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Some help needed XOXbox -No sound-
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Some help needed XOXbox -No sound-

by YoSc on Thu Feb 11, 2021 9:02 pm

Hi there all.

I am building a Xoxbox and eventually (and probably invertible:)) ran into some issues.

Main pcb, I/0 and such are from Adafruit as well a pre-burned Ic with Sokkos 1.9.1

During construction I did all test after finishing a part of the synth without any trouble.

5.33 V ok
12 V ok

All scope test were ok, as well as the gate test and tone/sound tests with a headphone.

FT USB to Serial driver properly installed and chip gets recognized by Pc

All Jumpers (J1-J7) connected, powered it up but no sound from headphones and Mix Out!?

(I must first mention that I did not put in any of the 40 LED,s and their resistors as I want to experiment with different ones I have lying round before getting a whole bunch, but that should be a problem getting sound out of the synth right)

I checked Voltages on BA6110 and all seemed fine according to the Wiki.

DC bias Voltages on LA4140 are a bit off, but nothing special I think

Pin 1 = 0.7 V
Pin2 and 3 = 3V
Pin 4 = 3V
5= 0V
6= 3V
7= 6V
8= 5.7 V
9= 3V

Is there something I have overlooked? Or maybe someone has an idea what to check to narrow it down?

Many thanks in advance.

Cheers! YoSc

YoSc
 
Posts: 4
Joined: Thu Feb 11, 2021 8:18 pm

Re: Some help needed XOXbox -No sound-

by YoSc on Fri Feb 12, 2021 9:59 am

I might have placed a wrong IC in IC12

I found a HEF4066BP, but after some searching on the forum it seems to have different specs, so I am going to change that first.

Also,

After some continuity tests, I found a "short" between pins 2 & 3 of J7 on the I/O board side. Could that cause any problems?

Regards

YoSc
 
Posts: 4
Joined: Thu Feb 11, 2021 8:18 pm

Re: Some help needed XOXbox -No sound-

by YoSc on Wed Feb 17, 2021 5:54 pm

I did some testing and measuring:

There was actually sound, but it was so low I had to crank-up my Gain it got blurred by the noise floor of the mixer.

So putting the xox in Random I hear the random pattern and Keyboard mode works fine (handy for the debugging process)

Holding a headphone to Pin 6 of IC14 I can hear the pattern loud and clearly, Ribbon of J7 is put in right order and measure continuity between the end of the leads.

Did found out I had put in Tantalum C42 in backwards, chanced that.

I use the XOX_Voltage Map the check voltages respecting to ground when turning on the synth (keyb Mode) and the checks I did so far are that I have some Off readings at J5

Pin 1 = 4 V (should be 5.95)
Pin 2 = 0 V
pin 3 = 6 V (should be 341 mV)

Someone have any idea(s)

Regards.

YoSc
 
Posts: 4
Joined: Thu Feb 11, 2021 8:18 pm

Re: Some help needed XOXbox -No sound-

by YoSc on Tue Apr 06, 2021 4:00 pm

[SOLVED]

In the end a bad ribbon cable (J5) was the one that kept me up nights doing numerous tests and measurements I found here on the forum.

At least I am sure everything works like a charm now:D

One of the things I had done first a few weeks ago was swapping the HEF4066BP with a new CD4066BE, but this had no result on my sound issue. After I found the issue today, I just was curious if it made any difference so swapped them again...All worked fine as well, so I guess you can get away with it if you have a older HEF4066BP lying around collecting dust:)

And Now...It's time for some Acid

YoSc
 
Posts: 4
Joined: Thu Feb 11, 2021 8:18 pm

Please be positive and constructive with your questions and comments.