Shaka Tube debug - I'm Stumped!?!

[Grizz]

The power supply is suppose to be 120vac to 12vac not ac to dc...I got mine a radio shack, it's suppose to be for a answering machine.

[awitee]

oh, so it really wont work for dc? coz it doesnt produce a sound..
and how do you measure for the voltage? is the black probe on ground?
coz i tried the ac adapter for out modem, 12VA 500ma, and it still wont work, the values i get when i place the black probe on ground with the red probe on V+, V-, bias, opamp are all negative which is wrong, even if i change the probes, it comes out all positive which is still wrong

[Grizz]

I'm the wrong guy to ask about probing and such...But try messing with your bias, I know if I move mine all the way in one direction I get no sound.

[awitee]

i tried moving the trimp pot
no sound...
i still dont know wats wrong...
i might just redo the whole thing
EDIT
turns out it was a faulty ac adapter
i got the power supply biasing to work properly when i used the ac adapter for the other modem
so the power section work v+= 14.47V v-= -12+ bias= 11+ i also tried it while adjusting the trimpot from end to end
but still no sound... so problem is in the opamp pcb.. coz i tested the tube on my valvecaster and it works, the adapter by the way reads 14+ V and it is 1.2A
i swapped a bunch of opamps and still no sound.. i rechecked the wiring of the tube socket all correct...
hmm pls help
how do i test if the caps are broken? maybe it broke when i was using various power sources

[Paul Marossy]

oh, so it really wont work for dc? coz it doesnt produce a sound..

No, it won't work with a DC power supply - it needs an AC power supply.

[awitee]

yeh i got the power part to work, but still no sound..
see my previous post for more info.. thx for the reply

[Grizz]

oops I reread my post about the wallwart I made it sound like you need a answering maching wallwart...The one I bought said it's for an answering maching but it has the right specs...my bad.

Look back at pushtones posts...One of them has what the readings should be.

[Grizz]

I just had a thought...Did you make the pcb from paul's ready to print pcb? Because a couple of the traces were real close and it could be real easy to lay some solder down where you don't want it.

[awitee]

yeh i got it from paul's pdf file, although i checked the traces for shorts nd there seems to be non.. im gonna try chainging some of the parts (ic, caps, resistor) later, if it still wont work, i guess ill have to redo it..
i have a question btw. in the valvecaster, the power was directed at pin 5 whil in shaka the power is at pin 4, same difference? valvecaster is powered by 9v dc btw
EDIT
darn i circled our mall but i cant find any 220vac to 12 vac adaptors... does anyone have a schematic of how i can just make one?

[Grizz]

Could you wire in a transformer like paul did...I think paul did on one of his.

[awitee]

hmm i see, how do i wire that? hehe
still havent figured out why my pedal wont work, ill probably move on to another project till i get a permanent power supply for this, because the only 12vac adaptor in the house is the modem's which i need hahaha

[Grizz]

Where do you live...I just notice you said 220vac to 12vac...if you live in the US I think it's 120vac, or was that a typo.

could you post a picture of the back of the smaller pcd...not the side w/ the components.

[awitee]

haha i live in the philippines so no typo there

[Paul Marossy]

My only suggestion is to make sure that you have all of the grounds connected together.

You'll have the following things connecting to ground via wires for it to work correctly:

1. Pin 5 of preamp tube
2. Input jack
3. Output jack
4. Power section PCB
5. One side of 12VAC power from wall wart
6. Ground connections on main PCB

You should have continuity between all of these ground connections. If you are missing one somewhere, it won't work correctly.

Also, 12VAC should be going to Pin 4 of the preamp tube and the power section PCB only.

[awitee]

yep cheked it..
so i guess its probably a broken component.. hm dang it haha
anyway ill probably redo this when i get my hands on a 12vac adapter so its easier to test without using the one from the modem hehe

[Grizz]

I can't tell a whole lot from your pictures because they're kind of blurry but some of your solders look suspicious and what are those holes in the upper right hand corner?

[Paul Marossy]

Those holes at the upper right hand corner would be where the 12VAC/ground is connected.

[awitee]

the power pcb is actually workig fine, i can get the right voltages when i measure the wire coming out of v+ v- and bias, bias can get from - to +
im really suspecting the opamp pcb...

[awitee]

whahahaaha finally got it to work
AND I DONT KNOW HOW!!!
i just left it lying for a day, when i tried it again it worked!!!
although im using a 9vac adapter... so im not gonna be able to use it properly until i get a 12vac adapter, but at least it works!!!!
sounds fuzzy with the 9vac haha
and there's something wrong with the gain pot, but ill fix it when i get a permanent power source for it hahaha
i think its the ic, coz im not sure wat ic i used before so i inserted the first one i found when i tested it again hehe that means the first 3 ic'si used before were duds.. what luck haha
thx for the help guys, cant wait to get a 12vac adaptor!

[Paul Marossy]

Well, that's a good sign.