I've been working on a custom 5.1 LM3886 based amplifier that has Dolby/DTS decoding. I got the Dolby Decoding working the other day, and am working on cleaning everything up and improving all the wiring and what not. One problem that I now have is that occasionally when I touch the amplifier, I discharge static on it. Sometimes nothing happens other than a little jolt, but sometimes the static discharge travels along the volume knob I guess, which is using a rotary encoder and connected to the microprocessor board. The discharge is enough of a jolt that it reboots the microprocessor.
The chassis is anodized aluminum, but it's connected to earth in the places where I've exposed metal. But the outside surfaces are non conductive. All the through components are isolated though, so they shouldn't be grounded, at least not via the chassis. The encoder is grounded via it's connection to the microprocessor board.
My question is, is there any way to mitigate that? The static discharge isn't unique to the amplifier - it's cold and dry here and the same thing happens when I touch a door or other items sometimes. I can run the power and ground to the main digital PSU, but the encoder will still be connected via the two signal lines to the board. My only other thought it is to maybe tie a capacitor between the chassis and volume knob ground, similar to the RCA jacks.
Anyone else have any ideas?
Here's the amplifier and the volume knob for reference:
https://www.dropbox.com/s/jk9wcpsrtym4l3a/IMG_3251.mp4?dl=0
The chassis is anodized aluminum, but it's connected to earth in the places where I've exposed metal. But the outside surfaces are non conductive. All the through components are isolated though, so they shouldn't be grounded, at least not via the chassis. The encoder is grounded via it's connection to the microprocessor board.
My question is, is there any way to mitigate that? The static discharge isn't unique to the amplifier - it's cold and dry here and the same thing happens when I touch a door or other items sometimes. I can run the power and ground to the main digital PSU, but the encoder will still be connected via the two signal lines to the board. My only other thought it is to maybe tie a capacitor between the chassis and volume knob ground, similar to the RCA jacks.
Anyone else have any ideas?
Here's the amplifier and the volume knob for reference:
https://www.dropbox.com/s/jk9wcpsrtym4l3a/IMG_3251.mp4?dl=0
Last edited:
Some transient voltage suppressors on the supply usually works well to remove static. They can be added to other lines as well. Basically a hefty Zener diode.
Use a plastic volume knob, or else discharge yourself before touching the amplifier.
Does it only happen when you touch the volume knob? If so, can you make a brush to make contact with it and still allow it to rotate? You could do this temporarily with the stripped end of some stranded cable and connect the other end to ground. Tape it to the front panel with the stripped ends touching the volume knob
Brian
Brian
- get a humidifier
- place gear on a static mat, touch the mat first
- wear a static strap
- install a static floor mat near the gear
- get some plants to help humidity