I'm Another "First Pedal Won't Work" Idiot (Triangulum)

[JimF]

Hi all,
Currently building the Triangulum Boost (clone of a Fortin 33). Surprise surprise, it doesn't work.

The LED works, I get sound with the pedal on bypass but with MASSIVE earth/ground hum. When the pedal is engaged I get a different hum (60hz?). I'm taking this to be two seperate problems.
When the pot is turned, the hum sounds different. Well, to be honest it sounds like an interference hum with a clean boost dimed This makes me think the pedal is functioning correctly, but the issue is with the signal getting through the switch.

I've checked continuity through the pins of the footswitch, all seems fine.
I've used IPA and scrubbed the back of the board with a toothbrush.
I've re-flowed the solder joints, including adding more solder to any suspect looking ones.
I've noticed that IC1 doesn't get warm, only IC100. I checked the voltages and whilst I can't remember them exactly, they didn't seem to match up to what they should be.

I'm a bit stuck for ideas now.

Pics attached below. The zoomed in pic is to show those rogue strands of wire aren't making contact.

If you're explaining things, please speak like you're talking to your dog. This is probably only the 10th time I've soldered anything. I don't have a great understanding of electronics, but at least I'm honest! I wanted to build the pedals I couldn't afford/find locally, rather than start a pedal building business or something.

First build & first post, be gentle please! Thanks for reading!

 

[peccary]

It's hard to tell how long the leads coming out of the solder side of the board are, but is there any chance that any of those are coming in to contact with the enclosure? Either way I'd snip them, but it could just be my own pet peeve. You can find decent and inexpensive flush cutters on Amazon.

 

[irvmuller]

This may not be the problem but anything that looks like this I would give a little more solder to just so that it you can confirm the connection there is good. You want to have just a tiny bit of solder visible on the other side from where you put it.



Don't get discouraged. It's your first build. The more you do it the better you'll get at it.

 

[JimF]

This may not be the problem but anything that looks like this I would give a little more solder to just so that it you can confirm the connection there is good. You want to have just a tiny bit of solder visible on the other side from where you put it.

View attachment 8949

Don't get discouraged. It's your first build. The more you do it the better you'll get at it.

Thanks, will try that! I'll make sure they're all topped up so to speak. I'm a bit scared to "cook" any components so the soldering is probably minimal.

 

[JimF]

It's hard to tell how long the leads coming out of the solder side of the board are, but is there any chance that any of those are coming in to contact with the enclosure? Either way I'd snip them, but it could just be my own pet peeve. You can find decent and inexpensive flush cutters on Amazon.

I've not actually fitted it into the enclosure to test it. Where the jacks etc would have earthed against the enclosure I earthed them with wires to the jacks. I left the wires long as I had visions of it being impossible to fit everything in and didn't want to make life difficult for myself.

 

[JimF]

Reflowed all the problematic ones tonight. Tested with my amp, no change. Although I can hear a VERY feint and interfered-with signal behind the huge hum, which also seems to change (tighten?) as the knob is turned. Which to me suggests its working in principle, but something has gone wrong somewhere... Which is reassuring, if that makes sense!

 

[Danbieranowski]

I haven't read every response in this, so let me know if you've already done this, but you may want to use a probe to find WHERE the signal starts goofing up. If you aren't familiar with using an audio probe, check this out.

 

[JimF]

Not familiar with that so will watch the video and give it a go! Thank you. I’ve also tested it with and without the enclosure so I can rule out anything being trapped or stuff like that, and I get the same results with both.

 

[irvmuller]

Not familiar with that so will watch the video and give it a go! Thank you. I’ve also tested it with and without the enclosure so I can rule out anything being trapped or stuff like that, and I get the same results with both.

Here's a pic of a real simple audio probe I made...



Also, I would make sure you have a have a soldering iron with adjustable heat and one you can buy quality heads for. For the longest time I just used a $15 dollar one I owned. Ponying up for the better one made a HUGE difference. My soldering is MUCH cleaner now and I don't worry as much about burning things. I use the WLC100 40 watt one. While it's definitely not the best it's much better than a sub $20 iron.

 

[JimF]

Good tips thank you! That’s a really neat solution to the audio probe, I’ve loads of spare jack sockets so I’ll piece one together tomorrow. I had a cheaper variable temp one that died last week. I’ve bought a simple Weller single temp one to keep me going in the meantime.

 

[JimF]

Incidentally it turns out the Draper soldering station I was using (until it broke) looks to be almost identical to the WLC100. Albeit with a worse tip retaining system (threaded collar that loosens itself). The casing etc look identical.

 

[JimF]

More updates!
Progress but not fully working.
I used the audio probe. Not going to lie I didn’t really know what I was doing, but realised one jack was reversed. Sorted that and got sound. The pedal works!
However there’s an earthing buzz problem. Not 100% sure I haven’t got a loose capacitor (the big boy).
It’s such a relief that the internal witchcraft is working and it’s more likely a physical issue of my shoddy soldering!
So close!

 

[JimF]

Anyone got any hints? The pedal works but with a bad ground/earth hum, especially bad when not playing. Like you have your finger on the guitar lead.
I've been over the board with a fine toothed comb and I can't see any problematic areas. How would I check?
So close but so far!

 

[Barry]

Likely a cold solder joint, try taking a pencil eraser and gently tapping on suspect components

 

[JimF]

Good tip thank you!

 

[Chuck D. Bones]

Okay, I didn't realise my wifi went off and that reply didn't post, but here I am with voltages. Also cleaned the board off and reflowed any questionable joints.

Pin 2 (-input) - 19.7v
Pin 3 (Vref) - 17.4v
Pin 6 (output) - 0.14v
Pin 7 (Vcc) - 23.0v

Havn't had chance to test it (bit late to fire up the Engl), but I'm presuming I won't have magically fixed it with contact cleaner, a toothbrush and double checking the solder joints...

The opamp bias is screwed up. We need to correct that.

First problem: Vref is low. Should be more like 20V. R101 - R103 are all the right values. What kind of voltmeter are you using?

 

[JimF]

Ooh interesting!
I’m using a Sealey MM20 (pic attached).
Also checked the voltages again and they’ve each roughly halved... and the IC doesn’t get warm/hot anymore. Have I spoiled a component?
Think I need to come back to this with fresh eyes when I’m not so tired.

 

[Chuck D. Bones]

OK, I'll wait to hear back from you. I think the most likely cause is a bad solder joint. INSPECT everything under magnification BEFORE you go around and reflow everything. Repeated heating is hard on the board. Don't be tempted to replace random components, that will eventually wreck the board too and it's not a very effective way to troubleshoot. The number one way to find problems on a board is thru inspection. The next thing to do is make measurements.

This is just friendly advice. We've seen too many people come here to troubleshoot and they take a scattergun approach.

 

[JimF]

I appreciate all the advice and time taken by folks to reply, thank you! I'm going to investigate tomorrow with a good light source and a magnifier. I'm tempted to start again with a fresh board and chalk this one down to experience!

 

[JimF]

Checked again with a couple of different magnifiers and everything seems fine. At least to my beginner eyes.
You mentioned the bias being off on the opamp. Is that likely to mean the problem is inside the IC and replacement is required?

 

[JimF]

I caved and ordered a fresh board. Think starting again should yield better results