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Buffalo-IIIsePro28 2-Channel DAC w/Full Series Regulator Set does not work:
Crash of module:
Calibrated power supply with HD-placid without load and replacing the VR2 trimmer with a 2Kohm fixed resistance to obtain a more stable output voltage at 5Volt (not to be exceeded due to the presence of the trident modules).
An output voltage of 5.02 volts is measured under vacuum.
Without load, set 440mv at the ends of R1 (equal to a deliverable current of 440 mA) acting on VR1.
When the load is connected and to compensate for the voltage drop on the VD of the DAC (lowered to 4.50 Volts), it is activated again on VR1 with a measurement of R2 about 50mV (equivalent to a shunt current of about 50mA).
Finally, the two transformers are connected (Output of the transformer DAC, with wiring diagram from the DAC outputs to the two UTC HA-108 transforms) as in the previous Buffalo II.
And here the problems start, because the voltage under load dropped to 4,20Volt and the shunt current to zero (no voltage ie at the ends of R2) and no longer adjustable with VR1.
I also note that the voltages of the three trident modules were correct (3.3V, 3.3V, 1.3V) while the voltages of the AVCC-SR module (about 3.1V and 3.6V) were not correct, which also seems to have been inserted in the right direction on the card below.
Sergio
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Try measuring the output voltage as you adjust VR1. You should see the voltage rising back up to 5V as you increase current - you will not see any shunt current until its back up to operating voltage.
If this does not work or you have to wind the current up a lot more than 440ma, something is wrong.
Alternatively, temporarily remove the AVCC-SR and see if that brings voltage back to normal.
The AVCC-SR should be outputting 3.6 volts on both left and right. If its only putting out 3.1 volts on one side it may be faulty (I've had a couple of faulty SR tridents but they tend to cause a dead short when they go). Test the voltage and current on both sides of the AVCC-SR when its off.
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After having checked every passage and every tension, sure that I have not made any mistakes, at this point I am led to think that the AVCC-SR board is faulty, but I do not see how to request one to replace from the twistedpearaudio
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Rank: Member
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Joined: 8/5/2012(UTC) Posts: 208 Thanks: 4 times
Was thanked: 16 time(s) in 14 post(s)
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Rank: Member
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Joined: 5/22/2018(UTC) Posts: 6
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The problem, now solved thanks to Brian, was caused by the AVCC board, but now, despite having checked every connection of my system, it is as if I listen to speakers connected out of phase
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