buz 103 for punch amplifier

[Ground Zero]

hello everybody "ps:sorry for my bad english i'm french "

i have an amplifier rockford punch 200.4 that i have bought 50 euro.
but it has a buz103 out of order in the power supply but it works.

is it possible that i replace it by a irfz44n mosfet?

thanks for your help

by++

[Perry Babin]

An IRFZ44N would be a good substitute.

You should also check the gate resistors and the driver transistors.

[Ground Zero]

hello perry babin

thank you for tour answer

the gate resistors and driver resistor are good

but if i change all buz 103 by irfz44n i must change gate resistors or not?

what does gate resistor do?

thanks

[Perry Babin]

If the gate resistors are within tolerance and are 100 ohms or less, you don't need to change them.

The gate resistors reduce the instantaneous/peak current for the driver transistors.

[Ground Zero]

thanks perry

ok the resistors are 10.5 ohms so i don't need to change them.

i have change 4 buz103 by irfz44n but when i make power the led is ok but there is noise in the power supply

what can i do for this

help please

[Perry Babin]

What are the numbers on the top of the gate resistors?

Do you have a 10 amp fuse in the B+ supply line?

With only the remote and ground connected (no B+), what is the DC voltage on the gate terminal of each of the PS FETs (black meter lead on the ground terminal of the amp)?

You should email Rockford tech support to get a schematic for the amp.

[Ground Zero]

thanks perry

the number of resistors are "R8, R9, R10, R11"

i have a 8 amp fuse in the b+ supply

i have 3.33 volt with 4 mosfet

thanks for your help

[Ground Zero]

hi everybody

the irfz44n are not good for this power supply
maybe it's cause of "RDS on" is not the same value, the irfz44n has a "RDS on" 17.5mohms and the buz103 a "RDS on" 0.04ohms

I have replaced the irfz44n by mosfet Nchanel fqp50n06
with "RDS on" 0.022 ohms and the noise in the power supply has gone.

the rockford fosgate work

can you confirm me please if it is the "RDs on "value that do the noise in the power supply?

thanks

[Perry Babin]

The RDSon should not be a problem. I use IRF3205s as replacements in Rockford amps. They have an RDSon of 0.008 ohms (8 milliohms) and I have no problems with them. I've used IRFZ44Ns in Rockford amplifiers with no problems.

Without being able to hear the noise, it's difficult to know what was causing it. In some power supplies, the transformer will make noise and simply touching the windings will quiet it. It's possible that you may have moved the windings slightly while working on the amp and that's why you no longer have the noise.

[Ground Zero]

thanks perry

i have a question, i don't know what is your job but i think you repair amp for caraudio?

so i would like to know what is the type of studies for doing this job and repairing amplifier in caraudio?

because i would like to do this


thanks for your help