Forums

HI All, After a long hiatus, I finally got back around to trying to spin up my CFA3 (rev 1.2) boards. After letting the magic smoke out of the output resistors a couple of times, replacing them, backtracking a few things / posts etc I finally got 1 side of one board to the reasonable point from both a dc offset and bias perspective without letting the magic smoke out. The other side of the board is still way off on DC offset (.4v) but nothing is smoking, so before I started probing that side of the board, I decided to plug my other one in to see where it was at. After backing off all the pots and then plugging it in, the output resistors immediately went nuclear on one side. I de-soldered them and I think the heat from the meltdown coupled with me de-soldering those resistors a few times now weakened the copper traces on the board and I have now lost a couple of pads on the output resistors. I know I could make a fairly simple repair to try and get it working at least for proof of concept but coupled with the other issues I am having with the board I think it may be time to start from scratch rather that de-soldering all the transistors etc on the board and swapping them out trying to find the core issue.  Does anyone have any headphone boards they can sell? I would either look for a single replacement 1.2 board or look for a pair / quad (?) of later boards and make a new complete pair. If anyone can assist, please dm me. I am based in the US but happy to pay freight from OS if needs be.  Cheers, Ben 

Yes Grahame. But, all of them involves instering things into urethra, well at least they use local anesthesia. As he told me there are 2 options; one uses shockwaves and one uses laser to crumble the stones. Can't remember the medical terms, it was really hard to focus on things he said after "we insert things into your urethra". Still I cannot make up my mind on getting the operation ASAP or wait, take better care of myself, drink yoghurt and pickle juice, as my father advised. Doctor thinks both help for passing them out and reducing the chance of clumping as well. It shouldn't be a big deal, just it seems it is just the begining to me. "More coming soon!" Dunno maybe I should be less dramatic about some teeny-tiny stones.   Damn "Transurethral cystolitholapaxy" sounds like name of a grindcore/goregrind song. But yea, that is the procedure he advised.

More than I wanted to know, with some long words ("Transurethral cystolitholapaxy") clearly explained  Bladder stones - Treatment - NHS https://www.nhs.uk/conditions/bladder-stones/treatment/ Did they say what your treatment options were, and tradeoffs / preference. Hoping for an outcome that works for you.

It’s a pretty ingenious design. It takes advantage of the fact that a cold filament draws more current than when it’s hot and thermally stable. The circuit outputs 2.5V by default at no load in case someone does a hot-plugging. An 2A3 draws more current than 2.5A when cold, and gradually drops down to 2.5A. The output is maintained at 2.5V. If it’s a 300B instead, the current would drop further, say, below 1.6A. The circuit would then switch to 5V, and the threshold also doubles to 3.2A. There could be some brief back and forth, but as the filament gets hotter, the current will drop further towards 1.2A while the circuit stays at 5V output. It should be okay for a DIYer to build a clone for his/her own use, but integrating the same in a “DIY” unit that sells for an atrocious price at “the marketplace” would probably be a different matter.

Patrick Leonard - It All Comes Down to Mood