Soldado / Active EQ from PCB Guitar Mania

[joelorigo]

I finished the Soldado & Active EQ combo from PCB Guitar Mania. The Treble pot acts more like a volume control with a really loud spot in the rotation. The Level control gets louder then quieter then louder again as it is rotated clockwise. In the attached video I have the Presence & Volume trimmers on the EQ board backed off a bit from full. (The Character trimmer was omitted & jumpered, and the 2 LEDs omitted with an added 1M resistor for one, as I didn't want/need any extra gain, based on advice from the Facebook PCB Guitar Mania group.)

 

[joelorigo]

Hi, just bumping this to the top

 

[PJS]

What voltages do you have on your IC pins?

 

[joelorigo]

Measuring IC pins is something I have never done. I am looking up how to do that now.

 

[joelorigo]

I found an instructional video on YouTube. Here are the reading I get:
The 14 pin IC on the Soldado PCB:
1 4.72
2 4.71
3 2.98
4 9.34
5 2.42
6 4.69
7 4.69
8 4.68
9 4.69
10 2.91
11 0
12 3.49
13 4.69
14 4.69

Active Q PCB:
IC1
1 2.87
2 2.87
3 2.83
4 0
5 .82
6 1.36
7 1.44
8 9.56

IC2
1 1.44
2 .98
3 .97
4 0
5 4.95
6 5.01
7 5.01
8 9.56

 

[PJS]

IC1 on the EQ board - what sort of voltage variation to you get with changes in the bass/mid/treble pots?

 

[joelorigo]

The above measurements were with the pots at noon.

Dropping them all the way down
1 2.86
2 2.86
3 2.83
4 0
5 .85
6 1.35
7 1.44
8 9.56

Turning them all the way up
1 3.25
2 3.25
3 3.20
4 0
5 .8
6 2.07
7 2.07
8 9.56

 

[PJS]

I'm out. That all looks about what I would expect. The only other thing I would check would be to actually measure the resistance of the 2 pots that are behaving badly and check for smooth changes in resistance across the travel. They are both specified as linear pots, so you should get a nice linear increase in resistance as the pot is rotated

 

[joelorigo]

Ok, thanks for your help!

Am I measuring the 2 outer lugs of the pot? Pedal plugged in? Knobs up and down readings?

 

[TGP39]

The two outer lugs of the pot will always remain constant. Say you are measuring a 100K linear pot. The two outer lugs will always show approx 100kohm. What you need to do is measure the wiper (middle lug) with lug 1. At 20% rotation, it should measure approx 20kohm. At 40% rotation approx 40kohm, etc.
The pedal does not need to be plugged in.

Steve.

 

[TGP39]

I took a look at the schematic over at the other website. What made you omit the character trimmer? You have the trimmer jumpered from pin 2 to pin 3, but the circuit leading to pin 1 is left hanging. I believe this may be the source of your problems. I would replace the green jumper with the appropriate trimmer in there and see if that fixes your issues. Best of luck,

Steve.

 

[joelorigo]

I took a look at the schematic over at the other website. What made you omit the character trimmer? You have the trimmer jumpered from pin 2 to pin 3, but the circuit leading to pin 1 is left hanging. I believe this may be the source of your problems. I would replace the green jumper with the appropriate trimmer in there and see if that fixes your issues. Best of luck,

Steve.

Thank you! Yes, I was advised by a post on the PCB Guitar Maina Facebook group by someone who paired the Soldado with the Active EQ that the LEDs didn't do anything and if I didn't need the additional clipping stage to omit the trimmer, jumper 2 & 3, omit the LEDs and add a high value resistor to LED1 or LED2. Currently there is a 1M in D1. Since I was going to first try the Soldado as a stand alone unit I thought I didn't need any extra clipping that the EQ circuit would add.

Anyway, I will pull the jumper and add the trimmer, but do you think I should also pull the resistor and put the LEDs in?

 

[joelorigo]

The two outer lugs of the pot will always remain constant. Say you are measuring a 100K linear pot. The two outer lugs will always show approx 100kohm. What you need to do is measure the wiper (middle lug) with lug 1. At 20% rotation, it should measure approx 20kohm. At 40% rotation approx 40kohm, etc.
The pedal does not need to be plugged in.

Steve.

I'm out. That all looks about what I would expect. The only other thing I would check would be to actually measure the resistance of the 2 pots that are behaving badly and check for smooth changes in resistance across the travel. They are both specified as linear pots, so you should get a nice linear increase in resistance as the pot is rotated

The seem normal. Around 100 all the way up, around 50 at about 12 o'clock, and 0 all the way down.

 

[TGP39]

Thank you! Yes, I was advised by a post on the PCB Guitar Maina Facebook group by someone who paired the Soldado with the Active EQ that the LEDs didn't do anything and if I didn't need the additional clipping stage to omit the trimmer, jumper 2 & 3, omit the LEDs and add a high value resistor to LED1 or LED2. Currently there is a 1M in D1. Since I was going to first try the Soldado as a stand alone unit I thought I didn't need any extra clipping that the EQ circuit would add.

Anyway, I will pull the jumper and add the trimmer, but do you think I should also pull the resistor and put the LEDs in?

Try installing the trimmer first. Then go from there based on your results.

 

[PJS]

If reconnecting the character circuit doesn't work then I am going to suggest disconnecting the EQ board completely, and focussing on one thing at a time. You seem to have problems on both boards (the level control you are talking about is on the preamp board yes?). I am a bit surprised that they have specified a linear pot for this control - I would have expected to see an audio taper pot here. Either way you shouldn't be getting a rise in volume then a drop. A linear taper might give you a slow rise then a sudden jump though. I wold expect audio taper to give a smoother rise through the pot travel.

 

[joelorigo]

If reconnecting the character circuit doesn't work then I am going to suggest disconnecting the EQ board completely, and focussing on one thing at a time. You seem to have problems on both boards (the level control you are talking about is on the preamp board yes?). I am a bit surprised that they have specified a linear pot for this control - I would have expected to see an audio taper pot here. Either way you shouldn't be getting a rise in volume then a drop. A linear taper might give you a slow rise then a sudden jump though. I wold expect audio taper to give a smoother rise through the pot travel.

OK, thank you! Yes each one of the pots in question are on a separate PCB.

 

[joelorigo]

Pulling the jumper and adding the trimmer didn't change the issues with the 2 pots.

 

[joelorigo]

If reconnecting the character circuit doesn't work then I am going to suggest disconnecting the EQ board completely, and focussing on one thing at a time. You seem to have problems on both boards (the level control you are talking about is on the preamp board yes?). I am a bit surprised that they have specified a linear pot for this control - I would have expected to see an audio taper pot here. Either way you shouldn't be getting a rise in volume then a drop. A linear taper might give you a slow rise then a sudden jump though. I wold expect audio taper to give a smoother rise through the pot travel.

I guess I will take our suggestion and try them one at time.

I have only followed a clearly laid out wiring diagram (BYOC Aion, PedalPBC. etc.), so just to confirm, this wiring looks good for the Soldado PCB, yes?

 

[PJS]

That looks right to me

 

[joelorigo]

That looks right to me

Thank you