A good starting point might be to find out if the issue is on the mpu board, or elsewhere. It looks like you have a couple of system 6's in your collection, the MPU327 should also be compatible with those. Place the MPU 327 in one of those machines, and see if you have issues. If yes, problem is with mpu/driver combo board. If no, then problem lies elsewhere, power board perhaps, or a wiring issue.

Another pinsider identified a design issue with the mpu327 in another thread. It's easily corrected, it's just that the board layout can cause a short to ground. It may be worth your while to investigate this as well. Could clear everying up.

https://pinside.com/pinball/forum/topic/warning-to-rottendog-327-owners-check-it-now#post-3267007

Ive been fighting the same issue for a while and have eliminated just about everything except the Rotten Dog board. Going to swap in my old, original boardset and drop my RD board in another game. Following this thread to see if you come across something. Ill post if I find anything here.

Why not contact Rottendog?

Maybe you can locate a pinsider local to you with a working sys6/7 for you to try the board in.

You might find it better to call Jim than email, he's very friendly and helpful, and will probably try to work through the issue with you.

I had (well, technically still have) an MPU327 for my Jungle Lord. Even with Jim's help I never really got it going again - in hindsight it could have been the grounding issue noted above, that thread came up after I moved on to something else.

Most rottendog repro boards are great but MPU327 seems to be prone to issues, I don't know how many of the boards are out there but there are many threads on them. It's tricky trying to troubleshoot the board since the pinwiki knowledge base isn't of any help as compared to original boards. If you can get your hands on an original MPU/Driver, it may save you money and a lot of time in the long run, that's the route I eventually went.

If the board locks up when both flippers are pushed you likely have a power supply issue. The 12v filter capacitor can't keep the 12v rail high enough causing the regulator to break down and the 5v rail dips down below what the system is stable at. In a low voltage situation,
you could be getting a false failures. I would ensure your power supply is solid before working on the main board.

IC13 is a ram chip on the stock WMS boards. System 3-6 era it was dip24 0.6" wide 6810 ram, system 7 it is a 0.3" wide dip18 2114/5114 style ram. What does the imprint on the Rottendog IC say you are trying to replace?

Might be worth seeing what Rdog says too. I assume they will take care of it.

John, what month sticker is on your board? My board is doing something similar. Once my ball drains the game locks up (not a switch issues, ruled out in test). Jim is working with me as well to fix it. Im going to try the board in a system 6 and see if the same results. Appears to be an issue with the newest batch.

Ill take a look when I get back to the warehouse.

Laserball is system 6 and uses a different address space than system 7 black knight. I would try another system 7 games in BK and see what happens. Laser cue, firepower 2, etc.

How high is your 5V ?

Where are you testing it at?

Is your BK a sys6 or sys7?

Last year I blew my mpu327 in my Black Knight somehow. Sent it to Jim at Rottendog and he said it was too far gone to really fix. (Though I feel he would have if it wasn't so toasted-he's a very nice guy and seems to care a lot about supporting his products). I bought a replacement mpu327 and after installing it I found I had similar issues as you in my Black Knight. It goes into attract, starts a game, says the intro speech, but then has no other sounds, wont start multiball, and when the ball drains it just sits there. Flippers work though. Jim says it's an unknown issue with the mpu327-2 (second edition). I found an mpu327-1 and will try that. I replaced power supply and rectifier to hopefully avoid damaging this third board.

I'll be interested to see how things turn out for you. I am nervous about putting my new MPU-1 back in the BK since the last one fried. I am going to work on it this weekend but I want to check for proper voltages EVERYWHERE first. I am wondering if there is anything else that could have fried my old board aside from the old power supply. With the new rottendog power supply and the inkochnito bridge board I am hoping I'm safe.

mixing up the in line square plugs. There is usually a black and a white colored connector between the head and cabinet. Mixing them up will cause all sorts of bad things.

I don't think that happened in my case because everything worked great for several years. I haven't unplugged the head since I bought and moved the pin back in 2012. This weekend I installed my new Rottendog board and so far everything works great! As far as the old board is concerned, I think the power supply failed (voltage regulator maybe??) and sent improper voltage into the old board. Theres also a possibility that there was some shorting on the back of the board where it could have come in contact with the original backbox mounting lugs (they are very close when you use the factory holes). No way to confirm this though since I no longer have the fried board.

Any updates on MPU327-3 coming out from RottenDog to fix the BK issues? I've contacted them twice, but get no answers. At one point, a tech who replied said they were in testing... but since then.... crickets

So did you ever get this fixed? Was it a new boot rom for BK on this board? I have 2 BKs with the MPU327-3 that are doing the same thing.

What kind of chips are used in the switch matrix section? Ie the name of the 2-4 chips by the two by the switch matrix plugs. WMS changed resistor choice around black knight (because of the drop targets / lock balls sitting down offending TTL levels?). 74HC logic type family may exhibit similar issues.

Hmmm...very interesting. With all original boards, I was having the very occasional lockup on my Black Knight. I figured it was probably the 40 pin interconnect, so I went ahead and purchased a Rottendog MPU (version 3). Unfortunately, when I put it in the game, it had the EXACT same problem (goes into attract, starts a game, says the intro speech, but then has no other sounds, and when the ball drains it just sits there - Flippers work ok).

I put the original boards back in, and thankfully I haven't had any issues. This leads me to believe there is a problem with those Rottendog boards with Black Knight....

Most interesting. I'll check the voltages on the switch matrix. If they are hanging around TTL logic grey areas, that would be very leading. Bumping the 5v line may get it out of the grey area

I wouldnt juice up the 5v. if they are using say a 74hc chip... swap in a 74hct or 74ls (supports ttl input). If there is a series resistor between the header pins and the switch matrix chips, try zero ohm / jumper link (that was the change wms did around BK on the driver boards).

Anyone got a clear picture near the header pins for switches of a board acting up only in BK ??

There are at least two versions of BK software out there. Not sure which one RDog is using, but that shouldnt matter unless they some how got a bad game ROM in there combined rom chip.

i wasnt thinking much, but just in the TTL valid range.

The drop targets cover like 6 columns, so would have to jumper nearly the entire matrix columns (or rows) accordingly. I dont have the schematic open

I'm going to try all 3 types (HC/HCT/LS) before changing the jumper/res

Posting here as well. Clastlesteve and I have another thread on the Rottendog boards as well.

Rottendog sent me a flashed IC that was supposed to resolve the issue. It did not. Still not ball in play advance or sound. If I pull my old version MPU327, 2015 build, from my Blackout my Black Knight works fine.

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still wondering what IC15-IC18 is in the driver section and if they are using the resistors or zero ohm links / foil track on board.

hmmmm. I'll have to inspect this board to see if it has these serial resistors on the MPU327-3. I'll definitely try this

74hc00 or similar part could be an issue too. Check the chips near the switch plugs.