Problems putting hi fi back together

[Nick Armstrong]

Having disconnected and packed away the hifi during decorations, I set it back up today... and encountered two problems

1) hooking the amp and CD player back up to the speakers, there's a loud 'buzz' through the speakers when I switch on the amp. (even when the CD player's not switched on).

Any suggestions?

And for the dirty Mac brigade:

2) I can't get 'airport utility' on my Macbook Pro to recognise / detect the presence of my Airport Express.

I've followed Steve's excellent counsel from Christmastime:

you need to use the Airport express or extend an existing network....

First of all do a hard reset on your new AE. To do that you need to press and hold the small reset button, with a pencil or similar, until the light flashes very quickly a few times - that normally takes 5 seconds or so. The leaflet that came with AE should show you where that is.

Once reset set open the Airport Express Utility - that's in "Applications/Utilities/Airport Express Utility"

When you launch that you should see a box near the top left saying that a new device has been found. Click on that and you'll be able to configure the AE to extend your current wifi network - you'll be asked to enter your existing network password.

Once thats been been done launch iTunes. You should now see the square box next to volume control. Click on that and select Airport Express from the list of options. Once you've done that the square box will turn blue and sound will come out of your Airport Express.

If any of that isn't clear let me know and I'll post another message with some screenshots.

Ive just tried this - I have a spare Airport Express - so know it can work.

Hope that helps.

That did the trick in December... but can't make it work now.

Frustration reigns at Caliban Towers...

Any ideas, techies?

[PJPJ]

Having disconnected and packed away the hifi during decorations, I set it back up today... and encountered two problems

1) hooking the amp and CD player back up to the speakers, there's a loud 'buzz' through the speakers when I switch on the amp. (even when the CD player's not switched on).

Any suggestions?

Sounds like RCA phonos not seating fully. Or speaker cables not fully pushed into sockets......

[richardfinegold]

Sounds like RCA phonos not seating fully. Or speaker cables not fully pushed into sockets......

Agreed. I'm assuming that you are using an integrated amp and a CD Player that connects via analog outputs. Do you have another source that connects to the amp, such as a DAC, Phono Pre Amp, tuner (digital or analog), Blu Ray, TV, etc? If so, and if they don't have the hum, then you can eliminate the speaker cables connection as the problem and concentrate on the connection between the CDP and the amp.
If you are not using an integrated amp, but seperate pre and power amps, then you need to check the connection between them as well.

I would be less value helping you with the Mac, but at least try to reboot the Computer and make sure that you have the latest upgrades. You can at least call Mac Support if that doesn't help.
Keep us posted, I'll check back to see how you are doing.

[MrGongGong]

And for the dirty Mac brigade:

2) I can't get 'airport utility' on my Macbook Pro to recognise / detect the presence of my Airport Express.

Does it find other devices / networks ?

[jayne lee wilson]

Is the buzz the same all day? Or are there any new potential sources of DC on the mains? Many amplifier transformers will produce a buzz from DC - even the ones in my Isolation Transformers which improve the mains supply in other ways... they're doing it now a bit. Neighbourhood dinnertime again...

[Nick Armstrong]

There was only a buzz once before jayne but I had no recollection of why or how I solved it - normally there's nothing at all. And messages 2 & 3 above nailed it - yes, checking all connections at the back and removing the cable previously connected to a radio tuner (now removed from the system) has solved it. Thanks folks

Still can't get the Airport Express to talk to my Macbook - that's one for Sunday !

[Dave2002]

Don't know much about the AE, but sometimes linking devices together has a time window of one or two minutes. This isn't always very helpful if it's difficult to get from one location to another to establish the connection. Does the AE utility have to be turned on after the AE reset procedure? Does it always have to be off before starting this operation?

If not, then maybe open that first.

If it does, then go with the procedure posted by stunners, and try a few times to seem if persistence will nail it.

Mr GG's msg 4 hints that it might also be worth checking that your wi-fi is turned on on your MPB, and that the laptop is seeing the devices.
Mine doesn't always lock on to the obvious routers, and sometimes it takes a while, and sometimes turning wi-fi off and on works. Also, if you've moved things around,
it's possible the AE might be in poor location - though if it worked before it should still work, unless you've put a lot of
additional stuff in the way, to block the wireless "waves". Devices at floor level, behind sofas etc. probably won't work as well as in other locations.

[Dave2002]

Or are there any new potential sources of DC on the mains? Many amplifier transformers will produce a buzz from DC - even the ones in my Isolation Transformers which improve the mains supply in other ways... they're doing it now a bit.

What kind of physics is this? OK - DC could produce heat, but that by itself should not normally affect the transformers. I suppose if there is more heat than usual, then the cores could expand and become looser, and then vibrate due to the AC. Otherwise I can't see any way that DC should have an effect. DC levels would perhaps also have to be sufficiently high for that to happen, though DC current flow could be high with primary windings presenting close to zero impedance to DC. Seems unlikely though.

Sounds as though caliban's humming problems are now fixed satisfactorily, though I was going to mention that routing mains cables away from signals cables sometimes helps a lot, and that if it's necessary to put them close anywhere, that right angle configurations are better than side by side connections. That spare tuner cable may have been causing a problem - now removed.

[MrGongGong]

Sounds as though caliban's humming problems are now fixed satisfactorily, though I was going to mention that routing mains cables away from signals cables sometimes helps a lot, and that if it's necessary to put them close anywhere, that right angle configurations are better than side by side connections. That spare tuner cable may have been causing a problem - now removed.

Worth remembering, I've had the problem of technicians "neatly" taping down leads together only to find that they have taped a mains lead parallel to signal leads and that is the source of unwanted noise.
Induction is a powerful force

[Nick Armstrong]

Thanks Dave, and again Stunning Steve - AE all hooked up and ready to go. Rebooting everything (and opening 'airport utility' - I still have a mental picture of a van servicing the toilets at Heathrow - only after re-setting the AE) and following S's advice from December worked this time.

I agree Dave that there sometimes seems to be a random element to the way the MBP 'sees' the wifi network here - I have a main router at one end of where I live, but as there are several thick walls and a good few dozen yards between that and the back of the place, it needs an 'extender' half-way along. This has the same hub name and password as the main router, but with "-EXT" on the end of the name. As there are other flats around, there can sometimes be up to 10 other networks floating around. The MBP is set only to pick up my two - but sometimes, when moving from the front to the back of the premises, it doesn't; or locks onto some other; or pretends it's never heard of mine before and demands that the passcode be entered. After an 'incident' like that, it seems to 'learn' and settles down - but then at random one day will throw toys out of the pram again and need to be taught everything again.

However. All is currently operational

(Interesting side-discussion about cable-jumble effects!)

[Dave2002]

The MBP is set only to pick up my two - but sometimes, when moving from the front to the back of the premises, it doesn't; or locks onto some other; or pretends it's never heard of mine before and demands that the passcode be entered. After an 'incident' like that, it seems to 'learn' and settles down - but then at random one day will throw toys out of the pram again and need to be taught everything again.

FIrstly, glad you've made progress and got things fixed.

We've had a few "incidents" where we've been asked to put in a passcode again over the last few months. In our area there is perhaps a low probability of external interference, though we can "see" easily routers from at least two other properties. Being very cautious I don't immediately put in the passcode, and often the problem does fix itself without my having to put in a passcode again. This is probably more of a problem with portable devices, and seems to occur more when a portable device has migrated away from one of the routers for some time. Usually bringing devices back within range eventually fixes the problem without confirming the codes.

I am extremely wary of re-entering any codes or passwords, as I'm sure that there's malware which is designed specifically to pick up codes, possibly for later use. Having said that, I have had to do that sometimes to get things fixed, but it's not the first thing I try. As we normally have two different wireless networks running, I can tell you that normally the devices are very capable of switching between them according to conditions, or if we want to force a device onto a particular network, for example to access a particular printer or scanner, or to check internet connectivity, or to balance loads, and they do this without requesting codes again.

There is very rarely ever a real need to re-enter codes which were set up some while ago in any of our devices.

You can call me paranoid if you like, but I would recommend thinking about your actions each time you are asked to re-enter any password which your systems should already have stored. Don't rush into action.

[Nick Armstrong]

often the problem does fix itself without my having to put in a passcode again.

Yes - of late, I usually don't, but out of laziness! I prefer to restart, which usually resolves it.

Indeed, since the new BT Infinity network arrived here 3 weeks ago, haven't once done a password re-entry, I don't think. Now that we have a brand new network with new codes, I shall be more careful in future!

[jayne lee wilson]

What kind of physics is this? OK - DC could produce heat, but that by itself should not normally affect the transformers. I suppose if there is more heat than usual, then the cores could expand and become looser, and then vibrate due to the AC. Otherwise I can't see any way that DC should have an effect. DC levels would perhaps also have to be sufficiently high for that to happen, though DC current flow could be high with primary windings presenting close to zero impedance to DC. Seems unlikely though.

Sounds as though caliban's humming problems are now fixed satisfactorily, though I was going to mention that routing mains cables away from signals cables sometimes helps a lot, and that if it's necessary to put them close anywhere, that right angle configurations are better than side by side connections. That spare tuner cable may have been causing a problem - now removed.

http://www.isol-8.co.uk/dc-on-the-mains.html

Just one of many references via google... the subject DOES tend to cause a lot of disagreement!
At a property inspection the other day my electrician said he couldn't get rid of a buzz on the corridor's fire alarm system because of... mains DC.