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I've got my LCBPS soldered up and wired up - but when I power it up, I get +22V on between GND and +V and 0V between GND and -V. I've looked over the board and I can't see any mistakes I've mad, so I'd appreciate it if someone could help me figure out my error! Additionally R3 and R4 get very hot which suggests to me that they're passing way too much current.
Thoughts?
Thanks
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Sounds like a short, can you post pics?
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Sure, I'll try to post pics, but I think I may have found the mistake - I think I have the diode on that side reversed. :| That'll be fun to remove. Thankfully I've got oodles of spare diodes. You wouldn't be the first. :) Edited by user Friday, March 7, 2008 9:37:26 PM(UTC)
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Rank: Member
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Or could it be a problem with the LM317?
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Comparing with the layout on the board, your bottom diode is most definitely soldered in the wrong way. Other than that I don't really see anything else that's wrong. Perhaps others will see something that I don't :)
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Davis, the diodes I see look fine, but I can't see D3, and D4. use is picture as a reference: http://www.twistedpearau...s/LCBPS/LCBPS_layout.jpgAlso be sure you don't have the LM317 and LM337 swapped. Your picture does not show how you had your trafo wired, that could also be an issue. Make sure each side get one secondary. Cheers! Russ
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Russ, looking at the layout you linked, that seems to be LCBPS rev. 1.0, while the rev 1.1 seems to have the D2 the other way. Comparing the silkscreen in the picture here against the layout of the one linked as "layout", it seems the only differences are Diode D2 and trimpot VR2 are swapped direction-wise. For what it's worth, I didn't even realize the LCBPS pcb was revised :) When did that happen Russ?  Edited by user Saturday, March 8, 2008 6:41:53 AM(UTC)
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If you look carefully at the two pictures you posted one is a LCDPS (dual PS) and one is a LCBPS (Bipolar PS). ;) The one I posted is a LCBPS. The revision was made to adjust the pattern for the common mode choke to make it fit the part better. Edited by user Saturday, March 8, 2008 7:07:52 AM(UTC)
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Ok now I think I see the point of confusion. It seems Brian accidentally linked the LCDPS image in the LCBPS product blurb on the OPUS page. If you go to the LCBPS page you will see the correct info. http://www.twistedpearaudio.com/lcbs/lcbs.aspx
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Russ White wrote:If you look carefully at the two pictures you posted one is a LCDPS (dual PS) and one is a LCBPS (Bipolar PS). ;) The one I posted is a LCBPS.
The revision was made to adjust the pattern for the common mode choke to make it fit the part better. Ah, your eyes are better than mine  Ok then, I really dunno why he's having issues :)
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Diodes D3 and D4 are correctly oriented. A1 and A2 are also correctly oriented. IC2 is an LM337 and IC1 is an LM317. Regarding the toroid transformer: I'm using the Avel Lindburg I bought from you guys. I have the black and red wired into S2 and the yellow and orange wired into the S1, so the secondaries are properly connected. Have I reversed IC1 and IC2? I don't think I have, but I can't figure out what else would cause this. The only active parts are the LM317 and LM337, unless they're blown. Brad Edited by user Saturday, March 8, 2008 5:19:57 PM(UTC)
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Okay, this is strange. I replaced the LM337 and LM317 and now I'm getting -15V on the - side, and it is responding to the pot to adjust it's voltage, but only +5V on the positive side, but adjusting the trimmer only changes the voltage from +5.2V to +5.8V. Odd odd odd.
Any thoughts on this?
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It really sounds like there might be a short, possibly a cap that got damaged?
Its probably time to check for shorts across each cap and diode. A lot of DMMs have diode test mode.
Also double check that you have DC continuity where you should have it say from the bridge through the choke. Also just make sure everything including the chokes has good solder contact. It probably does, but just need to check everything.
Hope that helps.
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