Question about Legacy 600 WATT 2 Channel MOSFET LA470 Car Amp Car Audio Amplifier

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Protect LED on

The Protect LED is on and of course there is no output. My guess is one, or more, of the power transistors or one of the MOSFETs is gone. Can anyone give me an idea as to how to check any of the above while still in the circuit? I have the pin outs for the 2 different types of transistors and the 2 MOSFETs. I'm not sure what to look for though. Thanks

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This is a basic procedeur just look for any short between pins of each component.

Posted on Aug 09, 2007

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Posted on Jan 02, 2017

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Hooking up the amp i had the ground wire connected and was going to hook up the power wire and it hit the case of the amp know the amp turns on but there is no sound from the speakers other amps work on...


sadly, your amps' output MOSFETS are more than likely toast.

your amp was grounded, and you touched the amp chassis with the power line.
electricity will follow any path available to find ground. in your case, the output mosfets became your main ground-path since they are directly connected to the amps chassis (heat sink) and internally you had grounded the amp so power would flow full force through the output transistors in the serach for a ground.

open up your amp and smell the row of MOSFET transistors. you'll probably even be able to see some burnt transistor legs.

repair or replace.

May 08, 2011 | Kenwood KAC-7202 Car Audio Amplifier

1 Answer

Amp is in protect mode


If you have'nt fixed your amp by now I thought I'd tell ya a couple of things why it's going into protect. The basics. Blown subs, bad power suply or mosfets, and blown output transistors/mosfets. Still need help let me know. I repair amps for a living and i'm the cheapest you'll find and honest. I also give the longest warranty. I'm tired of other people rippin people off on repairs. Let me know.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/mark_b53a7494531bf96d

Apr 24, 2010 | MA Audio HK401SX Car Audio Amplifier

1 Answer

What is the power output in a power amp and is it expensive


the output transistors are 5 to 10 bucks each for most.there are 2 or 4 on each channel,depending on brand .some high end amps have 10 transistors on each channel.mosfets are a different story as they run 20 to 50 bucks each and there is 2 or 4 on each channel.some amps use a big IC instead of transistors.those have 16 to 24 pins and are easy to change. Those IC are 25 to 75 for a stereo one like stk4141 etc.since most yamaha amps are dc coupled,when the output transistors go,they take out the driver transistors as well.If you replace the outputs and the drive transistors are shorted,they will blow the outputs again.

Apr 14, 2010 | Yamaha P3500S Amplifier

1 Answer

The amp is on lock mode and i do not know how to take it off


Hello, Could you please specify what type of clarion amp you have and what happend prior to the problem? I don't know what you mean by lock mode unless it has some security feature or you mean it's in protect mode. If it's in protect mode more thanlikely you have power supply mosfets shorted or output transistors shorted. If all wiring and speakers are good and your head unit. Let me know.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/mark_b53a7494531bf96d

Aug 25, 2009 | Clarion Car Audio & Video

1 Answer

Sony xplod 1200 watt amp quit no kind of protect lite on please


short answer yes... Long answer... Amp Failure: There are many different ways that an amp can fail but the two most common failures are shorted output transistors and blown power supply transistors (< those are not blown). There are several types of protection circuits in amplifiers. The most common are over-current and thermal. The over-current protection is supposed to protect the output transistors. Sometimes it doesn't work well enough to prevent the failure of the output transistors but it will work well enough to shut the supply down before the power supply FETs are destroyed. If the amp remains in protect mode, goes into protect mode or blows the fuse as soon as the remote voltage is applied, shorted output transistors are almost certainly the cause. If the fuse protecting the amp is too large, if the protection circuit doesn't respond quickly enough or if the power supply is poorly designed, the power supply transistors may fail. If you see a lot of black soot on the power supply transistors (near the power transformer), the power supply transistors have failed. Soot on the board doesn't necessarily mean the transistors have failed. Sometimes, technicians don't clean up the mess from a previous failure. Transistor Failure/Checking Transistors: In general, when a transistor fails, it will either short (common for output AND power supply transistors) or open (common for power supply transistors). Transistors act like valves. They control the current flowing through a circuit. A shorted transistor acts like a valve that's stuck open (passing too much current). In the case of an output transistor, the shorted transistors tries to deliver the full rail voltage to the speaker output terminal. If you've ever seen a damaged amp that pushed or pulled the speaker cone to its limits when the amp powered up (common on some Rockford amplifiers), that was almost certainly due to a shorted output transistor. When checking transistors, you most commonly look for shorted connections inside the transistor. You do this by using a multimeter to look for low resistance connections between the transistor's terminals. Note: I used the terms short and open on the previous paragraph. A short (short circuit) is a path through which current flows that should not be there. An open (open circuit) is a break in the circuit. It is most likely the power supply that has taken a ****.

Jan 01, 2009 | Sony Xplod XM-1652Z Car Audio Amplifier

1 Answer

Amp turns on just fine but no sound comes out


Amp Failure:
There are many different ways that an amp can fail but the two most common failures are shorted output transistors and blown power supply transistors (< those are not blown). There are several types of protection circuits in amplifiers. The most common are over-current and thermal. The over-current protection is supposed to protect the output transistors. Sometimes it doesn't work well enough to prevent the failure of the output transistors but it will work well enough to shut the supply down before the power supply FETs are destroyed. If the amp remains in protect mode, goes into protect mode or blows the fuse as soon as the remote voltage is applied, shorted output transistors are almost certainly the cause. If the fuse protecting the amp is too large, if the protection circuit doesn't respond quickly enough or if the power supply is poorly designed, the power supply transistors may fail. If you see a lot of black soot on the power supply transistors (near the power transformer), the power supply transistors have failed. Soot on the board doesn't necessarily mean the transistors have failed. Sometimes, technicians don't clean up the mess from a previous failure. Transistor Failure/Checking Transistors:
In general, when a transistor fails, it will either short (common for output AND power supply transistors) or open (common for power supply transistors). Transistors act like valves. They control the current flowing through a circuit. A shorted transistor acts like a valve that's stuck open (passing too much current). In the case of an output transistor, the shorted transistors tries to deliver the full rail voltage to the speaker output terminal. If you've ever seen a damaged amp that pushed or pulled the speaker cone to its limits when the amp powered up (common on some Rockford amplifiers), that was almost certainly due to a shorted output transistor. When checking transistors, you most commonly look for shorted connections inside the transistor. You do this by using a multimeter to look for low resistance connections between the transistor's terminals.

Seems as you have blown an output. Seek repairs.

Dec 29, 2008 | Power Acoustik A3000DB Car Audio Amplifier

1 Answer

Power On + red LED turns on + but final relay (click) don't come so no sound


Your audio output transistors are shorted and your unit is staying in "protect " mode to protect your speakers from 40 to 60 volts that is being sent at them from the shorted outputs. If you can use a meter you won't need the schematic MOST likely because the outputs are USUALLY the only parts that short out. The output transistors( or chip ) are mounted to the large, finned heatsink. The #'s on the transistors start with "2SA-" and "2SC-" followed by numbers. There are two output transistors per channel. If your unit uses an IC for audio output then the # on the IC will be "STK-" followed by numbers. These parts are available from tritronicsinc.com. Good Luck!

barneyluc

Oct 17, 2008 | Denon PMA-2000R 2-Channel Amplifier

2 Answers

Hifonics Taurus circuit diagra???


You need to measure the voltages at the output transistors. The previous "driver" stage may have a problem. These outputs use .6V as the bias differential. Check for DC voltage on the inputs to the transistors. These are standard designs. I'd check for DC anywhere along the signal path.
Dan

Apr 09, 2008 | Hifonics Brutus BX 1505D Car Audio...

3 Answers

El1500 turns on but so sound


Hello fordguy, love the name i'm a ford man myself if thats why you chose it. Anyway to the amp. I buy broken amps all the time from E-bay and find which parts are bad order them and replace them and the amps work great. I just bought and recieved the same amp, Bazooka EL1500 and right away when I put power to it the protect light came on. Let me tell ya a little about car amps and the mostly the main reason they go into protect mode. First it could be something small and stupid like a fuse, sometimes amps protect light will still come on even if fuse is blown. Maybe something inside is touching something else causing it to go in to protect mode like lets say a small peice of solder is connecting to solder traces together or whatever, you get the idea. Second and this is I'd say 80% of all protect lights coming on. You either have shorted out output transistors or powersupply mosfets transistors. This is mainly the cause of this all the time. Sometimes though it's not and you have to do further testing. With your amp, I don't know what was going on at the time of when it quit. The capacitor you speak of is fine it's just the protective shrink looks melted cause thats how it was done when amp was made. You need to test all output transistors and power supply mosfets with a digital volt meter set on diode check. Let me know what you find and itf you need help just opost a comment asking for my e-mail and I will taake you thru the steps. If this helps, please rate it so I can get out of this apprentice status.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/mark_b53a7494531bf96d

Feb 02, 2007 | Bazooka EL1500 Car Audio Amplifier

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