So I just got in a Memphis amp, the 16-MCD500, blown power supply, negative terminal got so hot it melted off the board, removed damaged FETs, resoldered terminal back in place, confined I had power supply switching, installed FETs but amp doesn’t power on just clicks, I pull rectifiers, still just clicks when applying remote, I check resistances (which I should have done before installed FETs) and the 1st 3 have a resistance e of 3.6k between gate and source, the next 3 have a res of 39k with probes one way, and 46k with probes reversed on gatw and source of Fet. I tried looking for the pull down resistor but can’t locate it, what would do that? That has to be the problem correct? I’m still learning but I know that’s off. Any help greatly appreciate. Ty!
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What do you mean by "confined I had power supply switching"?
Did you replace the driver transistors?
Did you replace the driver transistors?
My bad, fatfingered my keyboard 😅
Once I removed the damaged power supply FETs I confirmed the power supply is still switching on each gate pad.
No I did not switch out the buffer drivers, from the limited info I know if I am getting a square signal on each gate pad of the power supply FET sockets then the drivers must be good correct? Square wave does has some over/under-shoot but figured that was Because there was no FETs installed.
Once I removed the damaged power supply FETs I confirmed the power supply is still switching on each gate pad.
No I did not switch out the buffer drivers, from the limited info I know if I am getting a square signal on each gate pad of the power supply FET sockets then the drivers must be good correct? Square wave does has some over/under-shoot but figured that was Because there was no FETs installed.
You need to load the gate/source pads with a capacitor of 0.01uf-0.1uf. Without a load, the waveforms don't mean much.
Ahh ok, I never knew that, ty Perry 🙂 I’m just getting back to this amp, I’ll see if I can figure out where the buffer drivers are and prone them, I’m kinda new to buffer drivers but seeing firsthand lately the role they play. I’ll report back once I do, ty 🙏🙏🏻
They are on the PS driver board. Q15 and 16, I think. Confirm that their emitters drive the gate resistors.