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Old 25th December 2008, 07:51 PM   #1
rtill is offline rtill  United States
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Default transformer and transistor question

If a transistor is wired in wrong, can it hurt the transformer?
I suspect I have a transistor wired in wrong in my power amp I have built... the 300 watt mosfet http://www.circuits-lab.com/?p=81
My transformer gets extremely hot and starts to make a fizzle sound and there is no audio. I have my transformer and power supply setup as a test unit for all power amps I build, so I know that the power supply is correctly wired.
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Old 25th December 2008, 10:46 PM   #2
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Make sure that you have the mosfets placed correctly. Can you give your layout and I will browse through it to see if I can spot any mistakes.

Regards

Nico
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Old 25th December 2008, 10:58 PM   #3
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HERE IS THE FULL PROJECT PACKAGE including gerber plots and PDF files.

http://digisec.co.za/ras/music/RAS%2...mosamp%20Rev02

The PCB has been revised and made smaller. Remember that the power devices ar under the PCB facing up. In other words, the PCB clamps the power devices to the heat sink.

Kind regards

Nico
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Old 25th December 2008, 11:05 PM   #4
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Sorry, forgot the file extension

http://digisec.co.za/ras/music/RAS%2...mp%20Rev02.zip
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Old 26th December 2008, 12:33 AM   #5
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Default Re: transformer and transistor question

Quote:
Originally posted by rtill
If a transistor is wired in wrong, can it hurt the transformer?
If it becomes short it could overheat the transformer in a short period.

This is why I put fuses in the cct before the rectifier to catch any problems. 2 fuseholders is cheaper than a new transformer !
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Old 26th December 2008, 09:34 AM   #6
AndrewT is online now AndrewT  Scotland
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that's why I have to keep repeating that one should use a bulb tester for the start up of EVERY project and for the modification of EVERY project.
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regards Andrew T.
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Old 26th December 2008, 09:57 AM   #7
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Quote:
Originally posted by AndrewT
that's why I have to keep repeating that one should use a bulb tester for the start up of EVERY project and for the modification of EVERY project.
I AGREE WITH YOU.

I HAVE OFTEN LOST OUTPUT DEVICES THIS WAY.

AFTER I BUILD IT I AM ALWAYS SURE THAT IT IS CORRECT.

I AM PROVEN WRONG MORE OFTEN THAN I WOULD LIKE TO ADMIT.
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Old 26th December 2008, 10:06 PM   #8
rtill is offline rtill  United States
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Quote:
Originally posted by Nico Ras
Make sure that you have the mosfets placed correctly. Can you give your layout and I will browse through it to see if I can spot any mistakes.

Regards

Nico

Hi Nico...well, my layouts tend to follow the schematic exactly. ....part placement is exactly the same as the schematic. It just makes it easier for me to troubleshoot I guess. I did find my 2sj162 was wired wrong...I mistook the drain for the source and vice versa, I must not have looked at the schematic close enough. However, after correcting that, I plug in my amp and my transformer fizzles. I am assuming I probably ruined it from wiring the mosfet incorrectly. Am I correct in assuming that? Thanks for everyones help!
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Old 26th December 2008, 11:37 PM   #9
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Quote:
Originally posted by rtill



Hi Nico...well, my layouts tend to follow the schematic exactly. ....part placement is exactly the same as the schematic. It just makes it easier for me to troubleshoot I guess. I did find my 2sj162 was wired wrong...I mistook the drain for the source and vice versa, I must not have looked at the schematic close enough. However, after correcting that, I plug in my amp and my transformer fizzles. I am assuming I probably ruined it from wiring the mosfet incorrectly. Am I correct in assuming that? Thanks for everyones help!
I guess you have fried them.
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Old 26th December 2008, 11:40 PM   #10
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Quote:
Originally posted by rtill



Hi Nico...well, my layouts tend to follow the schematic exactly. ....part placement is exactly the same as the schematic. It just makes it easier for me to troubleshoot I guess. I did find my 2sj162 was wired wrong...I mistook the drain for the source and vice versa, I must not have looked at the schematic close enough. However, after correcting that, I plug in my amp and my transformer fizzles. I am assuming I probably ruined it from wiring the mosfet incorrectly. Am I correct in assuming that? Thanks for everyones help!

Have you put fuses after the transformer ?
If not it could be a transistor(s) is shorted and putting a huge load on the transformer and making it buzz.
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