(Topic ID: 300077)

BSD / WPC89: SOL1-8 Locking Issue / Possibly Bad CPU or ASIC?

By mnye82

37 days ago


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  • 24 posts
  • 11 Pinsiders participating
  • Latest reply 22 days ago by mnye82
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#1 37 days ago

Hi everyone,

I acquired my first pin ( Bram Stoker's Dracula ) in July but have had a series of issues that I've slowly been trying to track down and fix, learning as I go. At this point I seem to only have one real problem left, which is a problem I had soon after getting the machine, but its progressively getting worse. There's a lot of history but I'll try to only mention what's relevant:

1) I took possession of the machine, and within a couple of weeks I started having an issue where none of the high voltage coils would fire. Working with the seller, we assumed that the newly replaced MPU was to blame (he made mention that something similar happened to him but he thought he had resolved it with a MPU replacement). I got yet another new MPU board, swapped my ASIC/ROM/CPU and everything worked again. Important to note - this symptom was no ground going to anything on J-130 / SOL1-8 not firing.

2) 1-2 weeks go by and I start having issues again, but now fuse F105 keeps blowing. At this point I thought I had a new/unrelated issue and that I had a short on a drive wire for one of the high voltage coils.

3) After a lot of troubleshooting, I found Q76 was shorted and forcing J130-5 to ground (I assume the PDB became damaged from the original issue repeatedly happening & many F105 fuses blowing). Removing the PDB and testing this transistor proved to be bad. I ordered a new PDB (probably extreme, but I really want this fixed and my soldering skills suck).

4) I put the new PDB in and now we're back to the total inverse of 1; every pinout on J130 is grounded / all SOL1-8 coils perma-lock on startup and blow F105. If I remove the MPU > PDB ribbon cable and restart the system, J130 doesn't perma-ground. To me this points to an upstream logic issue, especially since the PDB is new.

5) I ordered a new 68B09E / CPU chip with my PDB because it was cheap and one of the last few pieces remaining to swap/test. So I remove the MPU and swap only the CPU chip, the new CPU chip is DOA and the system won't boot at all. I put the original CPU back in and the system boots fine and the J130 ground issue is mysteriously gone / everything works exactly like it should now. This was last night and I've played ~10 games with no issues, but I have no confidence at this point the issue will not return.

At this point I've replaced the MPU, the PWD, all ribbon cables & I'm relatively confident there's no short on the coils/wires. When I replaced the MPU originally, I have a feeling there was nothing wrong with the first MPU and just simply monkeying around with moving the ASIC/CPU/ROM was enough to "fix" the problem, just like how most recently just reseating the CPU seems to have resolved it. To add to this, it seems that the seller temporarily resolved the issue by swapping MPU's too, when it in reality it could have just simply been reseating/moving the ASIC/CPU/ROM.

By all logic at this point, it seems like the CPU is the culprit... but has anyone ever heard of SOL1-8 locking on or not firing at all as being symptoms of a bad CPU chip (or ASIC/ROM for that matter)? I'm going to order another replacement CPU, but I'm sort of at a loss here if/when it happens again if that CPU doesn't fix it. I did recently get a logic probe but am not 100% sure how to use it to troubleshoot this. Any advice on that would be awesome too?

Thanks!

#2 35 days ago

Hey, how goes it ?

For a first machine, you picked an awesome one ! "Blood is, such precious thing in this time"

I assume you have a digital multimeter, yes ?
You should totally test your parts before installing.

Honestly ? If i were you ? I'd make sure i have the manual in front of me and i would be testing every single thing for resistance and continuity and writing it all down. I would then take every single fuse in the game (yes all of them, even under the playfield) and literally throw them all out. Then with the help of the manual go and replace them all.

With the manual you can identify every part, then type it in a search engine and find out it's specs. Compare with your notes. Eventually you will have one or more items that are out of spec. Fix all those issues and see if that helps.

There might be a bad diode, or resistor or transistor or a break in the circuit path in the board, etc.

Or maybe you just simply need to re-solder something ?

Shotgunning parts into a machine usually never works. Knowing how to use a digital multimeter, logic prob and soldering are tools that will help you overcome this issue.

All these things can be learned from youtube, and this forum.

I will totally help you as much as i can, i take care of a Dracula machine at my work, so if need be we can compare machines and stuff !

#3 35 days ago
Quoted from JadedHesher:

Hey, how goes it ?

I would then take every single fuse in the game (yes all of them, even under the playfield) and literally throw them all out. Then with the help of the manual go and replace them all.

- why? seems like a total waste of money to throw away good parts. If they are the wrong rating of course replace with the correct fuse. but throwing away perfectly good fuses is silly.

Anyway back to the OP. It sounds like a connection issue to me. It could be on the MPU, it could be the socket for the CPU or the ASIC. Or the pin of the ASIC was bent/damaged during the transfer. Could also be an intermittent issue with the CPU chip, as it heats up a leg is losing continuity and things go off the rails from their. Which brand of board did you go with for your replacements for the MPU and Driver board?

#4 35 days ago

One pin on the ASIC slightly off can cause problems. Did you inspect the pins after you pulled it? If any pins look even slightly off, pull it back out, carefully straighten any bent pins and reinstall.

#5 34 days ago

Hey fellas,

Thanks for the replies! I do have a DMM + the manual and have been checking quite a bit as I go. The MPU board was sent to me by the seller so it was sort of a freebie replacement and the PDB was just because I think it got damaged from the original issue, and I wanted a baseline with a new board vs having the original + new issue to fight with. I did diode + continuity test all of the transistors when I had it out and that's how I determined Q76 was bad.

So everything worked fine for ~3 days, then I turned the machine on last night and it immediately blew F105 and the issue returned. I'm pretty certain the issue is data-related (for lack of a better term) coming from the MPU > PDB. I can have everything unplugged from the MPU except the power connector + ribbon cable going to the PDB, and all 8 pins on J130 will have continuity to ground. If I remove the ribbon cable/connection between the MPU and PDB, the J130 perma-ground is gone. I just replaced the CPU + ROM chips too so the only thing that's really left is the ASIC and possibly a different brand MPU.

The new PDB is a Rottendog and all the MPU's have been from Pinball Basement.

I've only had the ASIC out once when I swapped it between MPU's and two pins were definitely bent. I did straighten them out before putting it in the new MPU. FWIW, I thought that was the problem when I first noticed it, but the pins that were bent were not the SOL1 pin noted here so I figured it was unrelated at the time:

https://o.pinside.com/7/2c/a6/72ca6c306719e61e11cef9d6b026d609f791e0de.pdf

After fiddling around with the MPU once again, I have the machine working like normal today. I was testing continuity on J130 to ground while messing around with connections on the MPU and I think putting pressure on the ASIC may have been what broke continuity. It's so intermittent that it's hard to get good, consistent tests... but my next assumption is that it's the ASIC / the ASIC's connections in the socket; which jives with some of your replies! I'll do a visual inspection of the ASIC's pins.

#6 34 days ago

Do you have a chip puller for the ASIC, or did you just pry it up with a screwdriver or something?

#7 34 days ago

Nope, I used an IC extractor. I'm was super careful with it being the first time I've done it too. I think the bent ASIC pins were like that before I pulled it / were caused by a previous owner. That's why I was so certain I found the problem early on when I saw them bent & straightened them out, but the issue came back shortly after. Still though, all signs are pointing to it now it seems.

#9 34 days ago

Thanks G-P-E! I meant to say I used a PLCC extraction tool, not an IC extractor. That page looks like a great resource though and the next time I have the MPU out (i.e. - the next time it blows up), I'm definitely going to use that as reference to compare the pins.

#10 32 days ago
Quoted from Xenon75:

- why? seems like a total waste of money to throw away good parts. If they are the wrong rating of course replace with the correct fuse. but throwing away perfectly good fuses is silly.
Anyway back to the OP. It sounds like a connection issue to me. It could be on the MPU, it could be the socket for the CPU or the ASIC. Or the pin of the ASIC was bent/damaged during the transfer. Could also be an intermittent issue with the CPU chip, as it heats up a leg is losing continuity and things go off the rails from their. Which brand of board did you go with for your replacements for the MPU and Driver board?

Fuses are cheap and they go bad, causing resistance. A fuse can look good but be bad. When you get a used pin it should be the first thing you do.

#11 32 days ago

Coils 1-8 locked again today between the end of one game and start of another. I was quick enough to kill the power before it blew F105 though. Anyway, I removed the MPU and reseated the ASIC, bending all the pins out as suggested in the link G-P-E gave me. I did a pretty close inspection of the MPU too while I had it out, as I noticed a few spots with solder flakes melted onto the MPU. Is it normal/within tolerance to have balls of solder under sockets, and could they be related to my issue (maybe heating up just enough during play, I dunno)? It's hard to capture in a picture but there were two pretty noticeable balls under the ASIC socket from the edge that I could see. I also noticed this under some of the IC sockets. I attached some pics to try & illustrate the balls under the ASIC socket, but they aren't great.

I'm still leaning towards the culprit not actually being the MPU, just because the exact same issue happened with the last MPU and what are the odds... unless this is just a bad run and I'm very unlucky.

If the issue returns again after reseating the ASIC I'm just going to cave in and buy a new ASIC next I think. Unless there's something else more logical anyone else can think of?

Thanks again everyone,

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#12 32 days ago

Looks like a defective MPU board to me.
Extraneous solder balls under a surface mounted PLCC socket is never a good thing. Doesn't take much to dislodge a solder ball and cause random shorts - such as inserting PLCC IC into socket or reseating it.

#13 28 days ago

Just an update for anyone following. I got 6 days in after reseating/adjusting the ASIC leads before the issue returned and it did it right as the machine was turned on. I removed the MPU again in preparation to get the ASIC out for replacement, did another inspection of the board & I think I found more quality issues. I had ordered a new ASIC because I still can't really imagine two MPU's having the exact same problem, but I give up on this MPU and am ordering a Rottendog MPU today as well because there's clearly quality problems with it... and I feel like I'm chasing my tail with it being an unknown variable.

More pics attached of the MPU. 1) Half of U17 isn't even in the through holes and on the rear of the board. 2) There's a solder joint connecting what I think is W15 & W16 of the country pins together. Maybe that's normal / not important though? The front of the board does have the resistors connecting the country pin (image 3), so I wouldn't think any voodoo is needed on the rear of the board to short these, but I could be wrong?

Anyway, I'll keep updating as this frustrating journey progresses. Based on testing and everyone's feedback, I'm still leaning towards the ASIC or MPU at this point and both will soon be replaced.

Thanks again for everyone's help,

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#14 28 days ago
Quoted from mnye82:

Just an update for anyone following. I got 6 days in after reseating/adjusting the ASIC leads before the issue returned and it did it right as the machine was turned on. I removed the MPU again in preparation to get the ASIC out for replacement, did another inspection of the board & I think I found more quality issues. I had ordered a new ASIC because I still can't really imagine two MPU's having the exact same problem, but I give up on this MPU and am ordering a Rottendog MPU today as well because there's clearly quality problems with it... and I feel like I'm chasing my tail with it being an unknown variable.
More pics attached of the MPU. 1) Half of U17 isn't even in the through holes and on the rear of the board. 2) There's a solder joint connecting what I think is W15 & W16 of the country pins together. Maybe that's normal / not important though? The front of the board does have the resistors connecting the country pin (image 3), so I wouldn't think any voodoo is needed on the rear of the board to short these, but I could be wrong?
Anyway, I'll keep updating as this frustrating journey progresses. Based on testing and everyone's feedback, I'm still leaning towards the ASIC or MPU at this point and both will soon be replaced.
Thanks again for everyone's help,
[quoted image][quoted image][quoted image]

I would not buy rottendog boards, just asking for issues, I would buy DumbAss boards.

#15 27 days ago
Quoted from mnye82:

I give up on this MPU and am ordering a Rottendog MPU today as well because there's clearly quality problems with it

And you think Rottendog boards have better quality just because they been around a while? LOL

Money is better spent sending board set out for test/repair.

If this is a new Pinball Basement MPU board, there is a warranty on it.

#16 27 days ago

Will second the opinion avoid rottendog . Posts concerning quality at end Jims running business abound . Dumbass or Pinballl Basement better options .

If hard failed remember Clive Coin op board repair does great job . Seems your issue could get past a single session on the repair bench .

As many times as you have been pulling boards on a already old game should consider set cables from Great Plains . Very good quality .

Shane

PS when running great game !

#17 27 days ago
Quoted from bepositive:

Will second the opinion avoid rottendog . Posts concerning quality at end Jims running business abound . Dumbass or Pinballl Basement better options .
If hard failed remember Clive Coin op board repair does great job . Seems your issue could get past a single session on the repair bench .
As many times as you have been pulling boards on a already old game should consider set cables from Great Plains . Very good quality .
Shane
PS when running great game !

I have used both Clive and Chris Hibler for Board work when I was too busy to do my own.

There are many great bench testing tools that are inexpensive, data cable testers are a must tool IMO, but many just replace on old games. Just depends on your skill set and time. This group does a great job of providing a wealth of knowledge.

#18 27 days ago

Sorry I should have mentioned that I've tried 3 different MPU>PDB cables too at this point (& have replaced all other ribbon cables going to the MPU once too when troubleshooting). Since this is my 2nd pinball basement MPU, I'm a little hesitant to go with a 3rd.

I honestly have no idea the quality/rep of any brand boards and was just taking a stab with Rottendog since that's who makes the new power driver board. Thanks for the heads up though & I'll do more research / check out dumbass boards! Can anyone provide me a link with some info on what happened regarding the Rottendog drama?

#19 27 days ago

Based on glaring issues with that board, IC nearly pulled back, solder balls under PLCC socket and solder bridges, I have sincere doubts that this board has ever been inspected or tested. There's no excuse for this type of shoddy workmanship.

#20 26 days ago
Quoted from mnye82:

Since this is my 2nd pinball basement MPU, I'm a little hesitant to go with a 3rd.

You are contacting them and telling them you have two bad boards? Did the first one get sent back? What are the symptoms on the other MPU board? Again, these are under warranty.

#21 26 days ago

I have really tried to stay out of this thread. I appreciate all the recommendations. I am not about advertising. I am about word of mouth recommendations.

Quoted from mnye82:

Thanks for the heads up though & I'll do more research / check out dumbass boards!

My thread @ https://pinside.com/pinball/forum/topic/dumbass-test-and-reproduction-pcbs contains all the information. It's a long (and some might consider boring) read. It has grown organically so there is no order - other than chronological. The first post contains all the available boards - as bare or complete.

I have had to deal with some compatibility issues with Rottendog boards. Things to note about them (in general):

  • There are some circuits that have been re-designed to use MOSFETs rather than the original BJT. Not super important but worthy to note in that you cannot replace the MOSFET with a BJT if all you have is BJT parts for repair.
  • Some boards (System 11 CPU board) have documented compatibility issues with the speech section of the board. There is a thread here on Pinside documenting this. Not really relevant for your Bram Stoker's Dracula but is given as a general example.
  • Rottendog uses HCT family ICs in place of LS family ICs. There is good compatibility but in my experience I have seen cases where using HCT family ICs causes problems. Replacing the HCT family IC with an LS family iC (restoring to specification) fixes the compatibility problem. Since Rottendog boards have ICs soldered directly on the board you cannot easily identify if this is the cause of the problem.
  • Rottendog boards are known to have been manufactured and distributed with known incorrect component parts installed on the board (a WPC-95 Power Driver board with LM350T voltage regulator installed where a BT138-600E triac should have been installed).
  • <facetious>There is a reason why they advertise as a low cost solution.</facetious>

I have enough work that I'm not actively trying to find more of it. I do however like to help people enjoy their machines by making them work correctly. For the hobbyist by the hobbyist. All my stuff is hand built and fully verified on my bench testing rig before it leaves. This means that I have to put an ASIC in the WPC-89 CPU and TEST IT before it leaves. It's extra work for me but it also means that I have 100% assurance that if it doesn't work when it arrives at your end it means that something happened in transit (shipping) or you have connected something incorrectly in your machine (such as ribbon cable off by one). Speaking of ribbon cables ... my boards have box (shrouded) headers so you cannot make that mistake when connecting the cable on my board. You can, however, make that mistake when connecting it to other boards.

Do not feel obliged to read my thread. It's long and can be tiresome. If you're interest in finding out more about what I have just send me a PM. I don't post much although I do browse threads on occasion.

#22 26 days ago

I talked directly with Charlie from PB the first time around, which is how I got the 2nd board / exchange. The symptom with the first MPU was identical, which is why I still find it really hard to believe that the MPU is the problem / that it's more likely the ASIC. I did ask him for a post-mortem mid-August after he got the original MPU in his possession, but didn't hear back. For all I know, there was nothing wrong with it & to that point, there might not be anything wrong with this 2nd MPU either... but there's clearly build quality issues I'm finding and I'd rather just start fresh to be safe by removing these variables. I have no problem buying another MPU at this point.

I also didn't purchase the original MPU, the pin's seller did and he's who coordinated the the replacement of the first MPU between PB & I under warranty. This adds another layer to warranty/communication that to be blunt, is really no longer worth my time to deal with. I can purchase a new MPU and ASIC if that fixes the problem and consider it the cost of "learning". To clarify, I've never purchased anything myself from PB.

DumbAss - Thank you for all the great information. The new ASIC will be here mid next week and I'll try that first. Either way I plan on replacing my MPU and I'll probably reach out when the time comes if you're available to help with that.

#23 25 days ago

I wouldn't be fiddling with the ASIC so much. They are a delicate component and, if you weren't aware, are becoming rare and harder to find which also equals more expensive and eventually NONE available!

The ASIC is probably the most reliable part on the board so I'm not sure why you keep pointing the finger at it when there are so many other things that are more trouble prone?

Recently made replacement boards mostly use modern equivalents of the parts used on these boards 30 years ago. This is when many compatibility issues creep in.

You are 200% better off having an original board repaired than you are using ANY modern replacement but, if you must, read up on Rottendog boards - there is a reason they have that name!

I would go for an original and if that isn't an option DumbAss boards are the best way forward IMO.

Have you actually started AT THE BEGINNING? Measure all supply voltages and make sure they are within spec. If the power supply isn't right NOTHING else will work properly no matter how many ASICs you buy.

#24 22 days ago

Just checking in. For full transparency/disclosure, I ordered a Rottendog MPU from PBLife last Saturday, but I did this prior to my post and before all the advice against Rottendog. I thought about cancelling the order after reading all that, but I figured I'd let it ride for the sake of moving this along quicker, and if there were issues with the MPU I could just return it to PBLife. I might come to regret this down the road and if so I accept that / will figure something out at that time using the advice you guys gave me. I also have a new ASIC but I've yet to install it.

Anyway... prior to putting the the Rottendog MPU in, I could no longer fiddle with the PinballBasement MPU to get it working like I was able to in the past. I swapped my IC's/ASIC to the RD MPU, fired the game up, restored factory settings to clear errors and everything worked. I don't feel like I'm out of the woods yet since the longest I've gotten is 6 days and I'm only 4 days in, but so far no issues. Some observations I wanted to share that I thought were interesting.

1) With the PBasement MPU, every time I would power on, the system would do a full test where locked balls would drop, the mist motor would test, all the ramps/coils would test, etc; similar to when you exit the operator menu. With the RD MPU, the game just simply turns on and is ready to play. Being my first pin, I just assumed it was normal to go through all this testing every time power was restored. Note - Maybe not relevant, but the PBasement MPU did this with batteries+6264 and an NVRAM. No settings were ever lost, it just always did this test/reset. It also seems that the majority of the time when F105 would blow/SOL1-8 locked, it was during this initial power-on coil test.

2) I have a pinsound board and about half of the time when there was a ball save, the audio clip which played would be duplicated, causing an echo or having two of the available sounds for a ball save play over each other. That hasn't happened with the RD MPU. I always just assumed this was part of the community pinsound pack having a flaw. I've purposely drained a lot of balls trying to get it to happen with the RD MPU and it doesn't duplicate sounds. I can't really imagine how something like this would even be possible but I immediately noticed it not happening since it occurred so frequently before.

Replying to pins4u, I did initial voltage checks at the driver board test points early on and everything checked out. Removing the ribbon cable between the MPU > PDB when the grounding locks occurred to release the locks is what led me to rule out voltages at the time and point my finger at something upstream with the data. My more recent focus on the ASIC was just due to the fact that the MPU and all IC's have been replaced at least once and the same symptoms followed. Given the physical issues identified on the 2nd MPU and the stability/changes noted above with the RD MPU, I think its rational to assume the first two MPUs were the culprit (for now).

Edit / 9/29 update - I'm fairly certain it was the string of bad MPU's at this point and am marking this resolved. Thanks again for everyone's help.

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