Original Audio Amp modification to use with Nucore

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Eric A.
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Original Audio Amp modification to use with Nucore

Post by Eric A. » Sat Sep 12, 2009 9:11 pm

This is to document the modification that needs to be done with the original audio amp if you have one with your original box.

Time required is about 10 minutes! That's all!!!

Parts:
Old pair of walkman headphones with 1/8" or 3mm jack
10 K Ohm resistor
10 uF 50 volt capacitor

Start by cutting the wire as long as you can by the ear pieces of the headphones and stripping the wires and shields back a little bit in order to solder into the original location dedicated for a female jack. The holes are plated through holes so suck out the solder and place the white and red wires like I have them. Your speakers will then be controlled correctly with the game system.

Then connect the cap and resistor to pin one of original connector that went to the prism card. The other end of the resistor goes to the 5vdc pin of the power connector and the other end of the cap goes to the shield of the headphone jack.

Go out and buy an old computer power supply 10 bucks or so and plug it into your service outlet or get a splitter for the computer power connector and extend the wires to the power connector of the audio board!

That's it! Pics attached!
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Last edited by Eric A. on Wed Nov 03, 2010 6:36 pm, edited 1 time in total.

Tower5
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Re: Original Audio Amp modification to use with Nucore

Post by Tower5 » Sun Jan 17, 2010 10:45 pm

I'm sorry, but I need a little more help. Can you post a picture of the computer power supply you used? Also, I'm not seeing where the headphone wires attach. Thanks for any help.

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Eric A.
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Re: Original Audio Amp modification to use with Nucore

Post by Eric A. » Mon Jan 18, 2010 7:10 am

I don't follow you. ANY! Computer power supply will do.

However, with the way chuck mounted his usb board, on the inside of the computer case, you could do something similar with the audio amp and have no need to buy an extra power supply.

As far as the connection points for the head phone/ 1/8" jack goes it should be immediately to the right of the original white prism card interface conection.

I'm not sure if your Williams serial number sticker is on top of it but looking at the front of the board the connection is screened right on to the board.

Tower5
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Re: Original Audio Amp modification to use with Nucore

Post by Tower5 » Mon Jan 18, 2010 12:20 pm

Are we talking about any old three prong power cord (not just computer)? I'm way more interested in hooking it up to the computer's power, but I can't find the thread where Chuck explains how he did that.

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Eric A.
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Re: Original Audio Amp modification to use with Nucore

Post by Eric A. » Mon Jan 18, 2010 1:07 pm

COMPUTER power supply. They all have spare 5v/12v connectors. There is only 1 power connector on the audio amp which is a standard computer power connector.

Big Guys pinball sells their own redesigned audio amp which mounts separately to the wall of the cabinet but my method is if you want to use the original amp and save a few bucks.

Actually I forgot about the ground loop noise that will occur if you use the original amp with the nucore computer power supply so you will need an external computer power supply for sure if you want to use the original audio amp.

Tower5
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Re: Original Audio Amp modification to use with Nucore

Post by Tower5 » Mon Jan 18, 2010 9:55 pm

Okay, I think I've got it. Only problem I saw was when I went to add the audio cable. You seem to have three things to solder, while I only have two. Am I missing something (I don't think my cap is touching anything?

Photo attached.
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cyclonemystery
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Re: Original Audio Amp modification to use with Nucore

Post by cyclonemystery » Tue Jan 19, 2010 7:51 am

Hi,
the third wire is the ground of both cables (under the isolation).

Rüdiger

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Eric A.
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Re: Original Audio Amp modification to use with Nucore

Post by Eric A. » Tue Jan 19, 2010 8:00 am

STOP!!! STOP RIGHT NOW!!!!

Before you plug ANYTHING in, is the other side of "audio cable " with only 2 wires pluging into the wall or is it a 1/8" stereo jack that plugs into your computer? I say this because it looks like a lamp cord and if that is the case you're going to blow up the board if you plug it into the wall. If not, sorry I'm just being overly cautious. :D

If you used an old pair of old headphones or you went out and bought a cable like at radio shack you will ALWAYS have a shield and that appears what you are missing. Don't just cut the shield off you will get a lot of noise. The shield is under the insulation. Anyway can you take a better picture with a couple diferent angles and show me the end of your cable?

Tower5
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Re: Original Audio Amp modification to use with Nucore

Post by Tower5 » Tue Jan 19, 2010 11:15 am

Don't worry, those are audio cables (I bought a computer power supply to power the board). I'm not seeing a third wire on my headphones, but I'll check again.

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Eric A.
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Re: Original Audio Amp modification to use with Nucore

Post by Eric A. » Tue Jan 19, 2010 11:39 am

It's not really a third wire. It is silver braiding on the outside of the red and white wires.

When you strip back the insulation on the outside of the red and white conductors you will see some silver braiding/shielding. That is what you need to twist together and solder into the thirs position.

knapejor
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Re: Original Audio Amp modification to use with Nucore

Post by knapejor » Fri Feb 05, 2010 4:59 pm

I have a question about this modification:

I think I need to connect a power connector to the audio amp, is this correct? And if so, what kind of cable is it and how
does it look like?

Thanks :)

Regards,
Jord

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Eric A.
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Re: Original Audio Amp modification to use with Nucore

Post by Eric A. » Sat Feb 06, 2010 7:24 am

Yes, you need to connect an external power supply and NOT the one from the computer you are using. You will create a ground loop hum if you do. Go get a cheap ps from your local computer store and buy an extension cable like the one pictured here so you can mount the ps in the bottom of the cabinet somewhere. Following are a couple examples.

Power Supply:
http://www.coolerguys.com/840556026198.html

Extension adaptor:
http://www.pccables.com/cgi-bin/orders6 ... 341&rcode=

I get used ps fom my local computer store for like 5 bucks.

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Re: Original Audio Amp modification to use with Nucore

Post by knapejor » Sat Feb 06, 2010 8:00 am

Thanks Eric :)

Tower5
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Re: Original Audio Amp modification to use with Nucore

Post by Tower5 » Mon Feb 08, 2010 1:10 am

Note that you will not get power until you:

http://www.duxcw.com/faq/ps/ps4.htm

I still don't have any sound, but at least I have power now!

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Re: Original Audio Amp modification to use with Nucore

Post by knapejor » Thu Feb 11, 2010 2:03 pm

Uh.. I'm not sure how it's going to work:

Normally a power supply connects to a motherboard, and only then the 'other' connected items (like normally a
harddisk or dvd drive) get powered.

If I connect the power supply only to the audio amp (and offcourse the wall-outlet ;)) how is it going to power
up the audio amp?

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