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Old 2nd April 2005, 11:06 AM   #1
diyAudio Member
 
Join Date: Apr 2005
Location: San Diego, Ca
Default finding Pos n Neg Wires of Amp

Hi, I have a 4 channel Hifonics series 7 Amp (lost Manual and can not find an info on internet) It has Molex Connectors. my question is how would find out which is the positive and negative wires for the Speakers, or channels. I've opened it up and it doesn't say which is the positive or negatives...can anyone tell me how to find out which wire is Pos and Neg??? Please with a cherry on top...

thanks...

p.s. I was thinking using a multimeter but dont know how to go about it.
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Old 2nd April 2005, 01:07 PM   #2
sdoom is offline sdoom  Germany
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Join Date: Mar 2004
Location: Heidelberg
Hi


Speaker-wires:

At least, you can find out which of the wires are GND-connected .

8 measurements (No POWER connected !!! Amplifier off!!!) : Simply connect the multimeter (ohmmeter-mode) to each wire and to the RCA-jacks shilding . You should find 4 wires that have 0 Ohms.

Now you can doublecheck this. Plug the ohmmeter in between each of those 4 wires. You should always get 0 ohms. Now those 4 wires have GND-potential.

The other 4 wires are connected to each channelīs output.

Now the problem is : As far as I know the Hifonics series 7 amplifiers are all bridgeable. That means that 2 channels (of a 4channel amp) have a phase-shift of 180 degrees. That is because you could bridge 2 channels into 1. That means if you would connect each speakerīs minus to each GND-wire from the amp and each speakerīs plus to each other wire, 2 of those 4 connected speakers would run out of phase. This is not harmful, but you will be able to hear it.

If you have access to a signal-generator (sine-wave) and a scope you can hook the amplifier in between, power it up and check which 2 channels run out of phase. This is the best method , to be 100% sure.


__________________________________

Power-wires:

If you are not sure which one of the two connectors is "+12V" and which one is "chassis-GND" simply connect the multimeter ( in diode-check mode) to those 2 power terminals. (again, no power connected to the amplifier!!!)

If you have high readings (more than 0,6V) switch the two wires from your meter. If you now read aprox. 0,6V the minus-wire from your meter is connected to the "+12V" terminal of the amp, the positive wire from your meter is connected to the "chassis-GND" terminal.

Why ? The +12V and the "chassis-GND" terminals are protected with a simple power-diode. This diode is connected to the 2 terminals in reverse. If people connect 12V and GND correctly, nothing happens. The diode stays "open" . If people mix up the power wires, the diode is shortening the wires , causing a high current flow to blow the fuse. But this is theoretical, in real life most amplifiers blow up in smoke when the power wires are mixed up.


Good luck


Stephan
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Old 2nd April 2005, 03:15 PM   #3
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Join Date: Apr 2005
Location: San Diego, Ca
Thank you soooooooo much Ill go ahead and try it...I actually know the which are the power and ground, its the Speaker wires Im having trouble with....thanks a million,

Btw if there are other options (i.e.Checking the for which is Pos and Neg of the Speaker Wire let me know also... thanks again dude.
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Old 2nd April 2005, 04:01 PM   #4
sdoom is offline sdoom  Germany
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Join Date: Mar 2004
Location: Heidelberg
Hi again


Here is another method how you could figure it out.


First, check which 4 of the 8 wires have GND potential (use the method in my first posting) . You can also open the amplifier and check the curcuit board, 4 of your 8 speaker terminals are connected together, somewhere.


Now that you know those 4 GND - wires get 4 speakers. Connect each of the wires that has GND potential to the minus-terminal of the speaker. Now connect the "leftovers" , meaning the other 4 wires . Each wire to the plus-terminal of your 4 speakers.

Now connect RCA-cables and power wires to the amp. Power up the amplifier. When it is turned on, run music that has short bass drums in it.

Usually it appears, that you see that the speaker is moving towards you every time the bass is coming. If you see that the speaker is moving backwards than this one is out of phase. In order to get the speaker running in phase simply disconnect the speaker wires and connect them again , the other way round (always power off the amplifier when connecting/disconnecting wires!!!). Again test with music. The speaker now should move towards you .You should be able to find the two channels with this method. Maybe you need to try different songs. If you find the 2 channels that are out of phase remember those .


speakers:


If you are not sure which one is the plus/minus terminal at the speaker itself, connect a small 1,5V (AA)-Batterie to the speaker . The speaker will move towards you (out of the chassis) if
speaker + is connected to battery +
and speaker - is connected to battery -


If the speaker moves away from you (into the chassis) then speaker + is connected to battery -
and speaker - is connected to battery +



Stephan
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