SOLVED Cobalt Drive problems…..SOLVED……..FINALLY!

Jeff C

Jeff C

Active member
New member here and also new to building pedals, as you will shortly see. I previously built a BYOC Reverb pedal kit successfully and it sounds great. I’ve also built from scratch a Strat, a Tele, a 59 LP, and an LP Junior. So, I wanted a blues driver pedal and thought I’d take a whack at the Cobalt Drive from PedalPCB. The directions are not as detailed as in a kit so I’ve had some difficulty. Clearly in over my head. I managed to procure the parts from the list (not without trial and error on my part) from Tayda. I mistakenly bought a switch without solder lugs so after consulting a patient, helpful friend, bought a daughter board and did my best to figure out how to marry the two - having no skills whatsoever in electronics. History major. I have managed to assemble it but I get nothing from it except static pops when I plug it in. Bypass doesn’t work. No idea what I’ve done wrong but I suspect it revolves around needing to do more with the daughter board on the switch. But what do I know? Here’s a couple of pics (the power jack is not there but I did connect it to test). And I haven’t installed the LED yet. Any and all suggestions are eagerly welcomed. You may recomemd I should just start over but I hope not….. Thank you!
855EE297-D464-47F8-880D-F0D8B9C40E15.jpeg 15E06C0D-93DB-4AE9-944D-BA1BED3416FB.jpeg
 
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Well, it’s pretty clear I have no idea what I’m doing. Voltage readings are either 0 or .0001 or 2. There is no connectivity between r7 and Q1 source…..
 
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Jeff C said:
Well, it’s pretty clear I have no idea what I’m doing. Voltage readings are either 0 or .0001 or 2. There is no connectivity between r7 and Q1 source…..
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There's your problem: if you get no continuity between R7 and Q1's source you are gonna have floating voltages on the gain/source (thus the odd voltage readings). If you have alligator clips, try bridging the two and see if anything changes (keep in mind that one side of R7 should be grounded, the other connected to the source). If it does, the trace between R7 and Q1 may be broken (may be it was damaged when you desoldered the transistor) or one of the solder joints is not good.
 
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Okay, I have the black lead on ground and the red one on the transistor pins. Voltage readings from q1 (and all the transistors, for that matter) are either 0 or -.0001.
 
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Not sure how to bridge the r7 to Q1.
giovanni said:
There's your problem: if you get no continuity between R7 and Q1's source you are gonna have floating voltages on the gain/source (thus the odd voltage readings). If you have alligator clips, try bridging the two and see if anything changes (keep in mind that one side of R7 should be grounded, the other connected to the source). If it does, the trace between R7 and Q1 may be broken (may be it was damaged when you desoldered the transistor) or one of the solder joints is not good.
Click to expand...
the schematic doesn’t show a direct connection from r7 to q1.
 
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Your power issues are puzzling me. Look at the schematic here. I have highlighted where power will travel to Q3 drain (that's the top part of the J201). If you have power on both sides of the protection diode (1 side will be slightly less), but no power on Q3, then something is shorting out to ground and not allowing power to pass through.

1652989821478.png
 
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