When fixing mosfet amps...
1) You need to have a "static strap" on to ground yourself and eliminate static charges. You can build up thousands of transistor-killing volts just by the friction of your butt on the chair (no joke). No sense going to the trouble to replace parts, only to blow them with static as you do it.
2) If at least a couple outputs in a group are bad, it is usually simpler and cheaper to replace all the outputs in the group along with everything else that connects to them, especially all semiconductors, than it is to try to figure out which exact ones are bad.
3) If you have bad outputs, ALWAYS replace all the associated protection parts. Don't bother testing.
4) if you have bad outputs, always replace the associated 47 ohm gate resistors. Don't bother testing. These parts are "flameproof" types, should be available from Digikey.
5) It is a good idea to replace semiconductors one "level" farther out away from the bad output parts than you think you need to. Smaller parts are cheap insurance against blowing the thing due to bad parts that you assumed were good. *
6) You can often run the amp without the outputs (no load, of course) by temporarily "jumpering" the driver stage to the output before the new outputs are installed. This will show if the amp is ready to swing full voltage and prove out all the other stuff aside from the outputs and protection circuits.
7) Not all bad channels are due to blown mosfets. Check first before assuming that outputs are bad.
As for matched parts, outputs, etc. I don't know who has matched /grouped parts, but I have heard that they are for sale from various sources. You *can* match your own if you are reasonably electronically savvy.... and don't mind buying a bunch more than you will need. I certainly can't guarantee what anyone has done in terms of grouping parts for sale...... they MAY know what they are doing, or they may NOT.
Non-matched raw parts may be available from Digikey or Mouser, Future electronics, etc.
Other parts same sources.
Unless you are fairly electronically knowledgeable, it is likely to be easier and maybe cheaper to take it to a tech. However, checking the unit for obvious issues first is a good plan, even if only to "debug" what the tech says.
* I had a tech build one of the first protos of our mosfet amps. He made a few mistakes when stuffing the boards (I was on vacation) and managed to blow up ALL the very scarce sample parts I had scrounged up, by replacing ONLY what he knew was bad each time, and not even looking any farther before turning on the power again. I was NOT amused at what had happened to my schedule .................
1) You need to have a "static strap" on to ground yourself and eliminate static charges. You can build up thousands of transistor-killing volts just by the friction of your butt on the chair (no joke). No sense going to the trouble to replace parts, only to blow them with static as you do it.
2) If at least a couple outputs in a group are bad, it is usually simpler and cheaper to replace all the outputs in the group along with everything else that connects to them, especially all semiconductors, than it is to try to figure out which exact ones are bad.
3) If you have bad outputs, ALWAYS replace all the associated protection parts. Don't bother testing.
4) if you have bad outputs, always replace the associated 47 ohm gate resistors. Don't bother testing. These parts are "flameproof" types, should be available from Digikey.
5) It is a good idea to replace semiconductors one "level" farther out away from the bad output parts than you think you need to. Smaller parts are cheap insurance against blowing the thing due to bad parts that you assumed were good. *
6) You can often run the amp without the outputs (no load, of course) by temporarily "jumpering" the driver stage to the output before the new outputs are installed. This will show if the amp is ready to swing full voltage and prove out all the other stuff aside from the outputs and protection circuits.
7) Not all bad channels are due to blown mosfets. Check first before assuming that outputs are bad.
As for matched parts, outputs, etc. I don't know who has matched /grouped parts, but I have heard that they are for sale from various sources. You *can* match your own if you are reasonably electronically savvy.... and don't mind buying a bunch more than you will need. I certainly can't guarantee what anyone has done in terms of grouping parts for sale...... they MAY know what they are doing, or they may NOT.
Non-matched raw parts may be available from Digikey or Mouser, Future electronics, etc.
Other parts same sources.
Unless you are fairly electronically knowledgeable, it is likely to be easier and maybe cheaper to take it to a tech. However, checking the unit for obvious issues first is a good plan, even if only to "debug" what the tech says.
* I had a tech build one of the first protos of our mosfet amps. He made a few mistakes when stuffing the boards (I was on vacation) and managed to blow up ALL the very scarce sample parts I had scrounged up, by replacing ONLY what he knew was bad each time, and not even looking any farther before turning on the power again. I was NOT amused at what had happened to my schedule .................
