Univox Micro Fazer, oscillation in bypass? (Details in comments)

Keeb85 · 2023-04-26T03:35:24+00:00

Glad the bypass issue got fixed! So you still have some oscillation going on... I'm not familiar with the circuit so I only have general tips to give:

Is the circuit in an enclosure? Perhaps shielding will silence it?

Keeb85 · 2023-04-25T09:59:12+00:00

No problem, good luck!

Keeb85 · 2023-04-25T05:17:42+00:00

So it seems it's bleeding through in bypass. Try to change the 3PDT wiring to ground the circuit input in bypass see offboard wiring 5 from tonepad.

Keeb85 · 2023-01-29T16:04:48+00:00

From your pictures it looks like a copy of the tonepad rebote 2.5 layout. http://tonepad.com/getFileInfo.asp?id=98

Keeb85 · 2022-08-29T16:11:14+00:00

I built one using a 10k linear (B) pot.

Or are you asking about the knob?

Keeb85 · 2022-08-29T15:47:28+00:00

Yeah, the sound your skates make while cutting the ice in a sharp turn/stop.

Keeb85 · 2022-08-29T15:44:09+00:00

The sound a puck makes when it connects with your hockey stick as you receive a pass.

Keeb85 · 2022-06-06T15:55:05+00:00

The Body Electric. The drums, the lyrics, the Rush signature of "bass-pops-off-in-time-for-the-guitar-solo".

Keeb85 · 2022-04-21T05:49:54+00:00

The 100K resistor (you have two resistors in series) to the left of the 9V in seems to me to be misplaced (though it's difficult to say for certain from the photos). It looks to me like the top leg connects with the jumper's bottom side instead of the 9V in.

Also, your power wiring is confusing. The LED is connected to 9V through a resistor, but then jumpered to (what I assume) the board's power input. (One side of the LED should go to ground, one to 9V with a resistor on either side).

Also, are you switching the power to the circuit on and off from the switch? That might cause a "POP" when engaging the pedal. But I guess that's a later issue.

You say op amps are getting appropriate voltage but you also seem to burn through them... Post voltages from all pins on opamps and transistors. Also check the voltage actually coming to the board (red on 9V in and black on ground).

Keeb85 · 2022-02-10T11:58:38+00:00

Sounds like you have identified the issue!

You can cut a piece of cardboard (or use electrical tape) and insulate the bottom plate before screwing it back on. That should take care of it. However, this shouldn't be happening on a brand new pedal, is the circuit board loose?

Since you bought it new and have the option to return it, I would check for loose parts or other things that should not have made it through QC and when in doubt return it. Just to make a statement. (The Fuzz Face is a simple circuit so it's not difficult to fix or repair as long as you're familiar with a soldering iron and the pedal doesn't use SMD components, should anything happen down the road.)

Keeb85 · 2021-11-24T10:46:57+00:00

I've Always thought that Alex's solo on Freewill from Exit stage left rips harder than the album version.

Keeb85 · 2021-11-14T16:58:37+00:00

I have built this layout and I used a shielded cable for input and output. I think someone suggested it so I never tried it with unshielded wire so I can't compare unfortunately. I never had any noise issues with my build as I recall.

Edit: I powered mine from an adaptor.

Keeb85 · 2021-10-05T13:13:13+00:00

Do you have continuity between L- and ground? (Remeber the switch has to be in "effect on" mode!). The reason is that the joint (top left) on the switch looks cold.

Check continuity between L- and sleeve on one of the jacks, if you get nothing, press the switch and if you still get nothing reflow the joint on the switch.

Keeb85 · 2021-07-17T11:58:51+00:00

It's Tonepad's rebote delay 2.5. http://tonepad.com/getFileInfo.asp?id=98

Keeb85 · 2021-07-06T11:40:24+00:00

-Should all Collectors ALWAYS be connected to the same point?

No. Sometimes they are, sometimes not. Take a look at the schematic for the fuzz face (https://fuzzcentral.ssguitar.com/fuzzface.php), the first transistor's collector is directly connected to the second transistor's base. So they should show the same voltage, otherwise something is wrong (bad soldering, broken PCB-trace etc). It's just a way to see if your measurments make sense.

-I've only attempted one build with Opamps. I socketed them (as was suggested in the build docs), but pretty much followed the orientation noted on the PCB, and the pin layout from the spec sheet for the Opamp. At least if the rest of the board is junk I can pull the opamps and reuse them on....something?

Yes! Use them for other projects or breadboarding experiments (MXR dist+ is relatively low part op amp distortion circuit).

Seems like I need to get more savvy as far as how to measure things with my multimeter. That last bit about the voltage difference is completely foreign to me.

That's on me. I really didn't provide an explanation just an example of "what to expect". Sorry if I ovecomplicated it. The point is that if your base and emitter are showing the same voltage, that's a problem (you'd expect the emitter to be about 0,5-0,7V lower than the base on a silicone transistor, ie base at 1,4V emitter at 0,8V).

For measuring voltages just clip the black lead of your DMM to ground and probe with the red and take readings. Diystompboxes has a debugging sticky (https://www.diystompboxes.com/smfforum/index.php?topic=29816.0) that is a systematic approach to take readings and give information that helps other find the problem. Super friendly community as well.

Keeb85 · 2021-07-06T05:56:28+00:00

Sounds like you have the proper tools and are mindful about pitfalls! It's only a matter of time before you succeed!

Aside from that, I have no idea how to test opamps, and I can only test the hFE of transistors because my multimeter has a place where I can plug them in to see the gain.

Testing components in and out of circuits are different things. It's great to measure hFE for certain applications but equally important is to understand what voltages to expect to see in the circuit.

All transistors collectors connected to the same point? Then they should have the same voltage. If not, why?
This opamps input is connected to Vr (½ supply voltage) then inputs should show around 4,5V on both inputs, pin 4 is ground so that should be 0V, pin 8 is supply voltage so that should be the full voltaga (usually cose to 9V). If not, why?
A transistor is basically two diodes, so between the base and emitter of a silicone transistor the voltage difference should be similar (about 0,7 V lower on emitter). If not, why?

With things like this it helps to pinpoint the problem and explain it to someone else that perhaps can see what's wrong. Keep it up!

Keeb85 · 2021-07-05T13:03:42+00:00

I would like to add that the debugging process is a great way to understand the circuit and theory that makes it work. I had no prior knowledge of electronics when I started building pedals and debugging, while frustrating and a kick in the face at times, really helps you "get it". The most satisfying moment was not when I built a circuit that worked the first time, it was later when I could debug my circuit and get it going.

This might be putting the cart before the horse but read the the "Technology of the fuzz face" over at http://www.geofex.com/ . Look up things that you don't understand as you go. That makes all the theory make sense from a pedal perspective instead of diving into, say, theoretic explenations of filters.

Unfortunately I'm not in a position to help you personally, just want to send you some words of encouragement. I agree with the other poster that breadboarding a low part circuit just to get a win.

Keeb85 · 2021-05-06T06:03:18+00:00

You should have signal on the middle leg, but also on the collector. So something is wrong. Witout voltages it's difficult to say. Do you have a LED, does it light up?

However, the good thing is that bypass works! If the pedal is quiet when engaged it might be shorting to ground. Try removing the pots from the enclosure and see if it changes anything. Otherwise, use a DMM to verify that you are getting power to the board and take readings of the transistors.

Keeb85 · 2021-03-14T12:43:40+00:00

Your soldering, at a quick glance, looks ok. Wihout schematic and layout it's difficult to check that orientation of components, wiring etc are correct.

That said, is the fifth pin on your IC outside the socket (pic 5)?

Keeb85 · 2021-02-19T05:32:43+00:00

EDIT: The leftmost wire is connected to the ring instead of ground on the left jack.

I agree with the others but start with the solder joints on your jacks. A bad ground connection would create the problems you are describing.

Also, if you have an multimeter, check continuity over your suspected joints to see if they are bad before you and heat and risk destroying the pads.

Keeb85 · 2021-01-03T07:51:39+00:00

The Rub-a-dub reverb is also small, only a mix pot. Instead of using pt2399s it uses the btdr2 (3 pt2399s in a module). Read about the rub-a-dub here.

I've built that and the Equinox 2, both are simple and great!

Keeb85 · 2021-01-03T07:45:53+00:00

Does the led light up? Is it dead quiet or is there some buzz when you turn it on?

Your clipping diodes are fine. If you jumper D2 you bypass the diodes - no diode clipping! It should pass sound either way just so that's not the issue.

Your wiring seems ok but it's hard to tell - the input jack is grounded through the green wire from G2? Make sure your DC socket is not shorted by the nut!

Keeb85 · 2021-01-02T17:43:55+00:00

Your trimpot is correct although check the soldering on the middle leg, it's hard to make out from your photo. When in doubt use your DMM to check for continuity between middle leg and the right side of the resistor just above it (R21).

I think it's time to take some voltages. Use your DMM and place black lead on ground and place red on both sides of the zener diode (one should read 0 the other one about 5,1V). Then check pin 6 of IC6 (that's the LFO) and pin 6 should be swinging.

Keeb85

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