(Topic ID: 128031)

DCS Sound board HELP


By RampShot11

4 years ago



Topic Stats

  • 29 posts
  • 6 Pinsiders participating
  • Latest reply 4 years ago by RampShot11
  • Topic is favorited by 1 Pinsider

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#1 4 years ago

Hi Guys, I have no sound out of the backbox speaker channel of my Judge Dredd. Both channels were working fine and then one day I started getting loud popping and crackling out of the backbox panel speakers. I also noticed that the heatsink for the amplifier for that channel gets super hot after a minute of being on while the sub woofer channel stays pretty cool for as long as I play. I replaced the C20 Cap associated with that channel and the other cap at C32. Also replaced the amplifier transistor , nothing helped. Any suggestions would be greatly appreciated. Thanks.

#2 4 years ago

Have you checked the resistance of the back box speakers to see if perhaps one has shorted out?

#3 4 years ago
Quoted from jadziedzic:

Have you checked the resistance of the back box speakers to see if perhaps one has shorted out?

Yes, and I actually changed out the 5.25 speaker because it was aftermarket. I still had the original and put it back in with no luck.

#4 4 years ago

These are the components I've swapped out so far. Should I have also changed the counter parts for the cabinet channel even though it is working fine? I'm afraid I'll make it worse if I do that but will do it if suggested by someone with experience.

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#5 4 years ago

Anyone?? Should I change both the caps and both 1u63v caps also? If the heat sink is getting super hot, does that mean it is getting too much voltage? Could it be a resistor?

#6 4 years ago

It's lonely in here.....echo, echo, echo, echo

#7 4 years ago

Check for correct power first. Check for correct fuse values and that they are good. Yes replace both caps. They are old and need it anyways plus their cheap. Check continuity from caps to traces. Common for them to break.

#8 4 years ago
Quoted from Hawk007:

Check for correct power first. Check for correct fuse values and that they are good. Yes replace both caps. They are old and need it anyways plus their cheap. Check continuity from caps to traces. Common for them to break.

Thank You Hawk. Do I check continuity with ohms reading? On a multi-meter?

#9 4 years ago

Anytime....And yes. You can use OHMs or the BEEP continuity test on a quality DMM. Check power first as thats the usual suspect. Then caps.

#10 4 years ago

You mean check the power coming from the Amp? at U28?

#11 4 years ago

no, check the incoming power to the sound board itself

#12 4 years ago
Quoted from Hawk007:

no, check the incoming power to the sound board itself

Ok got it. I'll be home soon and then I can check. Thanks.

#13 4 years ago

If worse came to worse, could I run all three speakers off of the one amplifier? Or will that do major damage?

#14 4 years ago
Quoted from RampShot11:

If worse came to worse, could I run all three speakers off of the one amplifier? Or will that do major damage?

Probably not a good idea but I wonder about using the one channel for the backbox and then taking the signal to a powered sub?

#15 4 years ago

No I would not do that. Fixing the sound board issue is the only way I'm afraid.
good luck!

#16 4 years ago
Quoted from Hawk007:

No I would not do that. Fixing the sound board issue is the only way I'm afraid.
good luck!

Do I test it with the machine on?

#17 4 years ago

yes but be careful!!!!! if you are not sure maybe ask for help from a pinball friend close to you. Last thing you want is to hurt yourself.

#18 4 years ago

I tested both channels with the game on , I get a very high reading from the bad channel and very low stable reading from the channel that is working correctly. Not sure what this means, hopefully one of the very helpful pinsiders can shed some light.

#19 4 years ago

Check the transistor on the channel that is bad, it is also what could be causing your heat sink to be getting hot. I had this problem with my IJ, eventually you will see the dreaded sound board error, and the game won't boot.

#20 4 years ago
Quoted from buffaloatx:

Check the transistor on the channel that is bad, it is also what could be causing your heat sink to be getting hot. I had this problem with my IJ, eventually you will see the dreaded sound board error, and the game won't boot.

I replaced it once already but I'm thinking I might have pulled a couple through holes out with the old transistor amp. Maybe I'll try replacing it one more time and fill in the holes with solder. Drill a tiny hole through the solder.

#21 4 years ago
Quoted from RampShot11:

I replaced it once already but I'm thinking I might have pulled a couple through holes out with the old transistor amp. Maybe I'll try replacing it one more time and fill in the holes with solder. Drill a tiny hole through the solder.

Yeah, that's why I don't do my own board repairs. Too nerve wracking.
Do you have another board you can swap in? you could test voltages on that one and compare to the wonky board, could help point you in the right direction for a solution.
Good luck.

#22 4 years ago
Quoted from buffaloatx:

Yeah, that's why I don't do my own board repairs. Too nerve wracking.
Do you have another board you can swap in? you could test voltages on that one and compare to the wonky board, could help point you in the right direction for a solution.
Good luck.

Yeah I hear you, I think I got too big for my bridges. Unfortunately I don't have another dcs board but a friend of mine does so I'll try his soon. Thanks for the help. I'll let you know what I came up with.

#23 4 years ago

Typically with these boards I check the main amps. If it's shorted change it. If it's getting super hot sounds like it shorted again. I have seen them blow up by themselves or by exposed wiring going to the speaker/DMD panel, or a shorted speaker. When it's a shorted speaker it tends to blow out a resistor near the amp. Check those. If the main amp is good and it's not overheating and still no sound next thing I check is the 084 pre-amp chips.

#24 4 years ago
Quoted from kbliznick:

Typically with these boards I check the main amps. If it's shorted change it. If it's getting super hot sounds like it shorted again. I have seen them blow up by themselves or by exposed wiring going to the speaker/DMD panel, or a shorted speaker. When it's a shorted speaker it tends to blow out a resistor near the amp. Check those. If the main amp is good and it's not overheating and still no sound next thing I check is the 084 pre-amp chips.

Ok thank you very much for that info. I was thinking it might have something to do with a resistor because wouldn't that be why is getting so hot? It's getting too much voltage or power. Problem is Im not too sure how to test things on circuit boards.

#25 4 years ago

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Quoted from RampShot11:Ok thank you very much for that info. I was thinking it might have something to do with a resistor because wouldn't that be why is getting so hot? It's getting too much voltage or power. Problem is Im not too sure how to test things on circuit boards.

luckily on this sound boards the two output sections I believe are identical to each other. Just put your meter on the ohms setting and verify that the matching resistors for both amps are giving you the same values.

#26 4 years ago

As kbliznick says if the amp shorted again it will run hot. I also have seen shorted wiring and bad speakers as he mentions. Check your speaker load too with your dmm on ohms . If its too low or wired wrong you are basically shorting the amp everytime you hook up the speakers. Those amps are quite fragile.

#27 4 years ago

I see. Thanks guys. I will be home tomorrow and test it. Power should be on right?

#28 4 years ago

You can test the amps with the power off and the board out of the game. Simply check every pin to every other pin. I think every bad amp I have ever replaced has had a dead short between 2 of the 5 pins.

#29 4 years ago
Quoted from kbliznick:

You can test the amps with the power off and the board out of the game. Simply check every pin to every other pin. I think every bad amp I have ever replaced has had a dead short between 2 of the 5 pins.

Ok thanks for the tip. Very helpful Info.

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