With the receiver turned off, is there still power to speaker outputs.
Thanks, for some reason unable to search.
Thanks, for some reason unable to search.
No, no power or voltage is present when it is off.
When it is on the only 'power' present on the speaker outputs is the small audio AC voltage waveform.
The level of voltage depends how loud it is. Turn the volume down it there is no voltage anymore.
When it is on the only 'power' present on the speaker outputs is the small audio AC voltage waveform.
The level of voltage depends how loud it is. Turn the volume down it there is no voltage anymore.
Hmmm ... that's not good.
Disconnect your speakers and measure again, directly across the + and - speaker terminals.
Is it AC or DC ?
How much is it with with power on?
Is it on all channels?
Usually a DC voltage on one of the speaker terminals indicates a serious problem with the power output stages of that amplifier. But it can also indicate power supply problems if it's on them all.
Disconnect your speakers and measure again, directly across the + and - speaker terminals.
Is it AC or DC ?
How much is it with with power on?
Is it on all channels?
Usually a DC voltage on one of the speaker terminals indicates a serious problem with the power output stages of that amplifier. But it can also indicate power supply problems if it's on them all.
Hello, it is less with power on, 170 mv, magnavox mx 1571. Do not have speakers plugged in, testing b4 I do
If the speaker is connected via a relay then when off the sockets will be floating and may seem to pick up stray voltage... just a thought.
Try connecting a resistor across the terminal (like a 1k) and measure the voltage across the resistor.
Try connecting a resistor across the terminal (like a 1k) and measure the voltage across the resistor.
That's a long time. Do try putting a small load on it like Mooly's suggestion of a resistor. Any value from 4 to 1000 ohms would do.
Most semiconductor junctions stop conducting appreciable below 0.5V, this isn't an unsurprizing result given the large filter caps in audio amp PSUs.
"isn't...unsurprizing" ?? Help us out. Does this boil down to meaning surprising or not surprising?
It is most surprising to me. You do get half a volt of residual DC inside sometimes, but not at the speaker terminals. No apparent reason for that except a fault.
That Magnavox employs a capacitor-coupled amp, so naturally those capacitors if "unloaded" will retain a charge.
It's absolutely normal, and they should drain down if a speaker is connected.
It's absolutely normal, and they should drain down if a speaker is connected.
Whoops, yes, I meant it seems plausible for a circuit using BJTs - once the supply rails are down to 0.5V or so all the transistors will effectively be off and this allows the rail caps to stay at that voltage and anything coupled to a rail with a resistor could show a voltage for ages unless a bleeder resistor is present (or the speaker itself)
However if this is capacitor coupled amp then you have to allow for dielectric absorption - even if the capacitor is discharged at switch-off it can slowly build up in voltage as dielectrically absorbed charge leaks back the electrodes.
The dielectric absorption effect allows the rail caps to stay at a small voltage even if a small leakage current is draining them too, on the order of microamps.
In short check the amp works when powered up before worrying about this!