YJM DOD 308 problem

[spinninfred]

Hi Guys!

After some years of playing the guitar I thought I should use stompboxes instead of my pocket pod. I thought it's kind of a challenge, and a good way to save money, to build pedals. My first one is the YJM DOD 308 (cause I like Malmsteens tone). I've found some schematic on the internet, pcb, and layout. So I decided to buy every component and try to build it at home. I printed the circuit soldered everything, and it didn't work. I have not much knowledhe in this area so all I can tell is that the circuit is ok, soldering is ok, checked everywhere, and if I turn gain to 0, my amp beeps like when I am standing too close with the guitar. Could you advise something I can do with this thing?

My work is based on these: http://fuzzcentral.ssguitar.com/schematics/YJM308.gif
http://fuzzcentral.ssguitar.com/pcbs/yjmpcb.gif
http://fuzzcentral.ssguitar.com/pcbs/yjmlayout.gif

[deadastronaut]

hi spin

i made a verified vero layout of the 308 a little while back if you want it,

i'm not at home at the moment but i will post it up for you if you wish later.
this demo isn't through an amp, so it doesn't do it proper justice...

into clean marshall...
i think renegadrian also did a vero of it too...take a look in the gallery.


http://www.youtube.com/watch?v=0ZC2hMqzOM4

[spinninfred]

thank you, I would appreciate that.

And anyway I forgot to mention that I have a 22pF capacitor instead of 25pF.

[deadastronaut]

no problem...use it.

[Kipper4]

Can you post some pictures of the board Spin?
Componant side and trace side please so we can try to help you more.
Welcome to the forum by the way.

[spinninfred]

Can you post some pictures of the board Spin?
Componant side and trace side please so we can try to help you more.
Welcome to the forum by the way.

Thank you! Unfortunately I have just this crappy phone at home, I tried my best. The green cable that can be seen on both sides is from the + side of the 4,7uF capacitor, I missed one hole to drill. The component side is from the angle of the layout pic I linked in my first post. The IC is soldered thru those cables because I have forgotten to buy IC panels and I was afraid of melting the IC while soldering on the board (mainly because I have almost no experience in soldering). The darkgreen capacitors are 1nF, the brown electrolite capacitor is the 4,7uF one and the other is the 10uF cap. It's a bit hard to see but the cables on the upper left side of the pcb (component side) are into different holes, one of them is the input, and the other is the ground.
Anyway the whole thing is connected to a DPDT switch which works fine in bypass mode.

[Kipper4]

Have you got a multimeter to check for continuity and bridges?
You componants are a ways of the board. Which improves the chances of bridges (componants shorting)
The solder looks a bit blobby. That's not the best photo too.
Fortunately this is a quite simple circuit so hopefully we can help.
Tip I use a small screwdriver tip to bend the leads on resistors and fit as close to the board as possible.
Ic sockets are a good idea too as you know. It's easier to replace the ic in a socket and lessens the chances of frying them when soldering.
It might be a good idea to make an audio probe too. It's a fantastic debugging tool. Google it.
Do some continuity testing , do some bridge testing and see if you find anything.
Also if you can post some voltages from the ic pins it might help us.

[Kipper4]

You may also find this intresting.

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[deadastronaut]

hi spin:

as promised, 4 cuts under chip...and 2 other cuts. ...try 4558/1458 ic's.

this is verified ok, you should use a reverse log pot...but i didn't have one...merry xmas.

[spinninfred]

Hi guys, thanks for the replies, and the layout!

Unfortunately I don't have a multimeter, but one of my friends who has brought it 2 days ago so we checked the board and (which makes me feel stupid) everything is ok, he's even learning eletronic stuff for four and a half years now and did not find any problem, the multimeter beeps where it needs to beep and doesn't beep where it doesn't need... His only question was if it was a working schematic or not, but as I can see, Deadastronaut did his layout based on the same schem. After all I can only think 2 things, 1 is that the IC is burnt out, what I doubt, because we could measure 9-10 Volts on it, the other is that some of the components are wrong. We didn't examine resistors or capacitors, the electrolite caps are soldered well from the beginning. Should I try to change the components? I have a few because I planned to build a tubescreamer too, and these have some parts in common.

Things look like this, once more: I plug my guitar into the input jack, the output jack is into my pocket pod and that's into the amp. If I switch, the bypass mode turns on, and everything works fine. If I turn on the effect, there is just the basic electronic hum, what is coming from the speakers. If I turn the gain pot to zero, the amp starts to beep on a very high frequency. I looked at the schem and I see that the IC is from 2 equal component, and one of the 2 is unused basically. If I solder the tree cables to the otherside, to see if it works, should it work, right? I mean , can I left the other 3 legs of the IC free? (I am aware of that 2 legs are the + and - current)

[spinninfred]

Oh, and Merry Christmas to you all, too!

[spinninfred]

Oh guys, I replaced some of the capacitors and now it's working!!! Wow

But I noticed that if I turn gain to max (I've written it wrong in my past replies, the gain knob beeped on max), it beeps, but just on the very end, like on the last 5% turning of the knob. But I want to use it on max gain because anyway it's not that powerful I wanted. Maybe I'm just a blind Malmsteen fan

Well thanks for all your help, and if you have any advice in connection with this gain problem (or which pedal should I try to build) please write a reply.

Merry Christmas!

[deadastronaut]

cool, so did you make the layout above i posted?..

did you use a sheilded input cable?..

[spinninfred]

nope, the pcb was basically the same. One of the capacitors were wrong I guess.

Yes I do, and I'm thinking of shielding the whole thing. Hope it will be fine.