Question about Crossfire VR402 Car Audio Amplifier

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One channel dead - found one mosfet faulty + a resistor but still not working. Where can i download the free circuit of that amp.Is parts still availibile

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Re: One channel dead - found one mosfet faulty + a...

What make/model amp do you have?

Posted on Nov 28, 2007

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Fuse apx200m

If the fuse is blowing of then there is problem with the inverter stage of amplifier. There is an inverter stage in the amplifier to boost the 12V to + or - 30 to 40V normally. Its a switching circuit normally uses Mosfets and ferrite core transformer and a driving IC. If the mosfet is shot then the fuse will blow off immediately after power is connected.

Check on thing remove the REM connection and then connect the power. If the fuse blows the there is fault with the Mosfet Its short.
If the fuse blows only when you connect the REM then the amplifier stage is faulty.

Also check by disconnecting the speakers. if any of the speaker is faulty then there is a chance for fuse blow off.


Apr 27, 2012 | Clarion APX280M 2-Channel Car Amp

2 Answers

Kicker zr600 smokin havent even bumped yet today

Well it seems to me that the pictures of this amp show green ATC fuses which would be 30 amp fuses. What is your inline fuse from the battery? 40 amp fuses for the amp is too much current for the amps powersupply. If there was a short in the powersupply the max ammount of current that it could draw would be larger than designed to handle therefore damaging the amp.

Jan 02, 2010 | Kicker ZR600 Car Audio Amplifier

1 Answer

No sound out of it, took it apart and found one of the Irfz44n mosfets burned up and the resistor right beside it burned too, What would cause this?Thanks

Hello rjhunting,

Most often the output MOSFET's and associated circuitry will burn out when the amp draws excessive current. And excessive current draw is most often caused by operating the amp into an impedance that is too low. Of course, depending on the age and actual use, the amp could have failed from normal use. The US Acoustics USX-4085 is a relatively good quality low-end amp that was manufactured with excellent components.

All of their amps manufactured after 2001 carried a 3-year warranty. But when operated in "tri-mode", with normal speakers and a subwoofer, the subwoofer minimum impedance rating was 8 ohms. And the normal speakers should be operated through a high pass capacitor while the sub needed a 15.9 mH low pass filter inductor.

The MOSFET's and resistors can probably be replaced at a qualified electronics shop. If you are somewhat handy with a soldering iron and have a controlled temperature soldering station, you can do it yourself. Parts are available from: and

Hope this helps.

Sep 27, 2009 | US Acoustics USX-4085 Car Audio Amplifier

1 Answer

The protect led has turned on and will not allow the amp to work. I've tried re-wiring the whole unit, changed the fuse to a high wattage, I've given it time to cool off in case it was over heating. Ive...

mosfet have a built in shut off incase of a blown resistor, if the resistor blows,it will shut down the amp, the resistors job is to inhibit power to prevent overheating, you will have to check the OHMS of each resistor to find out which one has gone......hope this was helpfull

Sep 15, 2009 | Pyramid PB1000 MOSFET Bridgeable Amplifier...

1 Answer

Blown channel

Its possible to repair, but you have to crack the amp open and prod around a bit. I found that the failure is usually in the power components or the MOSFET drivers. If you have 1 channel out, I would focus on the MOSFETS (if you dont know what they look like just Google MOSFET - they are the black 3-legged chips and are usually mounted to aluminum to disperse the heat). Some things to look for:
- burnt / melted solder traces (where the MOSFETS connect to the main board)
- disconnected leads (same place as above).

If you find any connection that looks suspicious, it wont hurt to re-melt the solder around the joint to make sure its a good connection.

Hope that helps...

May 08, 2009 | Car Amplifiers

1 Answer

T1500-1bd burnt mosfet

First of all is the mosfet your talking about in the output section or in the power supply section? Most car amps use mosfets in the power supply section, some use them in the output section. To test the transistors in your amp, take a digital volt meter and set it to diode check. Then take the leads and put them accross the first and third legs of the transistors. Usally the red test lead on the first leg and black test lead on the third leg of transistor. If you get a reading of 000 then transistor is shorted. If you get a reading below 600 then transistor is on it's way out if not allready or it's next to a shorted transistor that is it's complimentry output transistor. comonly you will have 2 transistors working together, one NPN and one PNP per a channel, or 4 of them in a bridged type output circuit depending on the watts and how man channels your amp has. I was just looking at the specs of this amp and it's got me confused. It says it's a 2 channel but looking at all the info on different pages it says at 4ohm:200wattsx4 and at 2ohms:300wattsx4 and 1 channel mono 600watts into 4ohms. weird for a 2 channel. anyway that is how you test your transistors. Same way for the power supply section but, you will come accross a couple or more switching diodes that look like transistors and you will get a 000 reading when you test those like I specified. They rarely go out and most of the time there is only 2 of them. They will have a diagram like a diode on the front showing you which way the power flows. Let me know what you find out. Your amp should have went to protect mode if you smoked a mosfet.

Feb 08, 2009 | Audiofonics ADF-243 Car Audio Amplifier

2 Answers


The problem is that the driver circuit is also damaged. Try powering up the unit with the output transistors disconnected. Measure each pad and report the results here. You should see something like 0.6,B+,0.0 on each set of three. Some will be negative rather than + (-0.6,B-, 0.0).

Keep us posted.

Jul 03, 2008 | Car Amplifiers

2 Answers

Blown car amp repair (Lanzar Opti 150 stereo bridgeable car amp)

its better to change them all. than to change 1 or 2 mosfets, bcuz simetimes it affects the other mosfets. and please check your speaker or maybe there is an resistor, capacitors, or a relay malfunctioning in that area.

Jan 18, 2008 | Car Amplifiers

2 Answers

Audiobahn A6004T Amp Blown PLEASE HELP!!

They are most likely a MOSFET type of transistor. If they are in the power supply part of the amp then you will probably need to replace all the MOSFET's in the power supply along with perhaps some gate control resistors for them. They each have their own resistors. It wouldn't hurt to see if the 494 IC in the power supply is working properly too. This IC is what sends the pulse width modulated square wave to the MOSFET's. Next you will want to test all the MOSFET's that are used as the audio output drivers and their predrivers and bias resistors. Don't forget to check the DC bias and offset on the outputs too, to make sure everything is OK there. In short, you will most likely need to go to a repair shop that can do all this and who would know what the heck I'm talking about. Good luck.

Mar 05, 2007 | AudioBahn A4004T Car Audio Amplifier

1 Answer

Parallel connection of power mosfets with two of 5 smoking

The IRFZ46N are n channel high speed switches . They basicly drive the Mosfets. Sounds like you have some problem there my friend, and unless you paid alot for this amp. Its going to need probobly all the n channel switches as well as every mosfet + the bias resistors repalced. Before plugging in the amp jump out the fuse with a 100 watt light bulb.. If the bulb glows brightly when you apply power there is still a short in the unit and could be in the switching power supply section of the amp. If it glows bright and dims, The shorts are most likly gone. The bulb will minimize the amount of current the unit can draw and most of the time wont let the new parts blow out. Check out this service number and see if they can help you. Good Luck Main support number 978-823-0300

Jul 26, 2006 | Pyramid PB779X Car Audio Amplifier

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