Your Digital Media Has Never Looked So Good

 
jgtec
Posts: 11
Joined: Wed Aug 04, 2010 6:53 am

Re: PSU Dissected for Repair

Thu Aug 05, 2010 2:51 am

Les,

Thanks for that, I will build a separate, regulated 9V supply then. I have a suitable abs box with an aluminium lid somewhere, just need to find it!

Will let you know how I get on. Hopefully I'll get time to have a go at this over the weekend.

Cheers, John
Cheers, John

2 x M1001, 3 x M500 and 1 x ailing RB1000
 
jgtec
Posts: 11
Joined: Wed Aug 04, 2010 6:53 am

Just when I thought I knew what I was doing......

Fri Aug 06, 2010 10:41 am

Hi!

Have got my 9V regulator circuit all working just fine, but now I have a question about the 19V.

I have a 19V 'DC' laptop power supply that is rated for 6A that I was going to use. However, when I measured the AC ripple I got 40V! Same on a second one of these supplies that I have. What's going on? Many other posts have talked about using laptop supplies so I am confused.

Is what I am measuring a problem or should I just ignore what I have measured and wire it all up?

Cheers, John
Cheers, John

2 x M1001, 3 x M500 and 1 x ailing RB1000
 
S80_UK
Posts: 1035
Joined: Wed Oct 25, 2006 3:11 am
Location: Cambridgeshire, UK

Re: PSU Dissected for Repair

Fri Aug 06, 2010 4:46 pm

Hi John,

Some laptop supplies are very noisy - especially cheap ones.

Was this loaded or unloaded, and at what frequencies was the noise that you measured. Also, were you measuring between positive and negative or relative to somewhere else?

Les.
Roku M1000, M1001, M2000, R1000, Roberts WM-201, Stream 83i
 
jgtec
Posts: 11
Joined: Wed Aug 04, 2010 6:53 am

Re: PSU Dissected for Repair

Sat Aug 07, 2010 1:55 am

Les

Hi! The first two PSUs are Maplin "Universal AC Adapters" that I have around the place. I also tested the adapter on my new Dell laptop which also happens to 19V and this gave the same measurements. I have measured with two different makes of DMM, both gave similar readings. Both loaded and unloaded.

Just thinking out loud.........I have no idea how DMMs derive their AC voltage readings, but I guess they are designed for the 50Hz region, so maybe a smaller amount of much higher frequency noise (10s of KHz from a switching supply) could mess up the reading? I will see of I can borrow an oscilloscope and have a look at what's actually there. Also I might play with a few capacitors to see if I can reduce the AC figure, which I am now thinking is not quite what it appears to be.

Maybe this is just a measurement problem.

Anyone else care to measure the 19V rail of their working Radio that has been adapted to use a laptop supply using the AC setting of a DMM? I'd be interested to see what measurements you get.

Cheers, John
Cheers, John

2 x M1001, 3 x M500 and 1 x ailing RB1000
 
S80_UK
Posts: 1035
Joined: Wed Oct 25, 2006 3:11 am
Location: Cambridgeshire, UK

Re: PSU Dissected for Repair

Sat Aug 07, 2010 5:26 am

Hi John,

So how did you use the AC setting - with an in-line capacitor? If so then you measured noise, but as you suggest it would be heavily skewed by frequency components that the meter was not designed to deal with. If you measure 19v DC I would be happy to connect the supply. If you did not use a series capacitor when taking an AC measurement, then it is impossible to say what the reading would or should be, since the AC range on the meter is not almost certainly not designed to measure an AC component with a large DC offset.

Les.
Roku M1000, M1001, M2000, R1000, Roberts WM-201, Stream 83i
 
jgtec
Posts: 11
Joined: Wed Aug 04, 2010 6:53 am

Re: PSU Dissected for Repair

Sat Aug 07, 2010 11:03 am

Les,

Hi! That all makes sense, thank you.

I will look at what I have with a 'scope if I can next week. What value capacitor should I use with the DMM?

I have taken the plunge and connected it all up and on came the display. I then connected it to my network and played a track, but I only got the subwoofer sound, the speakers in the front of the unit are not emitting any sound. I guess that I need to get inside the front enclosure.........

I can see a large number of screws on this front piece but I am unsure how to procede. Is there a post detailing how to get into the front section? I have had a look but could not find anything. I'll keep looking in the mean time.

Cheers, John
Cheers, John

2 x M1001, 3 x M500 and 1 x ailing RB1000
 
jgtec
Posts: 11
Joined: Wed Aug 04, 2010 6:53 am

Opening the front section

Sat Aug 07, 2010 12:10 pm

Hi!
Just found this excellent set of photos on how to take the front section apart.......

http://www.flickr.com/photos/aaronferru ... 782154756/

Cheers, John
Cheers, John

2 x M1001, 3 x M500 and 1 x ailing RB1000
 
S80_UK
Posts: 1035
Joined: Wed Oct 25, 2006 3:11 am
Location: Cambridgeshire, UK

Re: PSU Dissected for Repair

Sat Aug 07, 2010 1:35 pm

jgtec wrote:
I will look at what I have with a 'scope if I can next week. What value capacitor should I use with the DMM?

If you're really determined to measure it (I don't think I'd be that bothered at this stage, then assuming a DMM has a high input impedance, you should be able to use something around 1 microfarad at a guess. 0.1 microfarad would probably be close enough in this context. It should be a non-electrolytic type, and when taking the measurement allow a short time for the reading to settle since the capacitor will need to charge to the 19 volts through the meter. Also, given the high impedance of the meter, don't hold it all together with your fingers - that will skew the reading.

Les.
Roku M1000, M1001, M2000, R1000, Roberts WM-201, Stream 83i
 
jgtec
Posts: 11
Joined: Wed Aug 04, 2010 6:53 am

Re: PSU Dissected for Repair

Sun Aug 08, 2010 2:26 am

Les,

Thanks for the info. Yes, definitely no practical use at all in measuring it now, but I will all the same so that next time I'll hopefully remember what to do properly.

Cheers, John
Cheers, John

2 x M1001, 3 x M500 and 1 x ailing RB1000
 
Steggl
Posts: 5
Joined: Fri Aug 15, 2008 2:37 pm

Re: PSU Dissected for Repair

Mon Aug 23, 2010 6:51 am

Did anyone (in Europe, Germany) try this (http://www.mercateo.com/p/108EL-163(2d)467P/Schaltregler_R_78B9_0_1_0_9V_1A_Herst_Teile_Nr_R_78B9_0_1_0.html) one already to step it down to 9V?
It looks pretty similar to the other one that is supposed to work (http://search.digikey.com/scripts/DkSea ... 02-1717-ND) and is probably not smart enough :wink: and could withstand the volatge surge when starting it up.
 
Steggl
Posts: 5
Joined: Fri Aug 15, 2008 2:37 pm

Re: PSU Dissected for Repair

Mon Aug 23, 2010 7:09 am

Now THIS (http://www.netzgeraet.de/index.html?net ... eil_9v.htm) sounds like a good idea in conjunction with a laptop power supply. Any opinions on that (sorry for it being in German)?

Image

Platinennetzteil einstellbar 5V 9V 12V 15V 18V 24V Untergruppe: 12V Netzteil 12V Gleichspannung und vielen weiteren einstellbaren Spannungen mehr. Universal Gleichspannungsnetzteil mit vielen einstellbaren Spannungen. Schaltnetzteilplatine einstellbar von 5...24Vdc max. 1,5A. Dieser Netzteil Baustein eignet sich vorwiegend zur Spannungsversorgung von Baugruppen, Geräten, Steuerungen aller Art und auch zur Speisung von LED Beleuchtung (z.B. 12Vdc oder 24Vdc) geeignet. Das Schaltnetzteil zeichnet sich besonders durch die stabilisierte Ausgangsspannung unabhängig von Netzspannungschwankungen aus. Gegenüber herkömmlichen Netzteilen hat dieses Netzteil einen hohen Wirkungsgrad (bis zu 85%), und ein wesentlich geringeres Gewicht sowie kleinere Abmessungen bei gleicher Leistung. Es stehen 6 Ausgangsspannungen zur Verfügung die mittels Jumper eingestellt werden können.


Technische Daten: Eingangsspannung: 230Vac 50..60Hz / Ausgangsspannung: 5V / 9V / 12V / 15V / 18V / 24V Gleichspannung / Ausgangsstrom: max. 1,5A / Abmessungen: (LxBxH) 90x60x45mm / Gewicht: ca. 115gr. Anschluß über Schraubklemmen. Offene Bauweisse.

18.95 EUR
ab 5 Stück: 17.95 EUR
ab 10 Stück: 16.95 EUR
Artikel-Nr.: 93-808-01820
 
DJans
Posts: 122
Joined: Tue Jun 20, 2006 7:06 am
Location: Germany

Re: PSU Dissected for Repair

Mon Aug 23, 2010 11:33 pm

English translation in some words:
-) Universal Switching power supply
-) Output can be set to 5V 9V 12V 15V 18V 24V
-) Output current 1.5A
-) Power Efficiency: 85%
-) Size 90x60x45mm
-) Weight 115gr

But remember for the US: :(
-) Input 230 VAC, 50-60 Hz
 
DJans
Posts: 122
Joined: Tue Jun 20, 2006 7:06 am
Location: Germany

Re: PSU Dissected for Repair

Mon Aug 23, 2010 11:51 pm

And additional:

I have rebuild a lot of R1000s to external 12V switching power supplies. It was not easy to find switching PSUs but I have found very good ones one year ago that work without any distortion (sold out now but I have some of these still here). The result is very good and in future if the PSUs fails it is only necessary to replace the PSU without disassembling the unit. All the people who use these units are very happy.

I add an additional ferrite coil inside to eliminate possible distortions from the PSU. Moreover I replace the removed internal PSU by a piece of fake sound proofing so that the volume of the woofer box and the sound is the same as original.
 
Steggl
Posts: 5
Joined: Fri Aug 15, 2008 2:37 pm

Re: PSU Dissected for Repair

Thu Sep 30, 2010 4:43 am

Thank you very much guys. I exchanged the capacitor yesterday thanks to your how-to and now she's back to life. Man, I did miss her :D
 
Steggl
Posts: 5
Joined: Fri Aug 15, 2008 2:37 pm

Re: PSU Dissected for Repair

Sat Oct 02, 2010 2:12 am

F*#%! :evil: Looks like my hopes were set to high. When the WiFi starts up it usually hangs or forces the Soundbridge radio to reboot. Maybe the soldering points weren't as good as I though..!?

Did anyone have similar experiences while working on his Soundbridge?

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