Welcome Guest! To enable all features please Login or Register.

Notification

Icon
Error

Login


Options
View
Go to last post Go to first unread
quade777  
#1 Posted : Sunday, February 22, 2015 6:55:02 PM(UTC)
quade777

Rank: Member

Groups: Member
Joined: 8/1/2014(UTC)
Posts: 8
Norway
Location: Tromsø

Thanks: 1 times
Hi
I measured 1.8v DC between +/- on the right bal channel. I was able to adjust it down to 1.14v but then I hit the limit of the variable resistor. Any idea what can be wrong?
Russ White  
#2 Posted : Sunday, February 22, 2015 8:58:54 PM(UTC)
Russ White

Rank: Administration

Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN

Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
I would start looking for open or shorted solder joints.
quade777  
#3 Posted : Monday, February 23, 2015 6:57:42 AM(UTC)
quade777

Rank: Member

Groups: Member
Joined: 8/1/2014(UTC)
Posts: 8
Norway
Location: Tromsø

Thanks: 1 times
Thanks. I bought my buffalo III with legato second hand in 2011 so I guess it has a Legato 1.02 or 1.03. I have redesigned it recently with a controller etc. and have found some disturbing solutions (the AVCC had output caps where the cap on one side was connected with + to NC and - to out, I guess it should be + to out and - to ground??)

Due to this I have two options as I see them
1: Try to fix the legato I have (and search for other possible faults)
2: Order a new legato 3.1

In your opinion. Is the legato 3.1 a soundwise upgrade from the older legatos?

One more quick question
Do you think thix adc module would be a good match with your retro riaa for at fully digital amp/preamp set-up where one would only want to turn the occasional record.

Edited by user Monday, February 23, 2015 5:07:32 PM(UTC)  | Reason: Not specified

quade777  
#4 Posted : Saturday, February 28, 2015 11:11:55 AM(UTC)
quade777

Rank: Member

Groups: Member
Joined: 8/1/2014(UTC)
Posts: 8
Norway
Location: Tromsø

Thanks: 1 times
I have checked the pcb and no apparent solderbridges. I then reflowed all rigth channel solderrjoints - still the same.

Then I measured the legs of the transiators and all right t channel transiators read lower resistance compared to the left channel
avr300  
#5 Posted : Saturday, February 28, 2015 5:31:41 PM(UTC)
avr300

Rank: Member

Groups: Member
Joined: 6/17/2008(UTC)
Posts: 921
Denmark

Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
Just so we can see which version Legato you're using can you post a picture of the board ?
quade777  
#6 Posted : Saturday, February 28, 2015 5:39:42 PM(UTC)
quade777

Rank: Member

Groups: Member
Joined: 8/1/2014(UTC)
Posts: 8
Norway
Location: Tromsø

Thanks: 1 times
It is the v3.1. I thought it was 1.03 but when i dismantled everything to reflow the solder today I saw that it was 3.1.
avr300  
#7 Posted : Saturday, February 28, 2015 5:44:11 PM(UTC)
avr300

Rank: Member

Groups: Member
Joined: 6/17/2008(UTC)
Posts: 921
Denmark

Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
Quote:
legs of the transistors


please clarify. Which transistors?
And how did you measure?

Edited by user Saturday, February 28, 2015 5:49:33 PM(UTC)  | Reason: spelling! ;-)

quade777  
#8 Posted : Saturday, February 28, 2015 9:08:47 PM(UTC)
quade777

Rank: Member

Groups: Member
Joined: 8/1/2014(UTC)
Posts: 8
Norway
Location: Tromsø

Thanks: 1 times
QP7-12 and the counterparts on the left side. Measured all transistor legs vs each other using the resistance function on a standard digital multimeter.

Edited by user Saturday, February 28, 2015 9:10:11 PM(UTC)  | Reason: Not specified

avr300  
#9 Posted : Sunday, March 1, 2015 9:41:33 AM(UTC)
avr300

Rank: Member

Groups: Member
Joined: 6/17/2008(UTC)
Posts: 921
Denmark

Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
Since QP7, QP8 and QP9 all are in parallel when measuring those you are to expect the same reading.

Same goes to QP10, QP11 and QP12.

Can you post a picture ?
quade777  
#10 Posted : Tuesday, March 3, 2015 9:10:27 PM(UTC)
quade777

Rank: Member

Groups: Member
Joined: 8/1/2014(UTC)
Posts: 8
Norway
Location: Tromsø

Thanks: 1 times
Legato front

Legato back

Edited by user Tuesday, March 3, 2015 9:14:07 PM(UTC)  | Reason: Not specified

avr300  
#11 Posted : Wednesday, March 4, 2015 5:15:22 PM(UTC)
avr300

Rank: Member

Groups: Member
Joined: 6/17/2008(UTC)
Posts: 921
Denmark

Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
I think a lot of the soldering looks less nice.

If I were you, I would use a magnifying glass and look for tiny solder bridges.


avr300 attached the following image(s):
cut.jpg (52kb) downloaded 11 time(s).

You cannot view/download attachments. Try to login or register.
avr300  
#12 Posted : Wednesday, March 4, 2015 5:18:29 PM(UTC)
avr300

Rank: Member

Groups: Member
Joined: 6/17/2008(UTC)
Posts: 921
Denmark

Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
Here I have marked examples of what I mean.

A lot of unwanted either flux and/or solder.

Edited by user Wednesday, March 4, 2015 5:19:43 PM(UTC)  | Reason: Not specified

avr300 attached the following image(s):
cut2.jpg (93kb) downloaded 19 time(s).

You cannot view/download attachments. Try to login or register.
thanks 1 user thanked avr300 for this useful post.
quade777 on 3/4/2015(UTC)
quade777  
#13 Posted : Wednesday, March 4, 2015 8:53:57 PM(UTC)
quade777

Rank: Member

Groups: Member
Joined: 8/1/2014(UTC)
Posts: 8
Norway
Location: Tromsø

Thanks: 1 times
Yes. I did not solder this myself. I think I will just buy a new one. Thanks for the help.
Rss Feed  Atom Feed
Users browsing this topic
GuestUser
Forum Jump  
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.