ITS8 (Tube Screamer 808 replica) dead...!?

[rpark71]

Hi all,

Another newbie query about a General Guitar Gadgets ITS8 - tube screamer build that fails to scream at all. Have tried battery and 9v power, but still nothing. Visually I've gone through the wiring and all seems to connected to the right place. Can a single bad solder, (if that's what it might be make a pedal silent?). LED not lit or any sound from guitar to amp whether switched on/off. Is this an obvious thing? Even tried a different chip, as had couple spare, but still nothing - I put the socket in wrong way round I think, but assume that's just a useful indicator for the chip, so as long as that's correct to the pub, that's ok? It may or may not help, but have included photo's in case something obvious someone can see immediately. Any help or kind advice welcome!

Thanks, Rich

[Bio77]

If you don't have sound coming through your amp in the off position then you have your switch/jacks wired wrong.  If you have sound in the off position but not the on position then it could be something else.  I also notice that you have a wire connecting the grounds of your jacks to each other but there is no wire from the jacks to the PCB.  The PCB needs to be grounded to work.  Same with your switch, it needs a ground from the jack or via the PCB for the LED to work.  Also, if you end up taking it apart, it's a good idea to sand the paint off where the jacks touch the inside of the enclosure.  This makes sure they can make good contact for grounding.  Hope then helps.

[rpark71]

Hi,

Thanks for your thoughts - good just to look at things again. I'll check the wiring again of the jacks, as I get no sound. There's a yellow wire connecting the two jacks and from the output jack lug there is also a brown wire going to middle 'G' on the PCB. I'm assuming this was ground. Another brown wire to centre post of switch and blue wire going to L-shaped lug of DC plug. Isn't that everything connected to ground?

Thanks Rich

[rpark71]

Ah...looking at the wiring diagram again and the input jack the black wire from the battery clip is going to the tip of jack and the green wire from the switch is going to the ring lug of the jack. I'm guessing this is the problem!? Thanks Bio77 - we'll see if this works!

[rpark71]

Just to update on last reply - switching the wires on the input jack worked! LED doesn't light, so not sure if blown but that's an easy swap for new one to see if it solves that problem. Thanks again for steering me in the right direction Bio77!

thanks, Rich

[jimilee]

Just to update on last reply - switching the wires on the input jack worked! LED doesn't light, so not sure if blown but that's an easy swap for new one to see if it solves that problem. Thanks again for steering me in the right direction Bio77!

thanks, Rich

It may just be backwards.


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[Bio77]

Glad it worked!

Do you have a multimeter?  If so, check the voltage at the purple wire going to the LED.  I don't know this circuit, but I'm guessing the resister closest to the purple wire is the CLR for the LED.  It looks kind of suspicious (maybe a cold joint). Also, if you have a multimeter it might have a diode setting that you can use to check your LED.  I've only ever blown an LED by shorting it with no resister, so, I'd be surprised if it was fried. That will also tell you if the orientation is correct, as Jimi suggested.

[jimilee]

Glad it worked!

Do you have a multimeter?  If so, check the voltage at the purple wire going to the LED.  I don't know this circuit, but I'm guessing the resister closest to the purple wire is the CLR for the LED.  It looks kind of suspicious (maybe a cold joint). Also, if you have a multimeter it might have a diode setting that you can use to check your LED.  I've only ever blown an LED by shorting it with no resister, so, I'd be surprised if it was fried. That will also tell you if the orientation is correct, as Jimi suggested.

I've blown more than I care to admit.



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[rpark71]

I tested the LED with multimeter and got nothing so removed and put a new one in that I tested first and now LED working too! Thanks again - feels good to fix it! Learning by mistakes always useful! A king of tone type pedal next project, so probably be back for help!

Cheers, Rich