Trying to repair MMats 3500.1

bass junkie · 16th January 2010, 09:56 PM

In the pic i have arrow pointing to one fet and diode. That diode is bad after testing all 6 diodes. The 1 fet is the only 1 shows 0.18 ohm (between G and S) dmm set to 20m ohm. The other fb4710 fets show 0 mega ohm between legs G and S.

Perry Babin · 16th January 2010, 11:21 PM

Was there a question?

bass junkie · 16th January 2010, 11:33 PM

yes your right. Did i properly test the output fets? are they dead?

Perry Babin · 17th January 2010, 02:05 AM

If you read ~0 ohms between the legs of any of the outputs, it's likely that at least one has failed and all of them (the IRFB4710s) will have to be replaced. You need to remove them to test them definitively. Replace the IC also. If the diode has failed, of course, you'll have to replace that.

If you're unsure of how to test the FETs, go to the following page and read the sections in the orange rectangles in this image (<- click).

Basic Amplifier Repair - Transistor Test Applet Link

bass junkie · 17th January 2010, 02:59 AM

Thanks for your help. Ic is it the one in the middle behind the blue caps? there are total of 4 chips do you know what their purpose is? What do you think about this amp, is it capable of 2700 rms, that is what it is rated.

bass junkie · 17th January 2010, 11:13 PM

do you repair amps?

bass junkie · 17th January 2010, 11:56 PM

just wanted to know how much it would cost to repair it.

Perry Babin · 18th January 2010, 01:34 AM

I was referring to the HIP4080 driver IC. This IC drives the output transistors.

The IC near the power supply power transformers produces the signal to drive the power supply FETs.

The LM2901 is part of the protection circuit.

The two 8 pin ICs are a buffer between the power supply driver IC and the power supply FETs.

The three 14 pin ICs near the potentiometers process the preamp level audio signal.

I repair amps but I really don't like these amps and don't want to repair it. Everyone tries to drive them into extremely low ohm loads (below what they can handle reliably) which causes them to fail. Also, in my opinion, the FETs they are driving are too much of a load for the driver IC.

bass junkie · 18th January 2010, 03:54 AM

Thanks a allot . Thats allot great information. What is the reason you hate them if i can ask ?

bass junkie · 18th January 2010, 07:08 PM

mmats d50hc still works in my car , after 1 1/2 years of abuse, wired to its normal ohm load. i always thought that the older mmats amps are more reliable then the new models.

Are there unregulated power supply amps that produce over 2k rms, that are reliable, that you can recommend.

16th January 2010, 09:56 PM	#1
bass junkie diyAudio Member Join Date: Jan 2010	Trying to repair MMats 3500.1 In the pic i have arrow pointing to one fet and diode. That diode is bad after testing all 6 diodes. The 1 fet is the only 1 shows 0.18 ohm (between G and S) dmm set to 20m ohm. The other fb4710 fets show 0 mega ohm between legs G and S.

16th January 2010, 11:21 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Was there a question? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

17th January 2010, 02:05 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If you read ~0 ohms between the legs of any of the outputs, it's likely that at least one has failed and all of them (the IRFB4710s) will have to be replaced. You need to remove them to test them definitively. Replace the IC also. If the diode has failed, of course, you'll have to replace that. If you're unsure of how to test the FETs, go to the following page and read the sections in the orange rectangles in this image (<- click). Basic Amplifier Repair - Transistor Test Applet Link __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

18th January 2010, 01:34 AM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	I was referring to the HIP4080 driver IC. This IC drives the output transistors. The IC near the power supply power transformers produces the signal to drive the power supply FETs. The LM2901 is part of the protection circuit. The two 8 pin ICs are a buffer between the power supply driver IC and the power supply FETs. The three 14 pin ICs near the potentiometers process the preamp level audio signal. I repair amps but I really don't like these amps and don't want to repair it. Everyone tries to drive them into extremely low ohm loads (below what they can handle reliably) which causes them to fail. Also, in my opinion, the FETs they are driving are too much of a load for the driver IC. __________________ 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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16th January 2010, 11:33 PM	#3
bass junkie diyAudio Member Join Date: Jan 2010	yes your right. Did i properly test the output fets? are they dead?

17th January 2010, 02:59 AM	#5
bass junkie diyAudio Member Join Date: Jan 2010	Thanks for your help. Ic is it the one in the middle behind the blue caps? there are total of 4 chips do you know what their purpose is? What do you think about this amp, is it capable of 2700 rms, that is what it is rated.

17th January 2010, 11:13 PM	#6
bass junkie diyAudio Member Join Date: Jan 2010	do you repair amps?

17th January 2010, 11:56 PM	#7
bass junkie diyAudio Member Join Date: Jan 2010	just wanted to know how much it would cost to repair it.

18th January 2010, 03:54 AM	#9
bass junkie diyAudio Member Join Date: Jan 2010	Thanks a allot . Thats allot great information. What is the reason you hate them if i can ask ?

18th January 2010, 07:08 PM	#10
bass junkie diyAudio Member Join Date: Jan 2010	mmats d50hc still works in my car , after 1 1/2 years of abuse, wired to its normal ohm load. i always thought that the older mmats amps are more reliable then the new models. Are there unregulated power supply amps that produce over 2k rms, that are reliable, that you can recommend.

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