Queen of Bone 2 - housing case

[deuce42]

Hi guys, could anybody help me with what I suspect is a rudimentary question with my build but is stumping me?

I have built the Q of B(2) circuit and it works fine out of its case. Whenever I house the thing it suddenly acts completely weird. Switching goes haywire and one switch either switches on two circuits or none. Turing pots goes weird etc.

I suspect the issue is possibly the metal case itself is somehow grounding parts of the circuit etc. Is there anything that I should be isolating from the case perhaps? - i.e. pots, input and/output jacks, switches etc?  The case is a standard 1590BB.

If its not a grounding issue with the case, would you guys have any idea why I've got this crazy problem?

Sadly build doc won't attach as its too large. I hope this doesn't mean I'm asking a blind question that nobody can answer!!

Thanks very much for any help.

[madbean]

It's likely a grounding or power issue. Are you sure you wired your jacks and DC properly?

[deuce42]

Yes have checked the input and output sockets and the DC socket as well. They appear to be fine

[AntKnee]

Post a pic if possible. It may help us get it sorted.

Does the board fit in the box ok?
Do the edges contact the enclosure?
Are any components standing tall enough to contact the lid or audio jacks?
Is there stress on any of the switches or pots when you mount the board in the enclosure?
Do the audio jacks contact the board?
What kind of dc jack did you use?

[AntKnee]

Oops. Double post.

[deuce42]

Thanks for your help guys.

Ive added a picture here to demonstrate.  I note that in this build, all the pots attach directly to the board so there is no wiring. I've checked to make sure:

1) none of the backs of the pots are hitting anywhere else on the pub.
2) even though the sockets are close to the PCB, with plugs inserted into the sockets nothing is still touching the pcb
3) PCB and pots/switches seem to fit well in case without any stress. At least they drop right in without having to wriggle or push anything into their respective drilled holes.

I'm just stumped.

Any help would be so appreciated.

[BrianS]

on first look I thought you had the ground on the input on the wrong lug but It's not. Your positive none of the jack lugs are grounding on the pots? Also when you have the jacks plugged in the out jack isn't grounding against the tone 2 board pads, is it? A quick way to make sure is to put a piece of electrical tape anywhere the lugs might ground. All your wiring looks good to me.

[deuce42]

Yes I've made sure wherever the plugs are inserted into their jacks, none of the jack lugs are touching anything at all. There is no contact to anything, even though it looks like a tight squeeze. I'ts just bizarre that it doesn't work when housed

[BrianS]

You're jacks are not getting a good ground because they are pressing on the paint.  You need to get all the paint off to bare metal where the jacks are mtg the enclosure.  Try that and see if that will correct the problem. That's the only other thing I see.  If that doesn't work then take the board out and post a picture of the bottom also. 

[AntKnee]

His jacks are grounded to the pcb.

I would hook it all up and "chopstick" around a bit. Gently poke and push on components and see if you can find a short. Put tape on the back of the pots that are under the pcb.

Have you attempted to trace the audio path with a probe?

[AntKnee]

I would also reflow all the wiring connections. Reflow the jumpers from the main board to the footswitch board and make sure there are no solder bridges there.

[deuce42]

Ok I've reflowed the solder joints, including the jumper pins between boards and the wiring. One led is permanently on regardless of switching, although I can hear both circuits switching in and out when I stomp on each respective switch. So its an Led problem I suspect? Could it at all be faulty switches themselves?

I just cannot seem to understand this.

[stringsthings]

It's unlikely that the switches are faulty.   

First of all, I would check the voltages on all the IC's with a multi-meter.  This would rule out
any power issues.  Since the circuit uses a charge pump, this is a very important step.

Second, I would break out the schematic and use an audio probe to figure out where the signal
is being lost.  Start at the input to the circuit and proceed from there.

Off the top of my head, I'd guess there was a short or cold solder joint in the area of the switching board.
Double check the connections from the PCB to the switching board and use your MM to check continuity in the
signal path.

[AntKnee]

If you overheated the switches during the soldering process, it could cause odd connections with the switches.

[deuce42]

Problem solved guys and thanks very much for all your advice.

For some strange reason, it seems that one leg of one of the LED was just ever so slightly touching the case. I mean it was just slightly grazing it. This was causing the grounding issue!!

Sounds good thanks.