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dem626  
#1 Posted : Friday, March 7, 2014 3:30:30 PM(UTC)
dem626

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Location: richmond, va

Working on a new BIII stereo build. I adjusted the LCPBS to 15v on both + and - rails but when I hooked up the Legato the R2 resistor on the negative rail of the LCBPS smoked!

I replaced the resistor and the LCPBS is still working.

I assume the problem is with the Legato since the LCBPS works standalone. Does anyone know how I can figure out what is wrong with it? Is there any obvious culprit (besides my craftsmanship!) involved here to focus on? I have reflowed the joints not knowing what else to try and don't see any obvious shorts.

I was thinking about putting two fuses holders between the two boards while troubleshooting, but other than that I don't really have any ideas. If anyone has any ideas, please let me know.
Thanks,
Doug
avr300  
#2 Posted : Friday, March 7, 2014 10:37:28 PM(UTC)
avr300

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Denmark

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What's the size of R2? (during time there has been a few values).

It might be 10R if it's an older LCBPS. The current version is using 2R7.

If it's a 10R, try shorting it (just place a wire link under the board)

I don't think there anything wrong with your Legato. It just demands current. A lot of it, especially when running at +-15v. Any series resistance will get hot.

Can you post a picture of the rig?
dem626  
#3 Posted : Sunday, March 9, 2014 5:05:42 PM(UTC)
dem626

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Location: richmond, va

Thanks avr300 for the info, but as it turns out I left the 2R7 in place on the LCBPS. I discovered, kind of accidently, that there was continuity between ground and negative on the Legato. I went over the board again running my iron between solder joints to make sure there was space between them. Then the continuity problem was cleared up. When I plugged it back up to the LCBPS there was no smoke. Now I have music coming out of the Legato! Wow that made me smile.

I'll post pics eventually. Right now I just have parts connected on a piece of plywood while testing everything. Currently using an RPI/I2S straight to the BIII. Moving on to the Hifiduino next.

Thanks to everyone who posted info, otherwise I couldn't do any of this.
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