I’ve recently repaired this amp but I find an occurrence I want to confirm, IRFB5620 are the output and a cross of IRFB4227 was referred as sub, after installed they got hot and no drive waveform, I swapped to another working channel and still warmed. Nothing else was damaged in the amp just one bad output. It was when I purchased the IRFB5620 then the amp worked.
Another puzzling problem is whenever I pulled the output from any one channel, the adjoining channel won’t produce any waveform regardless of four “independent seeming” channels (that is 1 or 2 and 3 or 4). Therefore, if one channel goes bad there is no three channels (like class AB) even if you remove the damaged outputs and free up voltage rails.
Can someone explain?
Another puzzling problem is whenever I pulled the output from any one channel, the adjoining channel won’t produce any waveform regardless of four “independent seeming” channels (that is 1 or 2 and 3 or 4). Therefore, if one channel goes bad there is no three channels (like class AB) even if you remove the damaged outputs and free up voltage rails.
Can someone explain?
They are IRS2092S, but two channels will work on the opposite side of any channel I remove output or drive IC (with led flashing, protect/warning) but the untouched adjoining channel won’t work.
I don't have that diagram but on a similar amp, there are two channels together for a protection circuit. If this is the same, it would explain why two channels work and 2 are in protect.
The ICs will go into protect mode when the outputs are not in the circuit unless you jump through a few hoops. Do original FETs run cool in all locations?
The ICs will go into protect mode when the outputs are not in the circuit unless you jump through a few hoops. Do original FETs run cool in all locations?
Yes, I had time to “play” with the banks. I had this same problem but I didn’t detail it on a Soundstream you helped me fix where the MCU was bad and I ran the power FETs direct with an installed driver board. IRFB4227 runs hot, no sound but when used IRF640 2pcs it ran cool and produce audio. I’ve never known the originals as they were scruffed and just remarked “H6” that amp still plays.
I've never known Taramps to deface parts. I guess that changed.
What are the gate resistors?
This may be the same diagram you're using.
What are the gate resistors?
This may be the same diagram you're using.
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No, the deface was on the SoundStream not the Taramps, was referring to what had happened when I try using the IRFB4227 with the IRS2092S, it wouldn’t work just heats up, however it worked with the IRF640N.
Clarify where you are right now.
Does the diagram closely match what you have?
The IRFB5620 and the 4227 are not similar. What was the problem with the IRFB5620?
Does the diagram closely match what you have?
The IRFB5620 and the 4227 are not similar. What was the problem with the IRFB5620?
Yuh know seh some of the FETs we think seh good Dem nuh good. Dem will pass the diode check on DMM but still out of spec. The likkle Chinese LCR tester Dem come in handy nuff time even with Dem yah beefy FET yah.
Cause the 5620 good fi 300 watts hence why Dem in a di 1200X4 but the 4227 good for 500 watts hence why Dem in a dis yah amp yah.
Post #9:
High RDSon can cause heating but only at high current. That said, the 4227 has lower RDSon than the 5620. It also has higher Qg, higher Ciss which can make it harder to drive/control.
High RDSon can cause heating but only at high current. That said, the 4227 has lower RDSon than the 5620. It also has higher Qg, higher Ciss which can make it harder to drive/control.
That's a given, it's a higher rated FET. But I'm referring to the fet is in a state that's not to spec but still functional. Like for instance, I'm fixing a bunch of Taramps DS 1200X4 and they use the 5620, as you know, they're in various states of damage.
When I use my DMM to test the FETs for shorts and also to turn them on in diode mode to see if they're conducting, and they do pass the test... But! When I test them with the cheapo LCR tester it tells me a different story.
The ones that I would consider good are the ones with a very low RDS, like .1 up to .9. but there's 5 bunches of FETs, first set measures in that .1 - .9 range , second set measures in the 1. Something range, 3rd set measures in the 3. Something range, 4th set measures in 8. Something up to 21 and the 5th set locks the tester up and after a while measures as a IGBT.
So I'm thinking those 4227 are out of spec that's why they're behaving that way.
When I use my DMM to test the FETs for shorts and also to turn them on in diode mode to see if they're conducting, and they do pass the test... But! When I test them with the cheapo LCR tester it tells me a different story.
The ones that I would consider good are the ones with a very low RDS, like .1 up to .9. but there's 5 bunches of FETs, first set measures in that .1 - .9 range , second set measures in the 1. Something range, 3rd set measures in the 3. Something range, 4th set measures in 8. Something up to 21 and the 5th set locks the tester up and after a while measures as a IGBT.
So I'm thinking those 4227 are out of spec that's why they're behaving that way.
Attachments
For testing the RCSon, you need to use something other than those types of meters. They're OK for JFETs and such but not for low RDSon FETs.
Take this to the following thread:
https://www.diyaudio.com/community/threads/testing-of-defaced-fets.424170/
Take this to the following thread:
https://www.diyaudio.com/community/threads/testing-of-defaced-fets.424170/
