Lightning audio in protect. Checked usuals

Justinh722 · 21st September 2011, 10:32 PM

I got a Lightning audio LA1.150.2 amp that I'm checking out for a friend. I unsoldered all the power FETS and output fets and tested them out of board and the outputs came back with .303 volts. I had another amp laying around with the same outputs that tested good and used those. I unsoldered 4 driver transistors by the IC and they all tested fine. I tested the gate resistor and it too tested fine.

I'm not sure what else to test. I have been reading Perry's BCAE1.com site to double check a lot of things. If anyone has any ideas, I'd appreciate the help. Thanks

Perry Babin · 21st September 2011, 10:45 PM

The protection circuit may be damaged.

If the outputs were FETs, they could read 0.3 if they're not checked in the right way.

Contact Lighting to get the schematic diagram and send me a copy.
babin_perry@yahoo.com

Justinh722 · 21st September 2011, 11:59 PM

The FET's are IRFZ46N transistors. I checked them out of the board the same way I checked the IRFZ46N's that I had removed from another amp and .3 seemed a little low. All the other FET's in the other amp measured .6 volts. I'll get a hold of lightning audio and see if they will send me a schematic.

I have a memphis amp where the gate resistors melted the board and I can't find where the traces are. I emailed memphis and they wouldn't give up a schematic. Hopefully I can get one from Lightning Audio. Thanks for the help

Perry Babin · 22nd September 2011, 01:33 AM

The Z46s are likely the power supply FETs, not the output transistors. If you don't discharge the gate, they can pass current which will make them appear to be defective. That's why I recommend shorting the gate to the source when testing.

Lightning has, in the past, supplied schematic diagrams for their amps.

If you have a question about a Memphis amp, start a new thread.

Justinh722 · 22nd September 2011, 01:37 AM

I did have a thread open in the class D section but didn't get many replies. I'll email lightning audio and get back to you. Thanks.

Perry Babin · 22nd September 2011, 01:40 AM

The class D forum is mainly for people building class D amplifiers. If it's a class D car amp, you would need to post the question here.

Justinh722 · 22nd September 2011, 01:44 AM

Thanks for clearing that up. I was a little confused on where to post.

Justinh722 · 24th September 2011, 04:40 AM

After waiting forever for Lightning Audio to reply to my inquiry, they said they don't service those units and they don't have a schematic on hand.

Perry Babin · 24th September 2011, 04:48 AM

You'll need to post good quality photos of the inside of the amp. If you need help taking good quality photos read this:
Basic Amplifier Repair

Justinh722 · 24th September 2011, 05:33 AM

I took a few pics. I'm not sure on the quality and where I was suppose to focus on but here they are.

21st September 2011, 10:32 PM	#1
Justinh722 diyAudio Member Join Date: Sep 2009 Location: Iowa	Lightning audio in protect. Checked usuals I got a Lightning audio LA1.150.2 amp that I'm checking out for a friend. I unsoldered all the power FETS and output fets and tested them out of board and the outputs came back with .303 volts. I had another amp laying around with the same outputs that tested good and used those. I unsoldered 4 driver transistors by the IC and they all tested fine. I tested the gate resistor and it too tested fine. I'm not sure what else to test. I have been reading Perry's BCAE1.com site to double check a lot of things. If anyone has any ideas, I'd appreciate the help. Thanks

21st September 2011, 10:45 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The protection circuit may be damaged. If the outputs were FETs, they could read 0.3 if they're not checked in the right way. Contact Lighting to get the schematic diagram and send me a copy. babin_perry@yahoo.com __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

22nd September 2011, 01:33 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The Z46s are likely the power supply FETs, not the output transistors. If you don't discharge the gate, they can pass current which will make them appear to be defective. That's why I recommend shorting the gate to the source when testing. Lightning has, in the past, supplied schematic diagrams for their amps. If you have a question about a Memphis amp, start a new thread. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

22nd September 2011, 01:40 AM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The class D forum is mainly for people building class D amplifiers. If it's a class D car amp, you would need to post the question here. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

24th September 2011, 04:48 AM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	You'll need to post good quality photos of the inside of the amp. If you need help taking good quality photos read this: Basic Amplifier Repair __________________ 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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21st September 2011, 11:59 PM	#3
Justinh722 diyAudio Member Join Date: Sep 2009 Location: Iowa	The FET's are IRFZ46N transistors. I checked them out of the board the same way I checked the IRFZ46N's that I had removed from another amp and .3 seemed a little low. All the other FET's in the other amp measured .6 volts. I'll get a hold of lightning audio and see if they will send me a schematic. I have a memphis amp where the gate resistors melted the board and I can't find where the traces are. I emailed memphis and they wouldn't give up a schematic. Hopefully I can get one from Lightning Audio. Thanks for the help

22nd September 2011, 01:37 AM	#5
Justinh722 diyAudio Member Join Date: Sep 2009 Location: Iowa	I did have a thread open in the class D section but didn't get many replies. I'll email lightning audio and get back to you. Thanks.

22nd September 2011, 01:44 AM	#7
Justinh722 diyAudio Member Join Date: Sep 2009 Location: Iowa	Thanks for clearing that up. I was a little confused on where to post.

24th September 2011, 04:40 AM	#8
Justinh722 diyAudio Member Join Date: Sep 2009 Location: Iowa	After waiting forever for Lightning Audio to reply to my inquiry, they said they don't service those units and they don't have a schematic on hand.

24th September 2011, 05:33 AM	#10
Justinh722 diyAudio Member Join Date: Sep 2009 Location: Iowa	I took a few pics. I'm not sure on the quality and where I was suppose to focus on but here they are.

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