Need help troubleshooting x0x #334

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tempomaster
 
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Need help troubleshooting x0x #334

Post by tempomaster »

This is an original adafruit x0x. I purchased it as a kit from adafruit with the USB pre-solder option and it sat in the box untouched until last week. The only thing not original is IC3. I am using one with sokkos 2.0 that I got from willzyx, as the one that came from the kit is running in an eBay x0x.

The build went smooth, I have lots of experience soldering electronics. I have a hakko desolder station and an SMD rework station. I have oscopes, and currently using a miniDSO201. Fluke DMMs. I have eagle, have designed simple boards with it, can read schematics, etc...

There are two problems... I'm not getting any sound, and the digital section isn't working. Initially, I think the digital section *was* working, but now it's not. More on both of these below.


1. No sound: When first completed, the digital section appeared to be working. All LEDs worked, and by spinning the Bank Select encoder, the LEDs would cycle. R/S button started and stopped... or at least turned on and off the corresponding LED. Tempo encoder changed the tempo. I had no sound on headphones or main out. I opened it back up and probed with my scope. I have saw and square at the waveform switch. Using a 2V supply at R90, I have the wave before R62, but after R62, nothing. I thought maybe C17 was backwards or shorted or something, so I pulled it. I then had sound on both sides of R62. The cap tested good and it was in the right direction. I put it back. Same results. I've probed around voltages on Q12, R70, Etc and everything looks good but I have no signal past R62.

2.) Digital section doesn't work.
I put things back together and now the digital section does not work. I looked it all over and realized that I had missed R240, R254 and R255. I definitely spun the function select encoder a lot before I realized 255 and 254 were missing. I might have pressed S6 I'm guessing this might have screwed up IC3? Upon power up, many of the LEDs turn on, and stay on.

I have molex connectors on all jumpers and have color coded them to make sure they go to the right places. For troubleshooting, I'm only connecting power and J3 and probing with the DSO, so there's not as many jumpers in the way. I realize that this disables the audio jacks, and that's okay.

Where should I go from here?

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antto
 
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Re: Need help troubleshooting x0x #334

Post by antto »

J3 gives power (5V) to the cpu and the other digital stuff
J4 gives power (5.33 and 12V) to the analog synth section
J5 gives power (6V) to the headphones amp
J6 carries out the Pitch and Gate control voltages
J7 carries the MIX-IN and MIX-OUT (main audio output)

if you only plug J3, the whole synth section will not work pretty much
but the cpu and sequencer stuff (buttons, leds, switches, dinsync, midi) should work

the audio signal on the other side of R62 is very weak, R62 is 220K after all
instead of measuring there, measure on the other side of the filter (after the signal has passed thru the ladder and has been buffered) for example at the junction of R96 and C14.. that's inside the filter
then, measure at C38, that's right after the output from the filter has passed thru the VCA (thus you'll only see anything here if you're playing notes)

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

Sorry, I meant that I was plugging in J3 and J4 (what I called power).

So I'm definitely getting audio signal through the filter. Can I force the gate? I'm thinking of injecting a voltage at R146.

So far it's looking like my analog section might be okay but the digital section wasn't operational enough to open the gate?

Now the digital section is definitely not okay. :\

Oh, I forgot to mention that x0xc0ntrol connects to the USB chip, but disconnects because it cannot find the x0xb0x.

Thanks for the quick reply antto!

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antto
 
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Re: Need help troubleshooting x0x #334

Post by antto »

you could fire the gate by following the test procedure in the build manual VCA section http://www.ladyada.net/make/x0xb0x/fab/vca/index.html
BUT in that section, the sequencer is not populated yet, so the test assumes that the cpu is not soldered yet
so if you perform this test - better remove the cpu from the socket
this also means you'll have to inject a pitch voltage at R90.. it doesn't have to be exactly 2.00V, it can be any voltage between 1 and 5 volts

if you can then hear a note after the VCA (at C38) then the most significant stuff from the synth section are working
what's left is the signal from there going thru the volume pot, and into the mixer and out to the IO board on the audio jack (for which you need the other jumper cables to be plugged in)
if all of this is working - your synth section is okay

if you're using c0ntr0l, at least on windows (no idea how it is on linux/osx) you have to configure the settings of the VCP driver from the windows device manager, in order to set the serial port bitrate, because it seems c0ntr0l just "opens" the port without changing the settings at all
for the atmega162 x0xb0x bootloader - the bitrate is 19200
for most firmwares, the bitrate is also 19200 (but each firmware may decide to use whatever bitrate it wants, so you should check that out in its instructions, if any) ... sokkos (up to version 2) uses 19200

you could try setting the x0xb0x to bootload mode, restart it (power off, power on) and attempt to flash the firmware with c0ntr0l
or you could also try with BANNED
if you're on windows or linux - try the latest version of BANNED (on linux you'll have to build it, and that may turn out tricky)
if you're on osx however, the version we have is older, and that one is not very safe in certain ways, but if you follow the "firmware update" instructions in the readme file and watch the demonstration video carefully - you could try it

an important note here is:
if the x0xb0x is running the bootloader (atmega162) and not the firmware, do NOT attempt to connect to connect to it as if it's running the firmware
because the communication protocol of the firmware is complex, and the app (be it c0ntr0l or especially BANNED) can send lots of information, which is very dangerous if on the other side the x0xb0x is actually running the bootloader, who's protocol is very delicate

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

Thanks heaps Antto.
I'm going on vacation today until May 1st, so the next steps will have to wait. I also have another stock firmware U3 that I purchased from willzyx that I could try, but I'm hesitant to do that while I'm not sure what made the first one freak out.

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

I'm now sitting with my working x0x (eBay) and non-working #334. I've swapped IC3 and 334 stays non-working. Turns out, each IC3 that goes into 334 dies. I've also swapped IC2 between the two. I've installed a different XTL1 in. All to no change.

Putting the IC3 back into the working x0x, renders it non-working as well. I've now tried this with an original 1.04 firmware, and two Sokkos 2.0 I got from willzyx.

I tried connecting with c0ntr0l, after changing the serial settings in device manager with no luck. I tried several times to no avail.

So now I have two non-working x0xen. Or rather, one working x0x without any firmware and one non-working x0x.

I'll have to burn some new firmware chips (I have 4 non-working total now) before testing more.

While I figure out how to burn these chips, do you have any other suggestions?

I really appreciate the help here.

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antto
 
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Re: Need help troubleshooting x0x #334

Post by antto »

check the voltages on your IC3 socket
something must be very wrong there

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

Using Pin 20 as Ground, IC3 not installed (IC2 installed):

4- 5.059
9- 5.089
10- 5.090
38- 4.985
39- 4.985
40- 5.089

All other pins had < .1 VDC on them, most had zero.

The voltages seem right to me by comparing to the schematic.

I measure 5.093 directly at the regulator IC20


Also, with no IC3 installed, all LEDS are on.

I just got my chip programmer, so I'll burn some copies of IC3 and see what I can find out.

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

It turns out that I purchased a PIC programmer. An AVR programmer is now on its way to me. The PIC programmer has a nice 40-pin ZIF socket that I'll reuse to program the IC3s. Funny how the entire PIC programmer was cheaper than the ZIF by itself. It's going to be a few more days until I get working AVRs.

Do my voltages look way off? Do you think I might have erased/scrambled the AVR programming with c0ntr0l? It seems unlikely that I would have "ruined" 3 chips, but I'm grasping at straws here.

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

FFFFuuuuuuuuuhh.h..

I have decided that I am presently out of my league when it comes to the AVR. I purchased a pocket AVR programmer from Sparkfun (this one: https://learn.sparkfun.com/tutorials/po ... okup-guide) and have made connections to my breadboard. I verified with a DMM on continuity mode that the correct pins of the ATmega162 were connected to the correct pins of the programmer. I based this off of the guide linked above and the ATmega162 datasheet: http://www.atmel.com/images/atmel-2513- ... asheet.pdf.
I have included a 16MHz resonator and connected it to the AVR the same way as in the x0xb0x, pins 18 and 19 and the center of the resonator to GND (pin 20) This is the resonator that I'm using: http://www.digikey.com/product-search/e ... 90-1214-ND

My computer (win 8.1) recognizes the AVR programmer and when I send commands to it, I see activity LEDs on it. Each time, AVRDude tells me "initialization failed, rc=-1"

c0ntr0l doesn't work for me as the AVR isn't getting a COM port assigned, and I don't see how c0ntr0l works without a COM port.

I've tried three ATmega162 chips (all which previously had either x0x firmware 1.04 or Sokkos 2.0 on them) and I get the same errors on all of them.[img]
AVR.jpg
AVR.jpg (141.1 KiB) Viewed 1343 times
[/img]

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

My connections from the usbTiny AVR programmer were technically right, but the breadboard was having trouble connecting to the pins of the atmega162. When I forced it down, things worked correctly. I've swapped in a ZIF socket and everything seems to work with the programmer now. It says the fuses on the atmega162 are E:F9 H:D4 L:FF. Is that correct?

I've programmed a chip and my original x0x works again. The bootloader mode doesn't work, but it didn't before. I'll try the newly programmed chips in x0x 334 tomorrow,

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

Great success!

Making no changes to the x0x#334 that I can recall, I've burned new firmware, put it in the socket and booted. Well, I *did* install the two main rotary encoder knobs so I knew what they were pointing at.

I have since used c0ntr0l to burn new firmware in-circuit using the x0xb0x BOOTLOAD mode.

#334 is alive!!!!

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

And now it's sick again.

Since I already have one stock x0x, I am modding this one to my heart's delight. I soldered some jumper wires to an external pot and pressed play. The first few notes sounded normal, and then went really high pitched. Now, it's stuck like that. I can hear the pattern, and it sounds like it's playing the right notes, but they're up 5 or 6 octaves, or it sounds like something is stuck in self-oscillation.

I'm going to drop in a new MCU tomorrow, but in the meantime, does anybody have any pointers?

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antto
 
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Re: Need help troubleshooting x0x #334

Post by antto »

try to figure out exactly what's high pitched, is it the VCO or the VCF or something else
a short audio recording of the issue might help

check your voltages, +12, +5.33, +5V
if it's the VCO, check the pitch CV output (on the IO board) it should give you 1 volt per octave, and the normal non-transposed low C should give 2.0V there
if that's alright, check the voltage at the middle pin of the tuning pot

to confirm if it's the VCO, a small hack you can do is: turn the waveform switch in its middle position, there is a small area there where it's neither connected to sawtooth, nor to square, so effectively it shouldn't feed any audio signal into the VCF
if you can still hear the high-pitched thing then - it's probably not the VCO

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tempomaster
 
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Re: Need help troubleshooting x0x #334

Post by tempomaster »

I've disconnected everything from the IO board (no jumpers to the main board) and the voltages on P4 were about double what is expected.

I suspected IC23, and pulled it, but the input voltages to IC23 were about double (11.23V IIRC)

The output of the 336 was about double what it should be. IC20 and IC21 have the correct outputs.
I swapped in a new 336 and now the output is about half what it should be (~2.3V)

I've pulled from circuit and tested C7, C8, R2, R3, R4, R5, D44-47. All tested good.

I didn't check R1.

My boss just got here, so I have to put it away until tomorrow morning. :-)

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