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Kokbox problem

Started by night-B, February 25, 2011, 03:34:59 PM

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night-B

Hi guys!
I've got a problem with my kokbox. I've populated the board and wired the 3PDT, then I tested it with my test box and everything went fine. Now that I boxed it i have a bypass signal, but no sound when the effect is engaged. The led is lighting correctly. The only issue I had is that I had to force a little to let the pots (9mm board mounted) pass into the drilled holes of the enclosure. So I soldered them again but the problem is still here. Do you think I must change the pots?
Tell me if you need gut pics or voltage readings.
Thanks for the help!

jkokura

Could be a grounding problem. Does it still work outside the enclosure?

Jacob
JMK Pedals - Custom Pedal Creations
JMK PCBs *New Website*
pedal company - youtube - facebook - Used Pedals

bigmufffuzzwizz

Do you have a multimeter? Try testing the pot. You can either test it with continuity or resistance. Touch from lug 3 to lug 2 and turn the pot fully one way. See if it goes from full resistance to 0 (or vice versa). Then with lug 1 to lug 2. If you get resistance or continuity then the pot should still be good and working! I've have weird shorting issues before. Look at how the jacks are orieneted. If would short if the tips where touching the enclosure(ground). I've rubbed all the components on a fresh build not working to find out the transistor wasn't in the socket enough! You never know. Also did you check continuity on the footswitch??
Owner and operator of Magic Pedals

night-B

#3
Damn! This pedal worked with my test box  :'(
Checked all the pots with the DMM and the resistance changes when I turn the pot.
Checked the 3DPT, it's switching correctly between the wires.
Even if the out jack is very close to the DC jack and the enclosure I don't see any grounding, and the bypass signal is OK.
Is it possible that I fried a BS170 with static electricity when I enclosed the circuit?
Edit : Even if the PCB is out of the box it still doesn't work

jkokura

Possible but unlikely. Take it out of the box and test it again. If it doesnt work then, remove the switch and jacks and just see if the board with pots works. If it doesn't, then start checking the board for issues.

Jacob
JMK Pedals - Custom Pedal Creations
JMK PCBs *New Website*
pedal company - youtube - facebook - Used Pedals

night-B

I think I'll unsolder the jacks and switch, and go back to the test box  :-\

night-B

#6
Signal from jacks to the pcb is Ok. I haven't found grounding issue yet.
The voltage readings are fine on the transistors but now the led never lights off, even If I unplug the jacks.
Looks like I have wiring issues I can't find...

bigmufffuzzwizz

did you get signal again with the test box? that LED issue has happened to me with a few of my builds. the LED stays light with no cables plugged in. but it doesn't happen with a battery so i don't worry about it!
Owner and operator of Magic Pedals

night-B

With the test box I get ground noise and no guitar signal... I have the Led problem with a battery! Maybe my DC Jack wiring is wrong... It has already confused me on an older build. I hope this is the problem.

night-B

I wired the left lug to +9v battery, center lug to +9v board, right lug to the ground on the switch.
Is it right? I followed this diagram http://www.madbeanpedals.com/forum/index.php?action=dlattach;topic=707.0;attach=212;image

[attachment deleted by admin]

pandadandan

That's right.
Were you careful with your BS170s?  They're extremely static-sensitive.

night-B

I might have damaged one when I boxed the PCB. the voltage readings are fine but I'll order some replacement transistors.

night-B

I'v fully rewired the pedal, this time I used the Pandadandan wiring method. I still have the same problem.
I'll take another set of transistors on my next smallbear order, then if it's still problematic I'll go on caps replacements...

bigmufffuzzwizz

Quote from: pandadandan on February 26, 2011, 11:48:04 AM
That's right.
Were you careful with your BS170s?  They're extremely static-sensitive.

what would be the proper way to handle theses if we don't have a static ground wristband?
Carefully with 2 sets of pliers??
Owner and operator of Magic Pedals

pandadandan

Quote from: bigmufffuzzwizz on February 27, 2011, 03:16:33 PM
Quote from: pandadandan on February 26, 2011, 11:48:04 AM
That's right.
Were you careful with your BS170s?  They're extremely static-sensitive.

what would be the proper way to handle theses if we don't have a static ground wristband?
Carefully with 2 sets of pliers??

Yeah I often just try and earth myself somehow before I handle them (just touching my amp faceplate is enough to discharge the static I'm carrying).  After that, I try and avoid generating any more static.  I don't use a wristband either, by the way.