[IN STOCK] DTM: Moog CP3-type discrete mixer PCB, Euro panel

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negativspace
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Post by negativspace » Sat Apr 23, 2016 7:19 am

An excellent question, and one to which I have no answer. :despair:

Personally, and I've tried... I could not find any observable difference between matched and unmatched pairs in this one.

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far
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Post by far » Tue Apr 26, 2016 2:43 am

I've just built this and it works (which is great as I built the Mix last night and can't get rid of a large hum).

But the '0' for me is odd, I've calibrated the transistor leg to -6.01v and the output at 12 o'clock and all inputs to 0 to I can get it to -0.1v.

But my output level is 0 (mute) at 2 o'clock, I get a level going clockwise from there, but the ideal output(s) is wiggling anticlockwise. I'm a bit confused. Should the '0' out be like an attenuverter and if so ... I don't understand, any help?

I bought both kits from Synthcube

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Stab Frenzy
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Post by Stab Frenzy » Tue Apr 26, 2016 3:28 am

far wrote:I've just built this and it works (which is great as I built the Mix last night and can't get rid of a large hum).

But the '0' for me is odd, I've calibrated the transistor leg to -6.01v and the output at 12 o'clock and all inputs to 0 to I can get it to -0.1v.

But my output level is 0 (mute) at 2 o'clock, I get a level going clockwise from there, but the ideal output(s) is wiggling anticlockwise. I'm a bit confused. Should the '0' out be like an attenuverter and if so ... I don't understand, any help?
Is the output pot log taper? (ie A10K) that would cause those symptoms I think.

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far
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Post by far » Tue Apr 26, 2016 3:36 am

Stab Frenzy wrote:
far wrote:I've just built this and it works (which is great as I built the Mix last night and can't get rid of a large hum).

But the '0' for me is odd, I've calibrated the transistor leg to -6.01v and the output at 12 o'clock and all inputs to 0 to I can get it to -0.1v.

But my output level is 0 (mute) at 2 o'clock, I get a level going clockwise from there, but the ideal output(s) is wiggling anticlockwise. I'm a bit confused. Should the '0' out be like an attenuverter and if so ... I don't understand, any help?
Is the output pot log taper? (ie A10K) that would cause those symptoms I think.
It's an A50k, the one that came with the kit I purchased. What should it be you think?

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synthcube
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Post by synthcube » Tue Apr 26, 2016 6:19 am

the kit should be packed with 3XA50K log pots and 1XB50K linear pot-- can you confirm? thanks!
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Stab Frenzy
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Post by Stab Frenzy » Tue Apr 26, 2016 6:39 am

Should be B50k (or BXXk, important bit is B)

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far
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Post by far » Tue Apr 26, 2016 7:22 am

synthcube wrote:the kit should be packed with 3XA50K log pots and 1XB50K linear pot-- can you confirm? thanks!
It came with 3xB50k which I used as the inputs
and 1xA50k which I used as output

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negativspace
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Post by negativspace » Tue Apr 26, 2016 7:33 am

That will definitely cause your issue! Sounds like you need some new A50k pots... in the meantime you can swap the A50 and one of the B50s so at least your output (and one input) will be proper.

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synthcube
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Post by synthcube » Tue Apr 26, 2016 7:36 am

indeed that would cause it.
we will send you the missing pots... with apologies.
please email us so we can make sure to get them to the right place
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far
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Post by far » Tue Apr 26, 2016 7:44 am

Yeah ok, well that's going to be pretty annoying unsoldering and resoldering 4x pots.

While i got you guys here, can I check the Mix pots, should they be 3xB50k and 1xa50k, I'm having major noise issues with this one and I can't work out why.

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synthcube
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Post by synthcube » Tue Apr 26, 2016 7:53 am

Jason can also confirm this, but the Mix BOM we kit uses 3XA50K Log and 1XB50K Linear
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far
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Post by far » Tue Apr 26, 2016 8:15 am

ok, well that part seems correct.

So what's a technique for desoldering a 3 legged component? Just spent the last 10 minutes with the iron across all 3 legs and yanking at it and it has barely budged.

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Paradigm X
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Post by Paradigm X » Tue Apr 26, 2016 10:33 am

cut the legs off first.

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Post by denoise » Mon Sep 19, 2016 3:29 am

Hi,

I'm having trouble trying to adjust the 100k trimmer. The voltage between ground and the tip of the output always give me about 10V no matter how I turn the trimmer.

I'm building the DTM v1.0 version of the board and I'm really confused about the LM337 position. As you can see on my pictures I made plenty of soldering marks in this zone trying to unsolder and reverse it.

can anyone help me with my build?

thanks!



Image

Image

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Stab Frenzy
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Post by Stab Frenzy » Mon Sep 19, 2016 6:06 am

Looks like you might have issues with your soldering, the solder should be going through the whole way. Looks like you're just dabbing it on, spend a bit more time on each joint to get it flowing better.

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denoise
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Post by denoise » Mon Sep 19, 2016 6:39 am

Stab Frenzy wrote:Looks like you might have issues with your soldering, the solder should be going through the whole way. Looks like you're just dabbing it on, spend a bit more time on each joint to get it flowing better.
I just re-soldered all my joints and I still have 10V between ground and the output :S

here is an updated picture

Image[/img]

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templar
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Post by templar » Mon Sep 19, 2016 3:36 pm

denoise wrote:Hi,

I'm having trouble trying to adjust the 100k trimmer.

Just to rule this out - you are using a 100r trimmer and not 100k right?

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denoise
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Post by denoise » Mon Sep 19, 2016 11:47 pm

templar wrote:
denoise wrote:Hi,

I'm having trouble trying to adjust the 100k trimmer.

Just to rule this out - you are using a 100r trimmer and not 100k right?
yes, sorry. I'm using a 100r trimmer

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Post by basicbasic » Tue Sep 20, 2016 1:14 am

Might be worth trying to contact MA directly. I know he stopped posting here recently and mentioned something to the effect.

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GryphonP3
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Post by GryphonP3 » Tue Sep 20, 2016 10:44 am

denoise wrote:Hi,

I'm having trouble trying to adjust the 100k trimmer. The voltage between ground and the tip of the output always give me about 10V no matter how I turn the trimmer.

I'm building the DTM v1.0 version of the board and I'm really confused about the LM337 position. As you can see on my pictures I made plenty of soldering marks in this zone trying to unsolder and reverse it.

can anyone help me with my build?

thanks!



Image

Image
What is that MLCC cap doing across the the PTC space? Take that sucker out and link them with a regular wire link clipped off a resistor.
My cat can eat a whole watermelon ...

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Post by emdot_ambient » Tue Sep 20, 2016 8:30 pm

GryphonP3 wrote:What is that MLCC cap doing across the the PTC space? Take that sucker out and link them with a regular wire link clipped off a resistor.
Those could actually be PTC resetable fuses. Some of those look very much like caps.

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denoise
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Post by denoise » Sat Oct 01, 2016 11:40 am

Hi... yes, actually they are PRC resetable fuses.

I managed to resolve the first problem. I was using a 78L12 fixed regulator which came with the building kit! so I changed it for a LM337 and now I get -6V as I should.

Now my problem is that between TP and the output I'm getting between 1V and 11V (with about 6V when the knob is on 12 o'clock). I just resolder every joint just in case, but nothing changed.

Do you have an idea what could be wrong?

thanks

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denoise
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Post by denoise » Sun Oct 02, 2016 12:04 pm

Should I perhaps measure the dc offset of the output and the ground (not the TP) ?


denoise wrote:Hi... yes, actually they are PRC resetable fuses.

I managed to resolve the first problem. I was using a 78L12 fixed regulator which came with the building kit! so I changed it for a LM337 and now I get -6V as I should.

Now my problem is that between TP and the output I'm getting between 1V and 11V (with about 6V when the knob is on 12 o'clock). I just resolder every joint just in case, but nothing changed.

Do you have an idea what could be wrong?

thanks

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denoise
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Post by denoise » Tue Oct 04, 2016 7:48 am

Just in case someone cares. I realized the -6V should be measured between the TP and the ground :doh:

Everythings is ok but I'm getting between -5v and +5v when I turn the output pot! I think it should be about -100mV to 100mV

I revised the circuit again, all joints, all resistors, etc but I cannot see the problem.

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pressurewave
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Post by pressurewave » Sun Jan 22, 2017 9:25 pm

Anyone have the V 1.3 board build guide? I couldn't find a link to it anywhere.

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