Medusa
Bally, 1981Quoted from StratDoc:The lamp is getting voltage but will not come on when grounded.
Temporarily install standard incandescent lamps in those two non-working lamp locations.
Go into display test mode (i.e. so the game is not activating any feature lamps).
In this state, the base and also the colored wire lug of the lamp sockets must both measure 6.5VDC. Is this what you're measuring?
On the 200k lamp I get a solid 6.93 to 7.09 vdc on both the base a colored wired. On the shoot again lamp solid DVC on the base but the colored wire jumps
around between 2.40 and 7.0.
I replaced the rear stand targets with transparent. It was not a full switch just the target and now having drop reset issues on top and right drop targets. When reinstalling the rear drops the orange came loose from the right solenoid. Soldered it on the wrong lug and blew the PF fuse and shorted Q5. Replaced Q5 and the PF fuse quit blowing and rear drops will set properly t game start - drops all targets but center target - but targets will not reset. Right 4 drop targets also not resetting.
Pulled the top drop bank out of the machine and with it out the right four will still not reset. Ground Q1 and the coil for the 4 right drops just buzzes. In diagnostic test the four drop bank will reset.
Another odd thing that is now happening. In diagnostic mode when cycling through the display test on some of the display numbers, for example, 6,666,666 the controlled lamps also flash. In solenoid diagnostic, some of the activated solenoids will flash the controlled lamps.
This thing is killing me. Thought I was close. Should have left well enough alone with the transparent targets.
Back in business. I resolved the reset issue and other seemingly related problems. I think the only things not working properly are the two controlled lamps.
Quoted from Quench:Temporarily install standard incandescent lamps in those two non-working lamp locations.
Go into display test mode (i.e. so the game is not activating any feature lamps).
In this state, the base and also the colored wire lug of the lamp sockets must both measure 6.5VDC. Is this what you're measuring?
On the 200k lamp I get a solid 6.93 to 7.09 vdc on both the base a colored wired. On the shoot again lamp solid DVC on the base but the colored wire jumps
around between 2.40 and 7.0.
Quoted from StratDoc:On the 200k lamp I get a solid 6.93 to 7.09 vdc on both the base a colored wired.
Well, that's good. The incandescent globe is a very low resistance which is why you get about the same voltage on both lugs in this test.
If you ground the colored wire on that 200k lamp it should work.
Quoted from StratDoc:On the shoot again lamp solid DVC on the base but the colored wire jumps
around between 2.40 and 7.0.
The Shoot Again colored wire goes back to pin 22 of J3 at the main lamp board so disconnect J3 from the lamp board and remeasure the colored wire at the lamp again (so the lamp board is out of the equation).
Quoted from StratDoc:Another odd thing that is now happening. In diagnostic mode when cycling through the display test on some of the display numbers, for example, 6,666,666 the controlled lamps also flash. In solenoid diagnostic, some of the activated solenoids will flash the controlled lamps.
Is this still happening?
Quoted from Quench:Well, that's good. The incandescent globe is a very low resistance which is why you get about the same voltage on both lugs in this test.
If you ground the colored wire on that 200k lamp it should work.The Shoot Again colored wire goes back to pin 22 of J3 at the main lamp board so disconnect J3 from the lamp board and remeasure the colored wire at the lamp again (so the lamp board is out of the equation).
I am getting 5.3 on the colored wire and 7.34 on the base. it will not light with ground to the colored wire.
Is this still happening?
Yes, the 200k lamp works with ground to colored wire.
With J3 disconnected, I am getting 5.3 on the colored wire and 7.34 on the base on the shoot again lamp. it will not light with ground to the colored wire.
Yes. In diagnostics it is activating the solenoid board on the pf and the lights flash - not all numbers and not all coils do it. Also the diagnostic switch test activates the sound. Crazy, this all started happening out of know where.
One more issue - I pulled the PF to get the wood rails back on. Can I say pain in the you know what - why they used braids to attach the wood rails is beyond me. Reinstalled PF and now the right sling activates the left sling, and the bottom right and left pops activate the left sling.
Quoted from StratDoc:Yes, the 200k lamp works with ground to colored wire.
Resolder the 6.5V braid wire on the lamp socket base - maybe the solder didn't stick to the base.
Quoted from StratDoc:With J3 disconnected, I am getting 5.3 on the colored wire and 7.34 on the base on the shoot again lamp. it will not light with ground to the colored wire.
Unsolder the colored wire and remeasure the voltage on that socket lug. If it now goes to 7.34V then that colored wire is shorted somewhere.
Quoted from StratDoc:Yes. In diagnostics it is activating the solenoid board on the pf and the lights flash - not all numbers and not all coils do it.
When this sort of thing happens, give us as much detail as possible. Which lamps, which solenoids, when exactly they're triggered, etc, so we can try to logically map out what's going wrong.
Quoted from StratDoc:One more issue - I pulled the PF ... Reinstalled PF and now the right sling activates the left sling, and the bottom right and left pops activate the left sling.
Sounds like you need to carefully go over that overcrowded under playfield looking for shorts.
At least go into switch test mode and do the tests again from highest to lowest switch as per earlier in this thread.
Re-soldered the braid wire on the base and no change. It has a good connection to the base.
I removed the colored wire on the shoot again lamp and tested vdc at the base and on the connector. The entire base registers 7.05 vdc but the connector registers between 3.5 and 4.5 . I guess I will install another socket. Strange it will be the third new socket installed.
I am interested in learning what is causing the strange diagnostic issues. It just started happening with no change other than installing transparent targets at the top of the PF. Here are the results.
In Display Test
- All 0s, 1s, 2s, 3s, 8s, and 9s - pf lights flash and solenoid expansion board activates
- All 3s, 4s 5s 6s, and7s - pf lights flash
In Solenoid Test
- Solenoids 16 - 22 pf solenoid expansion board activates and pf lights are dimly lit with activation
When diagnostic test is activated from attract mode the background music keeps playing throughout all diagnostic tests.
I will double check for shorts under the PF. This thing is a real beast but it is starting to look great!
Quoted from StratDoc:Re-soldered the braid wire on the base and no change. It has a good connection to the base.
So a few posts ago you mentioned this lamp now works when you ground it. Go back upstream to the lamp driver board and perform the SCRs tests previously done.
Quoted from StratDoc:I removed the colored wire on the shoot again lamp and tested vdc at the base and on the connector. The entire base registers 7.05 vdc but the connector registers between 3.5 and 4.5 . I guess I will install another socket. Strange it will be the third new socket installed.
Try another incandescent lamp first.
Quoted from StratDoc:I am interested in learning what is causing the strange diagnostic issues.
Can you try wiggling J1 on the MPU board and J4 on the lamp board during the display test - any difference? Sounds a bit like a poor connection on the Lamp Strobe #1 signal from MPU to lamp board.
I grounded the SCR and the 200k lamp will not light. I am showing continuity from the connector to the lamp.
I tried a different incandescent and still it will not light. It has a very, very dim glow.
I jiggled and re-seated the connectors at J1 on the MPU and J4 on the lamp board. Still having the same issue in diagnostic.
Quoted from StratDoc:I grounded the SCR and the 200k lamp will not light. I am showing continuity from the connector to the lamp.
Does grounding the 200k lamp wire at the lamp board connector illuminate the lamp?
Quoted from StratDoc:I tried a different incandescent and still it will not light. It has a very, very dim glow.
You're looking at basic electrical issues with both these lamps that are local to the sockets.
Base of the lamp sockets should have braided lamp power (6.5V). Manually grounding the socket tip lug completes the circuit and the lamp should fully light. Doing this test completely eliminates the MPU/lamp board from the equation.
If they don't light, inspect the lamp/socket/connections on the socket.
If they do light then go upstream to the respective colored wire at the lamp board connector and ground it in the connector then based on the result look for an open circuit on the wire to the lamp, or go further upstream to grounding the metal tab of the respective SCR.
Essentially the SCRs on the lamp board switch the colored wire connection at the lamp to ground under control from the MPU.
Quoted from StratDoc:I jiggled and re-seated the connectors at J1 on the MPU and J4 on the lamp board. Still having the same issue in diagnostic.
Is there any abnormal behavior during game play?
If you go into display test mode again and disconnect J2 and J3 (playfield and cabinet switch harnesses respectively) from the MPU board, does it make any difference?
I meant to say the 'shoot again" light. The 200k will light when grounded but not otherwise. I grounded the "shoot again" lamp at the connection and it also did not light. So there is something between the board and the socket or at the socket.
I disconnected J2 and J3 on the mpu during diagnostics and the strange behavior did not change. I have not fully populated the pf so have not played a game. There does not seem to be any strange behavior starting a game and activating coils, etc. with my finger.
I have the day off tomorrow. In addition to a lot of "honey dos" I hope to work on the pin more.
I have to 200k and shoot again now both lighting when I ground the colored wire, ground the connection at the board and ground the related SCRs. I am getting a pulse from the related IC legs on the driver board. Suggests two bad SCRs?
Quoted from StratDoc:I have to 200k and shoot again now both lighting when I ground the colored wire, ground the connection at the board and ground the related SCRs. I am getting a pulse from the related IC legs on the driver board. Suggests two bad SCRs?
Great! Time to manually test the SCRs
Jumper a wire from test point TP3 on the lamp driver board to the "Gate" pin of the respective SCRs. If the lamp lights, the SCR is good. If it doesn't light then based on the test results in your previous post, the SCR is bad.
If you look carefully at the lamp driver board, some of the SCRs have "C", "A", and "G" printed on the board near the SCR legs.
The "A" leg is the "Anode" leg that's also the SCRs metal tab - it connects to the lamp.
The "C" leg is the Cathode leg - it's soldered to ground.
The "G" leg is the Gate leg. This leg switches on the SCR and essentially connects the A leg to the C leg - i.e, provides ground to the lamp.
SCR Q40 controls the Same Player Shoots Again lamp.
SCR Q51 controls the Saucer 200k lamp.
If you're still not sure which is the Gate pin of the SCRs, refer to the last part of post #89.
As always, try the TP3 to Gate jumper test with working lamps to make sure you've got the process right.
So the SCRs did not activate the lamps. I replaced them and the lamps still do not activate - the alltek board has the nice design of having through holes below the lamps for replacement. To recap, both lamps now light when grounded - at the colored wire and at the connection.
Another strange thing. The alltek board installation says that when using LEDs you should connect a jumper wire from the alltek board to the 5vdc controlled lamp wire in the backbox. When I do this the pf solenoid expander clicks on an off and things lock up.
Quoted from StratDoc:So the SCRs did not activate the lamps. I replaced them and the lamps still do not activate ...
To recap, both lamps now light when grounded - at the colored wire and at the connection.
Does grounding the "A" leg of those SCRs light the lamps? Note the leg layout of the small and large SCRs is different.
Quoted from StratDoc:The alltek board installation says that when using LEDs you should connect a jumper wire from the alltek board to the 5vdc controlled lamp wire in the backbox.
Can you do me a favor and post a picture of the Alltek installation stating this instruction?
The wire needs to be connected to the braid on the lamp/display door that powers the feature controlled lamps which is either 5.4VDC or 6.5VDC depending on the generation of classic Bally/Stern.
On Medusa, the very bottom braid wire on the lamp/display door is connected to a thick blue wire and this powers the "Game Over", Tilt" and "Same Player Shoots Again" lamps. Note the thick blue wire also goes to the braid powering the "High Score To Date", "Ball In Play" and "Match" lamps.
The wire from the Alltek board needs to connect to the braid at these lamps where either of these thick blue wires connects.
Yep, that's how it should connect.
Same if you're using the Siegecraft flicker free boards on your Aux Lamp board.
Okay. Reconnected and now not a problem. Darn thing has gremlins.
Back to the lamps. I can ground the SCRs to the cabinet ground braid and lamps come. Grounded to tp3 on the board and no lights for the two lamps in question.
Quoted from StratDoc:Grounded to tp3 on the board and no lights for the two lamps in question.
TP3 should be jumpered to the "G" leg of the SCRs, not ground.
TP3 has the correct voltage used to manually test activate SCRs.
Yes. Misspoke. Per post 89 tp3 to right leg of small scr and left leg of left scr. Neither light. These are new SCRs soldered to the through holes of the alltek board.
UPDATE - 200k is now working an flashing in attract mode. Put in another new SCR and it is now working
Shoot again is still problematic. I have dropped in two new SCRs. Lamp will light when grounded. Will not light when left leg is connected to TP3. Is shoot again supposed to flash in attract mode?
A pf question. There are four(+) plastic posts that are taller than the rest. Where do they go? I took a lot of pictures when disassembling the pf but cannot tell from the pics and did not notice when I removed them
Quoted from StratDoc:Shoot again is still problematic. I have dropped in two new SCRs. Lamp will light when grounded. Will not light when left leg is connected to TP3. Is shoot again supposed to flash in attract mode?
If you ground the metal tab of Q40 and the Same Player Shoots Again lamp lights, but jumpering TP3 to the left leg of Q40 doesn't, then Q40 is faulty. It might have a short on the "Gate" (left) leg of the SCR meaning installing a SCR over the top will never work. If you want to butcher it, cut the left and right legs of the original Q40 to disconnect it from circuit and install your replacement SCR in the through holes. This location requires a MCR106 SCR.
Quoted from StratDoc:Is shoot again supposed to flash in attract mode?
The Same Player Shoots Again lamp does not light in attract mode. As per your Paragon project, not all playfield lamps light in attract mode. Use lamp test mode for testing.
Quoted from StratDoc:There are four(+) plastic posts that are taller than the rest. Where do they go?
I have them under the slingshots and the side plastics that are screwed to the rails - they're positioned where the top locking nuts on the posts are for those side plastics.
Really screwed something up. Was reassembling the playfield and got it all back to together and booted it up. The displays were acting crazy as were the playfield lamps. Displays were flashing - almost like they were scrolling - and the pf lamps were staying on or flickering. Shut the machine down and lifted the pf to find that a wire in the cabinet - not attached to anything - looked like it had shorted across the knocker. I am guessing that is what caused the problem but not for sure.
I thought I might have fried either U10 or U11. I replaced them with spares from another board. No luck. My next thought is U20 since the lights on the pf stay lit?
Feel like a real junk finger with this damn project.
Do you work in pyrotechnics? You seem to like blowing things up 
)
If a wire fell and shorted on the knocker then find out what that wire is for. Was there any smoke or burning smell?
Is your J1 connector at the MPU good? Both lamp and display info come from there.
Too funny. I feel like I am with this pin. Rebuilt a Xenon over Christmas no problem. This thing is another story.
J1 is good. The wire was a loose wire in the cabinet not connected to the board. One I had stripped and but not used. I suspect it shorted to somewhere else.
Displays just look like they scroll and pf lamps flash very quickly and stay on during attract mode. All voltages on sdb are okay. Pf fuse blew. Replaced it and things goes crazy. Pops fire, solenoid expander clicks fast. It eventually stops but sometimes not before blowing the pf fuse. Checked switches just to make sure all were gapped okay - they are. Did that when I reassembled the pf.
Installed my alltek board from the Paragon and have same problems with displays and solenoids firing, etc.
I installed my paragon SBD and displays have similar problems - think it is the connector at j1. Needs to be repinned. Solenoids, expander board, etc. did not fire. Looked at the SBD from the Medusa and noticed for the first time someone had miswired the ground mod. They had it connected to the wrong trace. Good grief. Pf fuse keeps blowing now. I am wondering if my whole SBD board is shot.
Do any of the problems go away when you disconnect:
Both J2 and J3 from the MPU board?
Or the lamp driver boards (J4 from the lamp board, J1 from the aux lamp board)?
Or all displays?
Or connect one display at a time - try different displays.
MPU J4 activates solenoids, so your issue goes beyond J1 on the MPU board.
Have you got a logic probe?
So I am back with it. A new sdb and arrived and the problems persist. I repinned the connector on J3 of the Sdb as well.
I have the displays looking like they scroll - I know that is not what they are doing but it appears that way. No solenoids work except flippers. In game sound is not there but okay during diagnostics.
All started when I think I shorted a spare wire across the cabinet knocker.
Installed my alltek mpu back in my meteor and now it the meteor is screwed up. Displays not working properly. Lots of missing digits.
Put original mpu back in the pin and now no displays light. Voltages at the displays measure correct.
Solenoid and pf fuse blowing is solved.
Displays still flicker.
Disconnect J3 on the MPU and displays go blank. Plugged j3 back in and displays still blank. Connector issue? At this point this morning cannot get them to come back on. Inspection of j3 connctor looks fine. At some point in the not too distant past someone repinned it with good robust terminals. Checked the board connection at j3 and reflowed solder joints as well. Blanking signal from J1 pin 10 is pulsing as well.
Increased voltage on SBD via trim pot and now have flickering displays. Unplugged j3 on the MPU no change in display flicker.
Unplugged j4 on lamp board and j1 auxiliary no change.
Unplugged all displays and plugged in one at a time - all were blank.
Plug all displays back in back to all displays flickering.
Turned pin off and back on and now all displays blank. Voltages at all displays check out at 190vdc 
Solenoid expander board also not working. Light flashes twice at pin start then goes out. Grounding connector 25 at J3 on the lamp board lights the bulb. Only showing 29vdc on the expander board at pin 9 instead of 43.
Quoted from StratDoc:Increased voltage on SBD via trim pot and now have flickering displays.
What's the display high voltage at now?
Quoted from StratDoc:Unplugged j3 on the MPU no change in display flicker.
MPU J2 is the more important one to disconnect since it's the playfield (where you've done most of the work) switch harness that partly shares the same data bus as the displays and lamps.
So you can start and play a game, just no displays?
Pick any display - are you getting pulses at all these pins on the displays connector:
4 -> enable first digit (ones)
5 -> enable second digit (tens)
6 -> enable third digit (hundreds)
7 -> enable fourth digit (thousands)
8 -> enable fifth digit (ten thousands)
9 -> enable sixth digit (hundred thousands)
15 -> display select
16, 17, 18, 19 -> four pins make up a binary coded decimal number for actual number to display
Do you measure 5VDC at TP1 on the display board?
Turned the damn thing on to check your questions and all displays working perfectly. What the heck. Crazy. It has to be the connectors. I have ordered connectr to repin everything.
Solenoid driver board light is not working. Flashes once when it goes into attract mode. Flashes during lamp test but no 43vdc present expander board does not click or buzz. Pf fuse is okay.
Quoted from StratDoc:Turned the damn thing on to check your questions and all displays working perfectly.
Wiggle the connectors to see which is affecting the displays.
Quoted from StratDoc:Solenoid driver board light is not working. Flashes once when it goes into attract mode. Flashes during lamp test but no 43vdc present expander board does not click or buzz.
Pin 9 at the solenoid expander connector (yellow wire) is the +43VDC solenoid power line. It's likely that yellow wire comes from the nearest coil so trace it.
I cannot get the displays to reproduce the flickering issue. I feel confident it is J1 on the mpu. I re-connected some of the wires and maybe that fixed it. I have ordered a new 28 pin connector.
Solenoid expander now working. It was the yellow connection at one of the pop bumpers.
Only thing not working at this point is the "shoot again" lamp. It still does not flash during the lamp diagnostic test. It will light be grounding the controlled lamp signal wire. I have replaced the transistor on the lamp driver board. It has a new socket - actually replaced it twice - and it has a constant 7.25vdc at the controlled lamp wire and socket base.
I also need to reinstall the 7 drop target and top of game lights. Those two get in the way when working underneath the pf so I removed them.
Very close - I hope.
Quoted from StratDoc:Only thing not working at this point is the "shoot again" lamp.
1) Does it light when you ground the Brown-Blue wire at the lamp driver board connector J3-22?
2) Does it light when you ground the metal tab of SCR Q40 on the lamp driver board?
3) Does it light when you run a jumper from test point TP3 on the lamp driver board, to the left "gate" leg of SCR Q40?
Quoted from Quench:1) Does it light when you ground the Brown-Blue wire at the lamp driver board connector J3-22?
Negative
2) Does it light when you ground the metal tab of SCR Q40 on the lamp driver board?Negative
3) Does it light when you run a jumper from test point TP3 on the lamp driver board, to the left "gate" leg of SCR Q40?
Negative
I have a bad connection to the pf somewhere for this lamp.
This has been a roller coaster ride!!! Man two thumbs up for sticking with it. and great job by quench with his step by step troubleshooting delivery. I've enjoyed reading this and am excited to see it complete as I know you will be too. Super close. Keep it up!
Thanks
Blake
Quoted from StratDoc:I have a bad connection to the pf somewhere for this lamp.
Ugh, sorry I said in the previous post the same player shoot again lamp wire is brown-blue. Not sure how I made that mistake but it's a Blue-Yellow wire. Is this the color you're seeing on that wire at the lamp socket and lamp board connector J3 pin 22?
There's no intermediate connector on that lamp wire either - it's direct from the lamp driver board to the lamp socket.
Quoted from Blake:This has been a roller coaster ride!!!
We're here for the long haul, can't have this game not working properly 
Quench, you are the greatest!
Okay, so whoever repinned J3 on the lamp driver board broke the top part of the IDC connector. The pin was in the connector but the wire was sitting in the connector but not connected to the IDC pin. I pulled an IDC pin from an old connector and installed. We are now in business. Cannot believe this has been the issue all along.
I have a long day today with work but off tomorrow. I will post back but hopefully I will be able to post a picture of the first game!
Quoted from StratDoc:Quench
What a hero...
I spoke too soon. I reinstalled the rear drops and they are now not resetting properly. Worked fine before pulling them out. The second, third, and fourth drops from the left when looking at the target stay up instead of dropping and leaving the center target up - ugh. Also blew PF fuse almost immediately when I started a game.
Quoted from StratDoc:started a game
Brutal!
You are reminding me of how important it is to have on-hand fuse-breakers wired into blown fuses for this portion of doing a swap... I've just been "luckier" for my 2 swaps...
;p
Starting with switch 48 and working backward during the switch test, targets 48 and 46 are not registering which is probably the cause of the rear drop reset issue. I have pulled the drop targets and cannot see anything that is problematic. Switches are gapped properly and all connections are solid with no bad diodes.
Quoted from StratDoc:I reinstalled the rear drops and they are now not resetting properly. Worked fine before pulling them out. The second, third, and fourth drops from the left when looking at the target stay up instead of dropping and leaving the center target up
The second and third drop target (from left) are both activated by the same driver transistor on the SDB. What happens when you ground the metal tab of transistor Q6 on the SDB?
Medusa_DT2_DT3_PF.jpg
Medusa_DT2_DT3_SDB.jpg
Quoted from StratDoc:Also blew PF fuse almost immediately when I started a game.
Has this been resolved?
Quoted from StratDoc:Starting with switch 48 and working backward during the switch test, targets 48 and 46 are not registering which is probably the cause of the rear drop reset issue.
The switch issues are separate to the solenoid issues. When the game is resetting drop targets, it doesn't consider the state of the drop target switches.
Check that you have zero ohms continuity from the top drop target switches to the MPU board as per below:
Medusa_SwitchMatrix_PF.jpg
Wanna join the discussion? Please sign in to reply to this topic.
Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
This page was printed from https://pinside.com/pinball/forum/topic/first-playfield-swap-medusa/page/3?hl=rack-em-up and we tried optimising it for printing. Some page elements may have been deliberately hidden.
Scan the QR code on the left to jump to the URL this document was printed from.
Chattanooga, TN
