DIY repair on old ART effects processor with a BUZZ

W

wjgypsy

New member
I bought this old ART effects processor (from the 80's?) for cheap at a thrift store. Figured I'd take a gamble and sure enough - it work's but there is also a loud "buzz" present in the output as well. It goes away when I hit the ART's bypass switch.

I'm novice when it comes to electronic repairs but have a soldering gun and a willingness to learn for sake of future repairs.

Thanks for any assistance
 
Have you got a schematic?

I guess I'd be looking at the grounding scheme first and then checking any caps to ground, but I'm an electronics noob myself.
 
Thanks, Steenamaroo! I Haven't tracked down a schematic yet but will search / contact ART about that.

I have my suspicions that the 'buzz' could be a grounding issue but that's about as far as my knowledge goes. Once I have the grounding schematic, what exactly should I be looking for? How does one check caps for grounding? This will be my first time cracking open any thing like this, but at least this is good piece of gear to cut my teeth on.

Thank you for your patients.
 
No worries.
As I say, I'm a noob in this world but I'd be looking at all the points on the schematic that show ground and continuity testing them against a common point. Chassis, or whatever.
If it's as simple a broken ground you'll be laughing. :)

Visual inspection of caps is another potentially easy one. Literally have a look at all the caps and see if anything's leaking or bulging.


You say the unit doesn't do it in bypass mode but check to be certain.
Is it a guitar effects processor? Quite often they accentuate a buzz that is there already.
Run the unit in bypass but amplify the output to make certain the buzz isn't coming from your instrument.
 
First off, reserve the solder gun for car repairs and buy a $50 solder station.

A model number for the unit would at least give us a fighting CHANCE at a schematic but anyway throw up a smudge!

Is the unit mains self powered? If so be very careful once you have it opened up. In fact one of the easiest ways to prove a lot of circuitry yay or nay, for hum is to cobble in a battery supply. How you do this depends of course on the voltages involved and the power required. Please give details of any "rating plates".

Like the aforementioned car work, there is a "critical mass" of kit you need before you embark on "fun" electronics.

Dave.
 
It is an Art Proverb 200 (1988). I found it's manual on Art's site but it held no schematic and I am still waiting for Art's reply to my email.
 
wjgypsy said:
It is an Art Proverb 200 (1988). I found it's manual on Art's site but it held no schematic and I am still waiting for Art's reply to my email.
Click to expand...

So, it is mains powered, as I say take care, a lot of this old kit was very badly served in terms of insulating and booting mains connections and switches/fuse carriers and (sorry chaps but..) a lot of gear of this era from the States was bloody lethal!

You can get a very good idea whether the hum is power supply or "earthy" from the spectrum. PSUs put out almost all 120Hz (100Hz here) whereas poor shielding etc tends to be 60(50) Hz and a continuum of harmonics.

Dave.
 
Further to ecc83 Dave's excellent advice above:
Capture the hum/ buzz on your "musician's storage oscilloscope" aka your DAW :p and use these rules of thumb to get you started.
100 (120) Hz saw-tooth or ramp waves are due to dried out electrolytic capacitors in the power supply.
50 (60) Hz rounded/ wobbly waves are usually due to magnetic inductive pickup.
Higher frequency jagged waveforms are usually due to capacitive pickup.
 
You must log in or register to reply here.
Back
Top