Baby build troubleshooting (DMM testing?)

[anonymous]

I built the Runt previously and housed it in a temporary enclosure. Now I decided to finally try and get it into the 1590A and have run into a few issues. I basically followed the baby build guide step by step. I got it to all fit. I checked the bypass which seemed to work. I installed the pots and connected up IN/G/OUT at the bottom of the board to the 3PDT switch, 9V and G at the top to the DC jack and fired it up to no great success...

I switched out C1 with a 2u2 electrolytic, and I believe I have the polarity correct (can this be tested with DMM?) - currently negative lead is connected to R1. I had it the other way around originally and was getting no signal.

I am fuzzy on the resistor that completes the LED circuit, but have attached a photo to show my interpretation of the baby build procedure.

I am getting a loud buzz when I turn up the volume, so I'm assuming this is a grounding issue, but I don't know where I went off.

[alanp]

Unrelated, but it might pay to heatshrink the wire/resistor join going to the LED... that nice bare wire, millimeters from the grounded enclosure, makes me nervous, especially with how bloody crammed these builds get.

[rullywowr]

You don't have to ground the jack sleeve but if you can it will help with reliability in the case the jack gets loose.

I couldn't tell from your post, but did you "rock it before you boxed it?" 

You say you get bypass signal but not effect?  I would suggest taking it out of the enclosure and try to make it work on the bench. If you ground that other output sleeve, you can plug right into the jacks. It's very hard to troubleshoot once it is installed in the enclosure. If you can make it all work on the bench then it's a matter of just ensuring the wiring is ok when you install it.

Seeing as you got everything to fit...you already did the most difficult part! 

[danwelsh]

Did you have the bottom plate cover on when you tried it? I know personally I've had some solder points touching my PCB and it was causing all kinds of weird problems.

[anonymous]

I couldn't tell from your post, but did you "rock it before you boxed it?" 

This build was working in a temporary enclosure previously, which is why I suspect it is something to do with the wiring - did I get the DC lug wiring correct? That is something I reworked when boxing In the 1590A.

Seeing as you got everything to fit...you already did the most difficult part! 

...and now I'm terribly afraid if I remove it, it will never go back in!

But I will do that, makes the most sense for troubleshooting. Any worth in continuity check while still in the box from IN to OUT jacks?


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[anonymous]

You don't have to ground the jack sleeve but if you can it will help with reliability in the case the jack gets loose.

Do I ground to the switch, the DC jack, or the input sleeve?

[rullywowr]

You don't have to ground the jack sleeve but if you can it will help with reliability in the case the jack gets loose.

Do I ground to the switch, the DC jack, or the input sleeve?

Any will work, input jack is closest so go for that.

[Govmnt_Lacky]

YIKES!!!!! 

I have to echo what Alan said.....

You need to heat shrink that LED resistor pronto! That could be touching the casing when you cram everything in there and shorting out your whole 9V supply 

As for the grounding.... Is that Brown wire on your 3PDT going to a Ground point on your PCB?

[anonymous]

Thanks everyone. Unboxed it, grounded the output jack and resoldered a few suspect joints. It was a good opportunity to get some use out of my DMM I just got. Cap had correct orientation, and I was getting continuity tones all over.

In the end it was indeed shorting out because the back of the board was contacting the enclosure. I put a piece of canvas over the back of the PCB and that was it.

Cool! First build! Looks kinda Sputnik and beat up, but I like it.

[anonymous]

Well, further testing has shown one more issue -  I am getting a high squealing when the tone knob on my bass is rolled up to the treble side and the distortion is past about 12. Also this happens in conjunction with the "Cut" on the pedal between 7 and, say, 10 or 11. I realize the Cut is very similar to the tone knob on my bass, but don't know what this means, or why more treble through those pots would cause this squealing. The pitch of the squeal changes as I move either the pedal Cut or guitar tone pots.

Anyone have experience with something like this?