Power Acoustik OV2-1200

m4ick · 24th January 2012, 09:24 PM

I found a solder bridge on an op amp in this thing and fixed that.

My concern is that after I power it on in the vehicle the power led stays lit for about a minute or so after powering down. I unhooked it and brought it back into the house and the power LED is still pretty bright. Is that normal for these amps?

Perry Babin · 24th January 2012, 09:38 PM

It's driven by rail voltage so it's probably normal. It takes a while for the rail caps to discharge through the LED.

fcruz · 24th January 2012, 11:23 PM

I have the layout of the series of POWER ACOUSTIK OV2

m4ick · 25th January 2012, 02:30 AM

The HP/Full/LP switch was bad in this thing.

Now when I run it one channel sounds terrible in high pass mode and in low pass mode it sounds worse.

I've run the pots all the way down and all the way up and it still sounds just as bad. Could that be an op amp or morel likely dirty pots?

Perry Babin · 25th January 2012, 05:05 AM

If the channel never produces clean audio, it's not likely to be a switch.

Post a photo of the distorted signal with a speaker or dummy load connected. Confirm that there is no excessive DC (no signal) before connecting the load. Have all transistors clamped.

m4ick · 11:59 PM

Sorry, I don't have a camera on hand yet (it's been SLOW), but I will have a friend bring one soon to take a picture of the waveform.

The channel produces clean audio in full pass mode, distorted audio in LP/HP mode. The customer just informed me that the amp got wet while connected to power but not powered on, which led me to believe it was dirty pots.

The distortion seems to only occur in the lower octaves (when bass plays).

Perry Babin · 26th January 2012, 12:57 AM

Check the output of each of the op-amps in the preamp section. Do any have more than a fraction of a volt of DC on their output pins?

m4ick · 30th January 2012, 04:10 AM

I found 14.xV DC on a NJM072D but the inputs/output were not connected to any circuit.

In LP mode I could plainly see the distortion. I looked at the signal on the base of the outputs and traced it back until it was clean. I found a broken solder joint on the pre amp board.

I asked earlier about the power light turning off slowly. I have a same series 4 channel amp (they were a matched pair that got wet) and the power LED turns off much more quickly. Are these amps power LEDs more likely wired differently or more likely something is not discharging the rails on the 2 channel?

24th January 2012, 09:24 PM	#1
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Power Acoustik OV2-1200 I found a solder bridge on an op amp in this thing and fixed that. My concern is that after I power it on in the vehicle the power led stays lit for about a minute or so after powering down. I unhooked it and brought it back into the house and the power LED is still pretty bright. Is that normal for these amps? __________________ Scope - DMM - 460W Computer PSU - Tutorial

24th January 2012, 09:38 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	It's driven by rail voltage so it's probably normal. It takes a while for the rail caps to discharge through the LED. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th January 2012, 02:30 AM	#4
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	The HP/Full/LP switch was bad in this thing. Now when I run it one channel sounds terrible in high pass mode and in low pass mode it sounds worse. I've run the pots all the way down and all the way up and it still sounds just as bad. Could that be an op amp or morel likely dirty pots? __________________ Scope - DMM - 460W Computer PSU - Tutorial

25th January 2012, 05:05 AM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the channel never produces clean audio, it's not likely to be a switch. Post a photo of the distorted signal with a speaker or dummy load connected. Confirm that there is no excessive DC (no signal) before connecting the load. Have all transistors clamped. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th January 2012, 11:56 PM	#6
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	Sorry, I don't have a camera on hand yet (it's been SLOW), but I will have a friend bring one soon to take a picture of the waveform. The channel produces clean audio in full pass mode, distorted audio in LP/HP mode. The customer just informed me that the amp got wet while connected to power but not powered on, which led me to believe it was dirty pots. The distortion seems to only occur in the lower octaves (when bass plays). __________________ Scope - DMM - 460W Computer PSU - Tutorial Last edited by m4ick; 25th January 2012 at 11:59 PM.


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24th January 2012, 11:23 PM	#3
fcruz diyAudio Member Join Date: Apr 2011	I have the layout of the series of POWER ACOUSTIK OV2

26th January 2012, 12:57 AM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Check the output of each of the op-amps in the preamp section. Do any have more than a fraction of a volt of DC on their output pins? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

30th January 2012, 04:10 AM	#8
m4ick diyAudio Member Join Date: Jan 2010 Location: Gainesville, FL	I found 14.xV DC on a NJM072D but the inputs/output were not connected to any circuit. In LP mode I could plainly see the distortion. I looked at the signal on the base of the outputs and traced it back until it was clean. I found a broken solder joint on the pre amp board. I asked earlier about the power light turning off slowly. I have a same series 4 channel amp (they were a matched pair that got wet) and the power LED turns off much more quickly. Are these amps power LEDs more likely wired differently or more likely something is not discharging the rails on the 2 channel? __________________ Scope - DMM - 460W Computer PSU - Tutorial

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