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How to check an unequal performance of AVCC shunt regulators on Dual mono mode
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I configured two Buffalo II units and IVY III units into a dual mono mode.
Analog output level of one channel is higher than the other.
When I just swap a piggy-back AVCC shunt regulators, the output level difference is also swapped. I suppose the cause of the difference is on the piggy-back board.
Is there any checking points to find the source of level difference on the AVCC shunt regulator board?
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Can you take close up pictures of the AVCC units? My only guess is that one side may have a gain resistor amiss. Both halves of the AVCC regulator share a common voltage reference.
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Also what is the output voltage you are getting on each side.
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These are pictures. The boards are not at my hand. I will report the output voltage values tomorrow. Value notations of the registers, R7 & R9, seem to be somewhat different between those on A and those on B. "4R7"(4.7 ohm) and "4R70" (4.70 ohm) However, the meaning must be the same. Board ABoard BEdited by user Wednesday, April 21, 2010 8:13:38 AM(UTC)
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There is some variation in the reference voltage provided by the LED(s). I assume this is where you are getting a difference. It shoudl not be more then a 10-15mV between the boards, however.
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Voltages measured at "OUT" pins of AVCC shunt regulator sub boards are;
Board A - Right: 1.4 V, Left: 1.31 V
Board B - Right: 0.25V, Left: 0.24 V
Voltages on the pins of Buffalo II main boards are;
Board A - Right: 2.45 V, Left: 2.42 V
Board B - Right: 2.40 V, Left: 2.45 V
I'm afraid that OUT voltages on Board B are abnormal.
Can you exchange the Board B if I require a normal one?
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Should be near 3.5 v for both sides.
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Those voltages are nothing close to what they should be. What voltage were you using at VD? The boards are tested before they go out, so there must be something else going on. Edited by user Thursday, April 22, 2010 8:47:24 PM(UTC)
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I asked re-measurements to the current owner.
The previous results from him must be at wrong points
New results are;
Board A
IN R＝5.44V L＝5.44V
OUT R=1.82V L=1.92V
Board B
IN R=5.44V L=5.44V
OUT R=3.46V L=3.46V
The Board A seems to be malfunctioning.
I will compare two boards by myself this weekend.
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Yes indeed, my guess is possibly a short across C2. Are the LEDs lighting up correctly? Edited by user Monday, April 26, 2010 3:01:37 PM(UTC)
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Checking the voltage across the LEDs is also a good idea.
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To Russ,
Thank you very much for your care.
Voltage results across the LEDs are;
(These were measured by the current owner.)
Board A Lower 1.87V Upper 1.85V
Board B Lower 1.91V Upper 1.83V
Bunpei
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Rank: Administration
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Joined: 10/24/2006(UTC)
Posts: 3,979
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Ok, the LEDs appear fine, I would check for a short at C2.
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How to check an unequal performance of AVCC shunt regulators on Dual mono mode
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