This is a Double pointer VU meters with drive boards For 5W-50W amplifiers .
The Power Supply Input is For The Backlight DC/AC 5-12V ＞0.1A
R1 And R2 Adjustable Resistance for Adjust  Pointer jump
Please Note :The Connect cable requires you to solder on the Driver board

Debugging method:
Method 1: Connect the power amplifier with the signal generator 1KHZ signal, adjust the volume of the power amplifier to the maximum, adjust the adjustable resistance, so that the meter pointer points to the 0 position
Method 2: No signal generator, you can use Android mobile phone to download the signal generator software, use the mobile phone to output 1KHZ signal to the power amplifier, adjust the power amplifier volume to the maximum, adjust the adjustable resistance, so that the meter pointer points to the 0 position