Electrical testing

bluenose1940 · June 7, 2020

Hi folks, I have a set of Bose speakers attached to my computer and they appear to have stopped working. I have had them connected to my laptop and my Samsung Tablet and there is still no output.

I have checked the fuse at the mains socket end and that is OK (it's a 1amp jobby) and I am now wondering if there is any way that I can check to see if the power is actually getting to the speakers.

At the mains socket end there is the usual 'transformer' type box and the end that goes into the speaker is a jack plug that is about 3mm diameter. it's the same sort of plug that's on the end of apple headphones. Can I check for electrical output by using a multimeter and if so can anyone tell me what bits to 'touch' with the black and red pins and what setting the meter should be on?

Many thanks in advance of any help/guidance offered.

Britprius · June 7, 2020

Hello Geoff.

Set you meter to a DC voltage range of around 20 volts or whatever is close to that. With the power supply plugged in and turned on connect your meter probes to the two terminals on the jack plug "it does not matter which way".
The meter should read the voltage output of the power supply "usually marked on the power supply". You may get a negative reading. Swapping the meter probes will correct this.

Any problems let me know.

John.

bluenose1940 · June 7, 2020

Thank you John for your guidance on this. I have done the test and there is no reading at all. As I say, I have checked the fuse and that is all OK and so it must be the 'plug/transformer'

I have a similar 'transformer' on another device and have noticed that these type of units get warm in operation and, the one I have tested is stone cold. I imagine that it is not a repairable item and so I will either have to source a replacement or it's bye bye speakers.

Do you know if you can buy replacement units or even get some sort of alternative?

Thanks again.

Geoff

ColinBarber · June 7, 2020

Should be possible to get a generic power supply that will work. What are the rating written on the transformer DC voltage and current? Post a picture if possible.

bluenose1940 · June 7, 2020

Hopefully this image will be clear enough to see what it is. If not I will re-take the shot.

Thank you.

steve2006 · June 7, 2020

Looks like 12VDC 1500mA ?

Post a picture of the plug that goes into the speakers, it looks like centre positive usually 2.5mm

I think I may have a suitable replacement you can have for the postage cost.

Or this will do the job

https://www.ebay.co.uk/itm/12V-Replacement-Power-Supply-AC-Adapter-For-Bose-Companion-2-Series-II-Speakers/232182598370?hash=item360f294ae2:g:d4YAAOSwB09YKepv

bluenose1940 · June 7, 2020

Hiya Steve, Thank you for your link. My speakers are the Bose Companion 2 series III (as opposed to the Series II shown in your link).

The only difference between my original power plug and the one for sale in your link is that mine shows as 12v - 1800mA and the one in the link shows as 12v - 2000mA.

Does that small difference matter?

Britprius · June 7, 2020

1 hour ago, bluenose1940 said:

Hiya Steve, Thank you for your link. My speakers are the Bose Companion 2 series III (as opposed to the Series II shown in your link).

The only difference between my original power plug and the one for sale in your link is that mine shows as 12v - 1800mA and the one in the link shows as 12v - 2000mA.

Does that small difference matter?

Geoff. Sorry for not getting back sooner.
The 2000ma rating is better than your 1800ma rating. It is the 12 volt that matters. If you have an old internet router power supply these are usually rated at 12 volts.

John.

steve2006 · June 8, 2020

As long as the connection plug is the same it will be fine, the plug is known as a barrel connector with a hollow centre pin connection usually 2.1 or 2.5mm in diameter.

Good idea with the old router PSU John we all tend have one knocking around somewhere.

bluenose1940 · June 8, 2020

Always the same isn't it, I only threw an old router out about 2 weeks ago! Ah well, I'll have a scout around to see what I can pick up.

Many thanks indeed to all who have offered help/advice.

bluenose1940 · June 9, 2020

I have managed to get hold of a couple of power units which hopefully will solve my problem.

The first one is showing as 12v 0.3A L.P.S. and the second reads 12v 1.0A

Which should I use do you think?

Many thanks.

EDIT - 10.44am 10/06/20 All working fine again now chaps. I used the 12v 0.3A power unit. Thanks for all the help given. Very much appreciated as always.