Hi, got an amp with BUZ71 mosfets I want to change out from the power supply as some are reading faulty, is there a newer equivalent I can put in and would I need to change gate resistors to suit? the amp is nothing special but interests me so would like to fix it up, it's a Precision Audio "Hot Shots", which is a bit of a joke amp but would like to see it work again!
Mark.
Mark.
It depends on the drive circuit. Post a photo of the power supply control area, including the drivers.
What gate resistors are they using.
What gate resistors are they using.
What's the value of R108? It appears to be in series between the output of the IC and the gate resistors.
What FETs do you have on hand?
What FETs do you have on hand?
R108 is 10 ohm, I would have to check what FET's I have, got various bits and pieces..
You can likely use anything up to something like the IRF3205. That FET would be overkill for this amp and may require a slight change like increasing the deadtime slightly or changing the value of the resistors. Eliminating R108 may be enough if there is nothing but the gate resistors and the IC connected to it.
I have on hand the following..
IRFZ034E
IRF540N
IRF3205 x5 only
IRFZ44V and N but not 6 matching..
IRFZ034E
IRF540N
IRF3205 x5 only
IRFZ44V and N but not 6 matching..
I doubt it has a regulated PS, not sure how you can tell TBH.
yes, I thought IRFZ34E would be a good choice for the size of amp... would 47ohm gate resistors be OK with these?
034 isn't 34. I could guess or confirm.
They would likely be OK. The Z44 would be better. You wouldn't likely need to make any changes with either.
To tell if a power supply is regulated, you vary the 12v supply voltage and if the rail voltage constantly changes from about 14v down to where the amp shuts off, it's unregulated.
If it has a range of 12v supply voltages where the rail voltage is constant and either the pulse width or the pulse amplitude driving the FETs changes significantly, it's regulated.
They would likely be OK. The Z44 would be better. You wouldn't likely need to make any changes with either.
To tell if a power supply is regulated, you vary the 12v supply voltage and if the rail voltage constantly changes from about 14v down to where the amp shuts off, it's unregulated.
If it has a range of 12v supply voltages where the rail voltage is constant and either the pulse width or the pulse amplitude driving the FETs changes significantly, it's regulated.