I have an Mmats SQ-4070 that has a burnt MOSFET. I'm having a problem identifying the MOSFET because the number is burnt off. The other MOSFET, that I believe to be the same as the burnt one, the number is faded and no longer legible. Does anyone know what MOSFET's these are? See attached photo.
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I attached a photo of the entire board if that helps in determining how those MOSFET's are being used. I did see the exact MOSFET that are in this amp listed on ebay. Based on what you were saying about the possible replacement you mentioned, I take it I shouldn't buy those from ebay either?
About the photo, I did notice the missing capacitor.
About the photo, I did notice the missing capacitor.
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They appear to be the drivers for the power transformer. If so and it's a standard push-pull supply (can't see the windings), the 3205s will work. I can't read the value of the resistors in front of the FETs (assuming that they're gate resistors -- connected in series between the output of the driver IC and the gate leg of the power supply FET). IF they're greater than 47 ohms, replace them with 47 ohm resistors.
I found the exact MOSFET's and installed them. Also replaced all 4 of the capacitors where it was missing the one. The amp doesnot power up. As soon as I turn on the power on my power supply, the power supply goes into protection mode and shuts down. Any suggestions on what I should check on the amp?
Where did you buy the FETs from?
Are you sure that there are no shorted output transistors?
What's the current rating of the 12v power supply?
There are two things that you might try, remove the rectifiers to see if the amp will power up. Remove the power supply FETs and look at the drive signal to see if it's OK.
If there are no shorted outputs or shorted rectifiers, the transformer may be (intermittently?) shorted.
Are you sure that there are no shorted output transistors?
What's the current rating of the 12v power supply?
There are two things that you might try, remove the rectifiers to see if the amp will power up. Remove the power supply FETs and look at the drive signal to see if it's OK.
If there are no shorted outputs or shorted rectifiers, the transformer may be (intermittently?) shorted.
I'm going to check the output transistors. The output transistors in this amp are a different style than those of the other amps I worked on (Orion amps).
The power supply I'm using is the one I use to test all of my amps. I just used it to test another amp today. In fact I have a question for you about that amp... It is an old school Orion Xtreme 400.4. It powers up but produces a load buzzing sound through the speakers. Music is there too but barely audible over the buzzing sound. Only does it when the RCA's are plugged in. Already checked RCA cables, etc... They are not the problem. It is definitely something in the amp. Any ideas?
The power supply I'm using is the one I use to test all of my amps. I just used it to test another amp today. In fact I have a question for you about that amp... It is an old school Orion Xtreme 400.4. It powers up but produces a load buzzing sound through the speakers. Music is there too but barely audible over the buzzing sound. Only does it when the RCA's are plugged in. Already checked RCA cables, etc... They are not the problem. It is definitely something in the amp. Any ideas?
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