Echo Foxtrot - power issue?

[Quirkey]

I finally got all the parts I needed for my build. Put it together today, carefully plugged it in and nada. Bypass works, but no LEDs, no sound when engaged. I tested continuity around the power section and seemed ok? I'm nervous to test voltages. Any ideas? The LEDs should still work whether the tube is good or not, right?

 

[vigilante398]

The only way a bad tube would kill the LED is if something in the tube were to fail short and it was bogging down your power supply, but that's generally unlikely. The LED should certainly light up even when the tube is removed, so if that's not happening then you certainly appear to have a problem with power. Where I would start:

1. What kind of power supply are you using? This build will pull over 350mA at 9V, so if you're using a 150mA supply it's not going to work.
2. You should probably probe around and measure some voltages. If you're comfortable doing that, skip down to step 5. If not, go on to step 3.
3. Check continuity EVERYWHERE. Make sure you have continuity everywhere you're supposed to and no continuity where you're not supposed to. Solder bridges and cold solder joints are a common killer.
4. Reflow solder joints. It's not fun, but go over every joint to make sure you have a solid connection and no cold joints anywhere. IF YOU'RE NOT COMFORTABLE PROBING HIGH VOLTAGE CIRCUITS, STOP HERE.
5. If you're comfortable doing so, with the PCB installed in the enclosure, insert the negative probe into one of the screw holes of the enclosure. This will act as your ground reference so you don't need to use both hands when probing.
6. Stick your non-dominant hand behind your back, in your pocket, etc to keep it away from the circuit. NEVER PROBE HIGH VOLTAGE CIRCUITS WITH BOTH HANDS. High voltage into one of your hands will hurt, but high voltage through one hand while the other is grounded CAN SEND HIGH VOLTAGE ACROSS YOUR HEART AND KILL YOU. Always always always tuck one hand away to avoid this, we call it "the one-hand rule" and it has saved countless lives, certainly mine included.
7. Now that your negative probe is connected to the chassis ground point and one hand is safely tucked away, start with the input voltage. Measure the pad right where the power wire comes into the PCB. It should read right around 9V. If it doesn't, that's a pretty good place to start.
8. If your input voltage looks good right into the board, the next thing you'll want to check is the 6V rail for the heater. The easiest place to do this is going to be to stick the voltmeter probe into pin 5 of the tube socket when the tube is removed. If you don't have 6V there, then you need to (first unplug the pedal, then) check on your L7806 regulator.
9. If both your input voltage and your 6V rail are good, it's time to check the high voltage rail. The easiest place to do this is going to be pin 9 of the tube socket. Just like you did with the 6V rail, with the tube removed, stick the voltmeter probe in there. It should read right around 240V or so.

I will say it again, IF YOU ARE NOT COMFORTABLE PROBING HIGH VOLTAGE CIRCUITS, PLEASE DO NOT RISK YOUR LIFE FOR THIS PEDAL.

That being said I don't like the community of people that gatekeep things like working on amps. "If you've never worked on an amp before, you shouldn't try working on an amp." How then will you get enough experience to work on an amp? You have to start somewhere. So if you've been around the block a bit and are comfortable with general debugging and trust yourself to be careful, I would absolutely say go for it.

If you are not comfortable, I would have no problem with anyone sending their pedal to me and I will be happy to troubleshoot it for you.

 

[Feral Feline]

If you are not comfortable, I would have no problem with anyone sending their pedal to me and I will be happy to troubleshoot it for you.

WW!

That's very cool of you, Nathan!

 

[Quirkey]

OK! I realized my power supply is low amperage so going to test tonight with a higher one. Also, I'm a little uncomfortable but I think I can probe voltages later, too. Will report back.

Thanks!!

 

[vigilante398]

OK! I realized my power supply is low amperage so going to test tonight with a higher one. Also, I'm a little uncomfortable but I think I can probe voltages later, too. Will report back.

Thanks!!

Excellent, keep us posted. And it's normal to be a little uncomfortable with high voltages, because that's what keeps you careful; when you start to get too comfortable you start to get careless, and that's when accidents happen. You should always be at least a little bit afraid, but hopefully not so afraid that you can't do it.

 

[zgrav]

I suggest that you wear nitrile gloves if you have them when testing. Make sure one lead on your meter is grounded to your case, and only use one hand when testing with the other probe, as in "keep your other hand in your pocket." Probably overkill for this pedals given the low amperage, but still a best practice.

 

[Mentaltossflycoon]

 

[Quirkey]

OK! It works!

I took the suggestion and wore gloves and had my hands in my pockets (I work in a kitchen during the day so no shortage of gloves). I probed and while 9V was going to D1 and C2 it didn't seem to be making it out. I probed around further and for some reason (probably a bad joint) there was no power going to the V+ connection to the switch board either. I replaced the 5817 and made sure the solder was good and viola, it was something on that joint.

So stoked! It sounds great. Thanks @vigilante398 for the awesome pedal and support!

 

[vigilante398]

OK! It works!

I took the suggestion and wore gloves and had my hands in my pockets (I work in a kitchen during the day so no shortage of gloves). I probed and while 9V was going to D1 and C2 it didn't seem to be making it out. I probed around further and for some reason (probably a bad joint) there was no power going to the V+ connection to the switch board either. I replaced the 5817 and made sure the solder was good and viola, it was something on that joint.

So stoked! It sounds great. Thanks @vigilante398 for the awesome pedal and support!

Excellent, glad you were able to figure it out and glad you like it