tube tremolo kit - first build

[drfreakypants]

Hi, First time posting, first build.  I put together the "officially licensed circuits" "Darth Fader" tube tremolo pedal recently.  I was shocked when I hooked it up and it mostly worked in terms of the signal and the effect.  There are two problems, and I'm not sure how to go about debugging them.  Firstly, the LED is not lighting up. Second, there is a substantial hum that kicks in when I turn the effect on.  Any suggestions on debugging these problems would be greatly appreciated.  I'm at work so I don't have pics of my particular build right now, but here is a link to the pdf of the instructions for the pedal:

http://www.olcircuits.com/documents2008/olc_darthfader_buildguide.pdf

In terms of the LED, I'm sure I got the polarity right.  The way they say to hook up the LED to the 3PDT looks different than I have seen in other pedals.  Usually the negative lead of the LED goes to terminal 4 of the 3PDT and in this design they have it go to 2.  Could just be a bad connection somewhere, but I was pretty careful.

As for the hum, could just be the wall wart, and I don't currently have another one to try, but I suppose I should get another.  Any other ideas about the hum would be appreciated.

[raulduke]

Welcome to the forum!

I would contact OLC themselves for support dude as it is their product/kit, therefore technical support is their responsibility.

However, for the hum I would highly suggest trying another wall wart/PSU if you can. I have found certain wall warts can cause major hum problems in certain scenarios.

The Voodoo Labs Pedal Power + that I use is as clean as a whistle, is built like a brick sh*thouse, and can power 10 pedals. It's a very worthy investment IMO.

[drfreakypants]

I have contacted OLC as well, I just thought it would be cool to start getting into these forums so that I can learn from a whole bunch of people.  thanks! I will check out that voodoo labs power supply.

[Scruffie]

What's the mA rating on the wall wart? Tube heaters pulling too much current?

[drfreakypants]

I'll have to check on the mA rating when I get home tonight.

[raulduke]

I have contacted OLC as well, I just thought it would be cool to start getting into these forums so that I can learn from a whole bunch of people.  thanks! I will check out that voodoo labs power supply.

Normally using a battery is the litmus test for an icky PSU causing hum... but unfortunately I think your pedal may pull too much current for this to be a feasible option.

If you have any other PSU's knocking about (Correct voltage and polarity of course) it may be worth trying them out (as scruffie says make sure they are rated high enough for the pedal).

Post the build in the build reports too dude; we love seeing them builds  !

[marauder]

If its using a 12A?7 tube, then it will pulling either 150mA, or 300mA depending on how the heaters are wired.

[drfreakypants]

I got this reply from another forum:

There's one huge omission in the build doc - they don't ground the stomp switch.  That's probably why your LED doesn't light up.  Connect either the top middle or bottom left lug (when looking at the diagram - they are connected to each other so it doesn't matter which one you use) to ground - the sleeve of the input jack is probably the easiest place.

does this sound right with anyone/everyone here?  You can see the build doc in the initial post above.

[DutchMF]

Checked the build doc, and yes, there is no mention of connecting ground to the 3PDT, so that might be the cause of the LED not lighting up. You do need ground to do that.....

[billstein]

Correct me if I'm wrong but isn't the LED connected to the wrong lug on the switch? Isn't that middle row common, so the LED once grounded will always be on.

[Vallhagen]

Correct me if I'm wrong but isn't the LED connected to the wrong lug on the switch? Isn't that middle row common, so the LED once grounded will always be on.

I had a look at the PDF manual, and it (still) confuze me a bit, as they have succeeded to only use 8 lugs of 9 at the footswitch...

***

A stated a few posts up, there is a fault in the instruction. Look at page 19; connect the middle lug in the top row of the switch, to gnd, and it shall work.

...still only 8 lugs used lol... strange. There ARE many ways to do the job though.

Cheers

[drfreakypants]

Hey everybody thanks for all the suggestions.  connecting the LED to ground solved the LED problem!     but the hum persists 

Here is a pic of the wall wart:



here's a picture of the build (sort of shy about this, being my first one and all - don't laugh )



maybe this can give some insight into what I can do to decrease the hum.

[gordo]

It's hard to see but is your output jack wired right?  Looks like the output wire is going to ground.

Dude, if that was my first build I'd have been strutting around like a peacock!!

[drfreakypants]

gordo, thanks, I did spend a lot of time doing this.  The output jack goes under the pcb to (what I understand to be) lug 8 of the 3PDT.

[jkokura]

One of your jacks, the upper one, is not connected properly. It looks like you have connected nothing to the tip of that jack, and are only connected to the sleeve. Connect the sleeve to ground on both jacks, and use the tip of each jack to connect to the switch. The tip is farthest from the enclosure hole, and the sleeve is closest to the enclosure hole.

Jacob