JL Audio 500/1 v1 Rev. 10 Board

RiLoWa · 20th August 2011, 10:12 PM

This amp is not passing audio. When I received it, the inputs were missing the insulators and were tightened down to the metal case grounding them out. Here is what I have on the 10 Pin connector with 14V on the B+.

1: 4.99V
2: -14.74V
3: 14.02V
4: 2.358V
5: 13.31V
6: 13.46V
7: .636V
8: 13.24V
9: 13.31V
10: 10.7mV

What do I check next?

Perry Babin · 20th August 2011, 11:39 PM

Can you find audio on any of the output pins of any of the op-amps on the preamp board?

Have you tried lifting then re-seating the preamp board a few times?

Have you tried operating all switches and pots through their entire range with signal and a speaker to see if audio ever played through?

RiLoWa · 21st August 2011, 12:48 AM

I find audio on the outputs of U1 and U3 only.

Yes & Yes to the next two questions with no improvement.
Currently low pass is off, subsonic is off and bass EQ section is off.

Perry Babin · 21st August 2011, 01:02 AM

What rev is the preamp board?

Recheck pin 4 on the 10 pin connector. It's lower than it should be.

If it's still reading less than 5v, measure the DC voltage across the points in the attached image.

RiLoWa · 21st August 2011, 01:47 AM

Preamp board is Revision 10.

Pin 4: 2.372V

If that is U400 in the lower left then I have 2.351V across those points.

Perry Babin · 21st August 2011, 01:50 AM

That's a 5.6v Zener if it's marked 5.6. It's used as a reference for some of the logic circuits so it needs to be close to its rated voltage.

What is the DC voltage on all of corner pins of U400?

RiLoWa · 21st August 2011, 01:55 AM

Yes it is marked just like your photo.

U400
Pin 1: .925V
Pin 7: 12.15V
Pin 8: 12.21V
Pin 14: .921V

Perry Babin · 21st August 2011, 02:01 AM

Those look OK so it may not be causing a problem but I'd suggest replacing it.

Does the amp produce absolutely no audio or does it produce a very low level output?

What is the DC voltage on the positive and negative speaker terminals (black probe on the amp ground)?

Do you have ±15v on the power supply pins of the op-amps just behind the input RCAs?

RiLoWa · 21st August 2011, 02:01 AM

I have another Rev. 10 preamp board BUT it is in another amp that needs it's output and power supply FETs replaced so it isn't known working. If you think we can introduce that variable, I can try it.

Perry Babin · 21st August 2011, 02:02 AM

Check the items in post #8 first.

20th August 2011, 10:12 PM	#1
RiLoWa diyAudio Member Join Date: Aug 2010 Location: Illinois	JL Audio 500/1 v1 Rev. 10 Board This amp is not passing audio. When I received it, the inputs were missing the insulators and were tightened down to the metal case grounding them out. Here is what I have on the 10 Pin connector with 14V on the B+. 1: 4.99V 2: -14.74V 3: 14.02V 4: 2.358V 5: 13.31V 6: 13.46V 7: .636V 8: 13.24V 9: 13.31V 10: 10.7mV What do I check next? __________________ Tools - 1. TPI Scope Plus 440 2. B&K 2125 20MHz Dual Trace 3. Sorensen DCR20-50B 4. B&K 4011 5MHz Function Generator 5. Weller WESD51

20th August 2011, 11:39 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Can you find audio on any of the output pins of any of the op-amps on the preamp board? Have you tried lifting then re-seating the preamp board a few times? Have you tried operating all switches and pots through their entire range with signal and a speaker to see if audio ever played through? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

21st August 2011, 12:48 AM	#3
RiLoWa diyAudio Member Join Date: Aug 2010 Location: Illinois	I find audio on the outputs of U1 and U3 only. Yes & Yes to the next two questions with no improvement. Currently low pass is off, subsonic is off and bass EQ section is off. __________________ Tools - 1. TPI Scope Plus 440 2. B&K 2125 20MHz Dual Trace 3. Sorensen DCR20-50B 4. B&K 4011 5MHz Function Generator 5. Weller WESD51

21st August 2011, 01:47 AM	#5
RiLoWa diyAudio Member Join Date: Aug 2010 Location: Illinois	Preamp board is Revision 10. Pin 4: 2.372V If that is U400 in the lower left then I have 2.351V across those points. __________________ Tools - 1. TPI Scope Plus 440 2. B&K 2125 20MHz Dual Trace 3. Sorensen DCR20-50B 4. B&K 4011 5MHz Function Generator 5. Weller WESD51

21st August 2011, 01:50 AM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	That's a 5.6v Zener if it's marked 5.6. It's used as a reference for some of the logic circuits so it needs to be close to its rated voltage. What is the DC voltage on all of corner pins of U400? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

21st August 2011, 01:55 AM	#7
RiLoWa diyAudio Member Join Date: Aug 2010 Location: Illinois	Yes it is marked just like your photo. U400 Pin 1: .925V Pin 7: 12.15V Pin 8: 12.21V Pin 14: .921V __________________ Tools - 1. TPI Scope Plus 440 2. B&K 2125 20MHz Dual Trace 3. Sorensen DCR20-50B 4. B&K 4011 5MHz Function Generator 5. Weller WESD51

21st August 2011, 02:01 AM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Those look OK so it may not be causing a problem but I'd suggest replacing it. Does the amp produce absolutely no audio or does it produce a very low level output? What is the DC voltage on the positive and negative speaker terminals (black probe on the amp ground)? Do you have ±15v on the power supply pins of the op-amps just behind the input RCAs? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

21st August 2011, 02:02 AM	#10
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Check the items in post #8 first. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Jl audio 500/1 powers on with low audio out help needed	ivkata	Car Audio	29	19th August 2011 12:21 AM
JL Audio 500.1 Part Needed	Jat40	Car Audio	1	23rd April 2011 10:30 PM
Can I run a 10 inch JL audio and a 12 inch JL audio off same amp	ash4kel	Car Audio	2	8th April 2011 02:12 AM
JL Audio 500/1	mike49504	Car Audio	1	15th August 2010 09:02 PM
jl audio 500/1	megael9	Car Audio	12	28th May 2010 11:01 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read