fli audio amp 900s autoprotect on ?

rob737673 · 14th April 2010, 03:27 PM

hi all, new to site but been interested in car audio since way back.my question was to see if anyone can help diagnose and possibly fix problem i.m having with my fli amp which was working fine but has now decided to stay on protection with red light. the power,remote ground are all sound and was installed professionally.i did have amp apart but made mistake of powering with board off heat sink and managed to burn out 3 fets?

(irz44n,s) which i have replaced but can anyone help with step by step checks to see if amp can be saved.thanks for reading.rob

Perry Babin · 14th April 2010, 04:40 PM

The output transistors likely failed causing the amp to go into protect. Can you post a photo of the inside of the amp?

rob737673 · 14th April 2010, 05:04 PM

thanks, trying to upload but think my file size to big what best way to import pic

rob737673 · 14th April 2010, 05:34 PM

pic

rob737673 · 14th April 2010, 05:51 PM

should the 3 fet,s blown even without heat sink? only them three went red hot ,others fine

Perry Babin · 14th April 2010, 07:03 PM

Email me the photo.
babin_perry@yahoo.com

They were more likely to fail if they weren't clamped tightly to the heatsink.

rob737673 · 14th April 2010, 09:27 PM

send it

rob737673 · 14th April 2010, 09:45 PM

the pcb board not sure which is output fet is prob cause of problem?

Perry Babin · 14th April 2010, 09:55 PM

With your multimeter set to ohms, measure the resistance between the legs of each of the output transistors (large, black, fully encapsulated components clamped to the heatsink).

If you read anything near 0 ohms between the legs of any individual transistor, it's likely shorted. Remove it from the board and re-check it.

rob737673 · 14th April 2010, 10:11 PM

did you recieve pic would they be the smaller one,s with silver face or larger all black ones. i think i had 0.65 ohm across one across 2 legs

14th April 2010, 03:27 PM	#1
rob737673 diyAudio Member Join Date: Apr 2010	fli audio amp 900s autoprotect on ? hi all, new to site but been interested in car audio since way back.my question was to see if anyone can help diagnose and possibly fix problem i.m having with my fli amp which was working fine but has now decided to stay on protection with red light. the power,remote ground are all sound and was installed professionally.i did have amp apart but made mistake of powering with board off heat sink and managed to burn out 3 fets? (irz44n,s) which i have replaced but can anyone help with step by step checks to see if amp can be saved.thanks for reading.rob

14th April 2010, 04:40 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The output transistors likely failed causing the amp to go into protect. Can you post a photo of the inside of the amp? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

14th April 2010, 07:03 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Email me the photo. babin_perry@yahoo.com They were more likely to fail if they weren't clamped tightly to the heatsink. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

14th April 2010, 09:55 PM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	With your multimeter set to ohms, measure the resistance between the legs of each of the output transistors (large, black, fully encapsulated components clamped to the heatsink). If you read anything near 0 ohms between the legs of any individual transistor, it's likely shorted. Remove it from the board and re-check it. __________________ 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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14th April 2010, 05:04 PM	#3
rob737673 diyAudio Member Join Date: Apr 2010	thanks, trying to upload but think my file size to big what best way to import pic

14th April 2010, 05:34 PM	#4
rob737673 diyAudio Member Join Date: Apr 2010	pic

14th April 2010, 05:51 PM	#5
rob737673 diyAudio Member Join Date: Apr 2010	should the 3 fet,s blown even without heat sink? only them three went red hot ,others fine

14th April 2010, 09:27 PM	#7
rob737673 diyAudio Member Join Date: Apr 2010	send it

14th April 2010, 10:11 PM	#10
rob737673 diyAudio Member Join Date: Apr 2010	did you recieve pic would they be the smaller one,s with silver face or larger all black ones. i think i had 0.65 ohm across one across 2 legs

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