Hi power supply fets heating up with no rectifiers in and drive voltage is around 3v is it too low if it is should i replace the buffer transistors and the 494 or just the buffers thanks in advance
You should always check the drive signal with a loading capacitor before installing the FETs.
What does the signal look like at the output of the 494 and at the emitter of the driver transistors?
What make/model amp?
What does the signal look like at the output of the 494 and at the emitter of the driver transistors?
What make/model amp?
Its a tg 18d targa and i do not have a oscilloscope as yet i only have a multi meter and a current limiter 12v supply
The voltage at the 494 is 4.5approx pin 9 and ten same voltage and voltage at emmiters is 4.19 with out any fets installed
You changed 2 things so the numbers don't mean much.
Why did you remove the FETs?
Are you sure that the gate resistors are the right value?
Why did you remove the FETs?
Are you sure that the gate resistors are the right value?
The reason i removed the fets is that i cannot keep it too long on otherwise it heats up. It doesnt heat up extremely fast but does heat up at a quick rate. The gate resistors are 33 ohms and those where in the amp
In a situation like this, you clamp them to the heatsink to give you extra time. You only need to power up, measure, power down, move to the next test point and repeat.
The voltage at the gate goes up until 3.14v. The voltage at the emmiter is the same 3.14v. The output at the 494 does not give a steady voltage it grows slowly but i cannot leave it too long on then the fets heats up
Pin1=118mv
Pin2=77mv
Pin3=104.1mv
Pin4=starts from 2.2v then drops to 200mv
Pin5=80mv
Pin6=3.7v start and then drops to 3.3v
Pin7=108mv
Pin8=b+
Pin9=1.8v
Pin10=1.8v
Pin11=b+
Pin12=5.6v
Pin13=4.87v
Pin14=78mv
Pin2=77mv
Pin3=104.1mv
Pin4=starts from 2.2v then drops to 200mv
Pin5=80mv
Pin6=3.7v start and then drops to 3.3v
Pin7=108mv
Pin8=b+
Pin9=1.8v
Pin10=1.8v
Pin11=b+
Pin12=5.6v
Pin13=4.87v
Pin14=78mv
Pin1=118mv
Pin2=77mv
Pin3=104.1mv
Pin4=starts from 2.2v then drops to 200mv
Pin5=80mv
Pin6=3.7v start and then drops to 3.3v
Pin7=108mv
Pin8=b+
Pin9=1.8v
Pin10=1.8v
Pin11=b+
Pin12=5.6v
Pin13=4.8v
Pin14=4.8v
Pin15=4.8v
Pin16=almost 1mv fluctuating
Sorry for the previous one was still busy measuring
Pin2=77mv
Pin3=104.1mv
Pin4=starts from 2.2v then drops to 200mv
Pin5=80mv
Pin6=3.7v start and then drops to 3.3v
Pin7=108mv
Pin8=b+
Pin9=1.8v
Pin10=1.8v
Pin11=b+
Pin12=5.6v
Pin13=4.8v
Pin14=4.8v
Pin15=4.8v
Pin16=almost 1mv fluctuating
Sorry for the previous one was still busy measuring