Minimoog D Pitch Bend modification (solved)

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RL
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Re: Minimoog D Pitch Bend modification

Post by RL » Mon Jun 10, 2013 12:59 pm

BTW, the voltage on the wiper of the pitch bend pot and ground should be around +4.3 Volts when the wheel is in the center position. Before this measuring make sure that there's zero Volt on the diodes.
http://www.moogmusic.de/index2

chris j
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Re: Minimoog D Pitch Bend modification

Post by chris j » Sat Jun 15, 2013 10:03 am

hello guys,
I didn't get your messages before tuning the minimoog, I've managed to tune it (but in fact it was already in tune except osc 3 that had the zero position slightly wrong, and while trying to change that i messed everything up as I was following old board guides, while having a new board, which I didn't know :) )
Before that I had set the trimpot of the Pitch Wheel mod so that the zero position have the notes played in tune on OSC 1 with the Tune button to zero.

Now I'm going to measure diodes to get the zero band mod working, it's not right now.
RL you say:
BTW, the voltage on the wiper of the pitch bend pot and ground should be around +4.3 Volts

what is a wiper ?

thanks!

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RL
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Re: Minimoog D Pitch Bend modification

Post by RL » Sat Jun 15, 2013 11:01 am

chris j wrote:what is a wiper ?
The wiper is the middle pin of the pitch bend pot (usually orange colored). The ground pin is usually the white wire of the pitch bend pot.
http://www.moogmusic.de/index2

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Re: Minimoog D Pitch Bend modification

Post by chris j » Sat Jun 15, 2013 11:18 am

OK thanks Rudy!
mesuring between wiper and ground I get 6.8V
and zeroV on the diodes.

so that means, I have to set the pitch wheel's zero point to 4.3V, then set the trimpot so that the diodes still show 0 V ?

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RL
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Re: Minimoog D Pitch Bend modification

Post by RL » Sat Jun 15, 2013 11:39 am

chris j wrote:so that means, I have to set the pitch wheel's zero point to 4.3V, then set the trimpot so that the diodes still show 0 V ?
Correct :idea:
http://www.moogmusic.de/index2

chris j
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Re: Minimoog D Pitch Bend modification

Post by chris j » Sat Jun 15, 2013 11:52 am

I've set the center position of the pitch wheel to 4.3V, then set the trim pot to be in tune, but there's still no zero band, I've been turning the trimpot very VERY slowly to see if the zero band was somewhere near, while touching the pitch wheel but it still goes out of tune in big jumps of +/- 30 cents whenever I just put my finger on the wheel.
thanks for the help!
Last edited by chris j on Wed Jun 19, 2013 5:26 pm, edited 1 time in total.

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RL
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Re: Minimoog D Pitch Bend modification

Post by RL » Sat Jun 15, 2013 12:13 pm

Hi Chris,
do you know who installed the modification?
http://www.moogmusic.de/index2

chris j
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Re: Minimoog D Pitch Bend modification

Post by chris j » Sat Jun 15, 2013 12:17 pm

No I have no idea, the guy that sold it me didn't know what it was.

I've been measuring the diodes, I get 0.1V whatever the position of the trimpot is, i go full circle and the diodes V values don't change

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Re: Minimoog D Pitch Bend modification

Post by RL » Sat Jun 15, 2013 1:20 pm

Hi Chris,
is the circuit on the small PCB like this circuit?

Image
http://www.moogmusic.de/index2

chris j
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Re: Minimoog D Pitch Bend modification

Post by chris j » Sat Jun 15, 2013 4:08 pm

...
Last edited by chris j on Wed Jun 19, 2013 5:30 pm, edited 1 time in total.

chris j
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Re: Minimoog D Pitch Bend modification

Post by chris j » Tue Jun 18, 2013 3:54 pm

Hi RL (and everyone), I've been trying to understand your circuit (I'm lost with VCC's meaning)
Last edited by chris j on Wed Jun 19, 2013 5:27 pm, edited 1 time in total.

chris j
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Re: Minimoog D Pitch Bend modification

Post by chris j » Wed Jun 19, 2013 9:57 am

...
Last edited by chris j on Wed Jun 19, 2013 5:30 pm, edited 2 times in total.

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Re: Minimoog D Pitch Bend modification

Post by chris j » Wed Jun 19, 2013 10:01 am

I looked at RL's picture, and I'll solder the 3 wires (red, orange and beige) the way they are on the pic.

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Re: Minimoog D Pitch Bend modification

Post by chris j » Wed Jun 19, 2013 10:46 am

bypassed the modification and set the pitch wheel to be in tune, I get 4.6V between the wiper and the ground.
Last edited by chris j on Wed Jun 19, 2013 5:29 pm, edited 1 time in total.

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Re: Minimoog D Pitch Bend modification

Post by thealien666 » Wed Jun 19, 2013 12:24 pm

Just for your info, VCC is the positive power supply. In the case of the Minimoog it is +10 Volts DC.
Moog Minimoog D (1975)
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