Looks like I have fried my Pro Co Rat !!

Weaseldust

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about a month ago the red diode light suddenly became very weak...days later didnt light up at all, but pedal worked..and then next time i tried a day later or something, nothing, just dead.

i took it apart and began troubleshooting the only way know...with a multimeter to trace the signal and see where it stops. I took far too long time before a saw the disasterzone ... a Diode right next to incoming current had made a brown mess ... This is what that diode is for, protecting against wrong polariity current...i found out later when i looked up the shcematic, something i should have done first thing

but there is no chance i could have done it...i only have one powercable that fits, it is a 3,5mm inputjack for power.

the only thing i can think of is over a year ago when i didnt have a powercable to a a little epiphone slash amp...they run with 24volts adaptercable, and i have an adapter you change values on and different tips for input, only the could i have done something like that...why would i all of a sudden try to hook THAT up to my Rat ???


Does anyone have any ideas ?? what could have happenend here ? ... And why did it die gradually over a few days ?? i thought something like that happend with a sudden.
If I did something last year, fed it 24v could that have damaged something else that since then just been a ticking timebomb??

any other helping tips...im unsure about how you troubleshoot a pot for example...or the op-amp chip LM308N if that is dead that´s no good...i always heard about that being something special..

So do have any pedal and electronics wizards here ?? Help please and thank you
 

hamerfan

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It was overvoltage or reverse polarity or both. Just swap the diode and use a proper 9 volt supply.
There are no secret parts in those effects, no sprinkling of fairy dust over vintage or boutique effect pedals. They are just proper parts (indeed there also fake parts on the market) of good quality, a good pcb or veroboard layout and a decent wiring. There is nothing mystic about the LM308, its just a plain IC. There some other equivalent types like the OP07, TL071 or even an NE5534. The LM308 where just the IC which were avaliable at the time of the design and now not longer in production.
 
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Weaseldust

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It was overvoltage or reverse polarity or both. Just swap the diode and use a proper 9 volt supply.
There are no secret parts in those effects, no sprinkling of fairy dust over vintage or boutique effect pedals. They are just proper parts (indeed there also fake parts on the market) of good quality, a good pcb or veroboard layout and a decent wiring. There is nothing mystic about the LM308, its just a plain IC. There some other equivalent types like the OP07, TL071 or even an NE5534. The LM308 where just the IC which were avaliable at the time of the design and now not longer in production.
Yeah i will find some similar diode then a try tonight.

Thanks
 

Weaseldust

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UPDATE !! =)

It wasnt the diode in the powersection, it was the resistor next to it!

A new on is almost in place...Another resister had lost one of the legs connection, probably me when i went over everything .. so i fixed that first, had to lengthen the leg with a jumper from a random old board to a soundcard, where i also found a equal new resistor to the burnt one !!

Now with one leg left to solder my nerves need a brake.
 

Weaseldust

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another little update-....

actually did not find a fitting resistor...in the haste i totally ignored what setting i had the multimeter on so the 47 ohm resistor aktually was a 47K resistor ... quite the difference. i dont know but i guess notihng would happend more than that i just wouldnt power on ... im guessing.

yeah anyways now i have found a 102 ohm resistor...closest i have found so far.. think im going to try with this ...

or should i not ???
 

Weaseldust

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IT`S ALIVE !!
1670940897638.png


And sounds like it should ... i think. I never really REALLY liked it ... palmmuting with it doesnt work, to mushy, no chuggachunggah. so when it died i just shrugged my shoulders and said, HUH !!

And i havent been super carefull fixing with it ... at all ... nope. as said, i think i broke 1 leg of another resistor troubleseeking...So in the end this was actually a good thing, i learnt some stuff and i not "afraid" to handle such things as electronics like its the most britle things ever. .!!

first test i semi put i together in its case...the jacks where the important thing and i tried it with a 15w tube combo...sounded fantastic actually ... so after that i immediatly put it all together all washers and knobs complete casing....

tried it on my peavey bandit....now i remeber it...sounded like i remember....kind of crappy....

hmm didnt expect that. but more headroom isnt automatic better for pedals...

well well ....

so i can recommend frying your pedals Lmao !!
 

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