I am repairing a ground zero 10000spl.
It was initially using IRFP360LC, but I decided to use FDA24N40F.
Usual problems, output mosfet in short (only in one of the 4 stages) broken driver board and perfect power supply.
I did the usual tests:
1) perfectly fixed the driver board
2) checked all gate (33r) and pulldown (100k) resistors, all perfect, but for safety I changed them.
3) checked the 4 resistors of VB (4,7r) all perfect, then I left them in their place.
4) to the eye there do not seem to be short circuits or shorted turns in any of the 4 inductors.
5) I detect all the low sides and with the help of an auxiliary 12v source (small battery) I also detect all the high sides, so everything is fantastic.
6) after fixing everything, I mounted only 1 IRFP360LC for each side (of each stage) using different production mosfets (but it was only a test) and the amplifier immediately started regularly showing a correct switching frequency on all four the stages, only that some mosfets warmed slightly (which could be normal, since I only used one per side and in addition, the mosfets were not all identical).
7) I remove the test IRFP360LC and install 1 brand new FDA24N40F per side (for each stage), I turn on the amplifier, but unfortunately I see that the amplifier does not start, that is, the frequency of RAIL TO RAIL, appears and disappears intermittently , as if it started and stopped all the time.
8) I remove the FDA24N40F to do some tests, but nothing has changed, everything is like in point 5, only now, I have reinstalled FDA24N40F but this time some output mosfets are shorted, so now I am forced to rework the driver board, what a great waste of time.
Anyone have any advice for me?
It was initially using IRFP360LC, but I decided to use FDA24N40F.
Usual problems, output mosfet in short (only in one of the 4 stages) broken driver board and perfect power supply.
I did the usual tests:
1) perfectly fixed the driver board
2) checked all gate (33r) and pulldown (100k) resistors, all perfect, but for safety I changed them.
3) checked the 4 resistors of VB (4,7r) all perfect, then I left them in their place.
4) to the eye there do not seem to be short circuits or shorted turns in any of the 4 inductors.
5) I detect all the low sides and with the help of an auxiliary 12v source (small battery) I also detect all the high sides, so everything is fantastic.
6) after fixing everything, I mounted only 1 IRFP360LC for each side (of each stage) using different production mosfets (but it was only a test) and the amplifier immediately started regularly showing a correct switching frequency on all four the stages, only that some mosfets warmed slightly (which could be normal, since I only used one per side and in addition, the mosfets were not all identical).
7) I remove the test IRFP360LC and install 1 brand new FDA24N40F per side (for each stage), I turn on the amplifier, but unfortunately I see that the amplifier does not start, that is, the frequency of RAIL TO RAIL, appears and disappears intermittently , as if it started and stopped all the time.
8) I remove the FDA24N40F to do some tests, but nothing has changed, everything is like in point 5, only now, I have reinstalled FDA24N40F but this time some output mosfets are shorted, so now I am forced to rework the driver board, what a great waste of time.
Anyone have any advice for me?
Make sure that muting circuit is cycling as it should. The rail voltage should reach full voltage before the amp begins to produce r-r oscillation.
http://www.bcae1.com/temp/ampstartup01.mkv
Of course, intermittently shorted inductors and damaged vias are also a possibility.
http://www.bcae1.com/temp/ampstartup01.mkv
Of course, intermittently shorted inductors and damaged vias are also a possibility.
Yes Perry, muting circuit is perfectly working because when i tested with IRFP360LC, the amp turn on and rail to rail was regulary present.
And yes, the switching start only after power supply have completely buil the rails.
There are no damaged vias both in driver board and output mosfet and also resistors.
All is perfect.
Is very strange, today i will remove all inductors and blue capacitor too see better.
Only for clarification, when i use a small battery to test the high sides, and they are perfect, can i have the certain that IRS21844 are working perfectly?
And yes, the switching start only after power supply have completely buil the rails.
There are no damaged vias both in driver board and output mosfet and also resistors.
All is perfect.
Is very strange, today i will remove all inductors and blue capacitor too see better.
Only for clarification, when i use a small battery to test the high sides, and they are perfect, can i have the certain that IRS21844 are working perfectly?