rockford p300-1 heating up

gmoney123 · 28th June 2010, 01:16 PM

hey i have a rockford fosgate p300-1 and it blew on me so i changed the mosfetts for ones that were compatible (similar) since the correct ones were out if stock. The tech at digikey said their shouldnt be any trouble with the replacements, but now the amp seems to heat up steadily until its blazing hot... any help?

Pano · 28th June 2010, 01:23 PM

Is this a Class-D amp?

gmoney123 · 28th June 2010, 02:10 PM

ya its a class D amp, its a 2 channel 300rms class D sub amp. Originally i had it installed by a local shop, a day later when i turned my car off after driving the amp stopped working. I took it off, opened it, the mosfetts had blown (substantially more on the main pin), so i ordered more that seemed compatible and installed them. Same problem the moment i turn off my ignition the amp blew. I decided to put a relay with a diode on the return infront of my amp and it now works without blowing up, however there is a constant heat increase until the amp feels like its going to burn up... help plz!

81bas · 02:28 PM

from description here Rockford Fosgate® - P300-1 I found it is a MONO 300w amp. With single inductor/transformer inside

I suppose it is a usual class AB amp, and you need to setup the bias (quiescent current) using this blue trimpot...

gmoney123 · 02:38 PM

ok cool, any chance i can get a step by step guide? im an electronics newbie but i know basic stuff

81bas · 28th June 2010, 03:42 PM

Hi,

it would be better to find it from the service manual, I think

Or ask it here: Car Audio - diyAudio

Pano · 28th June 2010, 04:29 PM

I also think it is class-ab, but the docs don't say. I think I'll move this to the car audio section were it will be better seen.

Perry Babin · 28th June 2010, 04:32 PM

If you set the bias pot to the fully counter-clockwise position, does it still heat up (no signal, no speakers)?

gmoney123 · 28th June 2010, 05:13 PM

just at work for another few hours but i will try and set the pot to fully counter-clockwise (off im guessing) when i get home and report back

brandes.cm · 28th June 2010, 06:16 PM

Future show stock on both the FQA28n15 and FQA36P15, these are used in the outputs of that style of amp. The power supply uses HUF75344.

28th June 2010, 01:16 PM	#1
gmoney123 diyAudio Member Join Date: Jun 2010	rockford p300-1 heating up hey i have a rockford fosgate p300-1 and it blew on me so i changed the mosfetts for ones that were compatible (similar) since the correct ones were out if stock. The tech at digikey said their shouldnt be any trouble with the replacements, but now the amp seems to heat up steadily until its blazing hot... any help?

28th June 2010, 01:23 PM	#2
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	Is this a Class-D amp? __________________ Take the Speaker Voltage Test!

28th June 2010, 02:30 PM	#5
gmoney123 diyAudio Member Join Date: Jun 2010	ok cool, any chance i can get a step by step guide? im an electronics newbie but i know basic stuff Last edited by gmoney123; 28th June 2010 at 02:38 PM.

28th June 2010, 04:29 PM	#7
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	I also think it is class-ab, but the docs don't say. I think I'll move this to the car audio section were it will be better seen. __________________ Take the Speaker Voltage Test!

28th June 2010, 04:32 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If you set the bias pot to the fully counter-clockwise position, does it still heat up (no signal, no speakers)? __________________ 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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28th June 2010, 02:10 PM	#3
gmoney123 diyAudio Member Join Date: Jun 2010	ya its a class D amp, its a 2 channel 300rms class D sub amp. Originally i had it installed by a local shop, a day later when i turned my car off after driving the amp stopped working. I took it off, opened it, the mosfetts had blown (substantially more on the main pin), so i ordered more that seemed compatible and installed them. Same problem the moment i turn off my ignition the amp blew. I decided to put a relay with a diode on the return infront of my amp and it now works without blowing up, however there is a constant heat increase until the amp feels like its going to burn up... help plz!

28th June 2010, 03:42 PM	#6
81bas diyAudio Member Join Date: Jan 2006 Location: Kiel	Hi, it would be better to find it from the service manual, I think Or ask it here: Car Audio - diyAudio

28th June 2010, 05:13 PM	#9
gmoney123 diyAudio Member Join Date: Jun 2010	just at work for another few hours but i will try and set the pot to fully counter-clockwise (off im guessing) when i get home and report back

28th June 2010, 06:16 PM	#10
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Future show stock on both the FQA28n15 and FQA36P15, these are used in the outputs of that style of amp. The power supply uses HUF75344.

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