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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Mcknib said:
I've just realised I should have told you to snip one side of D100 before jumpering it I was going on the path of least resistance but maybe it being soldered to the board it hasn't bypassed it

What I'd do is snip D100 out completely on the component side of the pcb and solder a jumper in place leave as much of its pins as you can then solder on a jumper wire

Before you do that continuity check the + power pad to D100 anode pin and cathode pin to R101 probe the actual diode pins just as a quick check to see if D100 solder pads are good
Click to expand...
So, checked the d100 pads and they connect to + power and r101 respectively. Attached the bridge but the IC stsrted heating up right away. The cathode pin does show connectivity to C100.
 
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😆 Scratch one diode! Well, they’re pretty cheap…… Meanwhile, still checking resistor values. No wrong ones so far - about half way through…….ok, all resistors check out correctly.
 
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Post a well lit pic of the component side so we can see all components clearly it's hard to get a good look with the images posted

You can check and re check and still miss something

Link where you got your DC jack

Again it's hard to see it clearly
 
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The big issue we are dealing with right now is power. That is first and foremost since the circuit won't work without power.

Secondly, those wires going to the footswitch are unclear if they are crossing since the fabric on them is blocking our view. Confirm that the metal within them are not touching.

Third, those yellow capacitors look like tantalums to me. This means that they are polarized like the electrolytic ones and need to be installed in a certain direction. This should be addressed once we get the power issue straightened out. The circuit will sound different if those yellow ones are installed backwards and we have no way of knowing which way they were installed based on the pic.

For the record @Jeff C I admire your persistence on this troubleshooting thread. 250+ threads and 3 weeks of this and it still isn't working. If I were in your shoes I would have pulled the rest of my hair out already with the amount of hours put in this and still no dice. Nothing is more frustrating than a non-working build. I don't want to discourage you from the building process so may I make a suggestion and think about your next project/build and start that up? You have already learned a lot so far in this thread and it will carry over in the next project. I'm saying this because putting something aside for a while may actually help in the long run instead of soldering/desoldering parts and potentially damaging your board. A lot of the peeps here are very knowledgeable and are helping you through this process.

In short, start a new build (potentially a less complicated circuit), take your time and focus on neatness. It will be nice to rack up a win in your book when finished and give you more confidence to go back to this project.
 
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BuddytheReow said:
The big issue we are dealing with right now is power. That is first and foremost since the circuit won't work without power.

Secondly, those wires going to the footswitch are unclear if they are crossing since the fabric on them is blocking our view. Confirm that the metal within them are not touching.

Third, those yellow capacitors look like tantalums to me. This means that they are polarized like the electrolytic ones and need to be installed in a certain direction. This should be addressed once we get the power issue straightened out. The circuit will sound different if those yellow ones are installed backwards and we have no way of knowing which way they were installed based on the pic.

For the record @Jeff C I admire your persistence on this troubleshooting thread. 250+ threads and 3 weeks of this and it still isn't working. If I were in your shoes I would have pulled the rest of my hair out already with the amount of hours put in this and still no dice. Nothing is more frustrating than a non-working build. I don't want to discourage you from the building process so may I make a suggestion and think about your next project/build and start that up? You have already learned a lot so far in this thread and it will carry over in the next project. I'm saying this because putting something aside for a while may actually help in the long run instead of soldering/desoldering parts and potentially damaging your board. A lot of the peeps here are very knowledgeable and are helping you through this process.

In short, start a new build (potentially a less complicated circuit), take your time and focus on neatness. It will be nice to rack up a win in your book when finished and give you more confidence to go back to this project.
Click to expand...
The yellow caps look like the dipped MLCC type to me
 
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Description for the DC jack says short lug is for the centre pin do you have that soldered to the + power pad making it centre positive

Continuity check which lug the centre pin is attached to

You want centre negative unless you're using a centre positive adaptor that is

If you're using a centre negative adaptor with DC jack wired centre positive it'll short
20220524_192105_copy_432x380.jpg
 
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Mcknib said:
Description for the DC jack says short lug is for the centre pin do you have that soldered to the + power pad making it centre positive

Continuity check which lug the centre pin is attached to

You want centre negative unless you're using a centre positive adaptor that is
View attachment 26667
Click to expand...
“normally the center is positive and outer negative”
Remember that pedals are not normal ;)
 
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giovanni said:
“normally the center is positive and outer negative”
Remember that pedals are not normal ;)
Click to expand...
Normally you'd know right away it's inverted with negative voltage readings, but I'm not reading through it all again to see if there are any!

Dare I say it.......hopefully

You @giovanni deserve a medal for your continued patience fortunately @Jeff C is a good humoured chap too
 
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Mcknib said:
Description for the DC jack says short lug is for the centre pin do you have that soldered to the + power pad making it centre positive

Continuity check which lug the centre pin is attached to

You want centre negative unless you're using a centre positive adaptor that is

If you're using a centre negative adaptor with DC jack wired centre positive it'll short
View attachment 26667
Click to expand...
Well, I check the voltage on the power cable and it reads -9v! If I connect the black cable to the center and red to the sleeve, it reads +9v. so, yes, I guess I’m feeding -9v to the +power pad. Damn.
 
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As soon as you said things were getting hot apart from your brow

I thought dead short but you placing your probes correctly ie + to + and - to - on the lugs and getting +9v as you would threw me especially when you didn't get -9v on the board

Anyway hopefully because you never kept it plugged in too long your active devices won't be fried TL series ICs can take a fair few volts as can J201s

Like everything else it's the current that'll kill them and a dead short would increase current draw

But the diode would have hopefully saved the day
 
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Harry Klippton said:
@Jeff C I keep checking this thread in hopes that you get your pedal working. Keep going!
Click to expand...
I second that... @giovanni has been doing a tremendous job working this out with you. I've been following up and tried to contribute without disturbing the troubleshooting path. But, you're not alone, we're many behind the both of you trying to sort this out.

Keep it going, I think you'll get there !
 
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EGRENIER said:
I second that... @giovanni has been doing a tremendous job working this out with you. I've been following up and tried to contribute without disturbing the troubleshooting path. But, you're not alone, we're many behind the both of you trying to sort this out.

Keep it going, I think you'll get there !
Click to expand...
I agree it was a saga but you learn a lot from your mistakes and keep passing it on

People like yourself @giovanni @zgrav @BuddytheReow @carlinb17 and many more keep this place one of the best forums passing on your knowledge and staying with it

Jeff's now armed with how to use a probe and lots of other debugging knowledge for future builds thanks to everyone's efforts

Who's gonna look and see if Jeff's set a record for the longest debug.......

Anyone?
 
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