Hi everybody.
By accident i connected the jl m4500 positive to negative and negative to positive on power supply. I could hear the little blow a d smoke... :/ stupid mistake...
Anyway i got the amp open i reconnected this tome the right way and i see that some transistors close to power source are getting red and smoke.
It is Q48, 49 and 50.
Could you guys tell me beside that it was idiotic if that is the only damage that happened and if I can i get this transistors somewhere ?
Greatly appreciate any help,
Thank you
By accident i connected the jl m4500 positive to negative and negative to positive on power supply. I could hear the little blow a d smoke... :/ stupid mistake...
Anyway i got the amp open i reconnected this tome the right way and i see that some transistors close to power source are getting red and smoke.
It is Q48, 49 and 50.
Could you guys tell me beside that it was idiotic if that is the only damage that happened and if I can i get this transistors somewhere ?
Greatly appreciate any help,
Thank you
Attachments
What are the numbers on the faces of the transistors?
The fuse in the amp was likely rated for too much current if the FETs failed with a reverse connection.
If the FETs opened, it may have allowed reverse voltage to be applied to the control circuit. If so, there could be more extensive damage. Some tests could possibly rule out more damage.
The fuse in the amp was likely rated for too much current if the FETs failed with a reverse connection.
If the FETs opened, it may have allowed reverse voltage to be applied to the control circuit. If so, there could be more extensive damage. Some tests could possibly rule out more damage.
You'll have to remove the 6 IRFZ44s. Remove the excess solder and clean the board so that you can confirm that there are no solder bridges between the pads.
After that, confirm that each of the 47 ohm gate resistors measures 47 ohms, ±5%.
Then power up the amp and measure the DC voltage with the black probe on the amp's ground terminal and the red probe on each of the gate resistors. What is the voltage on those resistors. You only need to post one if they're all approximately the same.
If you haven't done so already, read the basic amp repair page (link in sig line below). Read all of it, even the parts that you feel are irrelevant.
After that, confirm that each of the 47 ohm gate resistors measures 47 ohms, ±5%.
Then power up the amp and measure the DC voltage with the black probe on the amp's ground terminal and the red probe on each of the gate resistors. What is the voltage on those resistors. You only need to post one if they're all approximately the same.
If you haven't done so already, read the basic amp repair page (link in sig line below). Read all of it, even the parts that you feel are irrelevant.
For any power supply FET, if you read anything other than an open circuit (meter reads the same as probes not in contact with anything but air) from the gate leg to either of the other two legs (out of the circuit), the FET is defective.
4.65v appears to be OK as long as all gate resistors measure 47 ohms ±5%.
4.65v appears to be OK as long as all gate resistors measure 47 ohms ±5%.
4525 | TO-220 Package 19 x 9 mm Heat Sink Clip | AAVID THERMALLOY - Future Electronics
Order extras if you find them elsewhere. They are not reusable.
Order extras if you find them elsewhere. They are not reusable.
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