Trace transistor output

argonrepublic · 2nd February 2013, 04:29 PM

I need to find speaker outputs for a car amp that is missing harness. This is an oppourtunity for me to learn some basics. I have 4 output transistors which is the speaker positive output? P or N? which pin do I follow? Are the pins for the speaker lead directly in series with speaker leads?

Perry Babin · 2nd February 2013, 05:22 PM

What make/model amp is this?

argonrepublic · 3rd February 2013, 01:18 AM

Alpine MRP-T306

Perry Babin · 3rd February 2013, 01:55 AM

I don't have anything on that amp. If no one else can help, post a good quality photo of the inside of the amp.

argonrepublic · 3rd February 2013, 02:18 AM

The speaker connector is top center. I want to find two pairs of speaker leads. It is not apparent with ohmeter.

1moreamp · 3rd February 2013, 05:43 AM

If your meters black probe is connected to the center tap connection of the secondary of the power supply < true common ground of the audio side >, then any ground wire in that plug should read zero ohms.
Unless you have a open trace on the amp somewhere like on the bottom of the board.
Ground for the speaker will also be the common ground for the secondary side of the bi-polar power supply feeding the amp. All the rest of the hot speaker wires will read like diodes since they are reading thru the circuitry back to ground, so you will see diode like readings on the hot speaker terminals and zero ohms on the ground terminals.

Plus Alpine use to mark their connections on the bottom of their circuit boards but you will have to completely remove the board to look for those possible markings...hope this helps some...

JMFahey · 3rd February 2013, 08:01 AM

Ask Alpine (or google) the connector pinout.
In fact, it *must* be detailed in the User Manual.
Or ask some Car Audio installer, who probably knows it by heart.

2nd February 2013, 04:29 PM	#1
argonrepublic diyAudio Member Join Date: Apr 2005 Location: Simcoe Ont	Trace transistor output I need to find speaker outputs for a car amp that is missing harness. This is an oppourtunity for me to learn some basics. I have 4 output transistors which is the speaker positive output? P or N? which pin do I follow? Are the pins for the speaker lead directly in series with speaker leads?

2nd February 2013, 05:22 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What make/model amp is this? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

3rd February 2013, 01:55 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	I don't have anything on that amp. If no one else can help, post a good quality photo of the inside of the amp. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

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3rd February 2013, 01:18 AM	#3
argonrepublic diyAudio Member Join Date: Apr 2005 Location: Simcoe Ont	Alpine MRP-T306

3rd February 2013, 05:43 AM	#6
1moreamp diyAudio Member Join Date: Dec 2005 Location: Northern California	If your meters black probe is connected to the center tap connection of the secondary of the power supply < true common ground of the audio side >, then any ground wire in that plug should read zero ohms. Unless you have a open trace on the amp somewhere like on the bottom of the board. Ground for the speaker will also be the common ground for the secondary side of the bi-polar power supply feeding the amp. All the rest of the hot speaker wires will read like diodes since they are reading thru the circuitry back to ground, so you will see diode like readings on the hot speaker terminals and zero ohms on the ground terminals. Plus Alpine use to mark their connections on the bottom of their circuit boards but you will have to completely remove the board to look for those possible markings...hope this helps some...

3rd February 2013, 08:01 AM	#7
JMFahey diyAudio Member Join Date: Mar 2009 Location: Buenos Aires - Argentina	Ask Alpine (or google) the connector pinout. In fact, it must be detailed in the User Manual. Or ask some Car Audio installer, who probably knows it by heart.

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