Do-it-yourself pedal building
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Wed Feb 27, 2019 10:14 am
I took the switch out of the layout and still nothing, so I checked voltages around the circuit (board 2).
Here's a link to the schematic - https://i198.photobucket.com/albums/aa159/Mushro/deOK_zpsfdc7f3d3.png
I've got readings right up to the last two 100nf caps and nothing beyond.
Most of the readings after the first 10k resistor are either 1.10v or 0.61v (the battery is actually putting out around 8.5v) - would I be better off wiring in a 9v power supply? (is that the mistake, perhaps?).
Wed Feb 27, 2019 10:52 am
You probably won't read DC after caps.. that's what they do, block DC, keeping the DC inside the circuit and letting the AC of the guitar signal (or other melodious sine type wave) move on through.
9v is probably best, but I suspect that the circuit would work well below 9V as I have starves I added to numerous Devi designs. That being said try a fresh battery or 9v source and see if they jump up
Without seeing pics of your build, at this point I'd say verify pinout on your transistors, and verify component value .. I know.. all 6 of them or whatever
Wed Feb 27, 2019 11:21 am
Sorry for the lack of pictures, I shall remedy that now:
Hopefully they show someone who looks like he has some idea of what he's doing, even if this layout hasn't been successful
I'm tempted to try a different layout in the hope that it will work, but right now I'd prefer to solve this problem first.
I'm going to order some of those strips to allow me to plug in different transistors (and swap their orientation to check I've got them the right way round).
Wed Feb 27, 2019 11:46 am
Yeah it looks Ok to me (including cleverly omitting the unneeded cut from the tagboard layout) assuming your transistor pinout are good. Also I cannot see the color bands on the 10k, but your voltage seemed low so maybe double check that.
Then scrape all your rows to make sure there isn't a microbridge..
Wed Feb 27, 2019 12:19 pm
I bleep-tested the rows to check for any unwanted connections, but I'll clean the gaps just to sure as it would be foolish to assume anything at this point.
My digital meter has confirmed that both resistors are what they should be, though I must admit I was going to ask if that voltage drop after the 10k was what would be expected.
In theory my multi meter should be able to test caps and transistors, but I'll need to do a major search to find the manual for it (it's in my workshop somewhere) as there's nothing online.
Wed Feb 27, 2019 12:36 pm
Those should have 104 and 103 written on them, the 10n bottom left is 103, 100n are 104.
Wed Feb 27, 2019 1:02 pm
Yes, there are three 104s and one 103 on the board.
Much to my surprise the manual was where I thought it might be (it's been sitting there waiting to be read for at least 10 years).
I tested some of the components that are unused but bagged and marked and they're all what they claim to be, though the bit that tests transistors is pretty hit and miss as to whether it registers anything (I work with a lot of wood dust so it probably needs a strip down and clean to work properly) but it did confirm the orientation is what I'd assumed it to be.
Wed Feb 27, 2019 1:27 pm
Is it an optical illusion that the power line from the DC adapter is not going to the top row? It should be going to the top row .. I don't think you'd get voltage anywhere else if not ..
And then I guess it sounds dumb but make sure you're plugged in the correct way .. did you verify the jacks work? I think you said it worked bypassed ..
If none if that is the fix, you may have a <1% problem with an actual component.. with that design even if one of the caps was bad it would probably still work..
Wed Feb 27, 2019 1:33 pm
I'll build one after work and give you voltages if mine works;)
Wed Feb 27, 2019 2:55 pm
The power in does go to the top row, and yes, the jacks did work with a guitar plugged in and the switch bypassing the board.
I'll maybe strip one of the boards down and repopulate them with tested components - I've also considered removing the pots and connecting in and out directly to the board.
Wed Feb 27, 2019 4:44 pm
At this point if all your other troubleshooting checks out it could really just be the trannies. https://rover.ebay.com/rover/0/0/0?mpre ... 2976508347
Get you one of these.. great for caps and resistors, inductors, diodes, silicon transistors .. it doesn't calculate leakage so it's not the best for germanium but it can ball park.
I use mine every day
I also modded it to have a regular barrel 9V power adapter too
Wed Feb 27, 2019 5:11 pm
Good news everyone - I have a working board
The bad news is that neither of the OK boards are working yet
Because it shares all of the components from the OK apart from one transistor, components which I have, I built the Electric Brown and connected it up to the pots and jacks etc. from the OK board (still without the switch) and it worked first time
So with that I've managed to at least narrow the problem down to something on the OK board, either layout or component, which is good information even if I haven't tracked down the precise issue yet.
Wed Feb 27, 2019 5:30 pm
Good job dude
Here's to many many more
Wed Feb 27, 2019 6:09 pm
It's nice to know that I'm not a complete failure
Not only that, but I've learned a couple of useful things for future builds.
One - buying a component tester would make life a lot easier and Two - buying some sockets for transistors might be a good idea too.
Wed Feb 27, 2019 6:31 pm
Yes. That mega328 is legit
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