JL Audio 1000/1

Dr Zeus · 9th January 2011, 04:00 PM

I got this amp in for repair, and after loking at it for while I decided to give it a shot and fix it. The amp powers up but the output terminals have a +-15v triangular wave on them. After about 10 seconds of being powered on the resistor area near the two yellow transformers started smoking.

This area close to the output terminals appears to have damaged about 4 resistors. 3 large blue reisstors (one disintegrated completely) and one smaller white 5ohm resistor.

I measured all the majority of the TO-220 transistors and they seem to be OK. Then I found Q511 to be measuring in-appropriatly between legs 1-2 (measuring 25 Ohms). Unfortunately I defaced some of the numbers with the tool shown and all I can make out is 111, then F0348AD. There doesnt seem to be any other transistors on the board to match this one so Im not sure what it is.

I'm also not sure of the values for all the large resistors; The one that looks like a hamburger is measuring 79k, and the one above it is measuring 21M ohms. The one that looks like a burnt marshmellow is measuring 5Ohms but one of it's legs broke and needs replacing.

Perry Babin · 9th January 2011, 04:24 PM

Q511 is likely a J111. It's likely OK. This is covered on the 'Checking Semiconductors' page, item #6.

The resistors in front of the inductors are 5 ohms.

Clean the soot off of the inductors. Is there any signs of overheating?

Dr Zeus · 05:03 PM

I just read that about Junction transsitors about a week ago too... I'll put the J111 back in.

The two inducors which somewhat survived both have slight bulging and signs of melting but it may have been from C514's demise which was the one which disintegrated. The one which is marked 106k100 is measuring 22M Ohms, and the one marked 685J160 is measuring 80k Ohms.

C514 disintegrated
C515 is marked 106K100
C516 is marked 686J160

Dr Zeus · 9th January 2011, 04:59 PM

Also, the amp's top cover has a few signs of spots which probably didnt short; but may have been areas subjected to soot from overheating. The area on the bottom right of this photo is where the bass boost control sits over.

Dr Zeus · 06:24 PM

I cleaned up the PCB a bit and the amp looks better to work with now. With the inducers and resistor removed, the amp powers and is steady with about an 8A draw. The outputs on the scope are a +-60vAC sin wave. The amp seems to be stable enough for me to test things while powered on at this point.

The 2068 opAmps are getting +-13vDC

Dr Zeus · 9th January 2011, 11:59 PM

I cant quite figure this amp out. It sems to be very complex in it's design. Reading through information on a JL 500/1, Im trying to troubleshoot through the 10 pin terminal on the plug-in board.

Pin 1: 0 (Ground)
Pin 2: -13.8
Pin 3: 12.3
Pin 4: 11.04
Pin 5: 0.289
Pin 6: 13.15
Pin 7: ~0.728
Pin 8: ~0.420
Pin 9: 12.97
Pin 10: 0 (Ground)

Dr Zeus · 10th January 2011, 12:07 AM

The voltages onthe back of the power supply board match up what they should be.

Dr Zeus · 10th January 2011, 12:23 AM

Pin 7 of the small yellow transformer does not appear to be what it should. Its a waveform exactly like Pin 6 when it should be -0-.

Also Pin 4 looks like Pin 2, and Pin 5 has -0- on it at all but should look like Pin 4 is not.

Perry Babin · 10th January 2011, 07:36 AM

Have you replaced all of the burned parts?

You can't expect it to work properly with all of those parts missing.

Dr Zeus · 10th January 2011, 12:34 PM

OK I'll follow up after I replace the parts. Thanks

9th January 2011, 04:00 PM	#1
Dr Zeus diyAudio Member Join Date: Oct 2010	JL Audio 1000/1 I got this amp in for repair, and after loking at it for while I decided to give it a shot and fix it. The amp powers up but the output terminals have a +-15v triangular wave on them. After about 10 seconds of being powered on the resistor area near the two yellow transformers started smoking. This area close to the output terminals appears to have damaged about 4 resistors. 3 large blue reisstors (one disintegrated completely) and one smaller white 5ohm resistor. I measured all the majority of the TO-220 transistors and they seem to be OK. Then I found Q511 to be measuring in-appropriatly between legs 1-2 (measuring 25 Ohms). Unfortunately I defaced some of the numbers with the tool shown and all I can make out is 111, then F0348AD. There doesnt seem to be any other transistors on the board to match this one so Im not sure what it is. I'm also not sure of the values for all the large resistors; The one that looks like a hamburger is measuring 79k, and the one above it is measuring 21M ohms. The one that looks like a burnt marshmellow is measuring 5Ohms but one of it's legs broke and needs replacing.

9th January 2011, 04:24 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Q511 is likely a J111. It's likely OK. This is covered on the 'Checking Semiconductors' page, item #6. The resistors in front of the inductors are 5 ohms. Clean the soot off of the inductors. Is there any signs of overheating? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

9th January 2011, 04:49 PM	#3
Dr Zeus diyAudio Member Join Date: Oct 2010	I just read that about Junction transsitors about a week ago too... I'll put the J111 back in. The two inducors which somewhat survived both have slight bulging and signs of melting but it may have been from C514's demise which was the one which disintegrated. The one which is marked 106k100 is measuring 22M Ohms, and the one marked 685J160 is measuring 80k Ohms. C514 disintegrated C515 is marked 106K100 C516 is marked 686J160 Last edited by Dr Zeus; 9th January 2011 at 05:03 PM.

9th January 2011, 06:09 PM	#5
Dr Zeus diyAudio Member Join Date: Oct 2010	I cleaned up the PCB a bit and the amp looks better to work with now. With the inducers and resistor removed, the amp powers and is steady with about an 8A draw. The outputs on the scope are a +-60vAC sin wave. The amp seems to be stable enough for me to test things while powered on at this point. The 2068 opAmps are getting +-13vDC Last edited by Dr Zeus; 9th January 2011 at 06:24 PM.

10th January 2011, 07:36 AM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Have you replaced all of the burned parts? You can't expect it to work properly with all of those parts missing. __________________ 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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9th January 2011, 04:59 PM	#4
Dr Zeus diyAudio Member Join Date: Oct 2010	Also, the amp's top cover has a few signs of spots which probably didnt short; but may have been areas subjected to soot from overheating. The area on the bottom right of this photo is where the bass boost control sits over.

9th January 2011, 11:59 PM	#6
Dr Zeus diyAudio Member Join Date: Oct 2010	I cant quite figure this amp out. It sems to be very complex in it's design. Reading through information on a JL 500/1, Im trying to troubleshoot through the 10 pin terminal on the plug-in board. Pin 1: 0 (Ground) Pin 2: -13.8 Pin 3: 12.3 Pin 4: 11.04 Pin 5: 0.289 Pin 6: 13.15 Pin 7: ~0.728 Pin 8: ~0.420 Pin 9: 12.97 Pin 10: 0 (Ground)

10th January 2011, 12:07 AM	#7
Dr Zeus diyAudio Member Join Date: Oct 2010	The voltages onthe back of the power supply board match up what they should be.

10th January 2011, 12:23 AM	#8
Dr Zeus diyAudio Member Join Date: Oct 2010	Pin 7 of the small yellow transformer does not appear to be what it should. Its a waveform exactly like Pin 6 when it should be -0-. Also Pin 4 looks like Pin 2, and Pin 5 has -0- on it at all but should look like Pin 4 is not.

10th January 2011, 12:34 PM	#10
Dr Zeus diyAudio Member Join Date: Oct 2010	OK I'll follow up after I replace the parts. Thanks

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