Does anyone have experience with these cheap Chinese VU meters and the driver board. I want to use it on the line level of the preamp, between it and the power amp. But I'm getting nothing no mater how I turn the two trim pots......Any help?
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Check the meters with a multimeter at 2K range...are they dead or alive?
Then give an audio signal and power, say from the headphone jack of a device, see the meter dances with the music, so to speak....
And put LEDs as marked, see what happens.
You connected them to pre amp output, right?
What is the circuit of that?
Is it working, feeding the amp properly?
Then give an audio signal and power, say from the headphone jack of a device, see the meter dances with the music, so to speak....
And put LEDs as marked, see what happens.
You connected them to pre amp output, right?
What is the circuit of that?
Is it working, feeding the amp properly?
I wired in a set of RCA plugs....connected them to the outputs of my preamp with music playing...Nothing
When I touch the center pin of the RCA plug with my finger, I get full deflection of the meter. So the meter is working.
The lights light up fine.
???
When I touch the center pin of the RCA plug with my finger, I get full deflection of the meter. So the meter is working.
The lights light up fine.
???
You are playing music from the pre amp to the amp, and you tapped that wires set to drive the meters, and nothing happens, yet the meter works when you touch the RCA jacks, is that right?
That means the signal is not matching...
What does that circuit do?
What is the AC supply for?
Put a 10K in series with the pre amp direct to meter, see what happens. Then reduce it gradually.
That circuit is of no use. Connect the meters directly with an appropriate resistor.
Use Ohm's Law to calculate, 10V should be full scale deflection, put a proper resistor in series, and connect to signal and ground.
You can use the pots provided to set the value!
Start from max. value, reduce as needed, connected in series.
I just don't see the need for a power supply here.
That means the signal is not matching...
What does that circuit do?
What is the AC supply for?
Put a 10K in series with the pre amp direct to meter, see what happens. Then reduce it gradually.
That circuit is of no use. Connect the meters directly with an appropriate resistor.
Use Ohm's Law to calculate, 10V should be full scale deflection, put a proper resistor in series, and connect to signal and ground.
You can use the pots provided to set the value!
Start from max. value, reduce as needed, connected in series.
I just don't see the need for a power supply here.
The pinout is on the PCB:
Contacts CN2 and CN4 are those for connecting the two VU meters, CN2 for the right channel and CN4 for the left.
The AC power supply is on contact CN6
I see that there is nothing to connect to the CN1 connector but I think they are the audio signal inputs.
Do the Vu meters have two or 4 contacts behind? Because I see that there are contacts CN3 and CN5 on the board for connecting the LEDs
Contacts CN2 and CN4 are those for connecting the two VU meters, CN2 for the right channel and CN4 for the left.
The AC power supply is on contact CN6
I see that there is nothing to connect to the CN1 connector but I think they are the audio signal inputs.
Do the Vu meters have two or 4 contacts behind? Because I see that there are contacts CN3 and CN5 on the board for connecting the LEDs
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What is that long thing next to the regulator?
Some sort of IC?
He says the LEDs, whose connectors are next to the meter connectors, light up fine...meaning there is supply up to there.
Try reversing the meter wires?
Some sort of IC?
He says the LEDs, whose connectors are next to the meter connectors, light up fine...meaning there is supply up to there.
Try reversing the meter wires?
That's how it's wired.....And I have two of them and neither will register the line out of a preamp.....
I believe the AC(?) power supply is for the lights in the meters. But it is 12V DC
There is a bridge rectifier for the supply, so even reversing polarity will not matter, and you can reverse the DC, no problem.
The LEDs blink with music level?
Then connect a meter there, with a resistor in series, see what happens...
The LEDs blink with music level?
Then connect a meter there, with a resistor in series, see what happens...
LEDs do not blink with music....Stable. There is a third pot on the board that controls meter light brightness....
Maybe this board will only work with high level speaker output......Not sure I want to put that on the outputs of the amplifier.
Do Vumeters have two or four contacts behind them? Because two carry the variable signal and two the power supply for lighting.
The board has a diode bridge on the PCB and an integrated voltage stabilizer with a capacitor so it must be powered in alternating voltage
Purchase this and be done with it.
https://www.jlmaudio.com/shop/vu2-stereo-vu-buffer-kit.html?display_tax_prices=0
So this could be power supply to op amp to boost the level to meters, apart from lights.
Dirty and quick trick: try with headphone or toy speaker, trace the signal from in to out, connected to music source.
Dirty and quick trick: try with headphone or toy speaker, trace the signal from in to out, connected to music source.
These look to be the same ones.... although I'm not sure how much you might learn from it!
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The analog VU meters are just 0-10 V AC meters, with high impedance, so as to not disturb the signal by loading it.
The meter coils can be checked on resistance scale of digital meter, or even simply by briefly connecting to a 3V cell, if it deflects, then OK.
It looks like the wiring is faulty, or the IC is blown, which means work...358 will be enough if you need to replace IC.
Or just connect the meters directly, like I said above, with resistors in series, bypassing the IC, and use the power supply to light the meters.
The meter coils can be checked on resistance scale of digital meter, or even simply by briefly connecting to a 3V cell, if it deflects, then OK.
It looks like the wiring is faulty, or the IC is blown, which means work...358 will be enough if you need to replace IC.
Or just connect the meters directly, like I said above, with resistors in series, bypassing the IC, and use the power supply to light the meters.
Either
1) You have wired the RCA wrong (short signal to ground, reverse ground and signal,...)
or
2) the signal applied to RCA is too low (much lower than the noise you produce with your finger)
Assuming 2) is the case and looking at the attached (similar, not exactly yours) schematics:
- first, notice that it is possible to adjust the potentiometers in such a way they will short the vu-meters, so make sure you are not in that situation: disconnect power and the vu-meters and with an ohmmeter connected at each vu-meter connection, rotate the corresponding potentiometer until the measured resistance is maximum. Once you will have some Vu-meter movement you can readjust this.
- second there is a divider/attenuator at the high input; your board does not have a low input; an even better schematic would be to replace the fixed divider at the input with a potentiometer at least until you figure things out.
a) remove C8 ( C1 for the other channel)
b) remove Brown Brown Black Brown Black ? (really not sure, better see attached picture) resistor
c) short the Green Blue Black Brown Brown (not sure, better see attached picture) resistor
Make sure you don't put some big DC component (static or transitory) at the input.
I am surprised to see no resistor between pin 4 and 1 and no resistor between pin 6 and 1 of the IC on your board
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