(Topic ID: 254299)

Fixed-Tech: Help! ~~~ TWD is Dead :(


By kvan99

45 days ago



Topic Stats

  • 25 posts
  • 6 Pinsiders participating
  • Latest reply 6 days ago by kvan99
  • Topic is favorited by 4 Pinsiders

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Stern_TWD-.indd (1).pdf (PDF preview)

#1 45 days ago

I'm hoping someone with better skills can help me out, I've been trying to fix this game for a week now. I was playing a game last week when I noticed smoke coming out of the back box, I found C6 15000v cap had burned up. I also noticed F7 had blown, I looked around the board everything else looked ok, so I shotgunned it...I replaced C6 and put a new fuse in. Well, 30 seconds after the turning the game on I noticed C6 was getting cooked again, and almost at the same time F7 tripped too. I turned the game off and started to troubleshoot it properly this time, I also noticed the entire hi volt transistor section Q1-Q16 was super hot. I took the board out and went through it and found Q6 and Q7 were shorted (these are the 2 magnet transistors) I also checked their diodes and they tested kind of flaky. I replaced all 4 components and took out the magnets and checked the resistance in them, the magnets were both reading between 5.5 -5.7 ohms, which I was told is ok.

I figured that should take care of it, I put everything back and kept both magnets disconnected, everything was fine and the hi volt section was cool. I even played a game...all good, but when the wellwalker magnet was connected F7 tripped and the hi volt section got hot again I tested again with the prison magnet connected and the other disconnected...same results. I found out Q6 and Q7 both were shorted again. I don't know what's causing this.....I checked the wiring and took out both magnets to make sure they're not shorting. I'm out of ideas.....
Stern_TWD-.indd (1).pdf

#2 45 days ago

i tried attaching the PDF but it's low res.

#3 44 days ago

sounds like the magnet diode is wired backwards.

Edit: Nevermind ... Was thinking Whitestar :/

#4 44 days ago

Since fuse F7 is in the 50V circuit and capacitor C6 in the 20V, I would suspect a short between these 2 circuits.
That could be in the wiring or flashers and coils touching.

Check the harness for pinched wires and all 20+50 Volt related components that are close to each other.

I have no manual of the Walking Dead but I think all that is connected to J6 and J7 are 20 Volt solenoid+Flashers.
And J8 + J9 are 50Volt solenoids.

#6 44 days ago
Quoted from Pin_Guy:

Here you go:

: ) , thanks !

and page 9 confirms J8 + J9 being 50V solenoids and J6 + J7 for 20V flashers + 1 motor

#7 44 days ago

Sounds like Zaza's comments are spot on.

OP: Got some pictures of the magnet, wires, and related boards? Maybe someone can spot something.

#8 44 days ago

Thanks everyone for the help, I did go over the wires to no avail, but I did noticed the left ramp flasher was working weakly in test mode, also there is a buzz when the left flipper is actuated...not sure if these are related to my issue.

I also want to point out the new C-6 cap is holding...it's not burning up. The game plays normal with the magnets disconnected, but when either magnet is connected the hi-volt section heats up and Q6 and Q7 short out. I did replace the STP22NE10L with IRL540N...But I went ahead and order the originals.

#9 44 days ago
Quoted from kvan99:

the new C-6 cap is holding...it's not burning up.

Check diodes D6 + D7 to be sure

5249 Q6-7.jpg

#10 43 days ago

Thanks Zaza, I did change them out when I replaced Q6 and Q7. I hope the IRL540N is compatible part....I took out the board and checked all the transistors and diodes... I also checked the BRs. I even metered the magnet wires to the connectors J8, J9 and J10 to see if there was a short between the wiring for the magnets and other hi volt components......no joy.

So here is the list of events and things I've replaced
1. Replaced C6 cap burned up, replaced and it burned up again, it was replaced again and now it's ok
2. Replaced Q6 and Q7 with IRL540N twice, the first time the diodes were not replaced, the second time the both the Qs and diodes were replaced but the Qs shorted again.
3.Diodes D6 and D7
4. checked for shorts around pf and flashers
5. Magnets ohm reading is 4.5-4.8

game plays fine with magnets disconnected.....with magnet connected hi-volt section gets super hot.

#11 43 days ago
Quoted from kvan99:

Thanks Zaza, I did change them out when I replaced Q6 and Q7. I hope the IRL540N is compatible part....I took out the board and checked all the transistors and diodes... I also checked the BRs. I even metered the magnet wires to the connectors J8, J9 and J10 to see if there was a short between the wiring for the magnets and other hi volt components......no joy.
So here is the list of events and things I've replaces
1. C6 cap (twice)
2. Q6 and Q7 with IRL540N (twice)
3.Diodes D6 and D7
4. checked for shorts around pf and flashers
5. Magnets ohm reading is 4.5-4.8
game plays fine with magnets disconnected.....with magnet connected hi-volt section gets super hot.

Short in the magnet itself?

#12 43 days ago
Quoted from WackyBrakke:

Short in the magnet itself?

I swapped the magnets around but the hi volt section got very hot with either one connected and F7 blew too. I'm not sure if the magnets can both go bad. I also metered them, they read around 4.5-4.8

#13 43 days ago
Quoted from kvan99:

I hope the IRL540N is compatible part

The IRL540N should be a good replacement for the now obsolete STP22NE10L.

You may want to double check D6 and D7 are still in the circuit after replacing the transistors. IMO, your symptoms are just too similar to a failed/missing flyback diode to ignore.

#14 43 days ago

Just for grins a giggles, measure voltage on the drain lead (circled). Maybe on the other side of the diodes too, along with voltage at the unhooked magnet.

No sure if it will help you, but given the odd nature if the issue, might shed some light.

Besides Zara's 'look for shorted wires' good suggestion, it does sort of sound like a diode problem.

Got a scope or just a multimeter?

This might be a little risky (i.e. possible damage), but you can alway measure the DC voltage on C6 when there is an issue. See if it really is going to 50V. Just use caution, maybe put in a smaller amperage fuse and make it a quick measurement. But that might tell you a LOT (i.e. Is 50V really getting back to the 20V section?). Your call - don't want you damaging the pin further, so please be careful. Pulling F10 might be helpful if you decide to try this, that would at least kill the 20V, but I don't know if the pin would boot up correctly - maybe someone else could chime in with more experience.

Don't have any experience with the Stern boards...so some stumbling here.
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#15 43 days ago

Also - snooping around the schematic some...this isn't related to the shaker motor, is it? I only say this because I see both 20V and 50V in that area. Reading your posts, it doesn't sound like it is. Just curious if D3 is OK. But the F3 fuse might blow if D3 is shorted.

Again - just food for thought. Sorry I can't be more helpful!

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#16 41 days ago

Thank you all very much for your help, I went back and rechecked the diodes and noticed the D6 and D7 were good (getting OL in one direction and .593 in the other), so I went ahead and checked the neighboring ones, they read .593 one way and 2.93 the other......not just one diode, all of the 1N4004 diodes read this way.
Edit: I originally thought this was the issue, but it seems diodes in circuit may not read like diodes out of circuit. I checked my IM and I got .11 both ways, so I'm not sure what's up.
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#17 41 days ago

Does seem a bit odd all of them would read bad even on the low side considering theres not much that could cause excessive current through all diodes simultaneously to damage them all, so I'd double check that meter before plunging into a lot of soldering, something else on the board could also be affecting the readings but apart from the flipflop IC driving that circuit (74htc273) I cant see a component that jumps out at me or rings bells....its a tricky one..... probably wrong and missing something but just my gut feeling

#18 41 days ago
Quoted from Hul1gn:

Does seem a bit odd all of them would read bad even on the low side considering theres not much that could cause excessive current through all diodes simultaneously to damage them all, so I'd double check that meter before plunging into a lot of soldering, something else on the board could also be affecting the readings but I cant see a component that jumps out at me or rings bells....its a tricky one..... probably wrong and missing something but just my gut feeling

I just checked my IM, and the diodes are reading from both sides as well, although the values are not the same as TWD....I'll edit my last post for clarity.

#19 41 days ago

Just for kicks, if you have the board out can I see a pic of the underside in that area?

#20 41 days ago

also, what do they read with the 9 pin connectors removed? any change? not thinking its the diodes but isolating the circuit may help pinpointing a possible culprit.
you are correct in saying in circuit or out can change things, a cap holding charge can be enough to bias a diode or 20...

#21 41 days ago
Quoted from Hul1gn:

also, what do they read with the 9 pin connectors removed? any change? not thinking its the diodes but isolating the circuit may help pinpointing a possible culprit.
you are correct in saying in circuit or out can change things, a cap holding charge can be enough to bias a diode or 20...

Yeah sure, here you go....
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#22 41 days ago

thanks, nice soldering... hmm nothing strange there...was hoping to see something odd. back to the drawing board....
I'm thinking you have a roasted coil or two... if there are flywheel diodes on them and said diodes test fine disconnected... Its pointing to the coils.
Even if a coil tests fine while not energised, its possible its been overheated and the insulation then breaks down under load thus drawing too much from the driver circuit.... 50v is enough to see that type of thing.

sorry mate, thats all I've got.

1 month later
#23 8 days ago

Update: today, I took out the board of my IMVE and installed in the TWD, I first disconnected shaker and the magnets just to be sure, it does not short the transistors or blow fuses...I tested it, everything was fine, I plugged in shaker and tested again..played fine. I finally plugged in the magnets one by one and the game played 100% no blown fuse or transistors.....so I'm now pretty sure I have a board issue.

#24 7 days ago

Update again:

Looks like I may have bought some fake IRL540Ns, that' maybe the reason why the transistors were shorting out on the first try.... I ordered some original STP22NE and replaced both Q6 and Q7, the transistors for the Prison and Well Walker. It seems the game is now working fine.

There is however one new issue I noticed: the +12vdc light on the driver board is off.....? I'm not sure what it's used for, but the game is seems to be working fine. If anyone has a line on why the light may be off...please let me know.

#25 6 days ago

Final update:
So it seems the electronic gods wanted me to really work for this fix...so it wasn't bad enough that I had counterfeit transistors, the +12vdc light that was out was only the LED, I checked the voltage at J-17 and verified I had +12vdc...I checked the 12vdc Led with a battery and it came on, then I figured it must be tapping power from somewhere, I looked on the back and saw that the C7 cap I replaced had a trace going towards the LED...I checked it with a meter and it didn't ring. I then checked my solder work on the C7 leg and it seems the eyelet may have been damaged enough to not send power to the LED, all I had to do was to scrape a bit of the trace near the cap leg and reflow solder, I checked it again and the LED for the 12vdc is back on. I must say this was a doozy...it tripped me up every step of the way....thank you all for your input. I also want to give props to Chas from Stern who recommended I use the original transistors instead of the IRL540N.....without that I would have been scratching my head still.

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