Unknown_User Posted January 29, 2019 Posted January 29, 2019 Can anyone assist me in cracking open a defective guitar pedal? My mate has a Moen tremolo pedal that keeps cutting out. I stupidly offered to have a look at it for him but I'm having problems getting into it properly. I can remove the base plate but the circuit board seems fastened somehow. The 3PDT switch is soldered to the board so I loosened the nut around that, the pots and the flip switch on the top of it thinking that would do it but the board was still stuck in there fast. Unfortunately when trying to take the knobs off the potentiometers, one brought the stem of the pot out with it. Now I could easily repair or replace that if I could get to it somehow, but I can't remove the PCB to do it. There's a small circle cut out of the middle of the board which looks to have a tiny screw in there (much smaller than any screwdriver I have). I suppose that must be the way to remove the board but before I mess with that and potentially compound error upon error, has anyone got any experience with these things and how to get into them? If I do manage it am I likely to be able to fasten it back up again? Thanks for any assistance. I promise I've learned my lesson about trying to be helpful! Quote
paulbuzz Posted January 29, 2019 Posted January 29, 2019 You didn't mention the input/output sockets, but I imagine they're probably fixed to the board and attaching it to the case too...? Quote
Unknown_User Posted January 29, 2019 Author Posted January 29, 2019 17 minutes ago, itu said: A pic or two would be very helpful... I'm not sure if it will, but here goes! Quote
Unknown_User Posted January 29, 2019 Author Posted January 29, 2019 10 minutes ago, paulbuzz said: You didn't mention the input/output sockets, but I imagine they're probably fixed to the board and attaching it to the case too...? Interesting. I never considered that. I'll have a look. You can't even wiggle the PCB even a little bit at any of the corners. So something is sticking it in there pretty fast. Unfortunately you can't really see anything under the board other than just the 3PDT switch. Quote
paulbuzz Posted January 29, 2019 Posted January 29, 2019 2 minutes ago, Unknown_User said: Interesting. I never considered that. I'll have a look. You can't even wiggle the PCB even a little bit at any of the corners. So something is sticking it in there pretty fast. Unfortunately you can't really see anything under the board other than just the 3PDT switch. If you haven't already, I should think you almost certainly need to remove their nuts from the sides of the case... 1 Quote
Norris Posted January 29, 2019 Posted January 29, 2019 The small screw in the middle looks like a trim pot. I doubt that is a fixing screw 1 1 Quote
itu Posted January 29, 2019 Posted January 29, 2019 (edited) Just on the right side from that trimmer (which looks like a flathead screw - do not touch it) you can see 6 + 6 soldered legs of the input and output jacks. Open the jack screws first and try again. If there is a power connection (9 V) somewhere, the PCBA may be stuck from that corner, so take your time. The power socket is maybe on the left side of those red&black wires and the trio of solderings look pretty lousy. It may be loose, so you just need a hot iron and some tin. I would wash the PCBA with (denaturated) ethanol to see, if there are other issues with solderings. Does not look so clean... Edited January 29, 2019 by itu 1 Quote
Islander Posted January 29, 2019 Posted January 29, 2019 Don't forget to remove the nuts from, the potentiometers and switch as well as the input/output jacks. Quote
Unknown_User Posted January 29, 2019 Author Posted January 29, 2019 Thanks all! I have managed to get the thing out by removing the jack socket nuts and some careful wiggling! I've only ever rolled my own pedals before so I hadn't seen those types of jack sockets that fastened onto the board before. Now I just need to find a way to force this potentiometer shaft back into the plastic bit! Quote
itu Posted January 29, 2019 Posted January 29, 2019 Here are few points (arrows), that may need some tin. The power socket and IN and OUT are marked with text. I am not sure, whether my reading is perfect (I just rely on the pic) but it seems that there may be issues in the PCBA. For example those arrows in the uppermost right corner showing problems may be of no use i.e. not important. 1 Quote
Unknown_User Posted January 29, 2019 Author Posted January 29, 2019 1 hour ago, itu said: Here are few points (arrows), that may need some tin. The power socket and IN and OUT are marked with text. I am not sure, whether my reading is perfect (I just rely on the pic) but it seems that there may be issues in the PCBA. For example those arrows in the uppermost right corner showing problems may be of no use i.e. not important. Thanks very much for that. At first I thought that white stuff around many of the solder joints was dust but having tried to wipe it I think it may be like some sort of lacquer off the circuit board has come loose. Or maybe melted during soldering? Quote
Islander Posted January 29, 2019 Posted January 29, 2019 It looks like there's been some sort of liquid contamination - is there anything on the inside of the bottom cover? It might be worth cleaning it off with a drop of isopropyl alcohol on a toothbrush or something similar. 1 Quote
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