Analog Sun - No Output (Noob making progress)

bcdbcd2 · Post by **bcdbcd2** » 06 Apr 2023, 22:10

I am working on my first pedal which is an Analog Sun Fuzz pedal from PCB Mania. I have made some good progress with help from this group. First I was able to fix my 3PDT connectivity and successfully got the bypass working. After checking some loose wires I got the LED working. It's kinda fun troubleshooting... but it will be even better when I can close this bad-boy up and play.

Situation: I have a full finished Analog Sun kit. It switches successfully, plays on bypass fine, but does not have any output when switched on.

Approach:
1. Continuity (good) - I verified with a continuity checker that both the inputs and outputs were routing into the board (see contiuity.png picture)
2. Grounding (good) - I checked to make sure all of the ground points had continuity between them. They do!
3. Voltages - I plugged in a 9V DC charger and took measurements where I could cross referencing with the circuit diagram (see circuit.png picture) Most of these voltages looked good. A couple of things that stood out:

Volume Pot - All the voltages on the volume pot were zero. Seems weird. Based on the circuit diagram it appears that it should be getting some voltage out of C3 Capacitor and isn't. That particular capacitor didn't solder well and I may have screwed it up.
IC1 Pin 7 - In the circuit diagram it shows pin 7 not connected to anything. In my measurements I had 3.9V on pin 7. Kinda weird.

Question:

Is it normal for the volume pot to have all zero readings? Could the pot be bad?
When I installed capacitor C3 ("MKT 10nF" https://www.musikding.de/MKT-10nF_1 ) I wasn't sure of the direction, could I have installed it backwards?
Any other approaches to troubleshooting?

mauman · Post by **mauman** » 07 Apr 2023, 23:20

bcdbcd2 wrote: ↑06 Apr 2023, 22:10
Volume Pot - All the voltages on the volume pot were zero. Seems weird. Based on the circuit diagram it appears that it should be getting some voltage out of C3 Capacitor and isn't. That particular capacitor didn't solder well and I may have screwed it up.

IC1 Pin 7 - In the circuit diagram it shows pin 7 not connected to anything. In my measurements I had 3.9V on pin 7. Kinda weird.

Volume pot should not show any DC voltage on any pin, it's isolated by C3. IC1 Pin 7 is OK, it's not used in this case so the reading doesn't matter. IC1 pin 5 is -8.91, not +8.91, yes?

bcdbcd2 wrote: ↑06 Apr 2023, 22:10 Question:
Is it normal for the volume pot to have all zero readings? Could the pot be bad?

When I installed capacitor C3 ("MKT 10nF" https://www.musikding.de/MKT-10nF_1 ) I wasn't sure of the direction, could I have installed it backwards?

Any other approaches to troubleshooting?

C3 polarity doesn't matter, and your polarized capacitors (electrolytics) look like they are oriented correctly. For other troubleshooting, based on your pictures at viewtopic.php?p=294650#p294650 I'd recommend touching up all your solder joints, but especially the pots, trimmers and transistors. Transistors could use a bit more solder, and the Fuzz pot may have a cold joint (that ball of solder looks suspicious.) 2 to 3 seconds with a hot iron and you should see the solder start to flow before you remove the iron. Then check the voltages on Q1 and Q2 again, currently they're not connected to your -9V.

Lani · Post by **Lani** » 08 Apr 2023, 00:59

This little straggler could cause issues also.

: IMG_20230406_075643_small~3.jpg (20.27 KiB) Viewed 698 times

When you re-solder the transistors directly to the board you should always put an alligator clip (or something similar that's metal) just below the transistor itself to act as a heat sink and draw heat away from the internal bits (even moreso on germanium devices like you have). Also take a break (30 sec) between each joint to let cool before you start the next one.
If you have no voltage readings on the transistor pins then yeah it's likely a soldering issue.
Keep at it and eventually you'll get there, good luck and at least your enjoying the process!!

bcdbcd2 · Post by **bcdbcd2** » 08 Apr 2023, 22:31

I removed the board from the box so I could test better and make sure the solder connections were good. Most of the connections look pretty good (for me that is.... LOL), but I'm still not getting any sound when the board is engaged. I am now able to take a reading of the C3 voltages, and it has -8.85V on one side (good) and 0.0V on the other. How would the pedal ever send a signal to the amp if the output of C3 is 0.0? I think i may need a new capacitor.

bcdbcd2 · Post by **bcdbcd2** » 08 Apr 2023, 22:43

Just so you can have something to chuckle at... this is my "good" soldering.

mauman · Post by **mauman** » 08 Apr 2023, 23:59

bcdbcd2 wrote: ↑08 Apr 2023, 22:31 I removed the board from the box so I could test better and make sure the solder connections were good. Most of the connections look pretty good (for me that is.... LOL), but I'm still not getting any sound when the board is engaged. I am now able to take a reading of the C3 voltages, and it has -8.85V on one side (good) and 0.0V on the other. How would the pedal ever send a signal to the amp if the output of C3 is 0.0? I think i may need a new capacitor.

Caps block DC and pass AC, so C3 is doing its job. Your signal is AC, so it will pass thru C3 just fine.

Next step might be an audio probe (linked here) so you can trace your signal from the input jack into the PCB, and see where it stops.

plush · Post by **plush** » 09 Apr 2023, 12:19

Also make sure b5k pot is not shorting the pads.

Solderjob looks meh, add more flux and resolder every pad.

bcdbcd2 · Post by **bcdbcd2** » 10 Apr 2023, 13:46

bcdbcd2 wrote: ↑08 Apr 2023, 22:31
Next step might be an audio probe (linked here) so you can trace your signal from the input jack into the PCB, and see where it stops.

Oooh... that looks pretty cool. Looks like I have a new project.

andy-h-h · Post by **andy-h-h** » 10 Apr 2023, 20:52

Hey there - check your measurements on the bias & sundial (and the board in that area). They should not be the same, as they're connected in series. Whatever's going on there, very little voltage is getting through. The fuzz face "ideal" is -4.5v on the collector of Q2. Your's isn't even hitting half a volt.

Good luck

bcdbcd2 · Post by **bcdbcd2** » 11 Apr 2023, 02:02

I took some more readings around the whole circuit and particularly in the Sundial and BIAS pot area. The diagram below shows the readings when i turn the sundial all the way clockwise (on) and counterclockwise (off). Here's some observations:

a) Sunface On is Off? - When I turn the sundial all the way clockwise the voltages go way down. Do I have these pots mounted on the correct side of the board? That would be very embarrassing.

LOL

b) Q2 Voltages - When I turn down the Sunface dial Q2 base gets bumped up voltage, but the emitter and collector aren't that different.

c) No Sound At All - When i turn on the pedal, there is a total lack of any sound in my amp. I would expect to hear some noise or something else. I have some weird suspicion that I have a bad solder at the end of the chain... the bypass works fine so the input/output solders should be good.

Lastly... I have ordered some parts to make the audio probe. I suspect I will need it and it sounds cool to listen to the signal at various places in the chain.

bcdbcd2 · Post by **bcdbcd2** » 11 Apr 2023, 17:00

I think I have one of the major issues figured out. Originally I thought the configuration of the dials was exactly the same as the Analogman Sunface. It is not, the volume is in the middle. I put the knobs in the wrong place. <hand to forehead/>

Sometimes you just have to laugh rather than cry.

andy-h-h · Post by **andy-h-h** » 12 Apr 2023, 08:17

bcdbcd2 wrote: ↑11 Apr 2023, 17:00 I think I have one of the major issues figured out. Originally I thought the configuration of the dials was exactly the same as the Analogman Sunface. It is not, the volume is in the middle. I put the knobs in the wrong place. <hand to forehead/>

Sometimes you just have to laugh rather than cry.

This is great - despite some embarrassment and frustration you basically worked it out yourself.

Lani · Post by **Lani** » 13 Apr 2023, 00:39

Are you at least getting sounds out of it now since you switched the pots? It happens to all of us trust me... Just recently I did something very similar

bcdbcd2 · Post by **bcdbcd2** » 13 Apr 2023, 01:58

Haven't swapped them yet, but I did make this bad boy audio tool. Now I'm dangerous.

My wife said she wants the dining room table back. LOL

bcdbcd2 · Post by **bcdbcd2** » 13 Apr 2023, 16:50

Sweet hum of success! The audio tool was a great way to trace signal. The clean Pot had a bad solder joint that was easy to fix.

Thx mucho!

bcdbcd2 · Post by **bcdbcd2** » 13 Apr 2023, 17:29

A couple of other noob pieces of advice. Get a solder sucker to remove solder when u screw up, and make an audio tool (linked earlier).

Lani · Post by **Lani** » 14 Apr 2023, 10:05

Nice man, glad you got er. That audio probe will help you in the future, for sure.

mauman · Post by **mauman** » 14 Apr 2023, 11:06

bcdbcd2 wrote: ↑13 Apr 2023, 16:50 Sweet hum of success! The audio tool was a great way to trace signal. The clean Pot had a bad solder joint that was easy to fix.

Congrats!

Analog Sun - No Output (Noob making progress) [SOLVED]