Electrovibe: noise on speed 2, bulb stalls on slower speed 1

[teringsaus]

First time posting here, so hi! Hoping to get some help with my Electrovibe build here. I actually bought and assembled 2 Musikding kits simultaneously. One with a couple resistor value mods that is working wonderfully and then a stock one that is showing some issues.

TL;DR: Noise is introduced into the circuit at Q10, how do I proceed?

Let's first get the important stuff out of the way, so directly below is a picture of the board.
I powered the effect with a Cioks DC10 (together with other pedals) as well as solo with a Visualsound OneSpot, this makes no difference.
All recordings are with the chorus setting engaged, however the same problem is also apparent in the vibrato mode.
I double-checked all component values and did not find any mistakes there, but another pair of eyes probably doesn't hurt.




Main issue: noise on speed 2
The effect is present, but horribly noisy when speed 2 is selected. I put a 130 Hz sine at the input and started probing with my scope, so far I managed to pinpoint the issue to leg 3 of Q10. The noise is also present when there is no input into the pedal. As expected, the noise is passed on to Q12 (image 4) and on to the final output (image 5), while the output is mostly clean on speed 1 (image 6). My question now is: how do I fix this?

Here is a clip of the noise. Guitar > Electrovibe > DI into a clean Twin Reverb model on Guitar Rig 6. In order you hear: bypass, speed 1, speed 2.

https://soundcloud.com/redstone-rocket%2Felectrovibe-noise%2Fs-6bCNNoRsHu8

Because the traces move around a lot due to the effect, I also have a video where I switch from speed 1 to speed 2 after about 3 seconds. Again, this is pin 3 of Q10.

https://imgur.com/xvHT339

Q10 leg 3, 130 Hz input, on speed 1


Q10 leg 3, 130 Hz input, on speed 2


Q10 leg 3, no input, on speed 2


Q12 leg 3, 130 Hz input, on speed 2


Output jack, 130 Hz input, on speed 2


Output jack, 130 Hz input, on speed 1



Second issue: bulb stalls on speed 1 at lower settings (possibly related?)
I'm also experiencing the bulb stalling when speed 1 is selected and set below 70%. On speed 2, the bulb behaves normally across the entire range of the pot. Similar to what is described in this thread which was never resolved.

To anyone who who looks into this: thank you for your time and efforts!

 

[teringsaus]

Bump for visibility. Anyone have a clue? Need any other info from me?

 

[music6000]

Did you use a proper Dual Gang insulator on the 2 Speed pots?, No electrical tape is reliable!

 

[franblanc]

Trying blowing compressed air into the offending pot to clean out any debris. If that doesn't work I would replace it. I notice that the 2N5088 transistors are not socketed. Music Ding are now providing sockets for them on the newer Electrovibe kits. Maybe one of your 2N5088 got damaged by heat.

 

[swelchy]

looks like all the transistors are socketed.... give them all a good wiggle and make sure they are seated and not loose legs anywhere..
Also..... to all interested with 3d printers.. I made a insulated cover for the back of dual gang pots and have it on thingiverse. Just search dual gang potentiometer.

16mm dual gang potentiometer cover by swelchy

16mm potentiometer dust cover/ insulator

www.thingiverse.com

 

[teringsaus]

I am so sorry for this slow reply! Never got notified of your comments from last month and this build has been sadly collecting dust in a drawer. Thanks for your input which reignited my motivation to finish this pedal!

Indeed all transistors are socketed and I had already reseated all of them prior to my first post. Rechecked the socket solder joints as well.

I did not have a dual gang pot insulator at hand, so thanks for the print file, will give that a go. There's an ultimaker 2 at work I can use. With some fudging I put on a normal insulator instead but that might not be sufficient. There does seem to be enough clearance between the print and the pot but I'll give it a shot regardless.