Weird intermittent hum from phono stage. Ideas?

As I understand ur post - u switched the kit off when no hum and later switched it on without u moving cables and hum was present . So it’s an intermittent fault with an item which is switchable ( not movable wiring ) even possibly related to the actual switch body bring loose . Be lucky and it’s easy to fix .

That’s right. Dunno which switch it could be though, it’s deffo emanating from the 401, whether it’s switched on or off (from the turntable switch, it goes when the turned off at the mains).

Hopefully the electricity witch has gone away for a while now to torment someone else.

Have you checked the mains cable earth/wiring. No idea why it might be a cause but must be worth discounting.

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Not yet, but worth a try.

Hum is back. :roll_eyes:

Time to start swapping cables out, then if that doesn’t work, some deeper fault finding. Deep Joy.

Not cables. And now if I power off the 401, the hum is still there, which is weird because last time it went away :thinking:

I think it might be the wall wart PSU for the Pro-ject Phono stage, I moved it to another socket and the hum decreased a little.

Sounds like an excuse to upgrade to a linear power supply :+1:

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Get your house rewired.

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The PSU output is 16v 1A. Just swapped it with a 15v 1000mA (surely 1000mA =1A? Why would you describe 1A as 1000mA? Strange.) and the hum is still present, but at a higher frequency.

Sigh.

I’ll try my Angle stage again, but I will have to switch the WiFi off because the Angle picks it up loud and clear.

Thinking back, I seem to remember having to replace a power rail filtering capacitor in my Pro-ject Phono II. It might have failed open circuit, which is the sort of fault which can develop intermittently, although in my case it hadn’t - there was just a deafening buzz when I turned the rest of the system on one day. Do you normally leave the Phono box constantly powered up ? Electrolytic capacitors are among the few components which have a design lifetime. If they’re operated at full voltage and full temperature then that can be just a few thousand hours (as few as 2,000).

VB

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I do leave it turned on Graeme, because it’s a pain to turn it off due to the sockets being behind the rack (no off button) and was just thinking something has gone pop in it because of that.

Just waiting for the battery in the Angle to charge up now, if it doesn’t hum, then I might have found the culprit.

Ok so unplugged from the mains everything apart from the amps, tt and Angle phonostage. There’s a miniscule hum, but I think that the Angle always had that as it trickle charges its battery. Doesn’t change as I move it around.

Plugged in each component and there’s maybe a tiny bit more hum, coming from the CD player, but nothing like what the Pro-Ject was picking up. and that hum does change/disappear as I move the stage around.

Think it’s the Pro-Ject then. Bugger.

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Would it be one of these tiny black things Graeme?

Have you tried a different house?

If you need something to test against the phono stage you have, give me a shout. I even have nice linear power supplies.

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Nope, they’re semiconductors or resistors depending on which tiny black things you had in mind. In my case the failed component was one of those biggish cylindrical things that we’re looking down on, between the twisted pair of wires and the multicoloured ribbon cable in your photo. They have a blue and grey plastic sleeve with, among other things, 25V 1000uF printed on it. There may be other similar devices on the board and if there are then it might be one of those rather than the ones in your pic. Of course it might also be something else - there will be a bunch of these capacitors in your wall wart for example.

VB

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A different person, e.g. someone who doesn’t have the word “potato” in their tagline, might have taken pics of the whole fucking thing-that-might-be-faulty, and not just one corner of it…

facepalm16

Not that I care or any, I wouldn’t want any ugly rumours starting…

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Ok, the big Blue caps don’t look like they’re bulging or anything, although I know that doesn’t prove anything. I tried a different wall wart with it and it still hummed, but at a slightly different frequency.

I have no way of testing them, so it’s going to have to be given to a grown up to look at.

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I took a pic of that corner because that’s the bit that the power socket is wired to, and the tiny black cylinders are the first thingies soldered to it. I know the bigger cylinders are capacitors, I just wasn’t sure if the tiny ones were too…

Anyway there’s pretty much bugger all else in there to see.

I might take you up on the loan Bob, I can’t use the Angle long term because it picks up interference from the WiFi, and if I had to turn the Internet off every time I wanted to play a record, there would be hell to pay from the womenfolk.

Otherwise it’s mm only through the Arcams built in phono stage. If that’s the way it’s going to be, I think I’ll just swap the Technics into the system, because I really can’t face having to set the Transfiguration up again when the Pro-Ject is fixed.