Help me troubleshoot Barton Bytewise Operator

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wendallsan
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Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Sun Jul 26, 2020 11:18 am

Hi all,

I have a Barton Bytwise Operator + Expander that needs some troubleshooting. It is not putting anything out on the +5V output when I feed it voltages into the X IN and Y IN with the X and Y offsets set to various positions and the switches and buttons in various positions. This is a tricky one, as I know what to expect to some extent for an oscillator or a filter or amp ... but I'm really not even quite sure what to expect from this thing when it IS working. I'm guessing that there should be SOMETHING coming out of the +5V output though, if things are working.

I'm just trying to troubleshoot the main board for now, and will look at the expander board once I'm confident that the main board is working as advertised. I've included voltage readings from the 3 IC's below as well as some pics of the board and wiring. I'm terrible at off-board wiring, but am fairly confident that I've properly aped the wiring guide provided in the build instructions.

Let me know what I should try next to troubleshoot this module! I'm happy to provide whatever measurements or other details needed, just ask.

Board front
Board back
Offboard wiring

Here are the voltage readings of the 3 IC's on the board with no signal being fed to the X or Y IN, and the X and Y Offset pots set to a far left position:

16F685
1 4.97
2 1.82
3 2.65
4 0.30
5 0
6 0
7 0
8 0
9 2.53
10 4.93
11 4.98
12 4.57
13 0
14 1.25
15 2.27
16 1.78
17 5.15
18 1.72
19 1.42
20 0

Upper TL074
1 0.82
2 0.82
3 0.75
4 11.61
5 4.98
6 0.05
7 10.97
8 10.97
9 0.05
10 4.58
11 -11.61
12 0.75
13 0.82
14 -3.33

Lower TL074
1 -4.67
2 0
3 0
4 11.91
5 0
6 0
7 -3.80
8 3.80
9 0
10 0
11 -11.60
12 0
13 0
14 4.69
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by guest » Sun Jul 26, 2020 3:11 pm

the links to the images arent working for me.

do you get a signal on either of the outputs? what happens if you turn the offset knobs?

first thing to check is that pins18,19 move with the offset knobs. then take a look at the expande pins, and see if any of them move with offset knobs. be sure to have both knobs somewhere in the middle. if one is at zero, it might just make all outputs zero.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Sun Jul 26, 2020 6:10 pm

Hi and thanks for the support as always!

Pins 18 and 19 do jump back and forth beween 0 and 5V as I adjust the offset knobs, so that much looks promising. Likewise, the voltage on the expansion header pins are also jumping back and forth between 0 and 5V when I adjust the offset knobs.

The 0-5V output remains at 0V at all times. The -5 - +5 V output oscillates around the zero point by ±0.2V but otherwise also doesn't change regardless of voltage offset settings.

Here are the images embedded this time, maybe they will work for you:

Image
Image
Image
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by tele_player » Sun Jul 26, 2020 6:46 pm

Suggestion to OP- Upper and Lower TL074 in your voltage readings would be much better replaced with the part designators from the schematic. Sure, we can figure it out, but...

Anyway, are you certain the PIC has been flashed?

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Re: Help me troubleshoot Barton Bytewise Operator

Post by guest » Sun Jul 26, 2020 7:00 pm

so far so good. what do pins1,2,3 of U2 do when you move the knobs around?

also, the pictures still arent working for me.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Sun Jul 26, 2020 10:04 pm

Many thanks again all for the input! I think I've finally fixed the images.
tele_player wrote:
Sun Jul 26, 2020 6:46 pm
Suggestion to OP- Upper and Lower TL074 in your voltage readings would be much better replaced with the part designators from the schematic. Sure, we can figure it out, but...

Anyway, are you certain the PIC has been flashed?
Sorry for the ambiguity. The "Upper" TL074 is the one nearest the 16F685 IC. I'm not very good at reading schematics, so wouldn't know how to identify one from the other by it.

I was told that the PIC chip was programmed and ready to go, so I THINK I'm good on whatever logic needs to be set up within that chip to make this module work.
guest wrote: so far so good. what do pins1,2,3 of U2 do when you move the knobs around?


I'm guessing that U2 is "Upper" TL074 (the one nearest the 16F685 IC). As I adjust the offset X and offset Y pots, I see that pins 1, 2, and 3 are changing, and they seem to swing between 0 up to 5v depending on the positions of the two pots together. The two offsets seem to be affecting each other, for example I can only get the pins up to a full 5v if I set both X and Y offsets up high, etc. The offsets seem to have a "zero" point about half way through its rotation, but both fully cwise and fully ccwise have a positive voltage of about 2.5V when the other Offset is set to its "zero" point. Let me know if there are other tests you'd like me to do with these pins, and I'll try it out.
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by guest » Sun Jul 26, 2020 11:00 pm

all those voltages seem correct. it looks like you do not have a ground on your jacks. in the build manual, the panel is raw aluminum, so its conducting between them all. on yours, you will have to run a wire between all the grounds on the jacks back to your PCB ground some place.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Mon Jul 27, 2020 9:30 am

Great to hear re: voltages so far!

Which of the lugs on the panel-mounted jacks is the 'ground' lug? I'm guessing it is the the "top-most" one, but figured I should ask to save myself some potential desoldering in the near future. Here is an image of the jacks I'm using:

Image
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by steviet » Mon Jul 27, 2020 9:39 am

You've got it! The right most lug in that picture is your ground.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Mon Jul 27, 2020 11:20 am

Thanks for confirming the ground lug! I've soldered a wire between each of them and found the unused 'ground' pad on the PCB and have connected everything together.

I'm now able to see the OFFSET pots adjusting the output of the ±5V output, but the 0-5V output is still not showing anything coming out of it. I feel like I'm getting closer, let me know what I should try out next!

Here is a new pic of the updated wiring:

Image
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by guest » Mon Jul 27, 2020 2:44 pm

it has to be something with the wiring or jack, as the +/-5 is derived directly from the 0/5, so the 0/5 must be working at the opamp. probe the opamp output, wire solder joint on either side, jack tip connector, etc.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Mon Jul 27, 2020 8:57 pm

guest wrote:
Mon Jul 27, 2020 2:44 pm
it has to be something with the wiring or jack, as the +/-5 is derived directly from the 0/5, so the 0/5 must be working at the opamp. probe the opamp output, wire solder joint on either side, jack tip connector, etc.
After much prodding and headscratching, I've realized that the module in the build doc has the UY jack and the 0-5V OUT jacks swapped from the position that mine are in. I dilligently did exactly what was in the picture so I've hooked my 0-5V output up to the UY jack. If I hook a cable up to UY jack, I see the expected output of the 0-5V output, which looks good at least. Mystery solved! I'll fix the wiring on those jacks and then might be ready to see what the expander board does if I've ironed out all the kinks in the main board.

Many thanks again for walking me through this. Like I said, I'm pretty terrible at off-board wiring!
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Wed Jul 29, 2020 10:07 am

I've rewired my jacks on the main board and have moved on to the expander board. Things look promising there, as lights blink merrily as I twist the offset pots on the module, which is promising!

Except for the Bit 2 LED, which never lights up. :goo:

I can trace a good connection from the expansion header on the main board for pin 2 through to the pin 2 on the expander board's header, and can then continue to trace a good connection from there on to pin 12 on one of the TL074's, so I think that much is good.

Measuring the voltage while the module is operating, I see some weird values at the opamp that pin 2 on the expander board goes to. While the other opamps are getting 5V at their input pins and outputting 5V at their output pin when their LED's are active, the opamp connected to the Bit 2 output and LED is showing 0V at pin 12 and -10.15V at pins 13 and 14. The other jacks are showing 5V and the LED's are showing 1.8V, but both the Bit 2 output and the LED is at -10.15V.

Let me know what I should try next or if you have any questions that I can answer to move towards getting this output working, many thanks! :sb:

Here are photos of the front and back of the board:

Image

Image
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by guest » Wed Jul 29, 2020 3:17 pm

try swapping opamps.

try removing the opamp, and see if pin2 on the header toggles 0-5V. check for 0-5V on the microcontroller pin that pin2 is connected to.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Thu Jul 30, 2020 10:28 am

Thanks again for the tips, I followed them and continued to poke around until I found a bad connection in my jumper ribbon cable that ran between the boards, which was the cause of the BIT 2 LED and jack not getting voltage. I replaced the ribbon with a fresh one, and have tested each of the cables in the ribbon to make sure they have good connections.

I delighted at the illumination of my BIT 2 LED finally coming on, then noticed that the BIT 5 LED was now not lighting. I don't think it ever did and I hadn't noticed until then because I had been holding the board by that LED while I was testing it earlier, so probably just didn't notice that it wasn't coming on. I followed the same process to test that you had suggested for BIT 2. Swapping opamps did not change the result. I am able to see voltage on the header pin (on both boards) that is comparable to the voltages on the other pins, and am able to trace that from the header on the expansion board down to pin 5 of the TL072. If I check the voltage at the jack and LED, the jack voltage is showing 2V rather than 5V and the LED is showing 0.47V while the other LEDS have about 1.75V. I've checked all the resistors on the board and they are the right values, which would be my default thing to check if voltages are arriving at a point but are not the expected value. What would you try next if this thing were sitting in front of you? Many thanks again, I think I'm close to done with troubleshooting this module, but these bit outputs are starting to feel like a game of electric whack-a-mole.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by guest » Thu Jul 30, 2020 1:41 pm

what are the voltages on pins5,6,7? you could try desoldering the 2 resistors that come from the output of the opamp, and check the opamp again. that will see if its getting loaded down by that part of the circuit.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Thu Jul 30, 2020 2:57 pm

guest wrote:
Thu Jul 30, 2020 1:41 pm
what are the voltages on pins5,6,7? you could try desoldering the 2 resistors that come from the output of the opamp, and check the opamp again. that will see if its getting loaded down by that part of the circuit.
The voltages on the pins on the TL072 are:

5 0
6 0 - 1.5V as I adjust the offset pots
7 0 - 1.5V as I adjust the offset pots (pins 6 and 7 seem to have the same voltage at all times)

If I desolder the resistors and test again, what sort of measurement should I expect see that would confirm that the circuit is loaded down here?

Many thanks again! :sb:
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by guest » Thu Jul 30, 2020 3:51 pm

somethings not right here. wasnt pin5 doing the right thing before? it should go 0-5v as you turn the pots. follow that signal again from the microcontroller and see where it stops doing that.
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Re: Help me troubleshoot Barton Bytewise Operator

Post by tele_player » Thu Jul 30, 2020 7:10 pm

It would be easier if the OP would use part designators as shown on the schematic. I’m pretty sure now he is referring to pin 5 on IC3 on the expander board.

OP: This would be a good time to learn how to read a schematic, and this one is quite simple.

Pin 5 on ic3 should have continuity to one of the pins on the MCU, pin 7, unless my eyes got lost reading the schematic on my iPad. If its voltage is stuck at 0v, when all the other LEDs are flashing as you adjust the offset knob, I’d look for a short to 0v somewhere in the path between the mcu and ic3.

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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Sat Aug 01, 2020 3:32 pm

Hi all, thanks again for the feedback. I'm taking another stab at this now and will try my best to identify things by the schematic designations.

I tried to trace the continuity from pin 7 of IC1 on the main board to pin 5 of IC3 on the expander board and found a trace that had been cut on the main board en route to the expander board header. After fixing that, I now have continuity between these two pins across the boards, but there is no change in the behavior of the BIT 5 LED -- it is still not lighting up.

Measuring the voltage on pins 5-6 on IC3 of the expander board again, I am now reading:

5 0 - 3.57V depending on the positon of the offset knobs
6 2.69 - 5V depending on the position of the offset knobs
7 2.69 - 5V -- this is always the same value as what is at pin 6

Let me know if these values seem like they are correct, and if so what I should try next from here. Thanks again!
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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Re: Help me troubleshoot Barton Bytewise Operator

Post by guest » Sat Aug 01, 2020 8:15 pm

its sort of looking like the microcontroller pin might be bad. do you measure 0v-3.57V on the micro pin as well?
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Re: Help me troubleshoot Barton Bytewise Operator

Post by wendallsan » Sat Aug 01, 2020 8:22 pm

guest wrote:
Sat Aug 01, 2020 8:15 pm
its sort of looking like the microcontroller pin might be bad. do you measure 0v-3.57V on the micro pin as well?
I'm able to get a range between 0.97 and 5V on Pin 7 of the microcontroller as I adjust the offset pots. Many thanks again! :sb:
Currently building or troubleshooting a Barton Bytewise Operator + Expander, NLC 1058 Triple Sloths v2, Fonitronic PS3100 Triple Vactrol Resonator, Befaco BF-22 Sallen Key Filter, and Befaco A*B+C. Planning a big build of Nonlinear modules for Fall of 2020!

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