Tonepad's Ross Phaser

[Impaler]

I have yet to get this thing working... I pnp'd the pcb and had no bad traces, populated the board with all new parts, checked my soldering for bleeding joints, checked and checked and rechecked all my connections... still, no go. When the effect is on, all I get is a boosted clean sound. If I turn the regen pot up, I get a buzz at the extreme right. I'm frustrated because I have checked and rechecked this board 30 times now and everything looks kosher... Any ideas?

[Mark Hammer]

I experienced the same damn thing.  Made another board, populated it, and it worked perfectly.  Made *another* board and that worked perfectly too.  Maybe you"ll have the same good luck I did.  (I hope I continue to.  I have a dual board with a Univibe configuration on one and a phasefilter on the other.  I setting up a switch so that they can each have their own LFO or be slaved to the same one.)

Francisco's layout are good, but they are tight.  Sometimes, even if you use PnP to make the board, it can be helpful to go over some of the pads with a pen and make them a little bigger in diameter.  I don't know about you, but between my bad aim with the drill press, and the way ferric chloride can eat away at the sides of pads/traces when you get distracted and leave the board in too long, sometimes what can LOOK like a reasonable solder joint ends up being nothing of the sort.  I also find it useful to buff up the copper nicely with fine steel wool, wipe some liquid flux on with a Q-tip and tin the board before populating it.  There are easier ways to do it, but this seems to assure that I don't bugger up any pads with finger juice and end up with "pretend joints".

[Impaler]

I have gone through every solder joint and re-heated them, and with my DMM, checked continuity from one end to the other stopping at each joint along the way. I've checked for shorts, bad wires (lord knows i've had a few of those over the years.) I even checked the switch for defects. Changed out the op-amp and still nothing... I'm not bald but this project  might make me bald...

As far as pads, I wound up drilling them with a Radioshack 1/16 bit because SOMEONE fergot to send my #60's (*cough* Steve *cough  :wink: )  so I did more of a point to point thing with my soldering. With those pads, drilling with a 1/16" bit will leave almost NOTHING for a pad so don't do it kiddies! =P

[Mark Hammer]

You can heat, reheat, and re-reheat joints all you want, but if the component is corroded or is sitting in the middle of a too-big hole over a tarnished pad, you're not going to get the  conductivity the circuit expects.

I used to reuse parts a lot more than I do now, and I'm finding I'm a little more successful with projects now that I use new parts and make sure my boards have nothing that will stand in the way of good connections.

And yeah, a 1/16th bit is probably not the ideal for that board.

Finally, note that LM13600s fry if you feed the Iabc pin too much current (and I understand that something like 2ma is "too much" current).  I'm not sure what the current coming from that 10k resistor on the output of the LFO is, but the amount of sweep the unit provides seems pretty close to max.  Possible you fried one?

[Impaler]

dunno, guess i'll order at least 3 more 13600's and redo the board. I have the right bits now, so hopefully it'll werk out... is there any way to check the 13600's to see if they are fried?