Frail and faltering follower of Jesus

Boss DS-1 Pedal Repair (with video)

By Gavin Davies

I bought a broken distortion pedal. I went on quite the journey to repair it!

Here was the posting on eBay:

£27.35 BOSS DS-1 Distortion Pedal - Spares / Repairs - No Sound When Engaged.

Lights up on PSU, bypass works - no sound when engaged Good cosmetic condition Sold as seen

I thought, OK, I’ll have a go at this! After all, the DS-1 is a legendary pedal for acid/techno…

The pedal arrived, I eagerly dismantled it, and was faced with some very clear issues:

It was clear that, the diode D1 was blown, and capacitor C23 next to it had a little mohawk from where it had bulged out upwards.

From the serial number, it seems this is an early 2000s model. I consulted a schematic I found online, and it was clear that both of these were in the power circuit:

I spoke to my mate Jon and he suggested that maybe someone had plugged in the wrong power supply - this totally makes sense that the components would blow if that’s the case.

I desoldered the diode, which was fully broken in two, and pulled out the cap also:

I tested the cap, yep, ESR meter suggests it’s totally borked!

So, I soldered in some replacements I happily had in my parts bins:

It still didn’t work. Oh no! Back on the test bed!

I could see that there was what looked like capacitor leakage around C15. So, I pulled out that cap and the surrounding resistors:

They all read fine, but I replaced them anyway; the resistors looked a bit grubby. I cleaned the PCB with some isopropyl alcohol and it looked much better.

It STILL didn’t work! At this point, I did some voltage tracing by putting a probe on neutral and measuring voltages at certain points corresponding to the schematic. Voltages seemed OK although I’ve never done this before so I wasn’t confident.

Eventually, I built a simple audio probe:

I traced the signal point-by-point through the circuit. I got as far as the op-amp and suddenly it all dropped out!

At this point, I realised that the op amp must be blown. I managed to find a few articles and threads online suggesting that this is a common issue when people feed the DS-1 the wrong power.

The waiting game

I found some replacement op-amps on Little did I know, they’d be shipping from Texas!! No wonder they wanted £12 for Fedex delivery!

When it eventually arrived, I socketed the op-amp so I could swap it out if necessary. Apparently there are a number of op-amp mods for this pedal

IT WORKED! I put it all back together and was stoked.

Closing thoughts

This is a greatly smoothed out version of what happened - there was a lot of flailing around! I probably spent about 8 hours in total on this project, including all the research I did, although that’s hard to quantify.

That said, I enjoyed fixing this pedal immensely. I found it so satisfying to trace the fault down and pursue it.

Whilst I spent a small fortune on components and shipping (I went down a few blind alleys with suspecting various caps I didn’t have in my drawers; components are reasonably cheap but you really get stung with the postage), so it cost more than buying a new one, it was the fun of the fight that I relished.

And next, to try it on synths!

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