Build Your Own Clone Message Board

Hi.

So, I thought I was man enough to make the Vibrato.

Here I am with my tail between my legs.

Here are the symptoms:
- bypassed, signal is going through
- effect on, signal is clean. when I fiddle with the 10k trimpot, the signal goes from weak to same as bypassed to distorted
- when I turn the 500k trimpot, the signal wobbles - it sounds like it's kind of working. But only when the trimpot is being adjusted; if I stop turning the screw, the vibratoey goodness stops.
- LED isn't lighting up.

The issues:
- my soldering iron was dying. so I bought a new one. I've been reflowing suspect looking bits. still no luck.
- one of the solder pads broke loose - it seemed to pop back in ok and the part soldered in as normal. I've had a close look and can't for the life of me, remember which component it was. possibly a capacitor.
- i understand how the ramp switch bit works, so that's not the issue.

As everyone else says, apologies for the lowish-light iPhone pics.

Quick question: why is there a wire soldered to the back of that pot? Not needed for grounding...

I was just following the instructions with the ground wire; the jacks etc are plastic, not metal so they don't ground to the chassis.

You have the LED installed backwards.

Can't see enough detail to inspect the quality of your soldering. I personally do not recommend using adjustable wattage irons. I only use fixed wattage irons. A 25W pencil style and a 150W gun for all my soldering needs.

backwards, as in poking out the wrong side of the board, or backwards, as in I have the positive bit in the negative hole?

I'll try turning it around tonight; though to save myself a lot of confusion, I'll 'borrow' a new LED from a friend who has a stash of them.

RE: soldering iron; the iron that died was a 25w iron. The iron itself works, but the tip was corroding like crazy. I can't find spare tips that actually fit.

The new one I bought is one of those stations with a stand and a bit for a sponge. It's adjustable wattage, but is working well for now.

Ok, I turned the LED around.

Now I have light (it works!) but no sound. Bypassed, it works. Effect on, there's no wet or dry signal.

Last night, I re-wired a bit of the switch that looked dodgy and a few joints here and there.

What I failed to do was to remove the IC's from their sockets ... Could this be it?

Ok wait...

I had my guit plugged into 'out' and amp plugged into 'in'.

It's the right way around now, but still no wet signal. As in, with the effect on, sound comes thru, just not vibratoey.

It sounds like most of your pedal is working, but the LFO is not. That's a good thing! You can verify this by measuring voltage at the middle lug of the depth pot. It should go up and down.

Here's a voltage tutorial if you need it: http://www.ladyada.net/learn/multimeter/voltage.html

From having looked at other posts, i knew you were going to say!

Ok, n00b here ... Red probe on middle lug, black probe on negative battery thing...

Depth knob set to zero gives a reading of 4.24

Depth knob on full gives a reading that oscillates between 3.17 and 5.11

Good job; you have an operating LFO. Now we need voltages from the 3207 and 3102, keeping in mind that DIP pinouts are orientated thusly:

This is with battery and guitar lead in, so the LED is on, correct?

3207:
1: 02.3
2: 3.76
3: 3.44
4: 7.15
5: 7.66
6: 3.75
7: 4.74
8: 4.74

3102:
1: 7.71
2: 3.78
3: 01.8
4: 3.78
5: 174.0
6: 7.48
7: 1.984
8: 7.18

3207 pin1 and 3102 pin3 and pin5 should be zero or close to it. Please recheck those, check that your meter is not reading millivolts on those. Also, check that 3102 pin7 is oscillating.

Ok. Meter is reading in mV for those pins.

3102 pin 7 is not oscillating.

Adjust the nearby trim pot to see if you can get pin 7 to oscillate. Also, remove/reinsert the 6110 and triple check it is in the right way.

I'll have to try that later in the day; I'm off sick for most of the day but have some things to get done.

For the 6110, the end with the little indent goes in the spot with the square on the component side of the board? Is that indicating Pin 1? Would I fry it if I turned it around the other way to see if it works that way?

Correct


I'm not sure. Go ahead and get voltages from all the 6110 pins and I'll compare to mine tomorrow.

I tried getting a reading from pin 7 whilst fiddling with the trimpot … it was a challenge with only 2 hands. It's oscillated very very slightly, and only while the trimpot is being turned.

6110 chip:
1: 4.24
2: 4.18
3: 47mV (I think - the first time I tested this one, it was oscillating really really slowly. Can't remember the #'s, didn't write them down, sorry. I went to, so tested it again; no oscillation)
EDIT: i tested again. It starts off really low (negative mV) and gradually rises. If i take the probe off then back on, it seem to start over again.
4: 1.160
5: 01.5mV
6: oscillating: 4.1 - 4.5
7: oscillating: 4.1 - 4.5
8: oscillating: 4.1 - 4.3
9: 8.37

Okay, things are looking good with the 6110. It's looking like your problem should be between the 6110 and the 3102.

Take voltage readings from the following components:
R37, Q6, D3, R32, VR4, D2, R33, Q5, R34 - these components all massage the voltage coming from the 6110, feeding the 3102.

Here is what I have (OSC = voltage is oscillating to some degree):

R37 - OSC
Q6 (top to bottom) - OSC/8.2/OSC (lower voltage than the top leg)
D3 - OSC
R32 - OSC
VR4 - 8.2 on left side, OSC about 3.4 - 3.6 on right side
D2 - OSC 2.5-2.3 non stripped side/OSC 7.6-7.7 stripped side
R33 - 8.2 top/7.7 w/low OSC bottom
Q5 (left to right) - 0.2 w/low OSC/7.7/0
R34 - 0.16w/low OSC top/0.21 w/low OSC bottom

Try to find something that does not match these readings, exam the value of the component, and resolder the connection (and surrounding connections) to rule out a cold joint.

Here are my results. I've been touching up suspect looking joints, and still no luck.

R37: slight osc
Q6: top -51.4mV
Middle 7.59, slight osc
Bottom wild osc.
D3: not osc. 1.920
R32: osc
VR4: left 7.57
Right 3.1 not osc
D2: non striped 1.915
Striped 7.19 niether side osc
R33: 7.55 top
7.18 bottom. Not osc.
Q5: 166.2mV left
7.16v mid
02.1mV right
R34: 120.1mV top. Not osc.
166.5mV bottom. Not osc.

I've been touching up lots of joints over the last few hours. I've re made the connections for the ramp switch, which looked like it was breaking. Every solder joint I can see looks shiny.

I'm anxious about the joints under the jacks now, but it looks like a massive effort to get them out to have a look.

It's still only oscillating when I turn the screw in the trimpot.

Q6 is off. The top is the emitter, the middle the collector, and the bottom is the base. The emitter voltage is off; I measure a slow oscillation in the 3 volt range on mine (about 2.9 volts up to 4 or so). Make sure that transistor is a C945. Measure continuity; you should have it from the emitter to the bottom of R36 and from the base to the bottom of R37. Tough up all of those solder joints; even if you have before. Make sure iron tip is clean, shiny, and hot, and add a little bit of solder if there isn't too much already.

Here is a continuity tutorial if you need it: http://www.ladyada.net/learn/multimeter/continuity.html

Q6 you say? The lug that i listed as osc wildly showed OL on the screen, which I've now learnt means open loop or no continuity.

Q6 says C945 and has 3 very shiny solder joints.

Following the traces to and from the bottom leg, there is no continuity. The middle and top legs are fine.

Edit: now that I look really closely, the joint from the .047 film cap to that leg of Q6 is the one where the solder pad broke loose. Should I run another lead between them?

Meant to include this with that last post:

Yes, that will screw it up. You need to ensure that the top end of C21 (the .047 cap) connects to both the base (bottom lead) of C6 and the bottom of R37. Measure continuity to see if all 3 are connected to each other.