hi everybody!
i've got a problem with my tonepad ts-808 copy...well i get very small amount of distortion...and only when the gain pot(470k) is at 0. when i turn it clockwise i hear only some unpleasant pops and very weak signal from guitar instead of nice distortion. i've got 1n914 diodes...the only things i've changed are:
- instead of 51p capacitor i used 50p
- instead of 0.0022 uF i used 0.0033 uF
i've got 2 IC - rc4558 and tl072 - they sound the same...
i've also tried connecting only two cords to the pot...it's the same as with 3
i've tried both asymetrical and simetrical diode connections
i also tried putting a 100k pot in series with one diode...there's a small difference...
please help...
sorry for my english...
Quote from: yoromv- instead of 0.0022 uF i used 0.0033 uF
They should be .22uf. They were originally tantalums. .0033 would be a rather large difference.
oh..sorry...i don't know why i made such a mistake...i meant 0.027 uF...and it's 0.033uF...
Ijust recently built that exact pedal using the same layout and it worked perfectly. Recheck all your part values, all your solder joints and all connections to external components. If you etched a circuit board check very carefully to make sure there are no broken or shorted traces.
I built mine using the 4ms CBCB method that uses the circuit mask as a pattern for what is essentially a perfboard build, but it does show (and I'm sure that the dozens of other people who have built this will also back this up) that the layout is not at fault.
hmm...i've checked connections and they seem to be ok...i've checked the voltages and there is voltage everywhere...i've noticed that there are big volume changes...for few seconds it's quite loud and then it becomes almost completely quiet...
please help...
sounds to me like the feed back loop may not be grounded, if it is gating.
also check to see if any of your opamp pins are cross soldered.
Check for 9V on pin 8 and 0V on pin 4. All others should be 4.5V (or a volt or so less if you've got a cheap multimeter like me). Like others, I have a working one at home, so the layout's good.
well i've checked the voltages and they are the same as you said...
Quote from: yoromvi meant 0.027 uF...and it's 0.033uF...
There is a .027uf on the input. Then there are two .22uf tantalums elsewhere. You didnt mix the location of these?
they are in place...but i don't have tantalums...they are normal ceramic...could it be the cause of the problem?
No, ceramic is fine, a little noiser. Is the diode orientation correct? Did you go over the pcb with a good magnifier to make sure no trace fragments or solder pads are touching?
well...i've checked everything...and it seemed ok, but i cleaned some connections and spaces between them...and it's working...:)...unfortunatelly weird things are going on...i was playing with it for about 3 min...and i left it working for about 30min...when i came back...and strumed the string i've heard only some silent pops and clicks...i disconnected the battery and connected it back...it was the same...i left it for about 5 min and put the battery back..it was better but still the distortion was quite unpleasant...so i disconnected it and connected after about 30 min and it's working back...i hear some weird noises...like something is not properly connected...but all the connections are ok...
I think your battery is dead. ;) But it can't draw that much current can it? Pop in a new battery and see what happens.
well i've checked the voltage and it's 9v so the battery is ok...
:| you can't have fried anything... not with 9v. I guess this is what some people like to call mojo. Strange.... You're absolutely sure that the circuit is correct per the schematic, right?
I guess you should check your off-board wiring and switch etcetera first-off... but that's a wild guess
i don't have bypass circuit etc. only cord to pots and sockets...and battery of course...and they seem to be ok...
Well the only thing I can think of is check the connections everywhere, make 500% certain you don't have a short.
Quote from: smoguzbenjaminWell the only thing I can think of is check the connections everywhere, make 500% certain you don't have a short.
Like Ben said, check, then triple check. Sometimes you can miss something. Check the two transistors to make sure the pinouts are correct, check the polarity of the diodes and electrolytic caps. Have you tried it outside of the box?
I second checking the pinouts on resistors and orientation of capacitors and diodes. I have a hunch that your problem resides in one of those areas.
A cold solder maybe? When a problem is intermittent like this I go over ALL of the soldering and re-melt each point. Sometimes it does the trick.
well there is a strange thing:
when i turn it on it works perfectly for 30 sec. and then some noises are becoming quite loud...they are like you blow air into a working microphone...
please help....
i've made an audio probe...and i checked the circuit...i found out that the .027 uF capacitor was faulty - after short time it was makin noise...i replaced it and now it works absolutely perfect...
THANK YOU ALL FOR YOUR TIME AND HELP...
I'VE LEARNT MANY NEW THINGS
AND THIS WASN'T MY LAST STOMP BOX :-)
THANK YOU ONCE AGAIN!!!
BEST WISHES
Glad it's working!! :D It's nice when they work right away, but you learn alot from debugging. Kinda like understanding the circuit after you've built it.
So....How's it sound?
Enjoy!
heh...i didn't expect that it will sound good...but...it's awesome :-)...really wonderfull...when i compared it to the original TS i don't really hear a difference...
THANKS AGAIN