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Yes. That is how the 'Cancel' function of the original version worked; by shorting the base of the transistor driving the bulb to ground.

There is no reserve polarity protection in that particular power supply section. Adding a simple diode such as a 1N4001 like you may have seen in other schematic provides a basic level of protection.

Something like this:

Thanks! That is extremely straightforward.

Thanks is extremely straightforward.

I'm putting together a basic op amp based clean boost and thoughts I might experiment adding a clipping indicator circuit to show when the op amp is close to or is clipping the signal. Surprise, surprise.

An online search found plenty for higher voltage power amps but nothing useful in regards to a 9-volt, simple op amp circuit à la the MXR Micro Amp.

Does anybody know of a simple, yet effective circuit or way of accomplishing this?

So, about those desoldering needles - 100% crap. Threw them away. Better off with a toothpick or dental pick.

Good to know.

Does anybody know where I can source a replacement pot of a Boss pedal? Specifically, a 9mm right-angle Alpha-style 250k reverse audio pot with a split shaft.

The only maintenance required is that after enough use you gotta clean the sucked up solder bits out of that cone-shaped spring. I rarely have to use it these days, and I've only cleaned it maybe 2-3 times in ~10 years.

I'm based in New Zealand, so will see if they make a 240-volt version.

Thanks for the comments.

I've been on a bit of roll at the moment repairing a number of commercially made guitar pedals.

One critical component in the power supply of one pedal, however, has a missing solder pad and broken trace. Possibly caused by a botched repair attempt. At the moment, I've got a jumper wire installed (crude but effective) to bridge the gap between the component in question and the next down the line.

My question is are there any thing more effective? I've seen the use of copper tape and conductive ink pens. Any other methods out there?

I think it's this exact model, but I only paid like $90 on ebay. Make sure you get one that's the right voltage though! Lots of ebay ones are set up for Chinese mains power.

Thanks. I've seen the Hakko FR-301 but they're really pricey. Is there much maintenance/cleaning required after use?

I have a desoldering gun with a vacuum pump on it. The thing is magic.

Pic, please.

Similar thread. I would not recommend the needles.

https://www.madbeanpedals.com/forum/index.php?topic=30940.0

Good to know.

It's a bit counter-intuitive at first, but adding fresh solder to a stubborn joint can help sometimes.

I discovered that one works well with the desoldering wick.

Haven't tried these yet, but desoldering needles look interesting.

Those desoldering needles do look interesting. My concern would be potentially damaging the plated through-holes. But they look easy enough to use.

If you don't care about the part cut it out first. You can often pull the leads out just with a soldering iron and wire cutters. Then you just have to remove solder from the pad. Works really well.

Done that plenty of times.

But, yes, I second bean's suggestion of destroying the part and removing its leads/pins one at a time.  It is the best way to ensure that you don't burn up the remaining parts/traces.  There is a corollary:  if you want to recycle a soldered part with multiple pins, the easiest way is to destroy the board.

Yes. No point adding work to a pedal repair by then having to repair other parts or traces you've damaged while trying to remove a faulty component.

Appreciate any suggestions.  And thanks to those who've posted already. I find de-soldering quite tricky

+1.

I've been doing a few repairs lately on a handful of commercial pedals that often require desoldering faulty components. My main to techniques involve desoldering wick and a good old solder sucker.

Does anybody want tricks and tips on better using these methods more effectively? Especially on double-sided PCBs?

My hands were shaking when I was trying to position the op amps not to mention soldering them. You'd get everything lined up perfectly on the pads and then bump it when attempting to solder it.

I should get some soldering paste, that would probably help hold things in position until you get both ends tacked down.