help with Nobleman output very low

[Fish]

Building a Nobels odr-1 for a duel drive with the boteh. Put it on the test board and the output is very weak. Bypass sound is fine. All the knobs work, but it’s a tad sputtery and very low volume. Any suggestions would be greatly appreciated

 

[andrewsrea]

I could not find anything glaring from the pics. I recommend checking and notating the pin voltages on the ICs, FET and Transistor, looking for anomalies (Vref not being in tolerance of half of the Vcc). Then I would throw a 1Khz sine wave into the input and trace it through each stage with an oscilloscope.

 

[Fish]

Thanks for your help. Would this all be done with a multi meter and then an audio probe?

 

[spi]

How legit is the 2n5457?


Also, do you have something protecting the middle pot from contacting the PCB?

 

[Fish]

Just went back and checked the 2n5457 are Tayda so im gonna say they are legit. I didn’t put a dust cover on the middle pot, but it was on a test board and there was plenty of clearance. The freaking thing wants to play i can here it in there its just low and muffled. Thanks for your help

 

[Paradox916]

Did you double check and verify all component values and orientation? If that all checks out audio probe time. Quickest and easiest way to figure out what’s going on.

 

[Fish]

I didn’t check every resistor but all other components are correct. Will an audio probe work in this case since it does produce sound, not like a dead spot in the signal?

 

[spi]

Audio probe is helpful here. Do you have a looper pedal? If so capture a riff and put in on repeat into the pedal. Then start probing. You'll have to start tracing the audio path from the input to the point where it gets weak.

If you don't have a probe they're dirt simple to build.

 

[andrewsrea]

Thanks for your help. Would this all be done with a multi meter and then an audio probe?

Yes. Digital Multi Meter set on DC voltage set to a range higher than 9V. Then you need a signal generator (I use a phone app) into the input and look at the sine wave oscilloscope, which is set to 1ms at .1 V on the AC setting. I check the input and out put of the devices, folloing the schematic.

 

[spi]

Yes. Digital Multi Meter set on DC voltage set to a range higher than 9V. Then you need a signal generator (I use a phone app) into the input and look at the sine wave oscilloscope, which is set to 1ms at .1 V on the AC setting. I check the input and out put of the devices, folloing the schematic.

how do you connect phone to pedal?

I just use audio--no oscilloscope necessary. What oscilloscope do you use?

 

[andrewsrea]

how do you connect phone to pedal?

I just use audio--no oscilloscope necessary. What oscilloscope do you use?

I use a four conductor 1/8" plug into the phone's headphone + mic jack, which terminates to (4) RCA plugs, to which I use an RCA female to 1/4" male adapter. The app I use is called 'PA Tone', is free and will do all the audio frequencies and multiple wave forms, plus pink and white noise. I typically use a 1k sine wave and have the phone volume just before it turns red.

My scope is a Tektronics 453A and a Tema probe with a 1x and 10x switch.

 

[Paradox916]

I didn’t check every resistor

Double check EVERY component… make a habit of troubleshooting thoroughly and it will save you a lot of head scratching down the road when you take on more complex projects and things go sideways.

 

[Fish]

Checked everything but the resistors

 

[Fish]

Audio probe is helpful here. Do you have a looper pedal? If so capture a riff and put in on repeat into the pedal. Then start probing. You'll have to start tracing the audio path from the input to the point where it gets weak.

If you don't have a probe they're dirt simple to build.

I built an audio probe a while back and run music through it with my phone. So it will work in this case, if i look for where the signal gets weak? Is there any certain spots to check or am i hunting and pecking around?

 

[GizzWizzKing]

I built an audio probe a while back and run music through it with my phone. So it will work in this case, if i look for where the signal gets weak? Is there any certain spots to check or am i hunting and pecking around?

Try to follow the signal path in the schematic. It should be pretty straight forward

 

[spi]

Start by measuring at the ins and outs of all the components along this path.
At the start it should pretty much match the input signal--at some point you'll read a point where it doesn't, which will give you more clue as to which part of the circuit is misbehaving.

 

[Fish]

Start by measuring at the ins and outs of all the components along this path.
At the start it should pretty much match the input signal--at some point you'll read a point where it doesn't, which will give you more clue as to which part of the circuit is misbehaving.

View attachment 80602

Thanks im gonna give it a shot

 

[Stickman393]

Checked everything but the resistors

Resistors are important too.

The wrong value in the wrong place could starve an active component of the voltage it needs to operate properly. Or attenuate your signal to hell. Or cause some other strangeness.

An audio probe might help with narrowing down *where* you need to check resistor values.

Then again, maybe there's a voltage divider in the power supply that has the wrong values, and you'd have to know the shorthand for common connection points throughout the circuit. Inset portions of the schematic for the power supply, etc.

I just write a list of each resistor in the circuit and write down the color code. Then, translate the code to ohms. Then, check against the BOM.

OR, protip, start using vishay dale RN55s and CMF55s. Those have got numerical values directly on the component.

Granted, they're a little pricier than tayda resistors.