18 April 2014

The Curse of Broken Traces: Repairing a Visual Sound Route 66 Overdrive

A music store owner in the area occasionally sends work my way (for which I am quite grateful—check him out at http://www.payettesmusictraders.com). One recent project was a Visual Sound Route 66 Overdrive, which is an overdrive and compressor in one pedal. The compressor side did not turn on. When you pressed the switch on that side of the pedal, nothing happened—the LED did not turn on and the sound did not change. He said it was probably the switch, and I went with that, a mistake that fortunately only set me back $6. 

I got it on my bench, checked it out, and it sure seemed like the switch, so I ordered one for $6 and didn't think much about it. The next day, though, I decided to have another look at it, because there was a sloppy jumper on part of the board (see pic below). Since a jumper often means a lifted solder pad or broken trace (or both), I started checking continuity along the circuit.
What the hell is this? Did the previous owner spill molten solder on the board?

When I got to the switch, there was very spotty continuity between two points that were clearly supposed to be connected. I poked the solder pad a bit with the meter probe and it moved. I think the copper trace was broken and disconnected, and being held in place only by the the thin green coating of the circuit board.

Two other nearby points were in the same condition, so I installed a couple of jumpers and replaced the solder blob in the picture above with new jumpers. That completely did in the solder pads (as you can see by the big brownish circles in the picture on the left below), so it wasn't as neat as I would have liked, but at the very least it is clear what has been done, since the jumpers are now lines that basically follow the circuit path, not just masses of solder.
Left: I replaced the solder blob with jumpers that will make the circuit much easier to follow for the next person who repairs this pedal. Right: The jumpers around the compressor-side switch that caused the problem.
As you can see, it sure isn't pretty on the inside (or on the outside, for that matter—this pedal's been ridden hard and put away wet a few times too many), but it works now and sounds great.



01 April 2014

Peavey Vypyr 75 Repair—Bad Name, Bad Design

I saw a non-working Peavey Vypyr 75 (seriously with the name?) at Guitar Center and couldn’t resist. These amps sell for $300 new and $150-$200 used, so I thought $80 was worth the gamble.

The main reason I took a shot was that it didn’t turn on. If something turns on, but doesn’t work, that can get pretty complicated, especially in a modelling amp. But if something doesn’t turn on, the possibilities are narrowed considerably.

And I was right—I quickly checked for anything obvious and saw the fuse, so figured I’d check that first.  I checked for continuity and there was none. I did not take an pictures, so here's a hastily made layout showing the location of the fuse. This diagram is pretty primitive, but there's not much to this amp, so if you can't find the fuse based on this, hie thee to an amp tech.



I quickly found the part I needed on ebay: 3-Amp 250-Volt fast blow fuse with axial leads for about $5, free shipping.

3A 250V axial lead fuse


The only minor pain was that this fuse has axial leads that are soldered to the board. You can’t just pull it out and pop in a new one—you have to remove the board, desolder the old one and solder the new one in. Well designed amps—of which there are many—have a fuse holder that is accessible on the back of the chassis, affording the owner the luxury of changing a fuse in a half minute instead of a half hour.


However, since I sold the amp for $140 a couple of weeks later, the time spent on this poorly designed beast was worth it. To be fair, I played with the amp for a while and had a lot of fun with it. It's a fun toy, but Peavey needs to head back to the drawing board.