x0xi0 Full Kit - Install & Troubleshooting

[lord.bix]

Hi Brian,

good news, the noise seems to be gone. So i guess it was a step forward into the right direction. Even the thin bass got a bit better, but its not 100% solved so far. This was a hell of soldering work between all the cables..

I am sorry, but i guess we dont have solved it all still there are the following open items, i may be need some help from you:

- Heating of IC304. This gets realy hot as reported before. It comes from teh top pannel.
- Poor bass sound. I will record it tomorrow in my studio (Tired now).
The symthom is that i can not open up TM3 to get the right effect on cutoff. Its to low in sum for my experience. If i switch high range on. It goes into the right direction.
- Clicking of VCA
It gets better if i switch on the envelope2 vca depth a little bit.
- noise generator
i dont know how that should sound, but what i get is almost nothing

Sorry Brian, i know a long list =) i hope you dont get pissed off me now..

Thank you in advance.

Regards

/Marco

[bcbox]

Heating of IC304

you mean IC305 right? This is normal. As long as you have the heatsink on the part it will get hot but is ok. The surface of the IC can get to 80 degree C and above, but will still be within spec for the part. This is the power supply for the whole x0xi0 circuit, including most everything on the top PCB, so if you disconnect pad D (12V to power circuits) it will cool down. If the heatsink gets over 120 degrees C then that would indicate a problem.
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Poor bass sound

ok, I will listen to the sample and go from there.
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Clicking of VCA.. It gets better if i switch on the envelope2 vca depth a little bit.

This is probably because the attack of the envelope generator eliminates the clicks because it is set to a slower setting. Even at the minimum setting the attack time is a few milliseconds and could be enough to eliminate the clicks. Do the clicks also go away if you adjust the VCA attack time to a higher setting?
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noise generator

The noise circuit outputs a pseudo pink noise. As long as the filter overdrive switch (Filter OD) is off you should hear the noise at about the same relative level as the VCO's. If you turn the VCO's down to zero then turn the noise up you should hear the noise pretty loud - typical white or pink noise. Sounds liek maybe it's not right. Maybe you can record a sample of this too.

[lord.bix]

Hi Brian,

i have just recorded the output from my xox. As said, much better but not right i guess.

You will find the file here:http://www.sendspace.com/file/l4j3ad
I have done follwoing thing with VCO1, VC2, Noise, Than all:
- all to 0
- cutoff 0 -100 - 0
- res 0 - 100 - 0
- envmod 0 - 100 - 0
- acc 0 - 100 - 0

Than i switched on filter hi range, played with cutoff and res.
Switched as well HI Reson., played a bit

Heating: It was IC305, yes =) So it seems ok than. It even smelled a bit plastic.. we will see =)

The clicking itself goes away, if attack time of VCA envelope is turned up little larger, yes. but the clicks from accent stay.


Regarding the noise. There is some. I guess you can judge if right or not =)

I realy appreciate your help

/Marco

[bcbox]

The level of the noise floor is completely normal. It's the same as the TB-303. The noise becomes much more apparent when you mod the x0x or TB-303 to decrease the minimum cutoff frequency or in this case allow the VCO's to be turned off completely. Nothing to worry about there.

The clicking is moderate. It sounds about average compared to other x0xb0x's. I think you have other x0xb0x's to compare to as well. However it's hard to hear but I think you may have some additional minor clicking that is more than the usual x0xb0x, that happens at the end of the gate-on signals or maybe on accents etc.. This is what have experienced on one of my x0xi0's. A good way to test for this that I mentioned before is to turn the volume of the x0xb0x all the way down and listen for the clicking; is it still there?

I can hear the signal from the noise generator. it sounds about right but it is very low level. It should be much louder. Check the signal at pin 7 of IC401. You should see the nosie on your scope and it should be about 7V peak to peak. If it looks ok there then you should check R434 and make sure it is the correct value (330k). The noise transistors were hand selected for noise quality and gain. I see you used the correct one there so it should be ok. If the level of the noise signal looks at pin 7 as described above try replacing R434 with 100k to increase the signal level at pad T where all the sound sources meet. If the signal level at pin 7 of IC401 is less than 5V p-p then there in a problem in one of the gain stages.

Overall the sound seems to be distorted, the signal level seems to be clipped. Something is definitely not right.
1. Make sure that the filter OD switch is off.
2. Check the signal at the VCF Output jack and make sure it sounds ok and check with the oscilloscope to make sure it is not clipping.
3. Put the the volume control about 80-100% rotation and check the signal at the junction of R151/R160/R161. Make sure the signal is not clipped. It should not be flat-lines against the supply rails. It may clip occasionally on accented notes but it should not be distorting continuously.

[lord.bix]

Hi Brian,

i think i have found the root cause tonite. The noise comes from the PAD V. I have desoldered it from R71. Now the sound seems to be right. For some reason the PAD V has a permanent SAW signal on it.

I have checked the schematics, and i dont think so, this is as its designed.

Even the noise level got better after desoldering it.

I guess i have a shortage somewhere on the board.

/Marco

[bcbox]

sounds like some good news.
pad V is the filter control voltage input. There are several sources that are routed to pad V, including the Filter CV In jack, filter tracking, ENV2 to VCF, VCO FM, etc.. so you definitely want to ge that straightened out. I would refer to the x0xi0 schematics and put together a good plan for debugging. Let me know if I can help with any specificd.

[lord.bix]

Hi Brian,

i have checked the schematics and know what to do, i guess. I will systematically disconnect all sources go to PAD V. I personnaly think its a shortage on front plate mod.
As i fight some flue these days it will not go as fast as i expect to get it done. =) But i know how to fight it =)...

Thanks for your help.

/Marco

[dnigrin]

So I'm moving along steadily with building my x0xb0x from scratch (up to the VCA section currently), including the x0xi0 full mod substitutions/removals as indicated on the left side of page 44 of the Full Install manual (with the exception that I am NOT replacing R121 and R122 as indicated earlier in this thread).

Once I finish the x0xb0x build, I want to stop and check that all is working properly before starting the x0xi0 mods. Will the x0xb0x still work correctly, even with the part substitutions that I have made, and in particular, the part deletions? I *have* connected TM4 and TM5 (with wire).

Thanks Brian...

[lord.bix]

Hi Brian,

i have checked the signal on R161. In comparision to my other x0x'es the signal pegel is far to low. I have a gain on the others at about 3,5 V. on 4 V base voltage. In the current i only have a gain of 1 V. The 4 V base voltage is the same. The signal on VCF out is not hiher than 0,5 V in total.

I have measured all the voltanges on the PADS of xox io as well. Will supply them later.

/Marco

[lord.bix]

Hi Brian,

On Top of that i checked all PAD's on IO and Top xtention. Pls can you check if the values are right. Thank you.

XOXIO Board:

A 0V, Signal
B 0V, Signal
C -
C -
D 11,8 V
E 3,76 V
F 4,44 V
G -0,04 V
H 0,51 V, Gate
I 0,51 V, Gate
I 0
C 0
C 0
J 0, Signal
K 5,35 V
L 0
M 6 V
N 6 V
N 6 V
------
O 1,3 V, decreasing
C 0
P 0,06 V
Q 0,20 V
R 0,20 V
S 5,32 V
T 4,35 V - VCO
U 3,27 V
U 3,25 V
V 3,27 V
V 3,27 V
W 0 Trigger signals
X 0,01 V Trigger
Y 2,79 V CV?
Z 2,8 V CV?
AA 0 Trig?
D 11,88 V
C 0

Top Pannel:

1 5,33 V
-----
2 6,57 V (5-9 V sqr Signal)
3 8,35 (5-12V saw signal)
4 5,26 V
-----
5 1,5V
6 5,33V
7 2,15 V (CV?)
8 8,08 V
9 12,11 V
10 1,5V (CV?)
C -
11 5,35 V
T 4,4 V (SAW 3-5V)
12 0
G 0
U 3,25 V
13 1,5 V
V 3,26 V
14 5,33 V (VCO Signal?)
15 5,33 V
----
C 0V
16 0V (Gate)
17 10,12 (Env 1)
18 0,11 V (Env1^-1)
I 0,02 (Env2)
AA 0 (Acc???)
19 0,01 (acc??)
-----
20 0V
21 5,33 V
22 0,08 V (Trigger? Acc)
D 11,88 V
----
23 0,16 V (Trigger?)
24 0,10 V (Decay? Soft Trig)
25 0,06 V (Decay? Soft Trig)
26 0,03 V (Env?)
27 1,73 V (CV Slide??)
Z 1,73 V (CV Slide??)
28 12,08 V (Trig?)
29 0,10 V (Env?)

On top of that i have checked the BA6110 Voltages. They seem ok. I will check the full VCF Voltages now.

/Marco

[bcbox]

Sorry for the delays in responding guys, I have no internet at home, possibly for up to another 10 days! I will do my best to respond in my free time at work.

Once I finish the x0xb0x build, I want to stop and check that all is working properly before starting the x0xi0 mods. Will the x0xb0x still work correctly, even with the part substitutions that I have made, and in particular, the part deletions? I *have* connected TM4 and TM5 (with wire).

From what I see you should be able to test it but few connections would need to be made temporarily.

1. Test VCO. You can test the VCO as is, just take the signal from pin 1 (sqr) and pin 3 (saw) of S1; then you don't have to put the switch in, and you should see the waveform on your oscilloscope or even tap in and send it to your mixer to listen to raw waveforms.
2. Test VCF. To test the VCF you would have to install R62 and C17 temporarily.
3. If you want to hear the whole box work you would also need to temporarily connect some of the parts in the VCA circuit. This would be D35, R133, and R123.

That should just about do it. If you've already cut the traces on the x0xb0x mainboard as shown on page 44 of the Full install manual you would have to temporarily jumper them.

[bcbox]

On Top of that i checked all PAD's on IO and Top xtention. Pls can you check if the values are right. Thank you.

I will get to this asap. My lab is not set back up yet in my new place but should be shortly.

[dnigrin]

From what I see you should be able to test it but few connections would need to be made temporarily.

Perfect Brian - this is the level of detail I was after. Thanks!

[dnigrin]

2. Test VCF. To test the VCF you would have to install R62 and C17 temporarily.

So I did this (installed R62 and C17), but am getting very low output on the VCF test when probing the pot. I can barely see any waveform on my soundcard scope, and when using an earbud, I can barely hear any output. Could the other substitutions that I've made per the x0xi0 instructions (R47, R61, C14, and C15) have anything to do with this? If not, I guess I gotta start debugging this - any suggestions greatly appreciated!

[bcbox]

So I did this (installed R62 and C17), but am getting very low output on the VCF test when probing the pot

The output of the VCF is very low, I want to say ~20mV or something along those lines. You may be a-ok. I would go ahead and move on to the VCA, double check everything and then listen to the signal at pin 3 of the volume pot (or do as described in x0xb0x build manual).