Hello to all.
I'm fixing for the second time rockford fosgate 1501bd power series.
For the first time, there were outputs MOSFET exploded(audio side), in addition, its MIC4420 and HCPL2211 were also broken, while the rail switchers were intact.
So I replaced the defective components and the amplifier returned to work in a spectacular way.
After 1 month, the amplifier was returned to me under the same initial conditions, the same components exploded, and before repairing it again, I would like to make it clear.
The owner say that he use it at 2ohm impedance.
I noticed that the constructor uses IRF3415 and IRF6215 both in audio and in rail switchers. IRF6215 are declared for 13Ampere while IRF3415 have 43Ampere, a big difference!
According to you, can i use IRF6218 instead of IRF6215 to try to shorten the differences between MOSFETs?
I'm fixing for the second time rockford fosgate 1501bd power series.
For the first time, there were outputs MOSFET exploded(audio side), in addition, its MIC4420 and HCPL2211 were also broken, while the rail switchers were intact.
So I replaced the defective components and the amplifier returned to work in a spectacular way.
After 1 month, the amplifier was returned to me under the same initial conditions, the same components exploded, and before repairing it again, I would like to make it clear.
The owner say that he use it at 2ohm impedance.
I noticed that the constructor uses IRF3415 and IRF6215 both in audio and in rail switchers. IRF6215 are declared for 13Ampere while IRF3415 have 43Ampere, a big difference!
According to you, can i use IRF6218 instead of IRF6215 to try to shorten the differences between MOSFETs?
I've never tried it. Some of the newer Rockford amp use the IRF6218. If the gate resistance used with the old FET's is correct for these devices, I would think so. I have not checked the data sheet for either and compared.
Are all the gate resistors within tolerance for the switchers and audio FET's?
Are all the gate resistors within tolerance for the switchers and audio FET's?
oh! When the amp was blown the first time, some gate resistors were burned.
For this reason, I have replaced those resistors with some new ones, of the closest possible value to the original one, so I assume they are not IDENTICAL to the original one, but I think there is a really imperceptible difference.
Could this cause a failure?
I also noticed a strange thing:
in the electrical diagram I have, I noticed that not all MOSFETs have the same gate resistor, for example, all P channel MOSFETs have a 15ohm gate resistor, while all N-channel MOSFETs have 22ohm and only two of this have 15ohm resistors.
if needed, I can provide the schema.
maybe a typing error?
They used various values that didn't match the diagrams. You rarely get the diagram that matches the exact revision.
I'd use 15 ohm gate resistors.
The 6215 FETs have been reliable. If they're failing, you may have a drive problem.
I'd use 15 ohm gate resistors.
The 6215 FETs have been reliable. If they're failing, you may have a drive problem.
I don't see drive problems with scope in both audio and rail switchers. After my first repair the amp produce clean audio signal at very high volume, so, for me the amp was perfectly repaired. The owner say that the amp was very powerfull after repair.
They are very similar component.
IRF6215 IRF6218
RDSon:0,29ohm 0.15ohm
ID:13 27
Qg:66 71
Ton:14 21
Tr:38 70
T0ff:53 35
Tf:37 30
Ciss:860 2210
the last parameter is very different.
What do you say?
It might work but having never tried the alternate part I cannot say. My preference would be to use the OEM part number. These FET's have been very reliable as Perry stated.
Be sure to check the gate resistance on all gate resistors, very carefully check the gate traces for intermittent connection. The traces are very small and easily damaged. I usually check from the FET's gate leg to the opposite side of the gate resistor. I then try to gently move or wiggle things of you will to ensure a good connection.
Have you confirmed the rail switchers are switching from positive to negative correctly?
Be sure to check the gate resistance on all gate resistors, very carefully check the gate traces for intermittent connection. The traces are very small and easily damaged. I usually check from the FET's gate leg to the opposite side of the gate resistor. I then try to gently move or wiggle things of you will to ensure a good connection.
Have you confirmed the rail switchers are switching from positive to negative correctly?
Ok, i ve ordered AUIRF6215 because from my reputable and convenient distributor (TME.EU), IRF6215 are not available.
Now the amplifier is running without output devices, the boot is perfect, and with the oscilloscope I can observe a perfect square waveform with a duty cycle variable depending on the signal I'm using at the input (100hz sine wave), this square waveform is perfectly opposite the pads of the rail switchers and the sound pads.
But how do I control that rail switchers are switching from positive to negative correctly?
I mean, for audio, when the output devices will be mounted, i can do it before the inductor with the oscilloscope but for the rail switchers how do i do it? They are connected to the general ground of the amplifier via a shunt!
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