AusTex64
Well-known member
- Joined
- Jun 3, 2013
- Messages
- 525
This forum has given so much to me that I wanted to return the favor, as little as it might be.
My original "gold horsie" Klon Centaur #917 developed a problem where in bypass it was fine (the buffer was working OK), but when the pedal was engaged it had very low gain and no distortion. I could barely hear changes when I turned the gain, treble and output controls up and down when the effect was engaged. The short version (for those who aren't into the details) is the problem was apparently caused by the tip/ring power connector coming from my Visual Sound 9V AC supply being too loose in the Switchcraft power jack on the Klon, which damaged the ICL7660SCPA charge pump in the power supply and TLO72CP in the distortion circuit. Once these two IC's were replaced the pedal works fine. Lesson learned - Bill Finnegan included a Switchcraft 780 .141" TINI male tip/ring plug (.141" TINI Plug, Solder lug & Cable clamp terminals, shielded handle | Switchcraft) with the pedal when it shipped. Now I see why, once I bought the Switchcraft 780 plug. It fits very snugly in the female Switchcraft power jack on the Klon, especially the tip. That was the greatest difference between the Switchcraft plug and the Chinese tip/ring plug on the power supply. Also don't plug the Klon power plug in while energized - there's too good a chance of it shorting to ground. I also see why all the pedal makers went to the Boss style power connectors, for this reason. There's a sacrificial diode that is ungooped near the top of the PCB/power supply jack that is supposed to fail before taking out other power supply components, but it didn't save me on this unit. Also, the Switchcraft power jack plastic casing was cracked. So while I was in there already and out of an abundance of caution, I replaced it with a new Switchcraft 142AX. Summary of this part: Use the Switchcraft 780 plug and don't hot plug power to a Klon!
Note: The Switchcraft 780 and 142AX are in stock at www.mouser.com
If you're not aware, the Klon PCB is gooped with black epoxy on both sides. This was the greatest obstacle for repair. I studied different degooping methods, and saw a video where a fellow boiled an automobile ECU to degoop it. I tried iso alcohol but it didn't do much. I was too afraid to try stronger solvents like acetone or MEK. After much experimenting, I settled on using a heat gun, X-Acto knife and dental pick to remove the goop. I have a FLiR handheld thermal imaging camera, which I used to learn how long to heat the PCB and goop to 200F-ish - the temp it would have been if I boiled it like the guy in the video. This worked out pretty good. The goop got gummy enough to remove with the tools for about 10 seconds before it cools and hardens up. It took me about 20 hours to clean the goop off enough to troubleshoot and repair the unit. The back side of the goop would pull off in chunks and was the easy part. The component side was the most tedious. I did break a resistor leg doing this and lightened up on the force used after that. We did replace all the electrolytic caps, since the outside plastic on the caps got torn up in the process. Plus when I talked to Bill he suggested an EL cap failure was the likely culprit. We hoped by replacing the EL caps it would solve the problem, but did not. Plus the PCB would have looked like ass with all those violated EL caps. I contemplated replacing all the film caps and the one tant too. But once the IC's were replaced the unit sounded and measured fine, so decided not to jack with the PCB anymore. The traces and pads on the PCB are quite small and delicate, another reason I felt we should leave well enough alone. I did remove all the gray wires attached to the PCB while I degooped, carefully labeling each one and taking lots of pics to aid reassembly.
Another point to mention is the multi conductor gray ribbon cable that connects the PCB to the dual gang gain pot on the front panel is quite brittle and the wires will break easily if they are bent enough times. That happened to me. Fortunately I was able to remove it on the broken end, strip back a little insulation and reconnect it to the PCB. But I wouldn't want to do it again. There's not much slack to work with. I reinforced the connection on both ends with E6000 to keep the wires from bending at the PCB attachment point while handling the dual gang pot during repair and reassembly. I also made a cardboard support for the three front panel pots to support the dual gang pot specifically, along with the I/O and power jacks. You can see it in one of the pics attached. Made it a lot easier to handle the PCB without worrying about breaking a wire again.
When reassembling, the trickiest thing was how to reattach the Carling on/off switch to the chassis. It has to be tensioned by the nut on the inside, otherwise there is risk of scratching the paint on the outer chassis by trying to tighten the screw ring on the outside of the switch. Miraculously I had a tiny, very thin 1/2" wrench (thank you God) that fit right under the switch, and was able to tighten the inner 1/2" nut with no problem. I'm guessing Bill attached the Carling footswitch first then soldered the wires. But the wires are short and the insulation shrinks with very little heat, and he wrapped the wire around all terminals in the unit too. Which makes it a PITA to remove them and reattach. I found using my little wrench was a much more foolproof way to go.
I hope this helps anyone that has to repair a Klon. Gotta say it was a harrowing repair but I'm very grateful it's working again. And a big thank you to Martin Chittum for the online schematic, that was quite helpful. And also thank you to Austin's own wundertech Cris Burns, who figured out it was the charge pump and TLO72 that failed.
My original "gold horsie" Klon Centaur #917 developed a problem where in bypass it was fine (the buffer was working OK), but when the pedal was engaged it had very low gain and no distortion. I could barely hear changes when I turned the gain, treble and output controls up and down when the effect was engaged. The short version (for those who aren't into the details) is the problem was apparently caused by the tip/ring power connector coming from my Visual Sound 9V AC supply being too loose in the Switchcraft power jack on the Klon, which damaged the ICL7660SCPA charge pump in the power supply and TLO72CP in the distortion circuit. Once these two IC's were replaced the pedal works fine. Lesson learned - Bill Finnegan included a Switchcraft 780 .141" TINI male tip/ring plug (.141" TINI Plug, Solder lug & Cable clamp terminals, shielded handle | Switchcraft) with the pedal when it shipped. Now I see why, once I bought the Switchcraft 780 plug. It fits very snugly in the female Switchcraft power jack on the Klon, especially the tip. That was the greatest difference between the Switchcraft plug and the Chinese tip/ring plug on the power supply. Also don't plug the Klon power plug in while energized - there's too good a chance of it shorting to ground. I also see why all the pedal makers went to the Boss style power connectors, for this reason. There's a sacrificial diode that is ungooped near the top of the PCB/power supply jack that is supposed to fail before taking out other power supply components, but it didn't save me on this unit. Also, the Switchcraft power jack plastic casing was cracked. So while I was in there already and out of an abundance of caution, I replaced it with a new Switchcraft 142AX. Summary of this part: Use the Switchcraft 780 plug and don't hot plug power to a Klon!
Note: The Switchcraft 780 and 142AX are in stock at www.mouser.com
If you're not aware, the Klon PCB is gooped with black epoxy on both sides. This was the greatest obstacle for repair. I studied different degooping methods, and saw a video where a fellow boiled an automobile ECU to degoop it. I tried iso alcohol but it didn't do much. I was too afraid to try stronger solvents like acetone or MEK. After much experimenting, I settled on using a heat gun, X-Acto knife and dental pick to remove the goop. I have a FLiR handheld thermal imaging camera, which I used to learn how long to heat the PCB and goop to 200F-ish - the temp it would have been if I boiled it like the guy in the video. This worked out pretty good. The goop got gummy enough to remove with the tools for about 10 seconds before it cools and hardens up. It took me about 20 hours to clean the goop off enough to troubleshoot and repair the unit. The back side of the goop would pull off in chunks and was the easy part. The component side was the most tedious. I did break a resistor leg doing this and lightened up on the force used after that. We did replace all the electrolytic caps, since the outside plastic on the caps got torn up in the process. Plus when I talked to Bill he suggested an EL cap failure was the likely culprit. We hoped by replacing the EL caps it would solve the problem, but did not. Plus the PCB would have looked like ass with all those violated EL caps. I contemplated replacing all the film caps and the one tant too. But once the IC's were replaced the unit sounded and measured fine, so decided not to jack with the PCB anymore. The traces and pads on the PCB are quite small and delicate, another reason I felt we should leave well enough alone. I did remove all the gray wires attached to the PCB while I degooped, carefully labeling each one and taking lots of pics to aid reassembly.
Another point to mention is the multi conductor gray ribbon cable that connects the PCB to the dual gang gain pot on the front panel is quite brittle and the wires will break easily if they are bent enough times. That happened to me. Fortunately I was able to remove it on the broken end, strip back a little insulation and reconnect it to the PCB. But I wouldn't want to do it again. There's not much slack to work with. I reinforced the connection on both ends with E6000 to keep the wires from bending at the PCB attachment point while handling the dual gang pot during repair and reassembly. I also made a cardboard support for the three front panel pots to support the dual gang pot specifically, along with the I/O and power jacks. You can see it in one of the pics attached. Made it a lot easier to handle the PCB without worrying about breaking a wire again.
When reassembling, the trickiest thing was how to reattach the Carling on/off switch to the chassis. It has to be tensioned by the nut on the inside, otherwise there is risk of scratching the paint on the outer chassis by trying to tighten the screw ring on the outside of the switch. Miraculously I had a tiny, very thin 1/2" wrench (thank you God) that fit right under the switch, and was able to tighten the inner 1/2" nut with no problem. I'm guessing Bill attached the Carling footswitch first then soldered the wires. But the wires are short and the insulation shrinks with very little heat, and he wrapped the wire around all terminals in the unit too. Which makes it a PITA to remove them and reattach. I found using my little wrench was a much more foolproof way to go.
I hope this helps anyone that has to repair a Klon. Gotta say it was a harrowing repair but I'm very grateful it's working again. And a big thank you to Martin Chittum for the online schematic, that was quite helpful. And also thank you to Austin's own wundertech Cris Burns, who figured out it was the charge pump and TLO72 that failed.
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