Amp came in with blown power supply fets .
I replaced the fets and 2 driver ic’s didn’t replace the smd transistors yet .
When trying to power the amp up it shows no signs of life .
Any ideas ?
I replaced the fets and 2 driver ic’s didn’t replace the smd transistors yet .
When trying to power the amp up it shows no signs of life .
Any ideas ?
What do you mean by 'no signs if life'?
Do you have a sawtooth waveform on the 494?
If so, post the voltage on all terminals of the 494.
Do you have a sawtooth waveform on the 494?
If so, post the voltage on all terminals of the 494.
The amp will not power up . It won’t produce rail or regulated voltages .
TL494
Pin 1:6.51
Pin 2:2.55
Pin 3:4.67
Pin 4:3.88
Pin 5:1.63
Pin 6:3.10
Pin 7:0.00
Pin 8:13.65
Pin 9:0.00
Pin 10:0.00
Pin 11:13.65
Pin 12:13.65
Pin 13:4.99
Pin 14:4.99
Pin 15:4.99
Pin 16:0.00
TL494
Pin 1:6.51
Pin 2:2.55
Pin 3:4.67
Pin 4:3.88
Pin 5:1.63
Pin 6:3.10
Pin 7:0.00
Pin 8:13.65
Pin 9:0.00
Pin 10:0.00
Pin 11:13.65
Pin 12:13.65
Pin 13:4.99
Pin 14:4.99
Pin 15:4.99
Pin 16:0.00
The DC offset transistor often fails and causes this (driver board out). It's Q226 in many of the class D amps.
Do you see any voltage across any of the protect/power LEDs?
Do you see any voltage across any of the protect/power LEDs?
It’s a digital display on the amp .
And yes the display lights up so there is voltage there
This is the transistor your talking about ?
And yes the display lights up so there is voltage there
This is the transistor your talking about ?
Attachments
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Like any time that you're disabling any protection, you have to be careful. That said, the amp will operate normally without that transistor.
Did you find a circuit that is like the one in that diagram?
Did you find a circuit that is like the one in that diagram?
Yes
I replaced Q226 and the amp powers up now .
The transistor I circled in an earlier post was actually Q225 .
Q226 sits to the right of it marked FR
So will put new outputs and a driver in the output section to see if the amp has anymore issues
I replaced Q226 and the amp powers up now .
The transistor I circled in an earlier post was actually Q225 .
Q226 sits to the right of it marked FR
So will put new outputs and a driver in the output section to see if the amp has anymore issues
Amp powers up now and produces rail voltage
But the amp isn’t producing any regulated voltages .
Any ideas ?
But the amp isn’t producing any regulated voltages .
Any ideas ?