Need help for amplifier

hello all,
i have a problem with my amplifier. maybe somebody can help me how it can be solved.

yesterday, i'm working with my amplifier, this is the schematic.

**broken link removed**

when the power is on, i found a abnormal condition. Q5 and Q7 is very hot.

maybe somebody can tell me why it could happen and what must i do?

thanks before

4 some odd reason, your picture does not seem to be loading, try converting it to .gif . . . jpeg should work fine though.

ajik said:

hello all,
i have a problem with my amplifier. maybe somebody can help me how it can be solved.

yesterday, i'm working with my amplifier, this is the schematic.

**broken link removed**

when the power is on, i found a abnormal condition. Q5 and Q7 is very hot.

maybe somebody can tell me why it could happen and what must i do?

thanks before

Click to expand...

Three things:

1) Do you have the output transistors mounted on a substantial heatsink?.

2) Have you set the bias correctly?, the preset resistor adjusts this.

3) Is the Vbe multiplier (the small transistor connected to the preset) thermally connected to the heatsink?.

If you're driving the amplifier hard the output transistors will get hot, it's why you use large transistors and big heatsinks.

WHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAT!?!?!?!?!?!? WHY CAN I NOT C THIS AND EVERYONE ELSE CAN!!?!?

WHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAT!?!?!?!?!?!? WHY CAN I NOT C THIS AND EVERYONE ELSE CAN!!?!?