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How to verify which transistor is creating protection mode?

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Take your ohm meter and measure the outputs one by one. with the power unplugged and the main board flipped to access this circuit. If they all check the same , no shorts , then You may have a preamp driver failure. Larry's Electronics ledstiles@hotmail,com

Posted on Apr 26, 2010

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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

No sound coming from speakers Blaupunkt GTA470 Amp


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.

Dec 31, 2008 | Blaupunkt PCA460 Car Audio Amplifier

1 Answer

I have an audiobahn A8000t amp with the protection light on


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.
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.

Dec 30, 2008 | AudioBahn A8000T 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

3 Answers

Sony STR-D611 receiver goes into protect mode when turned on.


I cleaned the contacts on the transistors and it's working great now. Previously, I spilled some drink on the unit and it went into protect mode and it was in the power amp section. It's all up and running again. Thanks for the info. --Steve B.

Dec 06, 2008 | Audio Players & Recorders

2 Answers

Denon AVC-A1SE in protection mode


The numbers of the transistors thay you need to replaced are on the transistor themselfs. Just take out the bad transistors and get the numbers that you need. I ALWAYS replace the output, driver and bias control transistor myself. One thing to keep in mind, if the number on the transistor starts with "A or B or C or D or K" you need to add "2S" in front of that number when you order it. Now that this problem has repeated itself, double check your wire and speaker. They can cause this problem.

Nov 09, 2008 | Audio Players & Recorders

2 Answers

600w legacy amp


9 times out of 10 if your amplifire is in protect mode and evrything externaly, like speakers, fuse, voltage, etc. checks out fine then
either you have shorted out output transistors or power mosfet transistors. Basicly that just about what happens with car amps.
It's easy enough to fix IF, IF you know what your doing. First you
need to check the output transistors with a digital volt meter on diode check, If they check out then check your power supply mosfet transistors. I can almost guarantee this is your problem. Very common. I buy non working amps all the time and repair them. Listen to pbabin also he has helped me out. Good luck

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

Sep 08, 2008 | Legacy Audio American Legacy II LA490 Car...

1 Answer

Protect Mode


Protect mode with nothing connected indicates an internal problem. Most likely one or more output transistors are shorted. This is a common problem with these and can easily be repaired by a shop for around $35 in parts plus the local labor rate. The output transistors are MN1620 and MP2488 (if memory serves me correctly).

Dan

Mar 31, 2008 | Sony STR-DE475 Receiver

2 Answers

My amp wont go past protect mode


Disconnect all speaker wires and signal cables from the amp. If it powers up (no protect light), the wiring needs to be checked. If it still shuts down (goes into protect), the amp likely has blown output transistors.

Dec 01, 2006 | Lanzar Vibe 218 Car Audio Amplifier

1 Answer

Protection mode


Driver ICs or transistors,op-amps that create the idle bias circuit,the protection circuit, the power supply. You should have a schematic of this unit and know how to check the solid state devices for shorts. GOOD lUCK

Jul 31, 2006 | AudioBahn A8000T Car Audio Amplifier

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