Hi!
I'm finishing my project of stereo amplifier with snubberized power supply based on Brian's Kit (http://www.chipamp.com). Yesterday I powered the amp and measured DC offset between the output terminals. It started with 110mV and then went down towards zero. Is this normal?
Second problem is the power LED. It doesn't go on. I tested the circuit with another led (certainly working one) with same results. Then I tested the resistor and diode on circuit, they're fine, but I'm not sure about the capacitor. How can I test that? I didn't get any voltages or currents measured from resistor's ends when amp was powered.
I also tried the amp with test speaker, but didn't get sound out of it.
I attached a couple of pictures, if they're helping any.
I would be very pleased if you can help me out of this problem.
I'm finishing my project of stereo amplifier with snubberized power supply based on Brian's Kit (http://www.chipamp.com). Yesterday I powered the amp and measured DC offset between the output terminals. It started with 110mV and then went down towards zero. Is this normal?
Second problem is the power LED. It doesn't go on. I tested the circuit with another led (certainly working one) with same results. Then I tested the resistor and diode on circuit, they're fine, but I'm not sure about the capacitor. How can I test that? I didn't get any voltages or currents measured from resistor's ends when amp was powered.
I also tried the amp with test speaker, but didn't get sound out of it.
I attached a couple of pictures, if they're helping any.
I would be very pleased if you can help me out of this problem.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi,
can you keep the safety earth attached to the chassis and disconnect the audio ground from the chassis?
Keep the audio ground floating above the chassis and add a disconnecting network from audio ground to safety earth. Do not remove the nut securing the safety earth, instead add the disconnecting network above the first nut and then use a second nut to secure.
The disconnetcing network can consist of a ceramic cap // power bridge diode// power resistor// power thermistor, or any combination of these.
can you keep the safety earth attached to the chassis and disconnect the audio ground from the chassis?
Keep the audio ground floating above the chassis and add a disconnecting network from audio ground to safety earth. Do not remove the nut securing the safety earth, instead add the disconnecting network above the first nut and then use a second nut to secure.
The disconnetcing network can consist of a ceramic cap // power bridge diode// power resistor// power thermistor, or any combination of these.
Your power supply board is fully populated with all eight rectifier Diodes, so it is set up for a transformer with Dual secondaries (4 wires). If you have a center tapped transformer (3 wires) you need to modify the power supply board and get rid of 1/2 the diodes and put in a few jumpers.
If you are running a centertapped transformer, see Brian's LM3875 Instructions on how to jumper the right diodes. The LM3886 instructions do not identify how to wire a centertap transformer.
If you are running a centertapped transformer, see Brian's LM3875 Instructions on how to jumper the right diodes. The LM3886 instructions do not identify how to wire a centertap transformer.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.