Egodriver Problem

[madbean]

Well, I can't really read the markings on the transistors, so I can't say much there.

I wonder if the long pins you've used to connect the pots might have lifted some solder pads through downward pressure. Phew, this is kind of a tough one!

[jkokura]

The markings made me think STI, but I couldn't find any details by googling. Not a symbol I recognize. If might be worth spinning them, but I'm also aware that flipping mosfets as clipping diodes doesn't seem to make a difference in some circumstances, so pinout shouldn't matter - right?!?

Yes this is a tough one. Immensely discouraging. I keep encouraging to leave this for a while and do something else for a while. Come back to it, and then start over. Sometimes what really needs to happen is to start over on something fresh. I've said it before, but only ONE board has ever defeated me. Some things was wrong with the traces, and that was a hand etched board. New board with the same components and it worked fine. I don't think thats' the case here, because the board is manufactured and the voltages seem pretty much correct.

One thing I've noticed a couple times is that your ground doesn't actually read 0 volts. It's sometimes only 1mv, but that's still not how ground should be acting. Perhaps as you turn the pot up and down somehow voltage is leaking to ground? The fact that it's oscillating may also indicated that something is going in cycles, which has to be driven by the IC or by a transistor, still pointing to a faulty IC for me.

Here's what I suggest. A couple shots you've give us has shown the board in an enclosure. I assume that you've got it hooked up to a switch and stuff, so I suggest that you pull the board out of the enclosure and eliminate the switch (you may already have). Just hook up the pots and the DC, and use a battery if you haven't been already. I know your power supply is a good one, but a battery just plain eliminates the powersupply from being the issue at all (It's good practice to use a battery to test ALL your pedals first).

If it works outside of the enclosure then we're one step closer. If it doesn't, it's easier to trouble shoot it outside of the enclosure.

Jacob

[Haberdasher]

Those trannies look like this to me.

[jkokura]

Possible.

Jacob

[petesz]

Just a suggestion, but i notice you havn't used a socket for your transistors. Maybe you fried them a bit when soldering them in?

[jkokura]

Not according to the voltages.

Jacob

[madbean]

Hey tenner...I can hook you up with another Ego board if you want to give it another go. You've tried really hard on this one, and you should be rewarded with a working pedal, after all. If you feel up to it, let me know.

[tenwatt]

Hey tenner...I can hook you up with another Ego board if you want to give it another go. You've tried really hard on this one, and you should be rewarded with a working pedal, after all. If you feel up to it, let me know.

Wow!  Thanx!  I'll likely take you up on that.  I built Jacob's testing rig last night and first made sure I was getting 9V out of the rig.  I was getting 9.25V so that was good.  I then desoldered my board from the switch and ran some new leads from the "IN", "GND", "9V, and "OUT" pads.  Hooked it up to the testing rig...nothing.  Put my DMM on the 9V pad and got 9.25V.  Tested R12....nothing.  Measured the resistance of R12 and got pretty close to 4.7k.  I'll sit down and measure everything on the board tonight...this thing's not going to beat me.

*EDIT* The Egodriver has a "SW" pad for the switch.  Would that have to be hooked up to the testing rig to test it properly?  Currently, I didn't hook it up.  I just thought of that.

[jkokura]

The SW pad is for the LED. Basically, what happens there is that R12 works as a current limiting resistor for your LED indicator. It helps to have that CLR mounted on the board so you don't have to have one free floating in your enclosure. You only need the SW to connect to your switch to turn the LED on and off. R12 is not in the circuit at all, it's just for the LED.

What's interesting is that you have power at the 9V in pad on your PCB, but not after that. What's it like at R13? You should have 9.25v at the side closest to the 9V in pad, and a little bit less than that on the other side. It may be that there is a problem that has arisen because of the unsoldering process.

Jacob

[tenwatt]

What's it like at R13? You should have 9.25v at the side closest to the 9V in pad, and a little bit less than that on the other side.

I'll check as soon as I'm home.  I can't remember off the top of my head.  I know that I measured a LOT of the componants and the majority was going haywire.

It may be that there is a problem that has arisen because of the unsoldering process..

That's kinda what I'm afriad of.  Everything looks clean with no burns or anything but that was my first time desoldering a board.  Shoot, it was only my second time to solder a board so the odds that I screwed up aren't to slim.

[tenwatt]

Yeah....R13 is dead as a doornail.  Here are some pics so you can see I didn't fry it:

[tenwatt]

Any other ideas?

[jkokura]

Ok, You should be getting the same voltage at the 9V in pad, and the pads for R12 and R13 that connect straight to the 9V in pad. If you're not, then you need to either resolder the pads or change a resistor out. Sorry Jeremy, that's all that there is at this point. You have to be getting voltage past R13 for anything to work. If you take a look at the schematic, you'll see that R13 is inline with the 9V in pad on it's way to powering everything else.

Jacob

[tenwatt]

I redid the IN, OUT, 9V, and GND connections and it's working again.  Here are the current readings:

R1 - 0mV/0mV
R2 - 4.26V/4.26V
R3 - 4.46V/4.26V
R4 - 0mV/0mV
R5 - 4.46V/4.46V
R6 - 4.46V/4.46V
R7 - 4.46V/4.46V
R8 - 0mV/0mV
R9 - 4.46V/4.46V
R10 - .7mV/.7mV
R11 - .6mV/.6mV
R12 - 9.25V/9.25V
R13 - 9.25V/8.85V
R14 - 8.85V/4.46V
R15 - 4.46V/0mV

C1 - 4.26V/0mV
C2 - 4.46V/4.46V
C3 - 4.26V/0mV
C4 - 4.46V/4.46V
C5 - 4.46V/4.46V
C6 - 4.46V/0mV
C7 - 4.46V/0mV
C8 - .3mV/0mV
C9 - 8.85V/0mV
C10 - 4.46V/0mV
C11 - 8.85V/0mV

D1 - 4.46V/4.46V
D2 - 8.85V/0mV

Q1 - 4.46V/4.46V/4.46V
Q1 - 4.46V/4.46V/4.46V


IC:

1 - 4.46V
2 - 4.46V
3 - 4.26V
4 - 0mV
5 - 4.46V
6 - 4.46V
7 - 4.46V
8 - 8.85V

VOL:

1 - 0mV
2 - .2mV
3 - .2mV

TONE:

1 - 0
2 - 0
3 - 0

GAIN:

1 - 4.31V
2 - 4.46V
3 - 4.46V

HP/LP:

.3mV/.3mV

Thanx again for helping so much and dealing with my ignorance.

[tenwatt]

So I don't how the voltages I put in the last post (one above this one) look compared to what they should be but I assume that the ones with low or no voltage are potintial problems?