SOLVED Electrovibe LFO not working when Speed 2 selected

[torcamaniac]

Hi guys,

I'm new to this forum. Just built an Electrovibe a few days ago. I already built many kits incl. Forumvibe and I am not really a beginner.
The electrovibe works great bypassed and the LFO works with speed 1 selected. The bulb pulses and I already set the lamp gain and bias and have soundwise a great chewy vibe effect and I am very satisfied.
But, when I press the speed switch to select speed 2 the bulb goes dim or pretty much off and ofcourse the speed 2 pot doesn't do anything. But I can hear that the sound is still "effected" but logically not vibing.
My first though was the speed pot or something on the speed switch but I checked the pot with Ohmmeter and did some continuity testing. Also the pulsating and bulb isn't working so I guess it shouldn't have anything to do with the pot? Can't say I took enough time for troubleshooting but
I'm completely at the loss here. Does any of you guys have ideas what could be the culprit?

I read all of the problems with electrovibe I could find on the net but there seems that noone had this problem yet.

Thanks in advance!!!

Also some pics.

 

[torcamaniac]

Tried this also to eliminate switch wiring:
At first I soldered the speed switch breakout board with pin headers (as many do) but now desoldered it, sucked the solder cleanly and wired the breakout with short wires but it is the same. I am still guessing what could be wrong here.

 

[Robert]

Did you insulate the backs of the dual gang pots?

 

[torcamaniac]

Did you insulate the backs of the dual gang pots?

Hi Robert.
With two layers of tape. Also checked by removing the tape, if the back of the pot has any contact with solder on the board but it was ok.
But, just before I measured both speed pots again with ohmmeter ( both pots in the middle). On speed 1 pot I measured around around 20k between both wipers to pins 1.
On speed 2 pot I measured around 20k only beetween upper wiper and pin 1. Between lower wiper an pin 1 I measured flunctuating 120k to 130k. Kinda suspicious. Maybe the pot is really bad?

 

[torcamaniac]

Anyway... I orderded new C100k dual pots. Unfortunately, right now I only have 100k linear dual pots. I'll try to wire one reversed to see if the LFO on speed 2 works.

 

[Erik S]

Some of the sizes look funny on your electrolytics. I imagine you're probably just using two sizes of 1u, but maybe worth a check on the values.

Only other thing I noticed was a couple joints without much flow-through. Also probably not a problem unless you totally missed them, but hard to tell from the pics.

 

[torcamaniac]

Hi Eric,

the values of caps are actually all correct. I just used my own resistors and everything else. Only the PCB is from Pedalpcb. Some electrolytic caps are bigger in size and some smaller. Just what I had but as long as voltage ratings are enough they are okay. Also I specifically used at least 5-6 10uF caps instead of 1uF in the phase circuit because of bottom end as per R.G's mods from geofex. Yeah I checked the PCB soldering. There are some places that look like there isn't enough solder from above side but all the soldering is good from the other (solder) side of the PCB.
Anyway, it is solved now. As I suspected before after measuring speed pot 2 it was defunct which I have cut out.
Just now I connected the linear dual gang pot I had with alligator clips in place of the defunct speed pot and it works

Thanks anyway.

I have to say I am extremely surprised with the intensity of the effect I get from the pedal. Much more throbbing and swirly than my forumvibe although almost everything is 1:1 including the mods. The only difference left is I used 9203 LDRs on electrovibe so I have to try them inside forumvibe also. Also forumvibe came with cover for the LDRs and lamp (also reflective inside). For electrovibe I made my own square cap from thin but strong paper and put a panzer band from outside to reinforce it better and than I placed aluminium foil on the inside to make it reflective.