(Topic ID: 290733)

Wpc sound board help please (Solved)

By UVAJED

3 years ago


Topic Heartbeat

Topic Stats

  • 21 posts
  • 5 Pinsiders participating
  • Latest reply 2 years ago by UVAJED
  • Topic is favorited by 10 Pinsiders

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#1 3 years ago

I recently lost my +5v in my Funhouse and had to replace the BR2. Everything is working good again, but now no sound. I'm not sure what could have caused this, but in the process of testing that the BR2 was fixed, I had unplugged the mpu and sound boards so I didn't mess them up.

The fuses are good, I reflowed the header pins, reseated the ribbon cable/roms/header plugs, and checked the speakers with a battery at the header plugs (all work). When I pulled the board it was warm as if it were getting power.

Also, there isn't the start up "bong" noise (apparently that eliminates the ribbon cable?). It will run through the sound test, but obviously without sound.

Any advice would be immensely appreciated and thank you in advance.

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#2 3 years ago

Board getting power ? Lose your 12 volts on the driver board ?

LTG : )

#3 3 years ago

Thanks for replying LTG. I have all good voltages on the driver board and 12.94 at 12v test point. Where on the sound board can I test for 12v?

Also, I noticed J116/J117/J118 all have the same color wires, pin orientation, and key on the plug. Wondering if they have anything to do with the sound board and/or if I have one in the wrong place?

#4 3 years ago

Did you check the fuses on the sound board? I can't tell if the top one looks bad or just dirty.

#5 3 years ago

Thanks grumpy and yes. I pulled both out and both are good.

#6 3 years ago
Quoted from UVAJED:

Where on the sound board can I test for 12v?

Check the connector pin outs in the manual for what is where.

LTG : )

#7 3 years ago

Thank LTG. J116-J118 all have the same traces/identical. I switched them around and nothing changed.

#8 3 years ago

Slight update. Professor Pinball suggested I turn the volume up to max and see if I could hear the volume faintly. I can.

#9 3 years ago

You may have checked this already, Do you have the regulated +12 volts at test point 3? test point 1 is unregulated

#10 3 years ago

Good question grumppy. I just looked into that
I have 12v+ and 12v- on the sound board at J503 pin 4 and 3. Also 5v at J502 pin 1. (That's thanks to Pinball Chris) I recently was able to find which plug-pinout does what...after reading blurry schematics seemingly forever.

Why aren't there simple charts for especially header/plugs evolved yet as to something like.. ..here's your mpu boad.. here's your pdb board...and here's your sound board....this header plug/pins do this, and what each of those pins do/control?!

I love but am calling b.s. on pwiki and ipdd for making it more complicated than it needs to be. Smfh

Regardless of common sense, thank you for responding and I hope I can get it figured out sooner than later.

#11 3 years ago
Quoted from UVAJED:

Why aren't there simple charts for especially header/plugs evolved yet as to something like.. ..here's your mpu boad.. here's your pdb board...and here's your sound board....this header plug/pins do this, and what each of those pins do/control?!

Usually there are in the manuals. Pages 3-16 and 3-17 of the Funhouse manual shows "Interboard wiring" It shows you the wire color, connector number , what is is assigned to and even what transistor drives what. It is missing the interboard wiring for the audio board, I assume it was supposed to be on page 3-18, but it's blank. For future reference most machines using WPC89 boards will be wired similar if not exactly the same between boards so using other manuals can help. Here's a picture from Fish Tales manual , showing you the board connections.

There is another voltage on board that I haven't see you test , its the 9v. This 9v drives the MC3340 attenuator before the audio enters the amplifier.

I doubt you lost voltages on board.. You did measure -12, +12 , +5 going TO the board. The 9v is regulated from the +12v and should also be there.

You say you tested the speakers with a battery at the header ? I would still check the wiring on the speakers.. It's not impossible there's a pinched wired (pinched to ground) that is pulling down the volume , hence why you might hear some if you boost it all the way up. Both speakers are in series. If any wire is broken , both speakers will not play.

Since you have all voltages , to troubleshoot the board deeper , an oscilloscope would be the best tool. If you know someone who has one, he should look at both green points I placed on the schematic, verifying if the amplifier has a signal at its input and output. Obviously the output is affected by the volume control. If there is no signal at the attenuator , then the volume control IC , x9503 (digital potentiometer) might be acting up (known issue with this part over time).

Very first thing to do , double check the speaker wiring for a pinched or cut wire.
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#12 3 years ago

Wow Roamin thank you very much. That is a lot of extremely helpful information. I will check the sleaker wiring when I get home later today and report back. I don't have an oscilloscope, but I do have a logic probe...if it could be of any use.

#13 3 years ago

Thank you again to everyone who has posted here.

The speaker wires are all seemingly good. Can I unplug the header plugs and use/jump an external speaker from a boom box etc (with the game powered off) just to verify?

After looking at the pinout diagram Roamin posted, I checked the voltages at J501 vs. the voltages at J503 like someone else recommended. At the sound board header plug at J501 I don't have any voltages there at all (using the grounding strap for the dmm neg lead). I still can't find J114 in the manual, but it is where the wires from J501 go to on the PDB or vise versa. At J114 I get around +12v with the corresponding grey/green wires that go to J501.

Does +18v power the sound board? I have +18v on the Pdb at the test point,, but nothing at J501.

However, if I turn the volume the whole way up I can still faintly hear the music playing.

#14 3 years ago

Just a quick note before I look into J114 and other things you mentionned, J501 is using AC voltage, that'S why there isn't a + or - sign in front of the voltage value. In order to measure the 18 VAC on J501 , you need to use your multimeter in AC mode (wavy line). You also need to place both leads on the connector , or both sides of the AC line. AC isn't measured to ground like DC is. Here , 18 VAC means every 1/60 of a second the voltage changes from -18 to +18 on and on (60 hz, other places in the world use 50hz). On the board, there are 2 voltage regulators, a +12V and a -12V, which are fed by the AC going from -18 to +18 .. These voltages appear to be fine since you've measured them elsewhere before.

So J501 is measured with AC , before it is regulated to DC.
J503 has been regulated to +/- 12V DC.

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#15 3 years ago

A quick test, you said you can hear the sound faintly when raised all the way up, correct ? If you leave it there , shut down the game and turn it back on , can you hear the "bong" now ? Even if faint ? That boing indicates it passed certain tests. It will chime more than once if there are errors, it could give an indicator. I will try to look deeper in the schematic and see what we can test with your tools (a multimeter and a logic probe you said).

#16 3 years ago

Roamin thank you very much again. I am learning a ton from you while trying to sort this out.

I apologize and I'm an idiot for not seeing that J501 is VAC. I do have 18vac at J501.

I hear 5 not the normal bong but higher pitched bongs as it flashes "press enter for test report". This is very faint, as is the music. This has happened before when a switch was bad, and now the switch 55 / superdog opto switch seems to be bad, as well as I do not have the time and date set.

If I go into the sound/music test I can hear all music and all sounds, including Rudy, but all very faintly at max volume.

That is correct...I have a multimeter and logic probe.

I am considering ordering and replacing these parts:

5370-09691 ... U17 ... IC 55536 CVSD
5370-12728 ... U1 ... IC Audio Amp LM1875
5370-12730 ... U7,U8 ... IC Op Amp TL084
5370-12742 ... U32 ...IC Op Amp TL082

Do you think that would do the trick?

Thanks again

#17 3 years ago

Are the connectors in J505 and J504 switched around ?

#18 3 years ago

Excellent question Zigzagzag and thanks. I double checked that and they are in the correct locations. I made sure to look at wiring color and pin numbers at least 5 times to verify.

#19 2 years ago

If I was going to change a chip blindly I would start with x9305, the digital potentiometer. Let me explain to you how to test that potentiometer. First locate W9 on the board. It is a simple wire jumper, and it's the output of the potientiometer going to the attenuator. Set your meter on DC voltage and measure from ground to W9 , on any side since it's a wire. What do you measure ? With the volume turned down to 0 on my Fish Tales, I read 3.58V With the volume turned to 8 I read 2.99V . So, as you see the higher the voltage read on W9 , the lower the volume will output. Every increase of the volume counter should lower the voltage you read here, increasing the volume. Now if the value is around 3.6 you can barely hear anything. Everytime you increase the volume , the voltage on W9 should drop by 0.06 to 0.09 approx.

If this voltage doesn't change at all , you'll have to check the logic driving the chip. It does seem to change a bit at least, since you mention that at max volume you hear a bit of sound. So it's probably not the circuit driving this chip that is at fault. The chip itself could very well be at fault.

I included in the picture the logic of how the chip is driven. You can test these points with you logic probe. Pin 1 should be driven low when you press any button, volume up or down. Pin 2 should be HIGH when you increase volume and LOW when you decrease it. Pin 3 , Chip select, should be driven low when changes to the volume are happening and should return high when you are not changing the volume. *** If you were to test this and the logic didn't work properly, your next move would be to remove the chip completely (without breaking it) and to do the test again. A broken chip *could* pull the voltages either HIGH or LOW and give bad results. If the results are the same without the chip , then we have to go look further and test the chip sending those signals.. But that's not for now. I've numbered the pins of X9503 if you want to test with your probe.

Now , if this chip is suspected bad, you can test the amplifying circuit. If you look closely at the schematic, J507 can be used as an "optional volume control" and if you follow the wire you can see it leads straight to W9. What you need to do here is to disconnect one side of W9 to remove the x9503 out of the circuit, and solder either a potentiometer to the header pins of J507 or just a resistor. The number 503 in x9503 means its a 50K potentiometer. If you have a 50k pot available you just use a pin from any edge and the center pin. Solder the edge to pin 4 and the center pin to pin 2. I have never done this myself so I would be extremely careful since the amplifier can be pretty loud. I would make sure that the measured resistance between the 2 pins are at 50k before I solder it and that the 2 pins don't measure a very low resistance, because the amplifier would probably blast extremely loud and could damage the speakers I guess.. There might be threads on mods using that optional pot. and tips on what to do. For a temporary solution I would just take extra care. The higher the resistance the less current will pass through, the safer everything is.

Before blindly changing amplifying chips , you really should test that pot.

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#20 2 years ago

Unbelievable. Who are you that seemingly has been on here less than a year, but; yet, are writing books above and beyond Roamin?!?

Thank. You. Sir.

I will hopefully be able to follow your lead tomorrow and hopefully I can balance the volume buttons and the logic probe at the same time. If not, I hope to have good/knowledgeable awesome friend here Thursday who hopefully has time to give me a hand.

I'm trying to understand and digest everything you are sharing before I just jump into it/break stuff, so that it sticks with me and I can better understand the 'logic' (that you seemingly have written the book on) with the not-at-all common sound board insightfullness.

I have 2 chips that I have to put in from previous advice, and it'll be good practice to replace (carefully) for me to replace a chip or 2?!?

I will report back by the end of this week. Ty VERY much. You have no idea how much I appreciate your time Roamin.

#21 2 years ago

It's fixed. I put in a new amp and nothing. Installed the CVSD chip and nothing. Then, as I was unplugging the connectorsbto install another chip, one of the volume header plugs fell into the cabinet. For something to do I touched just the wire to the speaker pin on j504 and boom comes the sound.

The speaker wires were one of the first things I tested....from the header plug with battery. Also, I used a screwdriver to make sure the wire was making good contact inside the header plug. I thought it was.

After it was all back to normal, I put the old CVSD chip back in and it still works. So, either the speaker wire wasn't making good contact the entire time, or after replacing the amp the speaker wire happened to get loose and it was the amp that fixed it. I'm guessing it was the speaker wire header plug the entire time, but either way it is fixed and what a breath of fresh air.

Thank you to everyone who has chimed in on here; and especially Roamin. Regardless of the issue not necessarily being anything anyone was leaning towards, I learned a ton about the wpc sound board and hopefully someone else might too in the future.

Sincerely, thank you all, and now it's time to go put Rudy to sleep.

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