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Hi all,
I have completed my Blue Overdrive a few months back and I have been unable to trace a very loud screeching sound when the drive level is at anything but its lowest point. I keep going back to it and I just can't seem to pinpoint the issue. Everything else seems to be in working order except when the drive is increased at all. Bypass is good, engaged it seems fine, LED is good and I have rechecked all joints and wiring as best as I can. The only thing that I can think of is that I might have a polarity issue with the tantalum capacitors(Mod pack) but I have no idea how to check.
Voltages:
9.3 VDC
Pin1-4.1
2-4.1
3-4.1
4-.7mv
5-3.9
6-4.1
7-4.1
8-8.2
I have used a fresh battery, DC transformer and bench power supply. I have attached pictures front and back as well as a close up of the tantalum caps.
Any thoughts would be appreciated.
Thanks!

Can you check the orientation of your tantalum capacitors, their polarized and appear to be backwards.

Agreed.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks for the replies! I went ahead and swapped the polarity on the caps and gave it a go. Still has a nasty squeal but now it only happens when both the drive and level are above half way. Under that I can get decent sound. Any other ideas are welcome but I may play through it for a bit to see if it will meet my needs.
Thanks again.

You might be getting some signal cross talk. You can try removing the wires that connect the PCB to the tips of both sleeves and lugs 4 and 8 of the foot switch.

Rewire so that the tip of the input jack connects directly lug 4 of the foot switch (you still want to keep the jumper between 4 and 9) and the tip of the output jack directly to lug 8 of the foot switch.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I want to follow up on this post - I am having the same issue with a loud squeal as I turn up the gain, tone, or volume. I have double-checked everything based on the comments in this post and the photos. Gain up to halfway - beautiful sound (reminiscent of the 1981 DRV), and then it just starts squealing, a hissy squeal like a Sonic Youth noise box.

I noticed that the gain knob is 'live' - when I touch it, it fizzles and changes the sound. I have a piece of notecard (folded) blocking the dual-gang pot from the board (and there is actually enough clearance without it). So, I'm at a loss - but I think this is the issue. Perhaps the pot is bad since there are only the six holes to solder and nothing else directly connected to the pot.

I wanted to find out if Keith's suggestion about the in/out being directly connected to the foot switch... Has that worked? Would removing the tantalum caps be an idea? Or, could it be the .1 film cap in the 473 spot? While my technical knowledge is limited, this is my 20th+ build, so I'm thinking the mods must be the issue.

The one difference between my pedal and the one above - I have the mod switch coming out the side.

Thanks,
Zach

While the BD-2 is called an overdrive, it is an extremely high gain circuit. BOSS actually wires the BD-2 slightly different than most of their compact pedals. They will wrap a ground wire around the send and return wires as a sort of shielding.

I've had squealing issues with modified BD-2s and using shielded mini wire fixed it, but I've never experienced this issue with one of our clones. The previous builder never reported back, so I don't know if it fixed his issue. We've had similar issues with chorus pedals where clock noise was getting into the bypass signal, and connecting the jacks directly to the foot switch fixed that. Sometimes you just get unlucky and you get the perfect combination of tolerance build up and other environmental factors that causes your pedal to behave differently than the rest. If that's the case and the squealing is being cause by some sort of high gain self-oscillation, then I do think re-routing the wires so that they go directly from the jacks to the foot switch will help. And if you have some shielded mini wire, that would be even better.

If you're questioning the mods, then I would suggest, simply removing them and verifying that the pedal works correctly "stock" first.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I've been messing with this again and have noticed one thing - the 250K dual pot is hot - when I touch it, it sounds like I'm touching the end of a hot cable.

I'm wondering if there might be a suggestion based on that information. Otherwise, I guess it'll be a noise box.

Thanks!

Do you mean with you touch the turn shaft? Or when you touch one of the solder lugs? And just to make sure I'm understanding you correctly....when you say "hot", you mean signal hot, not temperature hot?

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com