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branko  
#1 Posted : Saturday, May 5, 2012 4:09:31 PM(UTC)
branko

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Hi,

after upgrading my dual mono buffalo II with two trident sets left channel din not get lock anymore. after flipping right and left buffalo and some measurement it showed that 1 3,3 v trident (VD,GND,VDD at the side of the I2C pins) did not work while the two less did glow well.
Vin is 5,25 V but between GND and VDD i did measure 0 V. I double checked everything, resolderd some points but still nothing. After desoldering the trident and putting back the ferrite in place everything is working fine.

So how to test/measure the trident to identify the problem. I have set up a little power supply with 5,25 V an soldered a dummy load of 47R to GND and Vout.

thx

Branko

Edited by user Saturday, May 5, 2012 4:10:51 PM(UTC)  | Reason: Not specified

Russ White  
#2 Posted : Saturday, May 5, 2012 4:23:36 PM(UTC)
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Well the simplest thing to try first would be replacing the LED.

Other things to do, measure and record voltages across(not to gnd, but across the part) each resistor.
branko  
#3 Posted : Saturday, May 5, 2012 4:33:50 PM(UTC)
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Voltage across the Resistors:
R1 1,36
R2 0,02
R3 1,92
R4 1,21
R5 0,02
R6 0,0
R7 0,0
R8 1,64
R9 1,12


Why to change the LED? booth are working.

thx

Branko
Russ White  
#4 Posted : Saturday, May 5, 2012 8:07:15 PM(UTC)
Russ White

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My mistake, I thought one was not.
Russ White  
#5 Posted : Saturday, May 5, 2012 8:17:13 PM(UTC)
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On a normally functioning Trident 1 the voltage across R8 and R3 should be the same - or very close.

All of the other voltages seem ok at first glance. So my first suspicion is a dead opamp.

What is the voltage at the output to GND?

Edited by user Saturday, May 5, 2012 8:18:46 PM(UTC)  | Reason: Not specified

branko  
#6 Posted : Saturday, May 5, 2012 8:35:40 PM(UTC)
branko

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The Voltage between GND and Vout is 2,76 V (with resistor 47R as dummy load at Gnd and Vout)

Branko
Russ White  
#7 Posted : Saturday, May 5, 2012 9:05:52 PM(UTC)
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Ah I see, 47 is a bit low value for this test. Try 75R or 100R.
branko  
#8 Posted : Saturday, May 5, 2012 9:38:20 PM(UTC)
branko

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So now with 100R

R1 1,37
R2 0,02
R3 1,92
R4 1,18
R5 0,03
R6 0,01
R7 0,02
R8 1,92
R9 1,30

Voltage between GND and Vout 3,22

So after chaining the dummy load everything looks OK.
should I put it in again?

Branko
Russ White  
#9 Posted : Saturday, May 5, 2012 9:57:08 PM(UTC)
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Yep, that one looks fine. :)
branko  
#10 Posted : Saturday, May 5, 2012 11:44:06 PM(UTC)
branko

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Thank you,

do not know what it was. must have been some kind of bad joint? After putting it in everything is fine now.

Branko
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