Got another one of these in ..
Amp powers up and plays audio but if i switch the phase switch or the subsonic filter switch from 0 to 180 or off to on i get a voltage spike across the speaker terminals about 4 volts..
When sub is playing i also notice it jumping around like a voltage issue on the outputs..
when switching the switches and no RCA'S plugged in i also get the voltage spike across the output terminals..
Any ideas on where to start?
Amp powers up and plays audio but if i switch the phase switch or the subsonic filter switch from 0 to 180 or off to on i get a voltage spike across the speaker terminals about 4 volts..
When sub is playing i also notice it jumping around like a voltage issue on the outputs..
when switching the switches and no RCA'S plugged in i also get the voltage spike across the output terminals..
Any ideas on where to start?
Replaced the switches and checked for DC on the output pins of the opamps..
All voltages look good.. less then 1 volt
All voltages look good.. less then 1 volt
1v would be excessive. Bear in mind that the amp can be driven to clipping by about 1/2v. Switching from 1 op-amp to another with 0.2v difference could cause a near clipping voltage spike.
The only opamp that i see with excess DC on the outpu pins is U21
Here are the voltages i get ..
Pin 1:-8.39
Pin 2:0.00
Pin 3:-8.84
Pin 4:-9.62
Pin 5:4.98
Pin 6:8.23
Pin 7:4.99
Pin 8::9.67
Do these appear to be correct or is it defective?
All other opamps have the folloing voltages on the output pins
Pin 1:0.64
Pin 7:0.69
LM6171
Pin 6:-0.05
Here are the voltages i get ..
Pin 1:-8.39
Pin 2:0.00
Pin 3:-8.84
Pin 4:-9.62
Pin 5:4.98
Pin 6:8.23
Pin 7:4.99
Pin 8::9.67
Do these appear to be correct or is it defective?
All other opamps have the folloing voltages on the output pins
Pin 1:0.64
Pin 7:0.69
LM6171
Pin 6:-0.05
U21 isn't in the audio circuit but the voltage on pin 7 should be near -9v.
Do you have your signal source connected to the 12v power supply ground?
Do you have your signal source connected to the 12v power supply ground?
With everything connected as it was previously, what is the DC voltage from the amp's ground terminal to the RCA shields?
Do you happen to have a pic of the area around U7,U8,U9
Looks like a cap or resistor is missing someone has been inside this before
Looks like a cap or resistor is missing someone has been inside this before
On pins 1,2,3,5,6,7 of all TL072'S i get 0.64 volts also..
Could this cause the RCA shields to have 0.64 volts on them if 1 opamp is bad ?
Could this cause the RCA shields to have 0.64 volts on them if 1 opamp is bad ?
The shields of the head unit are directly connected to ground.
If the shields are intact and the source unit is connected to the 12v power supply for the amp, there is no way for you to have more than 1/2v on the shields if the RCAs for the head unit are plugged in.
If the shields are intact and the source unit is connected to the 12v power supply for the amp, there is no way for you to have more than 1/2v on the shields if the RCAs for the head unit are plugged in.
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