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Absolutely stumped fixing a friend’s Keisman Thunderbird.

Started by Tuxedo3, July 16, 2018, 12:42:40 PM

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Tuxedo3

I have a friend who had a Thunderbird that only was half working. Based on what he was explaining it sounded like a bad footswitch. After replacing it i've found out that it's something much sneakier, and would love some assistance finding out what it is.

If you don't know, the Thunderbird is like the Double Barrel, it has a Blues Breaker circuit and a TS circuit. Like I said, only half of the pedal works. If I move the board that doesn't come through around enough, I will hear the effect come through for a few seconds at a time, which makes me think it's a loose cable? But I've reflowed almost every cable that connects to the PCB with no luck. I've checked all points I can think of for grounding problems, but it all checks out. Absolutely no disrespect to Keisman, this pedal is super nice, it's just a mess of cable on the inside, which makes it hard to troubleshoot. Does anyone have a thought that might help me? I'll happul post a video I took of the problem.

midwayfair

No warranty?

If someone's going to manufacture something with a mess of cable inside making it hard to troubleshoot, they should probably do their own repairs for their customers.

That said, audio probe.

sonnyboy27

If it's using solid core wire then there could be a broken wire between the board and the switch. That would explain why you're hearing it when you shift it around. I just had something like that with a Morning Glory clone I made.

Tuxedo3

Quote from: midwayfair on July 16, 2018, 01:56:13 PM
No warranty?

I don't think Keisman makes/works on any pedals anymore. Can't find anything online about the company.

Quote from: sonnyboy27 on July 16, 2018, 02:25:36 PM
If it's using solid core wire then there could be a broken wire between the board and the switch.

This is a good thought, it uses stranded wire - plus I have reflowed every joint that looks suspect. I still can't narrow anything down.

jimilee

I'll second Jon, and audio probe will / should lead you straight to the issue.


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ahiddentableau

Just to state the obvious in clear terms because nobody else has: you seem to be set on wiring, but it could well be a bad component or solder joint on the board.  In situations like this I usually get my hands on the schematic, break the circuit up into sections, and then probe through each section of the circuit until I hit the spot where the signal goes foom.  Then you can work through the smaller section until you find the bad part/joint.  Even if you don't have a schem, the pedal doesn't sound to complicated, so you should be able to break it down without too much trouble.

Tuxedo3

Thanks all, I'll go at it with an audio probe. I appreciate the help.

stringsthings

Quote from: ahiddentableau on July 17, 2018, 08:00:47 PM
Just to state the obvious in clear terms because nobody else has: you seem to be set on wiring, but it could well be a bad component or solder joint on the board.  In situations like this I usually get my hands on the schematic, break the circuit up into sections, and then probe through each section of the circuit until I hit the spot where the signal goes foom.  Then you can work through the smaller section until you find the bad part/joint.  Even if you don't have a schem, the pedal doesn't sound to complicated, so you should be able to break it down without too much trouble.

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