Rank: Member
Groups: Member
Joined: 10/26/2011(UTC) Posts: 2
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Hi, I built a placid hd with the 15VA 9+9VAC transformer. However after I apply the AC input, I observed the LED lit up, but the output voltage remains at 11.1V throughout the range of VR1, until it suddenly drops down to 4V and below. At that point VR1 measures about 430ohms, but it fluctuates up and down so I suspect it is not a proper reading. I did not proceed to adjust VR2 and it was left at 1k. I re-flowed all the joints and same occurs. The desired output voltage is 5.25V to power BIII. None of the transistor got hot. Attached are the top and bottom view of the Can anyone please help?
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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)
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Voltage output is adjusted with VR2.
VR1 is for adjusting the CCS current.
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Rank: Member
Groups: Member
Joined: 10/26/2011(UTC) Posts: 2
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Thanks, I am embrassed... All adjustment are fine now. On a related note, what is the maximum voltage BIII can tolerate before the Placid warms up? I measured 5.35V output with no load and slowly came down to 5.25V.
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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)
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That should be just fine. Just try to stay under 5.5V max.
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