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Hi Everyone, Well, I finally got around to putting the Placid together, but the negative side can only be adjusted to ~ -12.7V. All the lights come on okay, and I didn't see or smell any smoke - Not sure what the problem might be, a bad transistor or something? I am pretty sure everything is in the right way, but here is a picture as well: 
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Rank: Advanced Member
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What´s the voltage on your transformer??
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Rank: Member
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I believe it's dual secondaries, 15V (the same as the one they sell on this site) - the positive rail reads 15V, but the negative only goes down to -12.7...I hope I didn't somehow damage it, but I am not sure how i could have.... Edited by user Wednesday, December 30, 2009 5:00:59 AM(UTC)
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Rank: Advanced Member
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Can't read your resistor values :(
When you use any resistor that has the code written on it, you should always install them on the board so that the writing is facing up. Makes it MUCH easier to check for errors.
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Rank: Member
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Yes, the resistors are correct, that was the first thing i looked at :)
b
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I got it working...had QN3 and QP3 switched! Sometimes I wonder if my head is on right...anyway, it works now, but damn QN1 and QP3 throw off a lot of heat!
b
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mantisory wrote:but damn QN1 and QP3 throw off a lot of heat!
b Then you have the CCS current set too high, and should drop it to be more appropriate for the load. If you have the current set at 250mA, but your load is only 50mA then you are running 200mA through those transistors - at 15V, that is 3 watts. Each! Way too much for those little heatsinks.
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what should they be set at for the audio section of the buff32
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Quote:If you have the current set at 250mA, but your load is only 50mA then you are running 200mA through those transistors - at 15V, that is 3 watts. Each! Way too much for those little heatsinks. At that power level, they will get hot, but should be fine. 60-70C continuous is not a problem, though I think they will only be 50-55C. Quote:what should they be set at for the audio section of the buff32 One per channel, or one for both channels? Edited by user Thursday, December 31, 2009 11:52:55 AM(UTC)
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Rank: Advanced Member
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Brian Donegan wrote:At that power level, they will get hot, but should be fine. 60-70C continuous is not a problem, though I think they will only be 50-55C Mine got to at least 60C during testing at 200mA shunted, probably a lot higher, and I'm using 2.5" sinks. With the included sinks you're looking at >30C above ambient for just a single device - but the close proximity of all the devices combined brings the ambient a lot higher than room temp. But yeah, loaded with the Buff32 output stage, it shouldn't be anywhere near that hot. Edited by user Thursday, December 31, 2009 1:28:03 PM(UTC)
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