Will do . Thanks

So I think I get it . You attach a wire to the white and then a wire to the black after the power switch . Those wires then get attached to LN (ac) on power supply. Do you run a separate ground to the connecctor to the right of LN that has the ground symbol? V2 is 12 volts out on this unit.

image (resized).jpg

You don't have to, but it's a good idea. Run wire from ground symbol to ground braid on your machine. That will make the case of the power supply safer if something should short AC to it's chassis.

Ok thanks Wayou!!!! Going to try this on a GNR for a color DMD. I checked schematic and it has a bill collector same as maverick
So I might just use that for 120 volt power to the power supply.

Just curious, would an old ATX power supply from a desktop computer work in this application? Has well regulated 5V and 12V DC. I'm having this same issue in my LW3. The hum was always there but tolerable. I just recently swapped out my old failing power supply with a new Rottendog and now the hum is really bad for some reason.

*** Nevermind! I just noticed this was addressed like ten times already. Gonna give it a shot.

Just to be clear with using an ATX PC power supply for the sound board: aside from plugging in the power supply to a 110AC source and jumping the supply to keep it always ON (which I am aware of how to do), all I would need to do is remove the CN2 sound board connector and connect my sound board's power input to the 5+, 12+, 12-, and GND to the ATX supply wires . It's as simple as that, correct?

Also, why is there a 12+ and 12- but only a 5+? I was always under the impression that with DC current you have a positive supply line and negative was essentially ground. So on a voltmeter, to check voltage would you connect 5+ and GND to check the 5V line, and 12+ to 12- to check the 12V line?

You got it

One of the problems with ATX PC power supplies is they usually have a fan. A fan contributes noise, moves dust around, and sometimes fails. Open frame power supplies don't require a fan. That's why I use open frame supplies.

The dual supply is needed to run the audio op-amps. To keep it simple, the audio waveform is an AC wave that crosses ground, and the dual supply is required to amplify both in the positive and negative direction with respect to ground. Google the subject if interested further.

As far as checking any of the DC voltages, they are always tested with GND as a reference, so for example, to check the -12VDC you'd put your negative (black) probe on the same GND that you would for checking the +5VDC. You'll then put your positive (red) probe on your -12VDC test point.

thanks for the info!

One more question, just out of curiosity are any one of those three lines (5+, 12+, 21-) most likely to cause noise/hum if the supply is dirty? If, for example, it was most likely the 5+ line, then in theory could you use a regulated switching 'wall-wart' 5v, 2-amp power supply and connect it's + to the sound board's 5+ and the wall-wart's negative to ground, while leaving the rest of the sound board's 12+ and 12- and GND pin connected to the DE power supply board?

Yet another question Is 22 gauge wire sufficient to run from an ATX supply in the cab up to the sound board?

Will this power supply work since the other one seems to be out of stock or price is $42 plus...

https://www.mouser.com/ProductDetail/MEAN-WELL/RPT-65F/?qs=V9a8iPeg90ytmS5g6o9MLA%3D%3D&gclid=Cj0KCQiA9_LRBRDZARIsAAcLXjdS5QJa30a8Zya9STL5V96xlxfil7rK-pLqDNhH1pQaxDG4LbZ9u7QaAgSZEALw_wcB

I would stick with 18 AWG

To anyone interested I did the ATX pc power supply mod (hack).... WOW! So silent in attract mode you could hear a pin drop from a mile away . Seriously, ZERO hum, and sound is crisper and bass seems to be more pronounced. Just beautiful.

Guys in theory would a PINSOUND with new speakers and wires solve this issue/ I'm having it in my JP and the right speaker is humming pretty loud, the right is quiet. Expensive fix yes but ive been eyeing this for awhile.

Most likely it will solve the issue. It really depends on the circuits design...and both the components used and the design are going to be quite different from the original sound board. In your case it sounds like the one channel has a faulty component compared to the other, which is most likely a board problem and not a supply power problem. My vote would be to go with the Pinsound.

A Pinsound definitely made my Lethal Weapon 3 quiet. No need for new speakers or wires. I did do a speaker upgrade (2 Pyle 4" and a GRS 8" Woofer, $25 total through Amazon) and they sound better also, but the noise would be coming from the card/amplifier, not the speakers themselves.

Thanks guys!! I'm going to order one today

Just greatly reduced the noise from my SW by using 4 rubber washers on the board. Should have done this years ago.

Ok I just put my pinsound in and that loud humming from the right speakers is gone!!!! It sounds amazing and I still need to install my Flipper Fidelity speaker kit next. I'm not even getting any low noise when the lights are cycling in attract mode anymore either Worth the money just to get rid of it!

Heres an unusual fix that i found on my Batman Forever Sega pinball that i picked up recently. I had tried everything that i could find on this and other sites. Previous owner had even cut the sub wire to reduce the hum sound. I temporarily hooked up an old ATX power supply and did find that it eliminated the hum. I went so far as to only hook up the 12V+ from the ATX power supply and it effectively eliminated the hum. So i assumed it had to be in the 12 V+ circuit from the power supply, so i changed all the capacitors. Wrong , did not help at all. After many hours of diagnosis, i decided to remove the sound board and start testing as per schematics. I still cant believe what i found. The 7805 voltage regulator (VR2) centre post did not have continuity to ground. With voltage attached, the 7805 that converts 12V+ to 5 V+ was showing 7.3 volts on the outpost and ground post. At first i thought i found my culprit, but continued to check the circuits comparing them to the schematics. Low and behold, the Diode (D2) that is attached to the center post of the VR2 was installed backwards (so not letting the VR ground properly). I looked at the soldering work on the D2 and it looked original, or someone did a fine job of replacing incorrectly. I unsoldered D2 diode, re-soldered it in properly and tried the sound board back into the game. Hum 95% gone. Taking test reading, i am getting 5.4 at output now. I will still replace the 7805, as it is slightly out of spec. Still not sure why temporary ATX power supply would work, but hope this may help someone else. Pat.

Nice. Any chance you could post a picture of your board and focus on that diode so I can compare to mine?

Wow, incredible find! Can we mark ruckster's post a key post?

Only once we get some pics so we can all fix it!

Most of my noise seems to be coming from the DMD and changes with the light show in attract mode, do any of these fixes apply?

I thought the same thing and was wrong. Disconnect the speakers or the DMD and confirm.

Unfortunately, that fix is only likely to be valid for the 4 DE games that use this version of soundboard. There were 8 different generations of sound boards spanning some 30 different games. Maverick doesn't have a diode in that circuit at all.

Screenshot_2018-01-21-17-10-50 (resized).png

Your JP and Star Wars have a soundboard similar to my Maverick. There is no diode in that circuit.

Interesting... so the older sound boards don't have a diode but the newer ones do. I wonder if they added this as an upgrade to help reduce noise?

This schematic is from the Baywatch manual... I've highlighted the two diodes that are not on the older game. Anyone willing to test out adding the diodes? Would it hurt anything?

baywatchsound (resized).png

Nah, that doesn't reduce noise. It bumps the output voltage up by a hair.

Bummer.

I see there is also an additional capacitor in the newer version. Would that possibly help with noise?

baywatchsound2 (resized).png

Actually I found its the later games that do not have the diode, but I have not investigated the earliest games

#520-5050-01: used from Batman to Lethal Weapon 3. Allowed the voice EPROMs to be as large as 27020.
#520-5050-02: used on Star Wars, Rocky & Bullwinkle, and Jurassic Park. This sound board allowed the voice EPROMs to be as large as 27040.
#520-5050-03: used on Last Action Hero, Tales from the Cyrpt, and Maverick. Very similar to the -02 generation (addressing 27040 EPROMs). No further info known on this board

edit: I looked at Laser war through Back to the Future since my Secret service is in this range (first 9 games used #520-5002-02 soundboard)
These sound boards do not create +5VDC on them, they get it from off the board - totally different from later generations.

If you had a specific noise problem attributed to that particular cap in question, yes. Otherwise, not likely.

I think the lesson here is "test points" Some board have schematics showing test points (usually voltage), but i couldn't find one for mine. On these sound boards it would be prudent to test VR1 (-5v out) and VR2(+5v out) to assure you are only getting 5V (4.8-5.2 is usually spec.) output. If outside of spec, further investigation is required. Careful, the outputs are different on 7905 vs 7805, check schematic or google it. Pat.

My Last Action Hero's hum is killing me. Loudest thing in my gameroom.
I suck at board stuff. Could you post a picture of your board, focusing on the actual diode? I will compare!
Thanks! What a find!

No diode on that game, sorry.

Yes, but just because the schematic says it's 5VDC and we assume that narrow spec range, what you really need is the "why" to include the diode in the first place. It's often used to fool the regulator with a false reference to change it's output voltage. Perhaps it could be that 4.8-5.2 isn't quite enough on some designs. I'm not sure on that one.

Has anyone had issues with the cabinet speaker starting to hum after the game is one for a little while? Something is obviously getting warm and messing up the output going to the sub down in the cabinet.

Classic symptom of a component failure in the cabinet speaker circuit, most likely in the final output amp section. Troubleshoot with a DMM and oscilloscope for a component going out of tolerance when it heats up. Btw, the stock speaker in the cab is a woofer, not a subwoofer.

Thank you!

Rebuilt the original soundboard with all new caps, and three new amps. Sound is working great now.

Nice!

I did that as well but it didn’t fix my hum. I still had to do the auxiliary power supply to correct the hum.

There is still a faint hum, the issue that I fixed was the sound going bad once it warmed up.

I picked up a JP several months ago and I'm finally looking into this audio hum. I wanted to share a few things

There are clearly 3 sources of hum (at least)
1) The DMD
2) The lighting
3) The speakers

For example,
1) if I disconnect the DMD power, I can still hear hum on the speakers.
2) If I disconnect the speakers, I can still hear hum
and so on

I decided to focus on the speaker hum.

Note: My JP has the XP-DE5047 replacement board.

To be brief
1) I tried floating the sound board. This improved things a little. But honestly, this just puzzles me. Even if one doesn't have the screws connect to ground, the sound board is stilled grounded by way of either the power cable or the data cable

2) I realized that the hum is independent of the volume stick. I can turn the volume all the way up or down and the speaker hum remains the same. This implies the hum is introduced after attenuation or after in the circuit.

3) Based on looking at the schematics and Bret's comments (quoted at bottom), I replaced some of the key caps in the voltage section of the sound board. Specifically

C31 / C52, used 1000 uF 25V
C60 / C67 / C74, used 470 uF 35V (Fry's didn't have 25V version)

This had a strange and disappointing result! Specifically

a) The hum was a little louder and
b) "floating" the sound board no longer made any difference. Yeah, kind of strange.

I decided I needed to get serious and pulled out my scope.

I looked at the sound board generated +5V and it was fine. No more than +/- 100mv from 5V and just random noise.
I looked at the sound board generated -5V anti was fine too. Same behavior as above

Then I looked at the +12V and found something interesting. I looked into the right side of C39 and there is a 120 Hz ripple in the 12V signal. See this image:

IMG_0056 (resized).jpg

(sorry it's a little blurry, I didn't notice until now)

In my case, I bet the hum I hear is the 120 Hz ripple on the 12V line. This 12 volt is used for the MB3730s in the output stage. But as mentioned above, I did replace C60/67/74 --- each of help smooth out the 12V line before it powers the 3730s.

I've run out of time for the moment to dig into this, but wanted to share. I'd appreciate any thoughts people might have.

... Altan

Is your hum steady, or is it pulsing with the controlled lamps? Seems there are several different noise problems in many DE games - each with different symptoms, causes and solutions.

I'm not certain that under a volt of ripple is a problem, certainly higher than that can, and much lower is desirable. As to if what you hear is the ripple, there's an app for that. When I was troubleshooting my Maverick I installed an audio frequency analyzer in my smartphone. A little crude, but enough of an indication that my problem was not at ripple frequency.

I have used the free version of SpectrumView for iOS with good results.

Agree there are multiple causes.

While the lights do impact the hum, I’m targeting the constant hum that occurs when Nothing else is going on. Specifically, I’m checking while I’m in the diagnostic screen. It’s a steady hum. This also occurs during attract when there’s no music

It’s “definitely” imho 120 hz on the speakers. There is a recording of it on YouTube and mine matches well. Using the app is a good idea, I’ll try that tonight.

Here's a hint: it looks and sounds exactly like dirty electricity. So probably some high frequency transient voltages that sound like the rectified 120Hz signal coming off of the main 12v rectifier.

So after putting many, many mods in my Jurassic Park I pinned down the hum and eliminated it. Long story short I added a power brick to Power my mods/colorDMD/topper, with the main power not straining the hum was eliminated. If I plug in just one mod id get a low hum, each item plugged in it got louder and eventually the sound would cut off. So pulling all the power off of it solved the problem. I used this power adapter https://www.amazon.com/SATA-Adapter-Cable-Power-Cord/dp/B001OOT804
Plugged into a 4 pin molex to 3 pin molex from Pinball Life https://www.pinballlife.com/index.php?p=product&id=1802
Then ran that to a 8 way splitter from pinball life https://www.pinballlife.com/index.php?p=product&id=4234

Then added a secondary power strip inside the cabinet and plugged it into the wall. Tying it into the main power inside the cabinet could be done possibly but I can live with a 2nd cord coming out of the back of my machine for now.

Thanks for sharing Crash

I did a quick test and it confirmed by thought, but added more. I eded up using Visual Audio as the other program didn't allow a more specific enough view of the frequency. Also, VA seems to do FFT transform and specifically told me my biggest points were

119.8 Hz (@ 41dB) and
839.8 Hz (@ 57dB)

And ... ~840 Hz is a harmonic of 120 Hz so I think this is a strong sign...