MTX Thunder 81001 - Page 2

mike49504 · 16th February 2012, 03:17 AM

Ok i dont know why i didnt catch this before..

All outputs test fine But i have full rail voltage on the output terminals

123.6 volts...

Any ideas?

mike49504 · 02:39 PM

I found some shorted transistors resistors and a diode..

Anyone have a high res pic of the area Around the rectifiers ??

I need the side containing D105,Q109,Q11 ect..

This is right behind the rca inputs

Perry Babin · 16th February 2012, 10:20 PM

See attached.

That is the -15v regulator.

mike49504 · 17th February 2012, 01:48 AM

R127 is a 5.11K resistor its measuring 5.42K is that close enough to the tolerance or should i change it ?

mike49504 · 17th February 2012, 03:42 AM

Ok i replaced the following components:

D105
R119
R123
R127
Q109
Q111
Q108
R122

All of theese were defective..

Should i check anything else before powering it up?

Also Do you have an idea on why all of theese were defective ? Seems like alot of parts were bad in this one area

mike49504 · 17th February 2012, 03:59 AM

Ok I powerd it up and the for service only lite it still on..

I have 8.95 volts of DC across the output terminals Any ideas?

Perry Babin · 17th February 2012, 06:17 AM

The service LED indicate that the caps are charged. Post the DC voltage on both of the op-amps near the opto-couplers.

mike49504 · 17th February 2012, 01:04 PM

NE5532D

Pin 1:2.02
Pin 2:8.48
Pin 3:8.40
Pin 4:6.94
Pin 5:1.73
Pin 6:8.55
Pin 7:9.10
Pin 8:15.67

NE5532D

Pin 1:15.56
Pin 2:13.99
Pin 3:14.35
Pin 4:6.95
Pin 5:14.50
Pin 6:14.04
Pin 7:15.42
Pin 8:15.72

Perry Babin · 17th February 2012, 01:56 PM

No negative supply.

mike49504 · 17th February 2012, 02:44 PM

On the non stripped side of D105 i have -15 volts

On the other side i have 0 volts

Directly across D105 i have - 15 volts

So do i need to follow the traces abck to see where im losing the -15 volts ?

16th February 2012, 02:29 PM	#12
mike49504 diyAudio Member Join Date: Sep 2006	I found some shorted transistors resistors and a diode.. Anyone have a high res pic of the area Around the rectifiers ?? I need the side containing D105,Q109,Q11 ect.. This is right behind the rca inputs Last edited by mike49504; 16th February 2012 at 02:39 PM.

17th February 2012, 06:17 AM	#17
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The service LED indicate that the caps are charged. Post the DC voltage on both of the op-amps near the opto-couplers. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

17th February 2012, 01:56 PM	#19
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	No negative supply. __________________ 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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16th February 2012, 03:17 AM	#11
mike49504 diyAudio Member Join Date: Sep 2006	Ok i dont know why i didnt catch this before.. All outputs test fine But i have full rail voltage on the output terminals 123.6 volts... Any ideas?

17th February 2012, 01:48 AM	#14
mike49504 diyAudio Member Join Date: Sep 2006	R127 is a 5.11K resistor its measuring 5.42K is that close enough to the tolerance or should i change it ?

17th February 2012, 03:42 AM	#15
mike49504 diyAudio Member Join Date: Sep 2006	Ok i replaced the following components: D105 R119 R123 R127 Q109 Q111 Q108 R122 All of theese were defective.. Should i check anything else before powering it up? Also Do you have an idea on why all of theese were defective ? Seems like alot of parts were bad in this one area

17th February 2012, 03:59 AM	#16
mike49504 diyAudio Member Join Date: Sep 2006	Ok I powerd it up and the for service only lite it still on.. I have 8.95 volts of DC across the output terminals Any ideas?

17th February 2012, 01:04 PM	#18
mike49504 diyAudio Member Join Date: Sep 2006	NE5532D Pin 1:2.02 Pin 2:8.48 Pin 3:8.40 Pin 4:6.94 Pin 5:1.73 Pin 6:8.55 Pin 7:9.10 Pin 8:15.67 NE5532D Pin 1:15.56 Pin 2:13.99 Pin 3:14.35 Pin 4:6.95 Pin 5:14.50 Pin 6:14.04 Pin 7:15.42 Pin 8:15.72

17th February 2012, 02:44 PM	#20
mike49504 diyAudio Member Join Date: Sep 2006	On the non stripped side of D105 i have -15 volts On the other side i have 0 volts Directly across D105 i have - 15 volts So do i need to follow the traces abck to see where im losing the -15 volts ?

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