Audiobahn a18001dt

audiobahnkid592 · 23rd May 2010, 02:32 AM

I just bought this amp for repair. Im really lost on this one im getting a ranging 24-34V DC on the speaker output at idle with not input or output. if nothing is hooked up to the speaker output the amp remains in protection. with a 2.7 ohm restistor on speaker out put it loads the amp(have powered through light bulb) and comes out of protection and puts out 6VDC. I have thus this far checked all the caps, output fets removed the driver card, and the four rectifiers or diodes not sure what terminalogy to use.

mike49504 · 23rd May 2010, 03:19 AM

With your meter set to ohms what are the readings on the outputs

Leg1-2:
Leg1-3:
Leg2-3:

You should have nothing near 0 ohms post your results

Perry Babin · 23rd May 2010, 04:56 AM

Are you saying that the amp is producing 6v across the speaker terminals (measured with one probe on each of the speaker terminals) with no driver board installed?

audiobahnkid592 · 23rd May 2010, 02:59 PM

mike the outputs are removed from board when producing the DC offset. Perry yes the driver card is currenly out of the board. with it out and nothing attached to the speaker output of the amp its a ranging 24-34V DC on the ouputs. with a 2.7 ohm 25 watt resistor hooked to the speaker out put then it droppes to 6V dc and will start to burn the resitor after 45-60 seconds. I do not have a scope either.

audiobahnkid592 · 23rd May 2010, 04:05 PM

Also when the remote is removed the DC offset bleeds down over about 30 sec so it is storing the power in the caps.

genral pics are here
A18001DT amp pictures by brandon250mx - Photobucket

Perry Babin · 24th May 2010, 12:53 AM

If the driver board is out and it's producing DC on the outputs (measured directly across the speaker terminals), you likely have defective outputs. Either they are shorted/leaking or there is one or more with an intermittent connection on the gate leg. They often break just inside the transistor body.

audiobahnkid592 · 24th May 2010, 10:45 PM

pery the outputs are not installed in the board when all my symptoms are happening

Perry Babin · 25th May 2010, 03:50 AM

If there are no outputs in the amp and no driver board, I don't know how DC could get to the speaker terminals (measured directly across speaker terminals) unless there's a solder bridge or leakage through a contaminant on the board.

audiobahnkid592 · 25th May 2010, 10:32 AM

looks like i bought a paper weight. ill go over it once more but i do not see anything touching at all or anything on the board.

Perry Babin · 25th May 2010, 11:17 AM

It's not likely to be anything serious. Connect your multimeter and the resistor across the speaker terminals and watch the voltage while moving/pushing/pulling on various components to see if you can get the meter to change.

What is the rail voltage when you have ~6v across the speaker terminals?

23rd May 2010, 02:32 AM	#1
audiobahnkid592 diyAudio Member Join Date: Mar 2007	Audiobahn a18001dt I just bought this amp for repair. Im really lost on this one im getting a ranging 24-34V DC on the speaker output at idle with not input or output. if nothing is hooked up to the speaker output the amp remains in protection. with a 2.7 ohm restistor on speaker out put it loads the amp(have powered through light bulb) and comes out of protection and puts out 6VDC. I have thus this far checked all the caps, output fets removed the driver card, and the four rectifiers or diodes not sure what terminalogy to use.

23rd May 2010, 04:56 AM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Are you saying that the amp is producing 6v across the speaker terminals (measured with one probe on each of the speaker terminals) with no driver board installed? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

24th May 2010, 12:53 AM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the driver board is out and it's producing DC on the outputs (measured directly across the speaker terminals), you likely have defective outputs. Either they are shorted/leaking or there is one or more with an intermittent connection on the gate leg. They often break just inside the transistor body. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th May 2010, 03:50 AM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If there are no outputs in the amp and no driver board, I don't know how DC could get to the speaker terminals (measured directly across speaker terminals) unless there's a solder bridge or leakage through a contaminant on the board. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th May 2010, 11:17 AM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	It's not likely to be anything serious. Connect your multimeter and the resistor across the speaker terminals and watch the voltage while moving/pushing/pulling on various components to see if you can get the meter to change. What is the rail voltage when you have ~6v across the speaker terminals? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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23rd May 2010, 03:19 AM	#2
mike49504 diyAudio Member Join Date: Sep 2006	With your meter set to ohms what are the readings on the outputs Leg1-2: Leg1-3: Leg2-3: You should have nothing near 0 ohms post your results

23rd May 2010, 02:59 PM	#4
audiobahnkid592 diyAudio Member Join Date: Mar 2007	mike the outputs are removed from board when producing the DC offset. Perry yes the driver card is currenly out of the board. with it out and nothing attached to the speaker output of the amp its a ranging 24-34V DC on the ouputs. with a 2.7 ohm 25 watt resistor hooked to the speaker out put then it droppes to 6V dc and will start to burn the resitor after 45-60 seconds. I do not have a scope either.

23rd May 2010, 04:05 PM	#5
audiobahnkid592 diyAudio Member Join Date: Mar 2007	Also when the remote is removed the DC offset bleeds down over about 30 sec so it is storing the power in the caps. genral pics are here A18001DT amp pictures by brandon250mx - Photobucket

24th May 2010, 10:45 PM	#7
audiobahnkid592 diyAudio Member Join Date: Mar 2007	pery the outputs are not installed in the board when all my symptoms are happening

25th May 2010, 10:32 AM	#9
audiobahnkid592 diyAudio Member Join Date: Mar 2007	looks like i bought a paper weight. ill go over it once more but i do not see anything touching at all or anything on the board.

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