Crackly knobs even when bypassed - What could be causing this on my pedal? #368

soma1975 · October 2023

Bought a 1991 pedal off eBay as am on a big alt rock trip at the mo. Appears to have a few issues.

1) All the knobs crackle when moved when engaged.

2) There is still level coming through the amp when all volumes are turned down to minimum.

3) The knobs crackling can also be heard when the pedal is bypassed.

Here's a link to a video of it here - https://www.dropbox.com/scl/fi/refpllbx3fjksewoj4ewx/PXL_20231006_121816088.TS.mp4?rlkey=e7twbzfd24ute6zthmf09fuft&dl=0

I've tried different power. Different patch cables and going straight in with this the only pedal in the chain. No difference.

I've dropped an email to the makers to see if this is normal behaviour but seems to melike it might a single thing causing all this and hopefully something easy to sort.

I'd like to have it working/bypassing properly rather than just return it. Any thoughts on the cause?

The pedal is otherwise mint aside from the whole not working properly thing and everything looks soldered well enough when you take the back off.

Thanks in advance. Obviously if you feel it's buggered and not worth getting sorted also do let me know.

Cheers.

ICBM · October 2023

Sounds like poor grounding. I found this pic online which seems to show that the only grounding to the casing is to both jacks, separately.

Image: https://funnylittleboxes.co.uk/cdn/shop/articles/Screenshot_20210810_142310_01069cc4-9610-45d9-9524-e1dc41bb113b_1200x1200.jpg?v=1630080263

Since this appears to be yet another small builder who doesn't believe in using shakeproof washers - notice he's left the one from the switch on the bench! - and the casing is painted on the inside too, it's possible that one or both jacks aren't contacting the metal casing properly.

Fixes: scrape the paint off the casing around the jack holes on the inside and make sure the jack nuts are tight. And/or: fit shakeproof washers - which will bite through the paint, as well as stopping the jacks coming loose.

soma1975 · October 2023

Nice one will have a look. Appreciate it.

ecc83 · October 2023

Just FYI the Blackstar HT range of pedals only ground the electronics to the case at one corner under an M3 screw (of 4) You generally don't want multiple ground points. Therefore if you get one of these pedals and it hums or makes other noises, check all 4 screws are present.

N.B. The screws were historically 'KING tight! Use a perfectly fitting pozi bit and sit the pedal case on a rock solid surface. If they won't move by fair means, warm the case around them with a hair dryer and then apply a drop of WD-40 or other penetrating lube. If you snap the head off you got trouble!

Dave.

soma1975 · October 2023

*deleted initial post here from the ebay seller cos the actual builder sent me a nice email*

The scraping around the pots seemed to have helped but I need to do a better job and pull th circuit out completely. Will get some washers at the same time. Cheers all.

Post from builder:

If the volume coming through when everything is at min is very faint then that is normal. There is a 1k resistor connecting the volume pot to ground which means that the volume is never truly off.

As for pot crackle that should not be happening and you should not be hearing anything from that pedal when it is bypassed. The fact that is happening makes me think it may be a psu or cable related issue as opposed to the pedal. My advice would be to try it with another pedal and see if the same happens. If it does then change your cables and try again. If not, I would recommend changing your cables and psu anyway if you can so as to determine the issue is definitely with the pedal and not another part of the rig.

I thanked him for clarification and mentioned the paint scraping seems to have alleviated it somewhat.

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Crackly knobs even when bypassed - What could be causing this on my pedal? #368

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