D-Class Amplifier - Transistor gets hot

[Piasa]

I have the Problem that the Pre-Amplifier Stage gets hot and burns. What could the reasons for that be ?


Thanks for your answers

 

[ubergeeknz]

You're going to have to provide a lot more detail to get any useful answers on this one [emoji106]

 

[rayma]

Post the schematic diagram.

 

[Mark Tillotson]

Wrong transistor
wrong pin out
missing heat sink
too much bias current
supply voltage too high
oscillation
short-circuit on pcb
short circuited component down-stream
circuit design is bad
wrong component(s) nearby
fake transistors from eBay


I'm sure there are various other possibilities too, some more details are needed to figure such things out!

 

[bucks bunny]

I have the Problem that the Pre-Amplifier Stage gets hot and burns. What could the reasons for that be ?


Thanks for your answers

It might be overtemperature

 

[Piasa]

There are no Shorts, the resistors All have the correct values just like the other channels.

How do i check for oscillation in the channel?

When i turn it on the voltage At the transistor sinks.

 

[mr l]

There are no Shorts, the resistors All have the correct values just like the other channels.

How do i check for oscillation in the channel?

When i turn it on the voltage At the transistor sinks.

Is this a car amplifier?
Have you checked the PSU voltages, checked the output transistors for shorts?

 

[Piasa]

The PSU voltage iswith 30 Volts both positive and negative rail good. I test it at the Moment without the output transistors but they arent shorted either.
Yes that is a car amplifier a Crunch MXB4150i

The voltage at the transistor is stable at the other channel

 

[mr l]

The PSU voltage iswith 30 Volts both positive and negative rail good. I test it at the Moment without the output transistors but they arent shorted either.
Yes that is a car amplifier a Crunch MXB4150i

The voltage at the transistor is stable at the other channel

Have you checked the output transistors (diode check)?
Have you checked the emitter resistors?

 

[Piasa]

I checked the output transistors they are good, no broken buzzing.
The Emitter resistors are fine too, 47R for the C1815 and 3R for the A1013 and the Emitter resistors for the output are 0,3 Ohm aswell.

 

[chebum]

Probably, it's normal? I have several hypex modules and all are warm even when there is no sound.

 

[Piasa]

With the Output Transistors in the circuit, the Emitter resistors burn trough.


It kinda works at least for a short time.


So I´m thinking that maybe i need to match the transistors or something like this.


The resistors have the correct value, i used the correct transistors to replace (A1015, C1815) and without the Transistors in the circuit the Voltages match.