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Showing posts with label MOSFET. Show all posts
Showing posts with label MOSFET. Show all posts

Monday 4 November 2019

#56 Apogee Ensemble Firewire teardown

[[[ Repair can be found here ]]]

This came up on eBay the other week as faulty - inputs 1/2 and outputs 1/2 seemingly dead. First instinct was, 'obviously', look up photos online in the hope of finding some internal shots. A few minutes later, bingo: four CS4272's in there. Now, what're the odds one of them is handling the bad pair of ins & outs? Quite a bit higher than the analog input of one, and the analog output of another to be bad, wouldn't you say? But let's not get ahead of ourselves (too much), and take things one step at a time...



Tuesday 14 November 2017

#25 Behringer ADA8000 "Ultragain Digital" revival

I got my hands on one of these Behringer Ultragain Pro-8 Digital a few months ago, as faulty (as in, totally dead) for about 50$ shipped. Having done some preemptive googling before going for it, i was expecting the transformer to be toasted. Sure enough, that's exactly what the problem was - one half of the center-tapped primary measured in the hundreds of kohm, so pretty much open-circuit (as opposed to the 50-odd ohms the remaining good half measured).


Initially i was planning on finding / getting a "drop-in replacement" toroidal transformer, ie. similarly sized physically and power-wise, but with less insanely-high secondary voltages. The stock one, according to some "inspection notes" i found online, seems to have had roughly 2x20VAC windings for the analog +/-15V (meaning the voltage regulators had to "burn off" uselessly much power / voltage), 12VAC for the 5V regulators, and a whopping 58VAC winding for the phantom power regulator. That's about a 50% overkill across the board. One can only wonder just what possessed them to spec the transformer quite like that, especially since it must've been a custom order - you'll rarely find retail units with more than two (identical) secondary windings, and when you do, expect to pay a pretty penny for'em.

Wednesday 26 April 2017

#6 Canon EOS 400D / Rebel XTi troubleshooting & repair

I got this old EOS 400D from a friend for about 35 bucks. She said it won't power on, even with a fully-charged battery. Might as well have a crack at it, eh?



On the outside it seems to be in pretty good shape. A bit of dust here and there, but hey, it's about a decade old, whaddya expect? Battery checks out fine, reading 8.15v, so that's definitely not it.


As chance would have it, between being offered the camera and receiving it, i did some digging around online, and i came across this little story here (scroll down to the second half of it). Could i (also) be fortunate enough to only need to swap out some fuses?

Wednesday 12 April 2017

#2 Amphion Impact 500 (DB Series DB5004) subwoofer amplifier autopsy (and repair, hopefully)


Right, so i've had this amplifier brought in last week (sans the subwoofer enclosure itself). When i noticed the brand, i remarked to the owner that, to the best of my knowledge, Amphion stuff is anything BUT cheap. He confirmed, this whole thing having costed him something over a grand(!!!), a couple years ago.


It had allegedly been serviced before, and he pointed at an electrolytic cap. A ChemiCon SXE - totally out of place on a board otherwise full of CapXons. Yep... Oh joy...