Replacement Power for a 5.1 Speaker system

Guest

Hey

i bought a second hand surround system for my pc of TradeMe (New Zealand Auction Website) and the guy selling it said there was something wrong with the sub speaker.

anyway i got it a few days ago and found that the insides had caught fire obviously from a power surge, i replaced the diodes that caught fire and a IC that cracked. but when i tried to power it up the Power transformer got really hot within 20 secs and started to smoke.... That's not a good sign...

i know for a fact that i did not cause this but the previous owner did maybe from trying to get the thing going.

My question is, i cannot find any transformers that output the same power as this one it takes 220~240v input and outputs 12v~0.9A and 10v~1A

i can find a transformer that outputs either 10v or a 12 easily but not both Sad

jts1957 · Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away

BRAND / MODEL NUMBER

Guest · Posted: Mon Jan 19, 2009 7:11 am Post subject:

Ok sorry for the lack of information on the product

the brand is AVLabs and the Model No. is AVL320.
if you would like pictures i can supply them too

jts1957 · Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away

Hello,
I think I found actual auction site: http://www.trademe.co.nz/Computers/Peripherals/Speakers/51-5-speakers-sub/auction-196368915.htm

Auction photos (& some other sites I went to don't show power specs - can't even tell if has internal transformer or "Wall Wart")
Can you show transformer rating plate/info and plug (end view)?

Does each secondary of transformer feed it's own rectifier & regulator?

If diodes caught fire, are you sure you replaced with suitable replacements? Were location numbers on board and info on semiconductors still readable?

DeathlyKnight · Joined: 19 Jan 2009 Posts: 6

Yeah thats the one lol
whats a "wall Wart" btw?

yes this does have an internal transformer
here are pictures i took earlier:

[/list][/list]

jts1957 · Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away

Can you say "ouch?"
I hope the top of board cleaned up nicely and the other side of board is O.K. I notice board says "BLU BLU YE GND YE," (BLU looks more like green to my eyes) "??10V" and "AC13V*2". So I assume center-tapped secondary (YE GND YE) can be 12 or 13 volts at .9 Amps (or more).
I'll take a look (Online and through my junk box) and post again if I find anything similar.

A "Wall Wart" is a transformer (sometimes with a simple rectifier/regulator built-in) that plugs directly into the AC wall outlet (usually blocking at least one other outlet, especially if you plug it into a multi-outlet power "strip"). It connects to the unit it powers via a wire (usually with a "barrel"-type plug & socket.

DeathlyKnight · Joined: 19 Jan 2009 Posts: 6

ok thanks, i guess the previous owner tried to plug this in and get it going a few times because it feels like the wax around the copper has melted and thats whats causing it to short. thats why this gets very hot in in 20 sec...

I have a 15.2 volt transformer (thats what my multimeter reads out), is it possible for me to do a simple voltage divider (using resistors) and outputting 12 or 10volts to both inputs?

jts1957 · Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away

Remember your AC 12/13 volt winding is center-tapped. Usually so unit can get equal but opposite polarities of voltage (Plus & Minus 18 volts, for example).
Can't tell from your photo how D3, D4, D7 & D8 are connected, but suspect are either a 4-diode "Bridge" or Two full-wave for 12/13. Can't even tell how many or location numbers for diodes in burnt area.
If you can find the main filter electronlytics for each supply and connect a ohmmeter across each, there should not be any very low readings.

DeathlyKnight · Joined: 19 Jan 2009 Posts: 6

here is two pics which should show that the rest of the board is just fine

DeathlyKnight · Joined: 19 Jan 2009 Posts: 6