Some notes don't play well [SOLVED]

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BastoonVaulav
 
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Joined: Mon Oct 07, 2013 5:32 pm

Some notes don't play well [SOLVED]

Post by BastoonVaulav »

Hi x0xb0x BANNED, I finished my x0xb0x a few weeks ago. Everything work normally in each modes(analog and digital part), except some notes that don't play well. By that, i mean that i can hear these notes, but they are not "filtered" like the others, they don't really sound acid.

I did test on pin 7 of IC11:

C: 2,001v
C#: 1,400v
D: 1,450v
D#: 1,550v
E: 1,575v
F: 1,650v
F#: 1,690v
G: 1,800v
G#: 1,830v
A: 2,824v
A#: 2,824v
B: 2,988v
C': 2,988v

So all notes under 2v are the ones that don't play properly, but i don't know what to do to fix this. When I transpose up or down, the situation is reversed, notes which didn't play before plays and the ones that played before don't play anymore.

Another problem is that A and A# have the same voltage, consequently, they play the same note! (as for B and C').
Maybe I should replace AN6562?

I hope my post is clear for you to understand!

Thanks by advance, and sorry if this issue was discussed in other posts, I dig a bit in the forum but didn't find anything about this.
Last edited by BastoonVaulav on Sat Nov 16, 2013 11:22 am, edited 1 time in total.

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pulsar256
 
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Re: Some notes don't play well

Post by pulsar256 »

can you make a recording of the "not filtered" notes? This sounds a bit crazy. It might be accented / non accented notes. maybe.

How does the x0x behave if you use it as a MIDI-Slave? Same issues? This would help ruling out the button scanning by the microcontroller. If it gets bogus information from the buttons, the results might be not very predictable (as in wrong notes being played and random accent behavior). If this is the case, get the schematics for the x0x and check everything in the "Tact Switches" section. If I remember correctly there were issues reported here with wrong type of the 74HC165N chips being used. If your chips do not read HC in the middle, they might be just too slow. If these are socketed on your build, try swapping them around, and see if the situation changes.

Things I would also check: R2R network (R75-R90) and die IC9. Also make 100% sure that your 5.333V line is sitting correctly. Look for solder bridges on IC9 and/or the R2R network and check the resistor values.

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mmm
 
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Re: Some notes don't play well

Post by mmm »

Since the voltages are all over the place I suspect IC9, the resistor network following IC9 or the communication between the processor and IC9. Probably all the notes between C# and G# will have the wrong pitch. You should experience a drop in pitch when playing C and C# sequentially and a strong jump upwards between G# and A.

This hints at the third highest bit missing.
Please check if you have similar jumps at:

transposed down 1 octave: between E and F
transposed up 1 octave: between E and F
transposed up 2 octaves: between C and C# and between G# and A

IC7 is very likely NOT the culprit here.

BastoonVaulav
 
Posts: 9
Joined: Mon Oct 07, 2013 5:32 pm

Re: Some notes don't play well

Post by BastoonVaulav »

Hi pulsar256 and MMM, since i don't have a sound card yet, i can't record or use my x0x with MIDI, I'll borrow one as soon as possible!
The chip used for IC16-17-18 are labelled M74HC165B1, i swapped them but the problem is the same!
The 5.333v is good, there is no bridge between r74-90 nor on IC9 but I don't get the right voltage:

Pin 1(next to R82, top): 5,333v
Pin2: 0v
Pin3: 7,5mV
Pin4: 9,2mV
Pin5: 0v
Pin6: 12mV
Pin7: 0v
Pin8: 13,2mV
Pin9: 5,333v
Pin10: 0v
Pin11: 6,2mV
Pin12: 8mV
Pin13: 0v
Pin14: 9,5mV
Pin15: 0v

So according to the eagle file, these voltages are mainly incorrect! I'm still looking for a short or a bad solder in this area.

And yes, when i transpose the problem is "transposed", i got jumps between notes.

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mmm
 
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Re: Some notes don't play well

Post by mmm »

The voltages on IC9 depend completely on the pressed key.

Please press the non-transposed C# and measure the following pins of IC9:

3, 14, 4, 13, 6, 11

(those are the lines coming from the processor)

2, 15, 5, 12, 7,10

(those are the pins going into the resistor network)

You can to do the same for non-transposed G# and A (however I think the first measurements will be sufficient).

BastoonVaulav
 
Posts: 9
Joined: Mon Oct 07, 2013 5:32 pm

Re: Some notes don't play well

Post by BastoonVaulav »

Okay, so i did the test again:

While pressing C#:

Pin2: 5,02V
Pin3: 4,98V
Pin4: 4,98V
Pin5: 5,32V
Pin6: 4,98V
Pin7: 5,32V
Pin10: 0V
Pin11: 0V
Pin12: 0V
Pin13: 0V
Pin14: 4,98V
Pin15: 5,32V

While pressing G#:

Pin2: 3,33V
Pin3: 4,51V
Pin4: 4,51V
Pin5: 3,67V
Pin6: 4,51V
Pin7: 3,67V
Pin10: 0V
Pin11: 0V
Pin12: 3,44V
Pin13: 4,51V
Pin14: 4,51V
Pin15: 3,67V

While pressing A:

Pin2: 5,02V
Pin3: 0V
Pin4: 0V
Pin5: 0V
Pin6: 0V
Pin7: 0V
Pin10: 5,32V
Pin11: 4,98V
Pin12: 0V
Pin13: 9,2mV
Pin14: 8mV
Pin15: 2mV

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mmm
 
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Re: Some notes don't play well

Post by mmm »

I'm not sure if the measurements are all ok. For example, this one is definitely not correct:
BastoonVaulav wrote:
While pressing C#:

Pin2: 5,02V
Pin3: 4,98V
Pin4: 4,98V
Pin5: 5,32V
Pin6: 4,98V
Pin7: 5,32V
Pin10: 0V
Pin11: 0V
Pin12: 0V
Pin13: 0V
Pin14: 4,98V
Pin15: 5,32V
This pattern looks (with the exception of Pin2) remarkably like the C pattern, not like the C# pattern. For "C" all the voltages (except Pin 2) would be ok. Please check again for C#.
While pressing G#:

Pin2: 3,33V
Pin3: 4,51V
Pin4: 4,51V
Pin5: 3,67V
Pin6: 4,51V
Pin7: 3,67V
Pin10: 0V
Pin11: 0V
Pin12: 3,44V
Pin13: 4,51V
Pin14: 4,51V
Pin15: 3,67V
This one shows a number of things that don't look okay; especially the breakdown of the 5V voltage to 4.51V. Apart from the the active pins are corresponding to the bit pattern one expects.
While pressing A:

Pin2: 5,02V
Pin3: 0V
Pin4: 0V
Pin5: 0V
Pin6: 0V
Pin7: 0V
Pin10: 5,32V
Pin11: 4,98V
Pin12: 0V
Pin13: 9,2mV
Pin14: 8mV
Pin15: 2mV
This looks ok with except Pin2 (which also should be 0V).

BastoonVaulav
 
Posts: 9
Joined: Mon Oct 07, 2013 5:32 pm

Re: Some notes don't play well

Post by BastoonVaulav »

Hi guys, I didn't check the voltage again, i'll try to do it asap, but I have a sound card now and I tested sending notes by MIDI and the problem still the same, you can listen what I mean by "they don't play well"

http://www61.zippyshare.com/v/61590591/file.html

The first pattern is a C and its sounds good.
The second is a D, here the sound is low and not "shaped" like the other one.
The third pattern is composed of C and D and it sound very strange.

I'll try to test the voltage of IC9 tomorrow if i have time!

Thanks again for you support!
have a good night!

BastoonVaulav
 
Posts: 9
Joined: Mon Oct 07, 2013 5:32 pm

Re: Some notes don't play well

Post by BastoonVaulav »

Hi again, so I tried with another IC9 that i borrowed from another x0xb0x and it works completely fine, all the notes plays. So it was IC9 which was fried!
Thanks for your help.

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