Noob Question - Removed Pedal Grounding?

[autonomy]

Heyaz, i have a flange pedal powered with battery clip connector. recently got a proper 1/8th inch headphone jack style connector for it, so i hooked that up and opened the pedal up to put the battery clip back inside.

since then the pedal has not sounded right, theres a helicopter choppiness continuously running. i noticed when touching the rear solder points on the pcb various blips and weirdness would occur and realised the grounding has gone. also noticed that the on LED was not quite fully lit.

that got me interested so i tried to find the ground point to fix it but had no luck. however i noticed that when the top most transistor had one of its metal teeth connecting to the pedal housing, LED went fully lit and the pedal operated as normal. also found that when i touched a wire from sleeve on the input to one of the 3 dc input connections it worked similarly.

was slightly impressed with myself and actually have 2 copies of the pedal which i was testing on as a base reference eg. to make sure the sound wasnt effected when touching rear solder points. the pcb on second flange was a little more stuck to protective sticky pads over the input and output jacks, i gently wiggled those free but now it's in the same boat with the grounding shot, helicopter noises and blips/weirdness when touching the pcb. i have checked the wires and solder points pretty damn thoroughly and i just don't understand how the ground connection has been lost? if there was some importance to the sticky pads? however im pretty much returning it as it was.

the same grounding tricks on the first pedal eg. touching transistor to the case, don't work on the second and 've noticed that the battery and output jack wires are slightly different on the second pedal.

my first question is, how can i know what will reliably fix ground on the first pedal? and the second pedal? and more importantly, what could have gone wrong here in both cases and how can i fix?

[GibsonGM]

Welcome to the forum, Autonomy.  Can you find a schematic of the thing anywhere online?  That might kinda show you where they intended the ground to be.  Might.

Other than that - there are just a few places where they'd make a chassis connection...I would really look hard at one of the jacks for this.  If you can find where the battery "-" hits the PCB, that area may well be 'where it all happens', and will lead you to where the intended ground should go.  Ask yourself - "What CHANGED??"   Something always changes when this stuff occurs - did a jack come loose?    The connection is there, it's just that YOU have to find it    It may still be connected, and just very loose or corroded!   Or a wire may be frayed and coming off the PCB at the other end....

Be careful poking with a wire, or shorting transistors to gnd!!!!   I hope you dodged the bullet on that one....esp. the 'LED glowing brighter' as you cause current to increase, lol - hopefully not to some excessive level.

At the end of the day, in the worst case, you CAN find the 'main ground point' on the PCB and run a wire to a jack, make your own ground connection, if it works.    Be aware of how you run this, you may defeat the jack power switching scheme.....don't forget to check THAT first, as something could've gone wrong in there! 

[duck_arse]

that got me interested so i tried to find the ground point to fix it but had no luck. however i noticed that when the top most transistor had one of its metal teeth connecting to the pedal housing, LED went fully lit and the pedal operated as normal. also found that when i touched a wire from sleeve on the input to one of the 3 dc input connections it worked similarly.

I don't wish to sound trite, I just can't help it, usually, but these metal teeth of which you speak have me intrigued. we are sticklers for the correct names of things around here as they can make all the difference. what are they, what do they look like, can we see them?

also, wlecome.

[GibsonGM]

Pix... 

[autonomy]

was actually an IC chip and i guess pins? rather than teeth would be the correct nomenclature, forgive me.

i've grounded it over and over and luckily it takes it, cause it makes the pedal operate perfectly again. i dont know enough but i'm pretty sure im touching the housing to the ground pin of the chip. touching any of the other pins result in oddball beeps

thanks for the advice, i've checked pretty thoroughly around the jacks to the point where i was thinking it was booby trapped or something to prevent tinkering but i guess thats silly. i'll check more thoroughly.

[GibsonGM]

A pic would help - too much monkeying and you might ruin that chip, man...

[antonis]

Strange case, indeed..  

If we are talking about transistors with metal housing then we point the Collector and if they are working with grounding then we deal with positive ground circuit...

(or maybe I need some extra cups of coffee...)