PT-80 questions! No signal when on, just hissing sound

[gguru3]

Ok, I built the PT-80 from GGG. Did everything slowly and correctly to make sure it would work on the first try.

Well, at first I powered it up using a 14V wall wart (verified working correctly, also wired w/ the correct polarity). I switched the pedal ON and got a loud dry HUMMMMM sound, but no signal from the guitar...and the diode across the input voltage started to smoke (well, I had electrical tape around it and THAT actually started to smoke...I immediately turned it off.

Then I removed the diode and hooked the PT-80 up to a 9V battery source instead of the wall power.

Now, when the pedal is switched OFF, I get the dry signal from the guitar. When I switch it on, I get NO signal from the guitar, but instead I can hear a wierd hissing squeel sound.  :cry:

The LED lights up correctly, and the 3 pots used to adjust the delay and such are working correctly, when I turn them up and down I can adjust the sound of the wierd squeelling sound, but no signal from the guitar when the box is ON.

Now, I'm guessing the the 9V isn't enough power because I wired the circuit exactly the way it came from GGG, which was intended for 18-24V, so that may be the reason for no signal from the guitar???

Just wanted some help, hope I was descriptive enough!

[niftydog]

dude, really difficult to say. there is obviously something majorly wrong. Just start checking and double checking your work. Trace through everything, bit by bit and eliminate bits as you go. Go logically though, start by checking the power supply is reaching all the parts, and it's at the correct voltage.

Did everything slowly and correctly to make sure it would work on the first try.

hmmm.

well, I had electrical tape around it and THAT actually started to smoke...

double hmmm. These two statements seem to contradict each other. Remember that electricity can be harmful or even fatal, then reconsider the attention you pay to the quality of your work.

[Brian Marshall]

my pt 80 worked great the first time arround.... I forwent the protection diode though..... remember that diode is supposed to have a breakdown voltage higher than your supply.... it is meant to protect YOU from voltage when your transformer melts and turns in to a giant conductor.  If you are using a standard si diode liek a 1n914 it wont work.

try using 2 9 volt batteries in series are report back.

[Samuel]

are you sure the wall wart is DC and not AC? I don't mean to be rude, I made this mistake with my PT-80 (it was my second project ridiculously enough) and I burnt out any number of components. I can't imagine the diode burning out otherwise...although perhaps with a reversed power supply....

[gguru3]

Thanks for your help guys. I have actually isolated the problem further.

Please check out my other post and hopefully some of you might have some other suggestions...

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=24081&highlight=pt80