Problems with guitar pedal Ibanez PC10

[eduardo_gj1]

no, i dont have oscilloscope, am just a hobby

 

[gophert]

no, i dont have oscilloscope, am just a hobby

Used scopes can be found at hobby prices. About $1/MHz of bandwidth for a generic scope and double that for premium brands. Bandwidth over 100MHz is half price) - at least that is the trend I see on my local Craigslist.org.

 

[eduardo_gj1]

i know, they are not so expensive, the big problem is i don't have a clue how to use in a circuit. i guess a usb scope its not the best option, but they are cheap

 

[rjenkinsgb]

A cheap USB scope is fine for audio work!

 

[eduardo_gj1]

ok can you pls tell me what i have to do with the scope?

 

[rjenkinsgb]

You would connect the scope probe ground wire to the 0V in the pedal.

Then, by touching the probe tip to the various points such as the ones you were looking at voltages on earlier, you can see the exact waveforms of the signals on them as well as the average DC voltage.

It allows you to trace a signal from the source through the circuit to its destination, in other words, and see any changes in level or distortion.


ps. Make sure you get one that comes with a proper oscilloscope probe that is switchable between x1 and x10 - the "x10" (actually divide by ten) setting is the most commonly used one, as that means the probe tip is high impedance and does not mess up the operation of the circuit you are working on.

 

[eduardo_gj1]

well for now i think i hat to put this project in stand by, in january i will buy a scope, and write you guys again, but i want to say thanks for your help

 

[unclejed613]

how old is this pedal, just out of curiosity... it's a long shot, but some of the potentiometers you are mentioning seemingly being at the edge of any operational range have electrolytic caps in the circuits. i say it's a long shot because it's not common for electrolytic caps to dry out unless subjected to elevated temperature or relatively high charge/discharge currents, but they do have a shelf life and can either dry out or change value if they aren't used for long periods of time (years).

 

[eduardo_gj1]

This pedal is approximately 35 years, a little more a little less, the problem of the potentiometers is that they are difficult to replace since I have tried to get a replacement and I have not been successful, they are 12mm D-shaft, and with the capacitor Well, since I do not have an ESR meter, I would not know if they are in perfect condition, because they measure their value correctly but it could be that the ESR is wrong, later I send you a photo of the inside of the pedal, and maybe you can give me a recommendation

 

[unclejed613]

This pedal is approximately 35 years, a little more a little less,

yeah, that would definitely be beyond the shelf life of most electrolytic caps. i've seen estimates of between 5 and 15 years depending on the formulation of the electrolyte, how well the end seal prevents evaporation of electrolyte, and the purity of the aluminum plates..

because they measure their value correctly but it could be that the ESR is wrong,

that can happen, and i've seen it often.

 

[eduardo_gj1]

Well, I just bought an ESR meter, this week it should arrive to be able to check and know if they are fine or not, thanks for your help

 

[eduardo_gj1]

how old is this pedal, just out of curiosity... it's a long shot, but some of the potentiometers you are mentioning seemingly being at the edge of any operational range have electrolytic caps in the circuits. i say it's a long shot because it's not common for electrolytic caps to dry out unless subjected to elevated temperature or relatively high charge/discharge currents, but they do have a shelf life and can either dry out or change value if they aren't used for long periods of time (years).

I have a doubt, most of the capacitors of this pedal are bipolar capacitor. Can't I messure the ESR in bipolar capacitors? And should I replace the entire capacitor on this pedal? electrolytic, ceramic, bipolar?

 

[Nigel Goodwin]

I have a doubt, most of the capacitors of this pedal are bipolar capacitor. Can't I messure the ESR in bipolar capacitors? And should I replace the entire capacitor on this pedal? electrolytic, ceramic, bipolar?

No, you can't measure the ESR of non-electrolytics, and there would be no point anyway - there 'probably' isn't any issue with them, unlike the antique capacitors used in very old valve gear, where they tend to go leaky.