#1
Hi, I've been following the guidelines given in
http://www.generalguitargadgets.com/projects/15-boostersrouters/215-aby-switch-box
there are some PDF-files there
http://www.generalguitargadgets.com/pdf/ggg_sw_aby3lg_sc.pdf
http://www.generalguitargadgets.com/pdf/ggg_sw_aby3lg_lo.pdf

I now regret that I know almost nothing of electronics, I just wanted to make a pedal to get started in all this. The pedal works, all LEDS work according to the switching being done, the only problem is that when switched to the A output no signal is given, not even to any channel in A&B-mode.

Can anyone help me to point out which wires the signal goes through when I want the output to be on A? And possibly what can be wrong?

Thanks in advance
#4
The fact that the LEDs work fine means nothing except that the LED switching circuit is wired properly.

Ok so I've been up since 11pm yesterday and my vision and brainmeats are shot so if you have an ohm meter, measure between a ground point and the tip (hot) connection of the A jack when the switches are set to A-only mode. Then do the same test to the A and B jacks with the switches set to A+B mode. Make sure to perform these tests with no guitar or amp plugged into the box (no need to have a cable plugged into the input as this is a passive circuit and requires no power except for the LEDs).

This will (hopefully) be a lot easier than me trying to decode a single somewhat blurry pic and you will learn a hell of a lot more, anyway. Troubleshooting is the best way to learn.
#5
Quote by Invader Jim
if you have an ohm meter, measure between a ground point and the tip (hot) connection of the A jack when the switches are set to A-only mode.

This will sound ******ed, but can you indicate a groundpoint for me?
Last edited by slash&angus at Jan 20, 2014,
#6
Not at all, sir.

You can just stick the black probe of the meter into one of the screw holes for the baseplate. I like to use the screw holes instead of holding it right to the box because it gives me a free hand and there is no oxidation in the screw holes so it gives a good electrical connection.

What you'll be looking for is infinite ohms between the hot and ground connections. If you get a short, you flubbed your wiring somewhere. A short to ground on the A jack would explain everything that you described.

Whenever you build a circuit, it is a great idea to print a copy of the schematic and highlight or tic-mark each wire after you connect it and double-check it. If you mark your progress like this and double-check your connection before continuing, it is very, very unlikely that you'd end up with a busted build.
#7
Quote by Invader Jim


What you'll be looking for is infinite ohms between the hot and ground connections. If you get a short, you flubbed your wiring somewhere. A short to ground on the A jack would explain everything that you described.




Ok, ////////////it gives infinite when only A is on, but zero when A&B is on (after only A on).
Also when only A is on, the tip on B gives zero.////////// wrong

CORRECTION:
When only A is on: zero on B tip, not on A
When A&B is on, zero on A and B tip
Last edited by slash&angus at Jan 20, 2014,
#8
If I read that right then the B jack is shorted to ground when A-only is selected; this is normal. If you look at the schematic you'll see that the A/B switch grounds the unused output. When A-only is selected, the B jack is grounded and when B-only is selected, the A jack is grounded.

However, the A+B switch should NOT change which jack is grounded.

Visually inspect the components to see if anything is accidentally touching the box. Inspect the switch lugs to see if there are any accidental solder bridges.

After that, get a copy of the schematic (or layout) and inspect and mark your wiring, comparing it to the diagrams to spot any errors.

Just noticed your edit. Something is wrong with the A+B wiring. In A+B mode the A/B switch is totally bypassed.
Last edited by Invader Jim at Jan 20, 2014,
#9
Isn't it strange that I have no sound when only A is on. Because I did get infinity at the A jack and zero at B jack which was normal.

And so when A&B is on (after A only is on) I get zero and zero on both tips.

I measured all combinations now:

Only B on:
Tip A and B : infinity yet no sound comes out of B

B on and then A&B on:
Tip A and B : infinity

Only A on:
Tip A: infinity Tip B: 0 seems normal but no sound out of A

A on and then A&B on:
Tip A and B: 0
#10
Ok problem solved! There was a connection between two pins on the A/B switch which I found by using a magnifying glass! It was just one or two little bits of wire from a whole bunch. Thanks for your help! Jim'll fix it indeed!