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Buffalo Dac not powering up.. Drawing excessive current
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Wow! Talk about murphy law!! It has to be the last ferrite that I desoldered...
So desoldering L1 removed the short. But of course - nothing turns on.
Russ - what would be my next step. I have painfully put the other ferrites back and left L1 open (lifted up actually)
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You shouldn't have powered anything up or put back any ferrites yet. With L1 still removed check C12 and C15. If they are shorted then your chip is most likely fried. Edited by user Friday, March 25, 2011 5:58:25 PM(UTC)
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Also removing L6 should also have created a high impedance to GND from VD.
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Yes.. they are showing a short with L1 removed.. :-(
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OK then very likely what happened is the 1.2V supply pins were compromised one way or the other.
The 1.2V (VDD) pins of the DAC are the most sensitive to both power supply malfunction (which is what I think the evidence points to since you PS went out at the same time) or ESD damage (also quite possible).
I am really sorry. I have destroyed many modules myself accidentally one way or the other.
Unfortunately I think your module is likely not practical to repair. At a minimum IC1(The DAC chip) and IC6(1.2V reg) need to be replaced, and possibly some caps.
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If you really feel like giving it a go you could just replace IC6, bu thats a long shot. IC6 could actually still be good, and only the DAC damaged or vice versa. Its really impossible for me to know.
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Scratch that, because L1 was lifted and not just L6 the DAC chip itself is nearly certainly dead. The only other (remote) possibility is a shorted cap (C12 or C15). Edited by user Friday, March 25, 2011 6:35:41 PM(UTC)
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C22 C15 and C12 lifted and the short is there.
Oh well...
Since I am quite sure it was not the PS - it has to be ESD or DOA. Damn sensitive chip!! Quite unbelievable.. but I will go where the bread crumbs take me
Thanks to everyone on the board for helping me out. The outcome of all this not what I had hoped.. but I learned a few things along the way.
Back to my Opus.... and lay low until I can get over this $300 fiasco... :-)
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ouch... 
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Russ White wrote:Not sure what your asking, reverse the polarity of the power supply? Or of the DMM leads? What? Reverse the polarity of the power supply. Although the chips are sensitive to static, I find that in my environment, the TPA chips/boards are quite sturdy to manual manipulation. I recall once I accidentally reversed the polarity of the PS on an OPUS board and not seeing any thing turning on, I cut the power right away. LCDPS did get very hot and fortunately I did not burn anything. One question: is the avcc still working by itself (not connected to the board). That board still worths two tridents :-)
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@Will - Yep Ouch :-) Sometime these hobbies are expensive :-) Of course if Russ were generous.. I will leave the rest unsaid ;-)
@GLT - Avcc works. If I am not mistaken and reading the circuit right, reversing polarity would not have affected anything - the regulators would have prevented a catastrophe
ESD is one answer and I would like to believe that. At least that makes me feel better in one way.. that it was truly beyond my control. DOA is another answer but considering the there is not a single person who has any problem with any TPA product (except me - I haven't seen any single complaint about any TPA product on any board) - I sincerely believe that Brian tested it and when it left TPA - it was ok.
So. I take a deep breath - and continue with this hobby. This is the only one thing that keeps me going... and folks like you guys...
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I think I will let my generosity speak for itself. :) How much is my time worth to you (rhetorical don't answer)? I have spent at least an hour or two (being very conservative) helping you with only sporadic and sometimes wrong information coming from you certainly that is generous at least from my family's perspective. Your welcome, and no I don't mind. Connecting the power supply backward may not always kill a module, but it quite certainly can and most likely will! The regulators would not have protected you, because any protection diode will very likely blow with excessive current. Not that I am going to connect one up reversed just to prove the point. :) The only way it would not kill a Buf II is if the supply is current limited (and I mean very). Moral of the story never ever ever connect a PS polarity reversed. Your very likely to have damaged something. All you need to do is read the datasheet to see why its important to safeguard against ESD. This is especially true with DAC and DSPs with 1-1.2V VDD because they usually don't have much protection. You must take precautions when handling them. Sometimes DIY is as much Destroy It Yourself as Do It Yourself. I have made my share of $300 errors. I did not expect anyone else to cover them. Edited by user Saturday, March 26, 2011 6:07:05 AM(UTC)
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All of that said you should still know I do sympathize with you very much. I know it is a big bummer to have something like that go wrong. That is why I try so hard to help out when I can.
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Whoa there! Russ... I was just kidding.. Take it easy man! Yes.. thank you for spending the time to help me with this.. It is much appreciated dude and I think I have mentioned that several times in my posts. Don't know what I said that ticked you off. I now sure you noticed the ;-) Quote:So. I take a deep breath - and continue with this hobby. This is the only one thing that keeps me going... and folks like you guys... "you guys" means you too Russ/Brian :-)
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Rank: Administration
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I am not ticked off in the least, just making a point. I was just not sure how to take this: quantumpot wrote:@Will - Yep Ouch :-) Sometime these hobbies are expensive :-) Of course if Russ were generous.. I will leave the rest unsaid ;-) So no worries if you were joking. Actually good on you have having a sense of humor. Sometimes dry wit comes off wrong in posts. :) Cheers! Russ
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Heh heh - "Add Smiley" Section doesn't have ;-) and :-)
Take care.. you will see my order again in the next stampede! When has one problem stopped me...
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Buffalo Dac not powering up.. Drawing excessive current
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