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I’m repairing an really old amp (at 25years+ old, maybe even more).
PS section was totally destroyed.
I don’t know the original gate resistor values and ps mosfets. TL494 was also dead (originally it was Toshiba TL494).

So i’ve replaced the TL494, fitted 47 ohm gate resistors and 4 irfz44. Initially there were no proper gate drive. I’ve noticed there are no any buffer driver transistors.

TL494 drives directly the mosfets through it’s E1 and E2 pin 9 & 10. There is only two resistor to ground from respectively pins 9 & 10 and a gate resistor per mosfet.

Originally the resistors to ground were big ones 2W at around 100ohm. With these there were no gate drive and the IC was getting hot.

I’ve replaced these ones with a 1/4W 200ohm (that’s what i’ve had laying around). This gave a proper gate drive, but the mosfets now are heating way too fast and way too much.

As I’m not an expert, I’m suspecting that the poor little IC TL494 can’t handle that much of a load in that setup.

I know it’s 100x times better to have a buffer transistors, but reading the datasheet of tl494 and threads here and there over the web, TL494 can drive a light load in the right condition.

If I match the resistors to ground to gate resistors and to the right mosfets
is there any chance I can get this PS working without ! any buffer transistors and modding the schematics ?

Today I will try using resistors to ground ~ 500ohms or 1kohm to see how this goes…