Amp is stuck in protect mode and I can’t figure out why. I apply power to the amp and no current draw or red light. I measured the voltage on Pin 4 of the TL494 and read 4.98 volts. I ground pin 4 and the amplifier comes on and draws 9+ amps of current. I realized it’s a short somewhere so I check the output section and not a single transistor, diode or mosfet is shorted. What have I overlooked?
After adjusting the bias the amplifier still isn’t turning on and 4.98 volts sit on Pin 4 of Tl494
Set the limit to about 7 amps and clip your meter across each of the 0.1 ohm source resistors and power up just long enough to see if there is voltage across it. The voltage will only be a few millivolts so set your meter to the lowest range. Power down, move to the next resistor and repeat. Which ones read above 0.000v?
Yes terminal 4 was grounded. I just powered it down and powered it up with terminal 4 grounded and It’s only drawing .20 amps. I did notice terminal 3 of the TL494 was reading 1.92 volts.
Will it power up now without 4 grounded?
Does it produce audio on all channels when drawing only 0.2 amps at idle?
Does it produce audio on all channels when drawing only 0.2 amps at idle?
No it still won’t power up without pin 4 being grounded. I put a 40hz test time through the amp and can see it on all 4 channels using a oscilloscope and still only drawing .20 amps.
With pin 4 on tl494 grounded
Pin 1 0v
Pin 2 0v
Pin 3 11.4v
Pin 4 1.6v
Pin 5 1.2v
Pin 6 2.6v
Pin 7 0v
Pin 8 3.8v
Pin9 2.6v
Pin10 2.6v
Pin11 7.2v
Pin12 0v
Pin13 0v
Pin14 0v
Pin 1 0v
Pin 2 0v
Pin 3 11.4v
Pin 4 1.6v
Pin 5 1.2v
Pin 6 2.6v
Pin 7 0v
Pin 8 3.8v
Pin9 2.6v
Pin10 2.6v
Pin11 7.2v
Pin12 0v
Pin13 0v
Pin14 0v
Grounding pin 4 is dragging the 5v down. Lift Q9, remove the short to ground and repost the numbers.
The amp won't turn off by remote with Q9 out of the circuit so you'll have to remove B+.
The amp won't turn off by remote with Q9 out of the circuit so you'll have to remove B+.
Pin1 0
Pin2 0
Pin3 20.6
Pin4 3.2
Pin5 2.4
Pin6 4.6
Pin7 0
Pin8 2.8
Pin9 4.8
Pin10 4.8
Pin11 7
Pin12 0
Pin13 0
Pin14 0
Pin2 0
Pin3 20.6
Pin4 3.2
Pin5 2.4
Pin6 4.6
Pin7 0
Pin8 2.8
Pin9 4.8
Pin10 4.8
Pin11 7
Pin12 0
Pin13 0
Pin14 0
There are two thermistors. One terminal of each will have 5v on it. What is the voltage on the other terminal of each one?