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Big O.
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December 19, 2021 at 1:01 pm #22023
Big OParticipantFinished up a standard Fuzzstortion. It has true bypass when a guitar and amp are plugged into the input and output of the pedal, and the LED lights up with the switch engaged, so there is power to the 3PDT board measuring 9.39V (power from a 9V power supply). I omitted the R5 resistor, which I believe is the CLR for an onboard LED.
The power wire from the 3PDT board is connected to the right sided solder pad under the printed +9V on the main board and I get a reading of 9.39V on the board where the power wire is soldered in. The voltage measurement on the adjacent +9V left sided solder (empty) pad measures -0.03V, which is something I did not expect. I thought it should measure the same as the adjacent wired 9V right sided pad (+9.39V). The measurements on either side of the R3 22K resistor, the first component after the power input, are also -0.03V so it appears that power is not getting to the circuit. The voltage measurements at the base of both Q1 and Q2 is 0.0V and interestingly the voltage at Q2 collector is -0.03V. I checked Q1 and Q2 with a DMM and they appear to be working properly. All components were measured prior to soldering on the board to make sure values were correct and continuity was check with all soldered wires.
Is the left solder pad/eyelet below the demarcated +9V the active one and the right sided one a ground, or do I have a bad connection/solder joint at the power input? Do I need a resistor in the R5 CLR location on the main board, although I believe this is unnecessary. See figure below.
December 19, 2021 at 2:19 pm #22024
BarryKeymasterI just checked one of my boards. There is no continuity between the two pads on mine. That is a board error. The solution would be to remove the +9v wire from the right pad and place it on the left pad.
Thanks for pointing that out so this gets fixed for a 2021 board.
December 19, 2021 at 3:29 pm #22025
Big OParticipantPower problem as I suspected. Moved the 9V power wire from the 3PDT switch board over to the left sided pad as above and it fires right up. The right sided pad under the +9V designation must be a ground. Using my continuity checker it is not continuous with the right sided pad. Either I have a bad board or it is the way the board was designed. I also figured out I was reading the circuit diagram wrong. The power goes to the +9V pad and connects with the R5, R6 and D1 pads. I checked and there was continuity from the left sided eyelet goes all the way to D1 (Duh).
I took a break and thought about it more – always a good thing to do when you are stuck. Sorry I missed your reply Barry, and I probably would have fixed it sooner had I checked back with the board quicker.
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