Thank you so much for your kind explanation. Your knowledge helps me a lot. Really appreciate it.Probably the capacitors although there could be other reasons. They are the three brown cylinders on the left of the board. They all eventually fail but I'm surprised they died so soon on a relatively new unit. Normally you would expect 5+ years before hum becomes noticeable. They are not expensive to buy and easy to replace.
I'm not sure where you are but my guess is you have 60Hz mains power at your wall sockets. That is the clue, the bridge rectifiers (the four gray things with silver bands at one end near where the yellow and green wires reach) convert the 60Hz AC into pulsed DC at a rate of 120Hz. The capacitors act as reservoirs to hold the pulses at a steadier level before feeding the voltage regulator circuit. If the capacitors become inefficient the reservoir holds less and the pulses start to show across them and then conduct to the rest of the circuit.
Brian.
Yeah I select 230, not 115In your picture there's no sign of problems in the electrolytic capacitors (bulging, leaking, etc). I actually would suspect a bad solder joint. Looks like everything was soldered by hand, and there are many pads without any solder visible. I would first touch up each joint with fresh solder to see if that fixes the issue.
Also if you're on 220VAC, I assume you set the selector switch to 230V, not 115V?
Actually looks a lot better from the bottom, at least every pad has solder on it. Hard to tell if they're actually good joints though.I disassembled the PSU again and took a picture of the back side of the board.
I think it looks terrible. Even tho I have literally no knowledge about it, I can feel it.. lol
Unfortunately high-end audio is an extremely predatory market. That power supply cost maybe 100$ at most to make. I'm guessing the mic was not much more.How could the PSU of 10000 dollars microphone be soldered like this?
Looks like the substrate is black, and there is no soldermask at all.Looks like the kind of PCB I would have designed by hand 50 years ago, but gold plated (or is the solder mask that color?) for show.
Substrate is dark green. Everything is so far apart soldermask is unnecessary.Actually looks a lot better from the bottom, at least every pad has solder on it. Hard to tell if they're actually good joints though.
Unfortunately high-end audio is an extremely predatory market. That power supply cost maybe 100$ at most to make. I'm guessing the mic was not much more.
The mic might actually work as well as the original u47. But $10K is still a ripoff.
Looks like the substrate is black, and there is no soldermask at all.
Hi,
instead of relying on smoothing capacitors only .. I´d rather use some voltage regulation / stabilisation.
But it depends on how you want to treat your device: for better quality or to keep the original circuit.
Kaus
Yes, this is one (popular) of many.Do you mean this kinda thing?
Anyone, who uses it should read it´s datasheet.Is it easy to install?
If you do an internet search about "voltage regulators" or "voltage regualtor circuit" .. i strongly recomend to keep on reliable informations fromI’m not gonna do it by myself, but studying is quite interesting.
Check if you are now connected to another socket differing from the one in the previous days, Many years ago I had a problem with an ECG equipment that exhibited noise artifacts only afternoon (perhaps due to some machinnery on the same building energy bus), and I solved it by adding a metal plate right below the PCB board, grounded to earth. Since your case is already metalic, you could check if there is a connection between the chassis and the ground pin on the power socket (with the appropriate safety care).I had used it with no problem, but a few days ago, a slight but noticeable hum noise occurred around 120Hz
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