Rockford fosgate 550x

mike49504 · 9th June 2011, 11:30 PM

I replaced the outputs in 2 of the channels. Also replaced the following transistors

Q105
Q106
Q112
Q113
Q114
Q115
Q116
Q117

I also checked all the 10 ohm gate resistors on the outputs i replaced.

Amp still draws excessive current But when i remove the outputs out of the 2 channels that were bad the amp powers up perfectly..

Any ideas?

seankane · 10th June 2011, 12:22 AM

Do you have any DC on the output bridging terminals?

seankane · 10th June 2011, 12:25 AM

I am sure you have some faulty smd resistors and smd bjt's. I dont have a schematic but have a similair 4 channels amp I had the same issues with and was able to figure it out.

mike49504 · 10th June 2011, 03:10 AM

Ok got the excessive current draw to go away..

Wondering what 2 transistors i pull to see if the distortion goes away on 1 channel?

Perry Babin · 10th June 2011, 03:28 AM

Bias pots fully CCW?

mike49504 · 10th June 2011, 03:32 AM

Yes I get distortion is only 1 channel other 3 channels work perfectly..

I cleaned all switches and pots

Perry Babin · 10th June 2011, 03:37 AM

What series parts are in the distorted channel?

mike49504 · 10th June 2011, 03:39 AM

200 series

Perry Babin · 10th June 2011, 03:44 AM

Can you post an image of the distorted waveform with a speaker load?

mike49504 · 10th June 2011, 03:47 AM

Ill have to wait on that for a lil bit havent got to the store yet to buy another camera

9th June 2011, 11:30 PM	#1
mike49504 diyAudio Member Join Date: Sep 2006	Rockford fosgate 550x I replaced the outputs in 2 of the channels. Also replaced the following transistors Q105 Q106 Q112 Q113 Q114 Q115 Q116 Q117 I also checked all the 10 ohm gate resistors on the outputs i replaced. Amp still draws excessive current But when i remove the outputs out of the 2 channels that were bad the amp powers up perfectly.. Any ideas?

10th June 2011, 12:22 AM	#2
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Do you have any DC on the output bridging terminals? __________________ Pyramid 46 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch

10th June 2011, 12:25 AM	#3
seankane diyAudio Member Join Date: May 2010 Location: Washington State	I am sure you have some faulty smd resistors and smd bjt's. I dont have a schematic but have a similair 4 channels amp I had the same issues with and was able to figure it out. __________________ Pyramid 46 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch

10th June 2011, 03:28 AM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Bias pots fully CCW? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

10th June 2011, 03:37 AM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What series parts are in the distorted channel? __________________ 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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10th June 2011, 03:10 AM	#4
mike49504 diyAudio Member Join Date: Sep 2006	Ok got the excessive current draw to go away.. Wondering what 2 transistors i pull to see if the distortion goes away on 1 channel?

10th June 2011, 03:32 AM	#6
mike49504 diyAudio Member Join Date: Sep 2006	Yes I get distortion is only 1 channel other 3 channels work perfectly.. I cleaned all switches and pots

10th June 2011, 03:39 AM	#8
mike49504 diyAudio Member Join Date: Sep 2006	200 series

10th June 2011, 03:44 AM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Can you post an image of the distorted waveform with a speaker load? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

10th June 2011, 03:47 AM	#10
mike49504 diyAudio Member Join Date: Sep 2006	Ill have to wait on that for a lil bit havent got to the store yet to buy another camera

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