Dead DOD pedal

[Jeff R]

I picked up a very clean (new cosmetic condition) DOD Envelope Filter off Reverb about a week ago. Sounded great, just what I wanted and worked fine until last night - I engaged it and it sounded weak and sizzly like a very dying to practically dead battery. Signal was fine without it on (true bypass).

It has been hooked up to my Voodoo Labs Pedal Power 2 Plus (9V barrel) with no battery and no problems. I then removed it from the power chain and put in a fresh battery and it still sounded like pfft. It hasn't been dropped or stomp-engaged, hell it's barely been used maybe a hour or so.

A quick visual with the back popped off showed no obvious evidence of altered circuit inside - adhesive foam over the PC board had never been disturbed until I pried it off to see if anything was visually hokey on the board. I saw no blown up components or clearly poor solder points.

There is continuous power to the board on a surge-protected power strip. No storms or spikes I'm aware of, and nothing else on the board is misbehaving. My workshop is on the cold side right now due to winter (dips to 50s), so I was thinking maybe the pedal has a weak solder joint somewhere (made in China) that the cold weather is affecting. I plan to warm the pedal with some mild heat from my heat gun tonight to see if that theory holds water. I figure it's a long shot, but what the hell.

In the meantime, any other ideas for me to try tonight?

[Armitage]

Dirty switch?

[Jeff R]

I clicked and clicked and clicked to no avail. No signs of excessive dust around the switch, pot mounts or inside the jacks, but I'll shoot a squirt of contact cleaner in the switch when I troubleshoot tonight. Good idea!

[Bloozguy]

You might try firing up your soldering iron and adding normal tin/lead solder to each solder joint you can see. RoHS-compliant (lead-free) solder is absolutely horseshit for reliability. Nearly all of the implantable medical products companies (many of them headquartered right here in my back yard) have obtained waivers so they do not have to use lead-free solder.

Anything you have with either "RoHS" or "CE" marking is likely to have some sort of reliability problem because of that.

[Jeff R]

Wise advice, and I will likely do that even if I find the problem elsewhere because I do not trust what I've seen inside so far. When I cracked the pedal's back plate and exposed the PC board, my first observation was all of the solder connections were a dull, storm-cloud gray (not shiny) and the contact points had what appeared to be as little solder applied as earthly possible. The PC board, IMHO, is more issues waiting to occur.

[Jeff R]

UPDATE: I disassembled the pedal completely and got it under my magnifiers. I isolated the problem to an IC chip soldered to the PC board. The chip would not move against the board but applying slight pressure to the side of the chip with a jeweler's screwdriver would make it either a.) work, b.) work noisily or c.) not work at all. I decided I would de-solder and reseat the chip, and I found out quickly these pedals were not designed to be altered, or repaired manually for that matter. Like I said before, the PC board appears to be pretty low quality. The IC chip's legs were so thin and brittle that the first leg I attempted to de-solder broke off inside the chip, effectively rendering it useless. And even had I extracted the chip successfully, the PC board design was going to make resetting it akin to microsurgery. This is a disposable effect IMHO.

My new plan of action is to extract pots and knobs, jacks, the mini switch and LED, the casing and see if they're worth taking up space in my parts bin. And shop for a different envelope filter.

[mrjamiam]

Bummer. Learn and move on. Thanks for sharing the info.

[geoff_hartwell]

Well, two things...

Another fella is looking for busted mics and stomp boxes to use in an art project, listed on the FS page.

Also, I almost never use an auto filter, but my favorite by far is the MXR auto Q.

Best of luck!

[chromium]

UPDATE: I disassembled the pedal completely and got it under my magnifiers. I isolated the problem to an IC chip soldered to the PC board. The chip would not move against the board but applying slight pressure to the side of the chip with a jeweler's screwdriver would make it either a.) work, b.) work noisily or c.) not work at all. I decided I would de-solder and reseat the chip, and I found out quickly these pedals were not designed to be altered, or repaired manually for that matter. Like I said before, the PC board appears to be pretty low quality. The IC chip's legs were so thin and brittle that the first leg I attempted to de-solder broke off inside the chip, effectively rendering it useless. And even had I extracted the chip successfully, the PC board design was going to make resetting it akin to microsurgery. This is a disposable effect IMHO.

My new plan of action is to extract pots and knobs, jacks, the mini switch and LED, the casing and see if they're worth taking up space in my parts bin. And shop for a different envelope filter.

If you are ever faced with this type of repair again, check into "drag soldering" or hand soldering techniques for surface mount devices.

You can get a flux pen (like he's wiping across the IC legs in the above vid) off amazon for not too much... $10-15:

http://www.amazon.com/Soldering-Flux-2331-ZX-FLUX-piece/dp/B005T8Z0IK/ref=sr_1_2?ie=UTF8&qid=1453071804&sr=8-2&keywords=kester+flux+pen+2331

...and it helps to have an iron that allows you to swap tips. For this, you'd be best off with one of those beveled tips like in the vid.

The SMD stuff is a big PITA, and it does take practice. I've learned the hard way too :/

[chromium]

Also, if you are feeling ambitious you might be able to desolder/replace that IC... Use a light touch, though, because the traces on a lot of these cheap PCBs of today will lift really easily.

[hamerhead]

I would be interested in the enclosure, should you decide to give up on it......