madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: Bman40 on November 13, 2013, 01:06:21 AM

Title: Runt build ... Problem
Post by: Bman40 on November 13, 2013, 01:06:21 AM
What does it mean if the pedal only works if I am holding all three pots in my hand?

Let me explain: I was having trouble getting any sound from a runt build, and found a few mistakes I had made ...cold solder joints etc retouched everything I could think of, removed the pots and the power jack from the enclosure, and then was giving the wires a gentle tug to make sure they had contact with the board etc

At one point I had all three pots in my hand with fingers contacting the pads on hey eh potentiometers and the sound came through!!

I am assuming this means a grounding problem, but I have checked all the connections against the build documents and all the grounds are going where they need to be. 

Suggestions?
Title: Re: Runt build ... Problem
Post by: madbean on November 13, 2013, 01:30:52 AM
Definitely a ground problem. What is your testing environment....on a breadboard? Do you have both input and output jacks grounded?
Title: Re: Runt build ... Problem
Post by: Bman40 on November 13, 2013, 02:16:40 AM
I don't really have a testing environment...I just build them and hope they work.

I wired it as per the standard wiring diagram -the input (stereo) jack goes to ground, but the output has the single wire connecting to the the 3pdt switch.  Is there a wire missing ?
Title: Re: Runt build ... Problem
Post by: jimilee on November 13, 2013, 02:20:17 AM
you have 2 wires going to / from input? One signal one ground?
Title: Re: Runt build ... Problem
Post by: Bman40 on November 13, 2013, 02:33:17 AM
Jimilee:  thinks for responding

Yes.  One wire from the 9v jack to the input and one one wire to the 3pdt bottom left lug, plus the wire from the input jack tip to the bottom right lug and then up to the centre lug as shown in the diagram.
Title: Re: Runt build ... Problem
Post by: jimilee on November 13, 2013, 03:07:36 AM
Now is where we need pictures and things. Do you have to hold all 3 pots for it to work? Also is it in an enclosure and you took it out?
Title: Re: Runt build ... Problem
Post by: Bman40 on November 13, 2013, 05:26:55 AM
I'll post some pics tomorrow

I have to touch the pads of the gain and volume pot both inside and outside of the enclosure.

It's odd as I've made a half dozen other projects and this has not happened before.

Barry
Title: Re: Runt build ... Problem
Post by: Bman40 on November 14, 2013, 07:06:34 AM
Here's a pic of the guts
Title: Re: Runt build ... Problem
Post by: Bman40 on November 14, 2013, 07:07:29 AM
And another
Title: Re: Runt build ... Problem
Post by: Thomas_H on November 14, 2013, 07:26:50 AM
As far I can see your wiring looks ok.
To be absolutely sure you can add a ground wire from the jack that has none to the switch or the other jack.

Your board is very close to the middle pod lugs. Can it be that the pot lugs are shortening against the PCB ?

Title: Re: Runt build ... Problem
Post by: Gledison on November 14, 2013, 08:08:48 AM
Hey! As Brian sayd, hast to be a ground problem! What about the jacks? Ive got sone cheap bastards and they were not working properly giving me ground probs! Check if all are ok!
Cheers
Title: Re: Runt build ... Problem
Post by: Bman40 on November 15, 2013, 02:53:33 AM
So... I replaced the jacks, no difference

But...I was digging around with a piece of wire seeing if there was a place to ground...I connected pad two on the volume pot to pad three in the cut pot and the sound is there....what might this mean?

Barry
Title: Re: Runt build ... Problem
Post by: jimilee on November 15, 2013, 03:01:41 AM
It means one of the pots isn't gounded and the other is, and running a ground wire between the two fixes the issue.
Title: Re: Runt build ... Problem
Post by: Bman40 on November 15, 2013, 03:32:02 AM
The Cut pot doesn't seem to do anything, but the volume and gain work really well! :D

Thanks for the help folks

Title: Re: Runt build ... Problem
Post by: wgc on November 15, 2013, 03:47:46 AM
Looks like you might have wire insulation in the pcb holes for the pots. Could easily cause an intermittent connection
Title: Re: Runt build ... Problem
Post by: Bman40 on November 15, 2013, 03:51:00 AM
Thanks

I'll take a closer look at it.
Title: Re: Runt build ... Problem
Post by: wgc on November 16, 2013, 12:25:06 AM
Sure thing. Could be cold joints there too, stranded wire can be tricky at first
Title: Re: Runt build ... Problem
Post by: Matt on November 16, 2013, 12:46:40 AM
Quote from: Bman40 on November 14, 2013, 07:06:34 AM
Here's a pic of the guts

Is that tape under the pots?
Title: Re: Runt build ... Problem
Post by: rullywowr on November 16, 2013, 04:12:34 AM
I agree, I would run a ground wire from the bottom left of the 3pdt to your out jack. Also make sure your board isn't shorting on the enclosure.
Title: Re: Runt build ... Problem
Post by: Bman40 on November 18, 2013, 06:55:38 AM
Yes I pit tape on the metal of the box...trying to avoid a short

Quote from: Dc10 on November 16, 2013, 12:46:40 AM
Quote from: Bman40 on November 14, 2013, 07:06:34 AM
Here's a pic of the guts

Is that tape under the pots?
Title: Re: Runt build ... Problem
Post by: Bman40 on November 18, 2013, 06:56:42 AM
Thanks

I'll take a look and add another ground wire