kicker 1200.1

timwebb · 1st June 2011, 04:19 AM

i got had a blown power supply. i replaced the drive transistors with MMBTA56.
also the 494 ic gets to warm and the drive transistors over heat.

Perry Babin · 1st June 2011, 09:53 AM

Does the amp produce rail voltage before the driver transistors overheat?

If not, do you get a square wave output on pins 9 and 10 of the 494?

timwebb · 1st June 2011, 11:35 AM

this is the signal from the 494 pin 9-10. volts div-.5 time div- 2us

timwebb · 1st June 2011, 11:38 AM

this is the signal on q11.and there are no transistors in the power supply.

Perry Babin · 1st June 2011, 02:10 PM

Which pin of Q11?

Does the same pin on Q5 look the same?

What's the DC voltage on pins 11 and 12?

timwebb · 2nd June 2011, 02:35 AM

Q11 on the emitter
pin 11 10.74
pin12-11.45

the amp goes in protect with Q5 in the circuit so i pulled it.

Perry Babin · 2nd June 2011, 10:20 AM

If that was the emitter and the base has the same signal as pins 9 and 10 on the 494, the a56 is defective.

timwebb · 5th June 2011, 01:42 AM

i pulled the drive transistor and the signal still the same.

Perry Babin · 5th June 2011, 02:56 AM

Replace the driver transistor with a new MMBTA56.

timwebb · 5th June 2011, 06:00 PM

ok i did now im getting 1v on the gate resistor.for q11
q5 is getting 5v at the gate resistor. i cant find what is pulling Q11 down.

1st June 2011, 09:53 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Does the amp produce rail voltage before the driver transistors overheat? If not, do you get a square wave output on pins 9 and 10 of the 494? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

1st June 2011, 02:10 PM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Which pin of Q11? Does the same pin on Q5 look the same? What's the DC voltage on pins 11 and 12? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

2nd June 2011, 10:20 AM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If that was the emitter and the base has the same signal as pins 9 and 10 on the 494, the a56 is defective. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

5th June 2011, 02:56 AM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Replace the driver transistor with a new MMBTA56. __________________ 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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2nd June 2011, 02:35 AM	#6
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	Q11 on the emitter pin 11 10.74 pin12-11.45 the amp goes in protect with Q5 in the circuit so i pulled it.

5th June 2011, 01:42 AM	#8
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	i pulled the drive transistor and the signal still the same.

5th June 2011, 06:00 PM	#10
timwebb diyAudio Member Join Date: Jan 2010 Location: memphis tn	ok i did now im getting 1v on the gate resistor.for q11 q5 is getting 5v at the gate resistor. i cant find what is pulling Q11 down.

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