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Problem identifying power supply FET
Problem identifying power supply FET
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Old 24th July 2004, 05:58 AM   #1
R33_Cam is offline R33_Cam  Australia
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Default Problem identifying power supply FET

hi all

first post here but have been reading a while, very good site and very informative.


i have a sony amplifier, about 5 years old model XM-504, recently stopped working, upon inspection found one of the power supply FET's has "blown" up, have searched and searched but havent been able to find any info on the thing, the markings on it are:


it is a motorola manufactured part as it has there symbol on it.

can anyone help with a replacement part number or point me in the right direction of where to obtain one from. (im in Australia, but overseas is ok as long as its easy to get here).

Also what could have caused this to happen, the amp was cutting out a bit for about 3 months, but if it was powered down then back up again it would be fine for a while, but now has just stopped.

any info would be great ppl.

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Old 24th July 2004, 07:57 AM   #2
moamps is offline moamps  Croatia
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Nch FET, 30A, 60V, 100W, 0,05ohm

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Old 24th July 2004, 12:57 PM   #3
Eva is offline Eva  Spain
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For those SMPS exact replacement is usually not required for MOSFETs

Replace them with something having Vds=50 to 60V, Rds[on] below 0.05 ohms and with not much higher gate-source capacitance than the old devices

Check gate drive waveforms with oscilloscope after removing the old MOSFETs and before placing the new ones [powering the amplifier and using 1..3nF as gate-source load]. Driving ICs, transistors or resistors usually blow when a MOSFET blows
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Old 26th July 2004, 09:22 AM   #4
R33_Cam is offline R33_Cam  Australia
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Location: Perth WA
Thanks for the info, i can get one of those from farnell here in australia for 5-6AU$ each.

one further question why would this have blown in the first place?
there are 4 of these FET's in the amp, with 2 wired up in parrallel, so would make it a pair, the 2 that were in parrallel have gone bust but the other 2 "look" fine, what would have caused this, as the amp has been in the same spot with the same levels for the past 5 years, nothing has changed.

thanks again for any info
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