Cabinet speakers to power supply

[mightychump]

Hello, I bought a fully working mame cabinet off ebay. The reason the person sold the cabinet was because the PC was broken and the seller didn't have any computer knowledge and could not fix it.

After I bought the cabinet I swapped the old PC out and put a spare one I had in it. Everything now works perfectly (after some initial problems with the arcade monitor). The only thing I have left to do is connect the cabinet speakers to my PC Power supply. This is how the speakers were connected to the old PC's power supply-






As you can see the 2 wires were just wrapped together and sealed with electrical tape (I have already taken the electrical tape off one off the wires). The power then goes back to the amplifier as shown below-



The left wire in the photo above goes to the PC's sound card, the grey wires are the ones that go to the power supply and the top black one goes to the J-pac speaker. Below is a photo of the black wires that go to the J-pac speaker-



What I need to know is if I can do the same thing with the new Pc's power supply? Below are photos of the new PC's power supply.





Some details of the old PC's power supply-
Compaq 175w- model number- 7171-1CF1
+5V --- +3.3V --- +12V --- -12V ---
8A         12A         3A          0.3A

12.8V--- +5.05V AUX --- +3.3V AUX ---
7.5A       2.4A                  1A


I don't know much about power supplies so any help would be much appreciated. Thanks

[Kevin Mullins]

The first thing you need to know is if the amp was running off the 5v or 12v.

Then just tap those two wires into any available pc power supply port of the right voltage. (with a proper connector or soldered preferably though)

[mightychump]

The first thing you need to know is if the amp was running off the 5v or 12v.

Then just tap those two wires into any available pc power supply port of the right voltage. (with a proper connector or soldered preferably though)

I think it is connected to the 12v. The other wire that is connected to the power supply is the orange wire and that is the one that plugs into the right side of devices like cdroms or hard drives (furthest from the red line on ide cables). Is that usually the 12v wire? Thanks

[mightychump]

I just had a look around the house and found a AC-DC adaptor 12v --- 150mA from an old portable tv. Would something like this be ok for powering the speakers? If so how exactly would I go about connecting the 2 grey wires from the amplifier to the AC-DC adaptor? Or would I just be better off using the psu from the PC? Thanks

[Kevin Mullins]

What is the part number on the amplifier chip?
Could just look the chip and to be sure on the voltage required.

[mightychump]

What is the part number on the amplifier chip?
Could just look the chip and to be sure on the voltage required.

I looked at the amplifier chip and it doesn't say anywhere on it what voltage it is. I am pretty sure that is must be 12v because that is what it was connected to on the old psu. It was connected to the orange and black wires on the old psu and the orange wire goes to the right side of the CDROM drive.

Below is a picture of the wires that go to the CDROM drive. You cannot see it very well but it says DC INPUT +5 GND +12 on the CDROM where the power connector goes to it. I used paint to edit the picture so I could put the writing to the left of where it is supposed to be.

[mightychump]

What is the part number on the amplifier chip?
Could just look the chip and to be sure on the voltage required.

Sorry I just had another look and I found a part number on one of the parts on the amplifier (the large black part) and it is a- NEC upc1185h2. I have been searching google for awhile now and the best information I have been able to find about it is- http://www.datasheetarchive.com/specsheet/UPC1185H2.html and http://www.icgo.com.cn/datasheet/html/UPC1185H2.aspx

Does that help anyone in finding out the correct voltage? Thanks

[Kevin Mullins]

Does that help anyone in finding out the correct voltage? Thanks

Yeah.... use the +12V source.

[northerngames]

it should be a 12V.

you could also go to radio shack and get a mini jack to RCA adapter and hook up a surround sound reciever.

plug the mni jack into the pc's sound jack plug the rca's into the adapter and the surrond sound and connect the speakers to the surround sound and it is ready to go with surround sound.

[mightychump]

Bad news I'm afraid. I wired it up today and turned on the power and blew up the amplifier    Once I turned the PC on I heard 2 loud bangs and then quickly turned the power off. The result-


Very bad smell after it happened and one of the capacitors ended up a few feet from the amp.

Thankfully it seems that nothing else was damaged- the pc, arcade monitor and j-pac etc still work. Not sure about the speakers since I can't test them at the moment.

Guess this will teach an amature like me not to mess with things I don't understand 

I think I will just use a set of PC speakers for awhile and not use the cabinet speakers, should be safer that way

[rovingmind]

Dont throw that amplifier board away.  It doesn't look like it has surface mount components, should be an easy parts replacement fix.

[Kevin Mullins]

Maybe ya got lucky and it didn't kill the amp chip itself.
Clean it up, change the caps.... and double check your polarity on the power leads.
( + and - might have been backwards)

[rovingmind]

and if it did fry the chip its still a useful board to repopulate,