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PDX-2000 MIDI In Mod


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  • 2 months later...

Hi!

 

Very interesting project, I am very interested in it...

Then, I have a question: you said you have used a microcontroller to change the pitch externally, and I was wondering how did you do exactly?

Could you please send a scheme so that I could understand?

 

Thank you for helping me to understand this great project!

 

Zom

Edited by zom
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Hi!

 

Very interesting project, I am very interested in it...

Then, I have a question: you said you have used a microcontroller to change the pitch externally, and I was wondering how did you do exactly?

Could you please send a scheme so that I could understand?

 

Thank you for helping me to understand this great project!

 

Zom

I guess you don't want the code and actual connections?

Very simply put its a Midi in circuit to a microcontroller to a digital potentiometer connected to the turntable.

The microcontroller is programmed to understand MIDI signals.

So..

If the microcontroller gets the note C# it then tells a digital potentiometer the exact resistance needed to make that pitch.

If you want you can get the schematic when Im done with the mod.

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Hi!

 

Very interesting project, I am very interested in it...

Then, I have a question: you said you have used a microcontroller to change the pitch externally, and I was wondering how did you do exactly?

Could you please send a scheme so that I could understand?

 

Thank you for helping me to understand this great project!

 

Zom

I guess you don't want the code and actual connections?

Very simply put its a Midi in circuit to a microcontroller to a digital potentiometer connected to the turntable.

The microcontroller is programmed to understand MIDI signals.

So..

If the microcontroller gets the note C# it then tells a digital potentiometer the exact resistance needed to make that pitch.

If you want you can get the schematic when Im done with the mod.

 

Ok, thank you I understand better now ;)

For the schematic, it is ok, I do not need it for the moment. But I am still concerned with the potentiometer.

Actually, I do not have any PDX 2000, but I will certainly buy one quite soon. So, I do not know the technical data concerning the ultrapitch that is already in the pdx.. What is the range of his resisivity? I suppose it starts from 0, but to which value? 10kOhm max?

And then, my other request concerns the power of the ultrapich (Watt), and what are the maximum current and voltage that are applied to this ultrapitch while running? I suppose you have choosen your digital potentiometer knowing it will not burn when you will use it! Perhaps just 0,5W or 1W potentiometer is enough...?

 

Thanks again for helping!

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There is no wattage to be concerned about.

 

The slide fader is a ALPS 100k linear dual pot.
But the pdx doesn't use the dual. So a single linear 100k will work if you want to replace it.

But why do you want that? Whats your idea?

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There is no wattage to be concerned about.

 

The slide fader is a ALPS 100k linear dual pot.

But the pdx doesn't use the dual. So a single linear 100k will work if you want to replace it.

But why do you want that? Whats your idea?

 

Well, I have no other idea than yours; actually, I know a bit about electronics, so I understand what you did and the only thing I did not have was the type of fader in the pdx, in order to know what kind of digital potentiometer to use. So basically, you used a 100k digital potentiometer ;)

 

Thanks a lot

Edited by zom
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  • 2 weeks later...

That's it, I now have my own PDX 2000 mk2!

 

Actually, I may be wrong in my last message... did you directly change the actual 100K potentiometer by the digital one, in order then to control it with the microcontroller?

 

I think you've found an easier way to do it, because your are talking about only 5 big soldered points, and replacing the actual potentiometer seems a bit more difficult...

 

In other words, I wonder how did you connect the digital potentiometer to the turntable?

 

Can you please tell me a bit more about it?

 

Thank you again

Edited by zom
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Hello Backtrack!

 

What you did is a great job man! I Think I need one :p

 

I understand what Zom said, that's right, we could replace the ultrapitch by a digipot by desolder it and solder the digipot instead I suppose.. and it is quite hard I guess!

 

But even if this is the way you did the mod, I can't do it by my own, espacially the programming part! Is it really hard to plug your system on a turntable? Do I need electronic knowledge (which I don't have :p) to do it?

Then, I am sure I will order one!

Edited by zertiff
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Well, this is definitely not the way he did that: I put over the ultrapitch, and this is not a 100K but a 5K!

So I simply do not know how he did the mod, because he made a mistake telling me this is a 100K.

We just now have to wait for him!

Edited by zom
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Guest rasteri

Dunno how I missed this. Great job backtrack. I presume it would be pretty trivial to adapt the same concept to any other turntable.

 

BTW, it might be possible to use PWM outputs instead of a digipot, thus saving on components. It really depends on how the turntable's control circuit works.

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Zom: I'm sure its a 100k on mine. It even says so on the fader.
How did you connect it? You have to desolder the slidefader it to measure it correctly. If you measure it connected you will get other resistances in the calculation. But if you have a 5k thats a problem. Can you check or take a pict of the slidefader?

 

Zertiff: I'm almost done with the mod so you dont have to learn electronics and programming :)
The mod will be done in a couple of weeks.

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Dunno how I missed this. Great job backtrack. I presume it would be pretty trivial to adapt the same concept to any other turntable.

 

BTW, it might be possible to use PWM outputs instead of a digipot, thus saving on components. It really depends on how the turntable's control circuit works.

Yea... If you would like to go hardcore on the programming it could be possible to hack the controlchip. Whithout help from vestax that could take quite a while id think.

Pulse modulating cant replace a digipot. The mod is made by bypassing the slidepot.

 

Zom again: Just saw your earlier message. I hope I understand you correctly.

The resoulution on a pretty basic digipot is 8 bits so that resolution is not enough to replace the analog pot. Im just bypassing the slidpot when in midi mode.

Im in the process of writing instructions for installation. People need to understand whats needs to be done and take that that into consideration before installing it. Its not just plug and play. But the most major thing of this mod is that you have to desolder the slidepot to make modifications to the legs. There are 5 legs and two needs to be modified before putting it back. Its not hard to remove the fader but its necessary for the mod. I will make very simple instructions and include desoldering braid.

 

The mod is not for people who never seen a soldering iron. But if you haven't you probably have a friend who has.

 

If you want to make your own mod I will help you all I can. You can get the schematics and sourcecode. Just PM me.

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Zom: I'm sure its a 100k on mine. It even says so on the fader.

How did you connect it? You have to desolder the slidefader it to measure it correctly. If you measure it connected you will get other resistances in the calculation. But if you have a 5k thats a problem. Can you check or take a pict of the slidefader?

 

 

Ok, So I did measure the ultrapitch (+-50%) after having desolered it of course, because of what you say, and I measured 5,23K exactly. Sorry for the picture, but I can't take a good one for the moment and I don't know how to join a file in the message; but "ALPS" is engraved on the width, and "512C-5KBx2" is written on the front side.

 

 

Right now im deciding if I want to use a analog switch to select the midi option or if I do it like on the 3000 (both 33 and 45 pushed in a the same time). My first idea was to doubleclick the reversebutton. What do you all think?

 

In my opinion, you should simply use an analog switch, it is easy to do and to put in the turntable if needed. A simple hole in the plastic and that's it. Then maybe some people will not want to drill the plastic of the turntable!

Edited by zom
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This is the pcb I have, unfortunately, we can't see what is written on the ultrapitch, because it is written on the other side!

But this is the one I desoldered, exactly the same pcb. Then, maybe there are other pdx 2000 with a 100K instead of a 5K for the ultrapitch? I suppose you don't speak about the +-10% pitch?

 

http://www.ebay.com/itm/Vestax-PDX-2000-mk2-Control-PCB-/151004013654

 

On the ultrapitch, I don't have 5 legs, but 2 pins on one side, 4 on the other side, and 2 in the middle (bottom side) for the earth...

Edited by zom
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On the ultrapitch, I don't have 5 legs, but 2 pins on one side, 4 on the other side, and 2 in the middle (bottom side) for the earth...

Yea...Sorry. Its 6 legs and 2 more for holding it in place. Just like you say. I write before I think

 

Looks like the mk2 has a diffrent PCB. Thanks to info.

I have a buddy who has a mk2 that he hopfully will let me take apart :)

 

 

 

 

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Ok, that's strange... Whatever, why did you say that if I have a 5K it will be a problem? In the program, the difference is just to adapt the new values for 5k instead of 100k, no?

Yes.

But I´ll have to make diffrent versions and tweek the code. Just didn't want do do that.

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Ok, that's strange... Whatever, why did you say that if I have a 5K it will be a problem? In the program, the difference is just to adapt the new values for 5k instead of 100k, no?

Yes.

But I´ll have to make diffrent versions and tweek the code. Just didn't want do do that.

 

Ah ok, I understand ^^ Yes that's right, but then it could be a way to adapt your system to other kind of turntables ;)

Otherwise, I have PM you for the codes and schematics, I can also check for it too :)

Edited by zom
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I was thinking about this modification between 5K and 100K... Tell me if I am wrong:

 

I think you have measured your ultrapitch after having desoldered it; Then, you know it is a 100K, but it has his tolerance, so maybe you measured 102K for example. So, in order to have the good values of resistances to put in your programm, you have made the calculation with 102K and not 100K. It means that for every new device you will make, you will have to adapt your programm after measuring the value of the ultrapitch, even if you just do it with 100K's (once you will measure 98K, another ultrapitch will be 99, 98.5, 101.5, etc).

 

In other words, for each new midi system to build, you will have to modify the programm...Isn't it?

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  • 3 weeks later...
Guest It'sPhilFromThursdays

I said it before and i'll say it again, you are a genius!

 

I'll defo be interested in one, as well.

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