Hey man , I kniw its a little old of a Post, but a Friends' amp aparently gave smoke and now is not working, but it turns on, with the blue lettering. I want to take a look at it to see if I can repair it, if its to change a mosfet and solder new ones, what do I have to look for ?? Black burnt colors ? And where is most commonly burn or damage areas? Smolten lead connections ?
Thnks Ian.
Thnks Ian.
Hi Perry, well I have not yet done anything, as it's my friends, but I will be going home for Xmass vacation and I will work on it, I wanted to read up and around in forums. Thanks a lot for the links in ur signature line I have already started reading it
By the 14th I'll going home so I will hit you up on this forum, thnks a lot
I have already started reading it By the 14th I'll going home so I will hit you up on this forum, thnks a lot
You'll need a meter to help in troubleshooting.
If it smoked, the power supply FETs are likely what failed. That means that there will likely be at least a few defective gate resistors and possibly blown driver transistors.
The supply could have failed on its own but may have failed due to shorted output transistors.
If it smoked, the power supply FETs are likely what failed. That means that there will likely be at least a few defective gate resistors and possibly blown driver transistors.
The supply could have failed on its own but may have failed due to shorted output transistors.
hey there Perry ,
welll finally got home and took a look at the amp, and well right off the batt i can see a few burnt resistors right below I believe the output transistors( they are ear the speaker hook up hub) on both sides of the amp. will be gettin a multimeter later to test the fets.
is there somewhere i can get a schematic to see what size resisters i shout get to replace these? because they are burnt away and can read the color bands ... :S
thanks Perry
welll finally got home and took a look at the amp, and well right off the batt i can see a few burnt resistors right below I believe the output transistors( they are ear the speaker hook up hub) on both sides of the amp. will be gettin a multimeter later to test the fets.
is there somewhere i can get a schematic to see what size resisters i shout get to replace these? because they are burnt away and can read the color bands ... :S
thanks Perry
Generally, the FETs near the power/ground/speaker terminals on hifonics amp are for the power supply.
There are a lot of parallel FETs so you should be able to read the value of enough of them to know what the rest should be. You'll need to remove the failed FETs before you can measure any of the resistor values. Cleaning them with alcohol or acetone will help read those that are just covered with soot and not actually burned.
If any of the FETs in the power supply have failed, it's likely that all of the FETs in the supply have failed. Even if only a few failed, you will need to replace all power supply FETs.
There are a lot of parallel FETs so you should be able to read the value of enough of them to know what the rest should be. You'll need to remove the failed FETs before you can measure any of the resistor values. Cleaning them with alcohol or acetone will help read those that are just covered with soot and not actually burned.
If any of the FETs in the power supply have failed, it's likely that all of the FETs in the supply have failed. Even if only a few failed, you will need to replace all power supply FETs.
well these resistor are kinda burnt throught their surface, the white ceramic like material is showing and they are away from the other resistors, the other ones which are not burnt on the other FETS are two next to each other so I cannot know if they are the same resistance of on or the other... but If you have a shcematic can u look it up for me? the burnt resistors are R32, R34, R48, R46, R47 to the other side R37,R36, R43, R42, R44
and of a visual inspection I can see damage on the legs of the FET# Q12 right above R36
and of a visual inspection I can see damage on the legs of the FET# Q12 right above R36
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
ok, no prob, I'll try my luck or maybe ask somewhere in this forum
so New FET's and gate resistors (All)
what should I look for next? what is the next step ?
you mentioned before:
"If it smoked, the power supply FETs are likely what failed. That means that there will likely be at least a few defective gate resistors and possibly blown driver transistors. "
the FETs are the black 3 legged component which lean on the heat dissapation plate correct?
gate resistors are the ones that burnt, correct?
what are the "blown driver transistors" and where are they and how shoul I measure or check them?
so New FET's and gate resistors (All)
what should I look for next? what is the next step ?
you mentioned before:
"If it smoked, the power supply FETs are likely what failed. That means that there will likely be at least a few defective gate resistors and possibly blown driver transistors. "
the FETs are the black 3 legged component which lean on the heat dissapation plate correct?
gate resistors are the ones that burnt, correct?
what are the "blown driver transistors" and where are they and how shoul I measure or check them?
Some of the 3-legged black devices clamped to the heatsink are FETs, not all. Some are regulators and rectifiers.
The resistors that burned are the gate resistors for the power supply FETs.
I'm not sure what the drivers are in this amp. Do you see transistors with circuit board designations of Q7, Q8, Q7A and Q8A?
Have you checked the output transistors to see if any have failed?
The resistors that burned are the gate resistors for the power supply FETs.
I'm not sure what the drivers are in this amp. Do you see transistors with circuit board designations of Q7, Q8, Q7A and Q8A?
Have you checked the output transistors to see if any have failed?
Perry this is like the Brutus I am working on. I'm back on it. It has the same problems. Yes this amp has q7, 7a and q8 ,8a. Most of the gate resistors are less than 12ohms. The only good looking one reads 48ohms and has yell,pure and blk stripes. Aka 47ohms. The transistors read shorts on all legs. They are WFP50n60.
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