Hello out there from Germany,
i blew up my JBL GTO 6000 car amp last week. A heavy box slit into the acrylic window, pushed it in (not broken) and all 10 MOSFETS from the PSU blew.
I still don't know why, the PCB did not touch the case bottom metal.
Mosfets were Fairchild FQP50n06, which are hardly to get here (20$ one!!!)
A TL494 PWM controller is steering 4 small transistors that switch the gates of 4 Mosfets for the normal channels of the amp and 6 mosfets that supply the sub amp. 2 transformers, a bigger one at the 6 and a smaller one at the 4 mosfets.
I replaced TL494, output transistors, mosfet gate resistors and added 4 bigger mosfets just for testing. it still works.
now my question to the electronic skilled:
can i replace these original MOSFETS:
http://www.fairchildsemi.com/ds/FQ/FQP50N06.pdf
with these i can easily get for 60 cent:
http://www.irf.com/product-info/datasheets/data/irfz48n.pdf
the data seems to fit except the "Avalanche Current" which is 50A on the original, and only 32A on the replacement device, although the replacement's Ids current is higher.
What do you think?
THANKS!!
i blew up my JBL GTO 6000 car amp last week. A heavy box slit into the acrylic window, pushed it in (not broken) and all 10 MOSFETS from the PSU blew.
I still don't know why, the PCB did not touch the case bottom metal.
Mosfets were Fairchild FQP50n06, which are hardly to get here (20$ one!!!)
A TL494 PWM controller is steering 4 small transistors that switch the gates of 4 Mosfets for the normal channels of the amp and 6 mosfets that supply the sub amp. 2 transformers, a bigger one at the 6 and a smaller one at the 4 mosfets.
I replaced TL494, output transistors, mosfet gate resistors and added 4 bigger mosfets just for testing. it still works.
now my question to the electronic skilled:
can i replace these original MOSFETS:
http://www.fairchildsemi.com/ds/FQ/FQP50N06.pdf
with these i can easily get for 60 cent:
http://www.irf.com/product-info/datasheets/data/irfz48n.pdf
the data seems to fit except the "Avalanche Current" which is 50A on the original, and only 32A on the replacement device, although the replacement's Ids current is higher.
What do you think?
THANKS!!
Hi there,
the IRFZ is switching faster than the original FQP.
I read in another thread, that as higher the number of an IRF Transistor is, as more unsuitable it is for audio applications.
Why?
Should i go for the IRFZ46N with less current?
I knew about only one mosfet per polarity is needed per transformer. Saying i added 4 test mosfets, this was 2 for each PSU.
Can you imagine why they blew, and why _all_ of them blew as they are in 2 separate PSUs? Could a failure of the TL494 have caused this?
thanks!
the IRFZ is switching faster than the original FQP.
I read in another thread, that as higher the number of an IRF Transistor is, as more unsuitable it is for audio applications.
Why?
Should i go for the IRFZ46N with less current?
I knew about only one mosfet per polarity is needed per transformer. Saying i added 4 test mosfets, this was 2 for each PSU.
Can you imagine why they blew, and why _all_ of them blew as they are in 2 separate PSUs? Could a failure of the TL494 have caused this?
thanks!
the fact i am new and under moderation totally scrambles the order of my posts.
the question to djQuan was referring to
sorry, i am really having a problem with no editing. I always get sth in mind i forgot to post.
So, in addition to the post with the picture:
I replaced the 1266 transistors with BC640 ( http://www.semiconductors.philips.com/acrobat_download/datasheets/BC636_638_640_5.pdf )
can that stay that way? are these ok for the job? 1266s are not available here.
thanks so much for your fast responses.
the question to djQuan was referring to
sorry, i am really having a problem with no editing. I always get sth in mind i forgot to post.
So, in addition to the post with the picture:
I replaced the 1266 transistors with BC640 ( http://www.semiconductors.philips.com/acrobat_download/datasheets/BC636_638_640_5.pdf )
can that stay that way? are these ok for the job? 1266s are not available here.
thanks so much for your fast responses.
I have built a few SMPS's and a car amp (200W, 500W) and that circuit is similar to the one I used.
I don't think 22R is too small. I used 100R and others use 47R. with the drivers I used in my schematic (www.djquan.angelcities.com/smps.html)the 220R resistors are 1k and gate resistors are 100R. the PNP transistors are 2N3906. I was able to drive three pairs of power mosfets for the 500W SMPS. the MOSFETS I used are 90A each(2 pairs for 200W amps, and 110A each(three pairs for 500W amp).
they are ok. just make sure the gate-source capacitance is not too large in comparison to the originals.
I don't think 22R is too small. I used 100R and others use 47R. with the drivers I used in my schematic (www.djquan.angelcities.com/smps.html)the 220R resistors are 1k and gate resistors are 100R. the PNP transistors are 2N3906. I was able to drive three pairs of power mosfets for the 500W SMPS. the MOSFETS I used are 90A each(2 pairs for 200W amps, and 110A each(three pairs for 500W amp).
they are ok. just make sure the gate-source capacitance is not too large in comparison to the originals.
The BC 640 is a special one that has ECB. I had to do with it days ago and i remembered it had the Base on the side, so that was the first fitting trans. i had in mind.
I'll build the amp up with 10x 22R and IRFZ46N (53A) next week and give you feedback.
Thank you so much for that fast help and competence.
I hope i can pay back someday.
Does anyone have a hint on how the whole thing could burn?
And how i could prevent that in future? The Amp's power cable as the amp itself were properly fused, no fuse tripped. I shut off by hand :/
I'll build the amp up with 10x 22R and IRFZ46N (53A) next week and give you feedback.
Thank you so much for that fast help and competence.
I hope i can pay back someday.
Does anyone have a hint on how the whole thing could burn?
And how i could prevent that in future? The Amp's power cable as the amp itself were properly fused, no fuse tripped. I shut off by hand :/
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