It looks like you may be missing a metal shield over the DMD. At least my game has one. That ground should attach to the metal stud on the lower left of that DMD.

There are definitely three different types of noise. Luckily I've never had an issue with the 60Hz noise from the main power but I have heard noise from both the DMD as the display changes and also noise from the playfield lamps as they change patterns in attract mode. My game (Rocky and Bullwinkle) has a little noise but it isn't too bad. I've heard much worse.

Lately I have had to repair quite a few Data East MPU boards (REV 3 and 4) and run them in my machine to test. While swapping around boards I've noticed when some MPU boards are running the noise is much worse and I've run across two that when installed the machine is quieter than normal. I have an extremely noisy board out of a Star Wars as well as another REV 3 board that is almost silent. I'm trying to compare the boards to see what the difference is but nothing has jumped out yet. I even pull off the inductors and tested those with a Sencore LC103 and the values were spot on with what the schematics say.

The schematics for the 5V section show a 470uf cap after the inductor besides the small .1uf one. That 18V lamp power doesn't have a similar cap to help smooth out the power for that so it may be worth adding one in parallel to C48. Maybe on the input side as well. It looks like the 18V lamp power is also used for the 12V regulator on the power board so a bit better filtering on that 18V supply may help.

I'd like to see if I can do something to the Star Wars board so it isn't as noisy. It would be nice to get it to a tolerable level without my friend having to install a separate power supply in his game to fix it.

I know that is an option but I think it would be cool if at least some of the root causes can be identified. It looks like some of the noise may be from the MPU board. That hasn't been mentioned much. Most of the posts I've read are how to deal with it on the sound board or power board. Looking at the MPU may be worth exploring. If it ends up being a dead end at least we tried....

It would help to have more data about what game are silent with everything installed and tighten down normally (no floating sound boards) and what ones where inherently noisy.

If you have a Data East game could you please let me know a few details about it?

- Game noisy or not?
- MPU board revision -3 or -4, etc
- What brand and exact part numbers for the TIP42 and TIP122 in the lamp matrix
- What brand and exact part numbers for the TIP122 for the solenoid or replace parts
- If possible a picture of the MPU showing parts.

I want to see if there is any pattern with certain parts causing more noise that others.

Somewhere earlier in this thread I think vid1900 said the design may have worked fine in the lab when first built. That may be the case and during the run of the boards other brand of parts were used. Some of those may have different and undersirable characteristics. But when placed in a bar or location people just didn't care and it wasn't an issue.

I've seen some TIP transistors contain an extra internal diode and some not even though they carry the same part number. Could it be that something was used on some boards and causing an unexpected path to ground causing a ground loop? Maybe a poor cross that would normally be a non issue could be one of the thing making this thread unresolved for over 6 years.

So, just posting what TIP you have installed and if any were replaced will help. Some may be Motorola, others ST, and maybe other brands.

Robert

I do have a scope and plan on pulling it out. I did watch the DVM on the 18V lamp supply and it was fluctuating a bit so it looks like there is some ripple on that line.

From what I can see on the schematics I don't see any issues with adding a 470uf cap but it is a good point to bring up. I'm going to get to see what the ripple looks like and if the cap helps or not.

There is one ground strap on the lower right side of the head that isn't connected in my Rocky and Bullwinkle. I posted the question in that forum topic to see if someone can get a picture of where those ground straps go so I can attach it to the proper place.

I have all the ground screws in the boards and they are tight. What I am seeing/hearing is that the issue shows up and varies by swapping out some different MPU boards (all other boards are untouched). So that leads me to believe that there is something going on with certain MPU boards that are generating some noise while others not. It seems to be one of the only unexplored areas in this whole thread. If it ends up being the source of noise then I think it would be good to resolve it at the source.

While the DE design of the power, MPU, and sound work I feel that some things are at the limits and right at the margins. If everything is perfect then it may be quite. If not then any of several different things could push it over the edge past where it should be and we get noise.

At the moment I am looking at the lamp matrix since that seems to make noise on some MPU's. I have theories as when the issue could be but it would help to get some data from other DE owners. If you aren't running the extra switching supply I (or of you are and had to) I really need to know what transistors are used in that matrix. Are they TIP42, TIP42C, TIP122, TIP 102, brand ST, Vortex, M Motorola, or something else? It would be interesting to see if there is any sort of pattern.

Maybe a certain brand or batch of parts were just off and although work may cause extra noise.

Anyone have a chance to peek in the backbox and see what is in there??

I was checking the voltage with the game on and running. I was measuring at c48 and c49 right where the lamp power was coming in. As I saw the light patterns change I could hear it and see the voltage jumped around a little. I'll have to see what shows up on the scope.

Back to the MPU I'm trying to find out what could be different on games that are really noisey and those that aren't. That is why I'm looking at what parts were used. I have different brands on these boards but not enough data to go by yet. That is why I need others to chime in about what parts are in the board and loud or quiet.

I've noticed that some transistors of the same type test as they have an extra internal diode. Mainly on TIP102 devices but others could be effective too. If the circuit was designed with that in mind and it isn't there or if it wasn't planned and is now I'm circuit then that doesn't follow the original design.

I agree with everything said about ground loops and how messy they are.

The matrix calls for tip122 but I've seen TIP102 devices dropped in as replacements. I still need to pull some of the data sheets for each of the parts. If I see enough of a pattern I'll pull all the tip devices out of the lamp matrix and swap the with another brand.

I've also seen similar pictures of tip122 darlington transistors. Some have that diode and some do not appear to have it. That is one of the things I want to see. Is the difference between these noisey boards and quiet ones due to a different brand tip122 that did or did not have that internal diode?

This doesn't mean there aren't ground loops or other sources of noise. Just trying to focus on this particular one.

I have one of those testers too and worth every penny. That particular gadget is one that shows the diode on some tips while others do not. Not all tip122 devices seem to be created the same. While it may not mater in some circuits is this a contributing factor in the persistent DE noise?

I think we're getting off track a bit. Given that the DE design seems marginal and unless things are ideal it may not take much to push it over the edge and have it start making noise. With everything else the same I have different MPU boards (some same revision) that are quiet and noisey. So at least in this isolated case something on the MPU is generating noise. A good portion of the noise seems to be from the controlled lamps. Since the boards are all functioning I'm looking at part selection and different vendors for certain parts as the cause of the noise.

Ground loops are weird. They are just a PITA and it had been stated earlier in the thread that a part going bad may provide an easier path to ground causing a ground loop.

Am I seeing the switching noise because of different TIPs or some other component? I don't know yet but can try some things on the noisey board to see.

As soon as I start getting data in about other boards that will help to determine what parts to try swapping out first.

If you get a chance can you get some pictures of your main board? Also what kind of TIPs on the MPU

Has anything been done to your original power board? I'd make sure that is ok first. If it hasn't been touched it will probably at least need the capmfor the 5v replaced. Those often leak and I've had to replace many if them. I prefer the original boards.

An odd part in regards to hum sound is that I've seen it come and go depending on the MPU board installed. I've got a couple boards that are almost silent and one that is insanely loud. When I get more time I want to see if there are components on the MPU generating the hum and sending it to the sound card.

It has come up before that the issue could originate from the MPU board. I have a MPU board out of a Star Wars that is really loud. I have another spare MPU that is almost silent. I haven't had a chance to compare the two boards but I had asked about what brand TIP transistors are used and other parts.

There seem to be at least 3 sources of noise on the Data East machines. Noise with DMD activity, noise from the controlled lamps, and general noise some from the power. Some games are worse then others. In attract mode when the machine is supposed to be quiet you can often hear when the controlled lights are moving.

I need to do some testing to see how much is generated on the MPU board. I have one MPU when in a game things are relatively quiet. Have another MPU when installed there is excess noise.

If any caps are bad then for sure re capping will help and in some cases may fix it. I just think there are other factors involved that hasn’t been isolated yet.

I have a Rocky and Bullwinkle. The noise isn’t too bad but most noticeable on the controlled lighting in attract mode. I guess I’m lucky that it isn’t too bad. I’ve also read that the loud constant hum is bad on some machines.

What does it run for one already to go?

I had to make a few of these for a friend who is local. Found that one of the power modules was a bit flaky. Ended up being a poor quality 10K adjustment pot. Replaced that with another that I had here and fixed it. Would be interesting to see if that is all that is wrong with the ones you have or if something else happened.

Has the power supply ever been serviced? There are a few caps on there that are known to fail and in some cases leak and start etching the traces. May be worth checking that out first. It may help some with the noise issue and even if it doesn’t it can ensure your game continues to run well in the future.

On the original sound board it may be time to have the caps replaced on that. It will cost less than any replacement board. Unless there are other parts that have failed that should help.

Nothing will eliminate all the noise but it can be made manageable.

Looks like your 5V is a little low. Has anything been done to your power supply? If nothing else check C2 on the power board. That often goes bad and leaks which can etch the PCB traces under it. I've also seen C7 leak and occasionally C3. I replace all of those. They are the main ones to look at.

This thread has been on-going for 9 years. There are multiple sources of noise and all can contribute. I tend to believe that many of these were noisy since day one. Back then most were probably in noisy arcades where no one noticed and no one cared. As they aged some may have gotten a bit worse but in a home environment people notice.

Some may be aging caps on the sound board, some from aging caps on the power supply, probably some from ground loops, etc. One of the more common sources seems to come from the 12V supply, at least on some games. That is where adding a DC/DC converter has helped on some machines. I've built a few of the adapters (but put them in plastic cases) and for those specific machines (one was a Star Wars) it really helped and cut down the noise to an acceptable level. It just doesn't help for all of the games.

It seems the only sure way to eliminate all the noise is just install a dedicated separate power supply for the sound card. From all the posts I've read that works when everything else has failed.

If the power supply hasn't been serviced there is no question that should be addressed first. That can affect the whole game. It just seems that even with that many games still make excessive noise when that has been done. Even if the sound card was done too.

While some of the aftermarket power supplies may be ok I have read about several instances where they performed worse than the original they were trying to replace. For the most part I prefer to rebuild the original boards. Exception is the early Bally/Stern rectifier boards which are often toast.

If you have a Pinsound then you shouldn't need this.

I believe with the PinSound you don't need to do any additional power conditioning. It is only needed for some of the original Data East sound boards.

For those it depends on a lot of variables but some of the worst noise seems to come from the 12V supply. For those you can install a whole dedicated switching power supply as some have earlier on in this thread. Or, you can add a DC/DC converter inline that seems to remove most of the noise on extreme cases. for this you can build your own as shown in this thread, get the Retro version, or there is another design on ebay that works similar.

My Rocky and Bullwinkle isn't bad at all. Installing one of these inline adapters didn't make any noticeable improvement. On other machines it makes a HUGE improvement where there is an intolerable hum/buz to a level that is totally acceptable. So use them when you need them.

Looks like there is another option to help reduce the annoying sounds on the Data East machines:

https://www.pinballlife.com/rottendog-data-east-buzz-buster.html

This one appears to have status LEDS for all the voltages.

If you look further back to around post 520 both boards get their roots from that inline power adapter. They just have different implementations of it.

Not exactly. Many people have completely removed the (buzz/hum) by installing a dedicated small switching power supply for the sound card. That was a sure way to clean up the sound before people started using the inline power adapters.

No need for a Pinsound.

I just noticed different version of this at pinball life. Looks like Anarchy PCB has one out now:

https://www.pinballlife.com/de-hum-eliminator.html

Is this a clone of the one from White North Retro? This one looks identical except for the orientation of the regulator IC. Or is this the replacement for the White North Retro? This looks like a direct clone/copy.