

#7 3 years ago

1. Unplug J3, then power up and check pin 8 for 11.9V. Most likely you'll have power there.

2. Power down, plug in J3, power up and plug test lead into connector housing on the orange wire, pin 8. If nothing there, repin the connector.

3. If #2 is good check the orange wire on SDB J3 pin 12. Smaller housing, but you can still force the test lead in enough to make a connection. This will probably be good unless somebody broke into your machine and started going crazy with wire cutters recently.

4. If #3 is good repin J3 and replace header pins. That should fix the break in the power chain. You can confirm this if you wiggle J3 and the power cuts in and out on TP5.

#8 3 years ago
Quoted from dothedoo:

1. Unplug J3, then power up and check pin 8 for 11.9V. Most likely you'll have power there.

Checked pin 8 on Rectifier J3 -- 11.9V.

Quoted from dothedoo:

2. Power down, plug in J3, power up and plug test lead into connector housing on the orange wire, pin 8. If nothing there, repin the connector.

Plugged back in J3, powered up, and machine came back to life! Odd, as I wouldn't think I'd have problems there -- a few months back I repinned all three of those connectors (board side AND connector side) on the rectifier.

THANK YOU!!!! I'll call this resolved. If you have any input on why you think this may have happened, to prevent future recurrence, I'm all ears.

#9 3 years ago

Buy an ultimate mpu replacement. Rebuild power supply. Redo all major headers and connectors. That is pretty much mandatory for all those old ballys at this point. Otherwise be prepared to chase problems forever.

2 months later
#10 3 years ago

Just as an FYI for people who might find this thread later for similar troubleshooting ... this problem reared its ugly head again. I continued following the path we'd started above; the wire coming off Rectifier Board Connector J3 Pin 8 was confirmed to be getting the proper ~11.9 voltage ... so I followed that wire to see where it went next. It ends in a connector on the SDB. So I pulled that connector and found the end of that wire was fraying/broken and coming loose from the connector pin. I popped it out and re-pinned it, and now it works fine!

3 months later
#11 2 years ago
Quoted from SkyKing2301:

Just as an FYI for people who might find this thread later for similar troubleshooting ... this problem reared its ugly head again. I continued following the path we'd started above; the wire coming off Rectifier Board Connector J3 Pin 8 was confirmed to be getting the proper ~11.9 voltage ... so I followed that wire to see where it went next. It ends in a connector on the SDB. So I pulled that connector and found the end of that wire was fraying/broken and coming loose from the connector pin. I popped it out and re-pinned it, and now it works fine!

Just wanted to say "thanks" for posting the follow up / solution. Was struggling trying to get my recently acquired Sky Gazer project machine working and your comment prompted me to double-check my assumptions when I added the missing J3 connector from the rectifier board. Sure enough, I had swapped the two orange wires and what should have been my 12V wire was only feeding 7.5V. Fixing that got me a step closer to working.

#12 2 years ago
Quoted from Fytr:

Just wanted to say "thanks" for posting the follow up / solution. Was struggling trying to get my recently acquired Sky Gazer project machine working and your comment prompted me to double-check my assumptions when I added the missing J3 connector from the rectifier board. Sure enough, I had swapped the two orange wires and what should have been my 12V wire was only feeding 7.5V. Fixing that got me a step closer to working.

Great! Glad I was able to help. This community has been so helpful for me; I'm thankful I'm able to give something back occasionally.

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