meatsphere troubles..

[luks999]

hi guys

i need ur help on this one. i know its not a madbean project but i know many of u have built this with great success

ive some problems with the madsphere build
ive built everything up as described in the doc. wiring is the same

and it works basically
but:
when i turn the up / down switch the signal is off. when i then reduce the insensity pot, the signal comes back but on lower vol and brighter

on some settings there is a vol drop but i guess thats normal?

and the led doesnt work at all. should show the modulation right?

any input appreciated. :-)

[Govmnt_Lacky]

Where did you get your LM1458 IC from?

[luks999]

got it from musikding
but its a mcp1458p. can that be the issue? ive read somewhere that not every ic works but i thought every 1458
i think i order a lm1458n from ebay

[luks999]

ok im really stuck here...

i bought an LM1458N from ebay and it doesnt work either.

altough i get some sound through the pedal, the following problems occur:
-) signal vol very low
-) up/down switch only works on one position, on the other the signal is off (comes back when i turn the instensity down)
-) the LED is off on the up/down position where i get a sound, on the other up/down position the LED lights but doesnt blink
-) the quack sound is increasing when i hit the guitar harder... that not normal right? when i pick the notes soft, the effect is only very minimal

i tried:
-) LM1458N instead of MCP145P
-) measure everything around the 1458 and the up/down switch. connections are all working as they should
-) removed the LED
-) changed the Rled from 2k2 to 300R

when theres a modulation problem where do i have to search / start?
any hints.

-) 3PDT wiring is correct
-) send / return switching works

can a contact failure be the problem? or a wrong part value?

Thanks! i appreciate any help here

[Govmnt_Lacky]

I had a "somewhat" similar problem with my full size build (the up/down working only in one position and other odd happenings)

It turns out that my V+ (9V) was shorting to Ground because my LED lead for the on/off was contacting a metal bezel.

Check to see if you are getting voltage on your ground. IF not, it would be good to post some voltage readings and good pics of your build (BOTH PCB sides, wiring, switch, etc.)

[m-Kresol]

at least it sounds like it generally works... in the up position the led is dark and when you strum it should light up. in the down position it lights up all the time and when strumming it will dim. also, it is normal that the quack is stronger when hitting the strings harder, the sensitivity controls how hard you have to strum.
unfortunately, no idea where to start looking though

[luks999]

Thanks !
at least i could fix the volume drop problem. i soldered in 7.5k instead of 1.5k :/ i swapped them and now it has normal volume

ok that means the LED generally works, but it doesnt light up or dim when strumming.

ok strange though, because sensitivity is all the way turned up.

i checked now all parts, and they are all correct. so it must be a contact failure with up/down switch. i measured it, and its connected correct, but yeah maybe the problem lies somewhere else.
I have a similar problem now: in one position of the up/down the pedal seem to generally work, in the other i get a strange noise, like its directly connected to 9V or so .... ill check everything for that

ill keep u updated

[bcalla]

Did you use the recommended VTL 5C3s, or did you roll your own?  Mine barely worked with the VTL 5C3s, but 2 green LEDs and Tayda LDRs made it sing!

[LaceSensor]

dont use proper vactrols, use green led and 2M dark photocells

try a different 1458 chip
even try other dual op amps. despite what taylor says, others do work, eg 5532

[luks999]

Thanks

at the moment i use everything as in the Musicpcb BOM.
I use the VTL5C3

ok i can try that. would photocells work, that i bought from smallbear for the univibe?
i have some lying around

i tried so far a MC1458P, LM1458N and a RC4558P, none of them has made any difference
i guessed that, saw no reason why other opamps shouldnt work

[Govmnt_Lacky]

Check your ground to see if it is getting ANY voltage. Mine was bleeding the LED voltage onto the ground circuit and was doing EXACTLY what you are describing now.

[luks999]

unfortunately it doesnt look like this is the cause. ground looks ok.
i checked back all connections around the up/down switch and everything should be working as designed...
i couldnt find any mistakes

down position works, up doesnt.
When the up/down switch engages the 9V to the Led resistors and the LED cathodes to the intensity pot, then the signal is off. but the voltage is there, because the LED is also on.
Everything else works.

as the higher voltage is pointing to the OUtput of the 1458, i wonder if this is able to work in any way...
the up / down switch doesnt swap the 1458 to the other direction...

any suggestions what i can try?

the VTL5C3 work, and dont seem to be a problem

[midwayfair]

I'm not totally convinced your pedal isn't working properly. Turn down basically EVERYTHING in up mode. Decay, threshold, make the attack longer, go to low mode, turn the sweep down, turn your guitar volume down, etc. Up mode in anything Mutron-based is annoyingly difficult to get working properly.

[luks999]

thanks for the tip, jon

when i turn down the intensity, i get a lower sound in the up position. but thats only working in some positions of the rotary switches.
when i turn everything up, and i chnage the filter switch to the highest frequency, i get a noisy signal, like some voltage gets directly connected to the signal path.
maybe i dont know the circuit not well enough, but i barely can find any infos on the web on this one, that helps me out here.

i watched a demo of youtube of the meatsphere, where this strange behaviour didnt occur (up/down switch)

[Govmnt_Lacky]

You are using the Meatsphere PCB from Taylor right?

Stupid question but..... Did you solder the Rotary switches on the correct side of the PCB?

It has happened before...