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Proper values for VR1 and VR2 in Legato
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lindamar  
#1 Posted : Thursday, August 12, 2010 7:59:58 AM(UTC)
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I´ve just got my Legato I/V and did realize there are no instructions on how to setup the VR1 and VR2 multi-turn trimmers and their proper values.

Any advice would be much appreciated.

best regards
Pepe
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avr300  
#2 Posted : Thursday, August 12, 2010 8:05:56 AM(UTC)
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Yes, here..

http://www.diyaudio.com/forums/twisted-pear/166975-legato-ivy-iii-outputs-buffalo-ii-6.html#post2264243

Edited by user Thursday, August 12, 2010 8:34:50 AM(UTC)  | Reason: Not specified
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lindamar  
#3 Posted : Friday, August 13, 2010 7:34:18 AM(UTC)
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Thank you !
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dhmpan  
#4 Posted : Thursday, October 28, 2010 9:36:31 AM(UTC)
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sorry but I cannot follow...
1. the manual says 0 V dc at input...
???
2. You say about measuring AVCC at BII...How?
3. Then check the BII outputs...
check what if there's DC ?
4. All these apply also for SE users?
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avr300  
#5 Posted : Thursday, October 28, 2010 9:39:47 AM(UTC)
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Hi..


1,2 and 3 - take at look here.

http://www.diyaudio.com/forums/twisted-pear/166975-legato-ivy-iii-outputs-buffalo-ii-17.html#post2284681

4. Yes

Edited by user Thursday, October 28, 2010 9:49:47 AM(UTC)  | Reason: Not specified
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dhmpan  
#6 Posted : Thursday, October 28, 2010 9:50:17 AM(UTC)
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thanks...
let's see

1. We do this with both units on and stacked?
2. measure each to gnd...
3. devide ...(should they be equal?)
4. measure at what points while adjusting VR's

sorry you do help....but I feel I have some more way to go...Drool
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avr300  
#7 Posted : Thursday, October 28, 2010 10:04:01 AM(UTC)
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1. Yes.
2. Yes.
3. They are (within the margin). I guess, you will measure 3.4v at AVCC points, and you will adjust to 1.7v at input.
4. At inputs of the Legato.
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dhmpan  
#8 Posted : Thursday, October 28, 2010 10:14:50 AM(UTC)
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yes but when they are stacked the output of the BII doesn't become the input of the legato?
So what's the point? Aren't they forced to be equal?

the legato's inputs are +/-/gnd
where should we check for 1.7? + and gnd ?
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dhmpan  
#9 Posted : Thursday, October 28, 2010 10:14:52 AM(UTC)
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yes but when they are stacked the output of the BII doesn't become the input of the legato?
So what's the point? Aren't they forced to be equal?

the legato's inputs are +/-/gnd
where should we check for 1.7? + and gnd ?
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avr300  
#10 Posted : Thursday, October 28, 2010 10:22:16 AM(UTC)
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"+ to GND" and "- to GND" will always be equal, so you can just measure "+ to GND" and trim it to 1.7 V

I have tried timing both unconnected and connected and to makes no difference. The Legato forces the DC offset of the BII to whatever you adjust it to.
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dhmpan  
#11 Posted : Thursday, October 28, 2010 10:32:49 AM(UTC)
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hmmm
it seems to be more clear now...
Do you think there would be any harm done to the unit if they are not set correctly ?
(I mean I don't know if the initial settings of the VR pots will have any crazy values)
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avr300  
#12 Posted : Thursday, October 28, 2010 11:13:51 AM(UTC)
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No.
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#13 Posted : Thursday, October 28, 2010 10:51:31 PM(UTC)
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hi guys.
i just finished my legato and avcc measures 3.5 volt.
i tried to adjust vr1,vr2 but nothing changes.
is there a problem if i leave it like this?

george.
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avr300  
#14 Posted : Friday, October 29, 2010 3:24:46 AM(UTC)
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The AVCC will not change when you adjust vr1/vr2.

The voltage at +/- input will.
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#15 Posted : Friday, October 29, 2010 7:07:43 AM(UTC)
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so i need to make the voltage input 1.7 volt?
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avr300  
#16 Posted : Friday, October 29, 2010 9:06:41 AM(UTC)
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yeps
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dhmpan  
#17 Posted : Friday, October 29, 2010 2:27:14 PM(UTC)
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I don't know if I did something wrong
but
when I first set the VR's so that the input reads 0
then it still reads 0 and I have to take it all the way to 1.75

So what is the point of setting it to 0 in the first place?

the legato BII combo plays just fine..but I don'tknow what I have adjusted

Edited by user Friday, October 29, 2010 2:28:02 PM(UTC)  | Reason: Not specified
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avr300  
#18 Posted : Friday, October 29, 2010 11:39:17 PM(UTC)
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If you can obtain 1.7v at input of the Legate you're good to go.
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dhmpan  
#19 Posted : Saturday, October 30, 2010 12:19:39 AM(UTC)
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avr300 wrote:
If you can obtain 1.7v at input of the Legate you're good to go.


look
I have 3.54 on avcc.
So I set them to 1.77
but...
since I set them initially to 0, when I mounted the buff it still showed 0.
So I took them to 1.77.
What is the point of setting them to 0 if in the end they have to go to 1.77?
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avr300  
#20 Posted : Saturday, October 30, 2010 12:54:50 AM(UTC)
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Just to ensure your initial setting. If you had made an error assembling Legato board and the inputs was at -15V - your BII now would have been upset.

You have done it just right.
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