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PostPosted: 16 Oct 2009, 01:19 
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Joined: 16 Oct 2009, 01:18
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Hi, I'm tinkering with an old subwoofer that came with a dvdset(Akai DV-3400SS), what i want to do is remove the amplifier and use it for another subwoofer, the problem is i believe it requires a b+ 10v power from a dvd to power on.
The small PCB that receives the 230v power cord has an OEG SDT-S-109LMR component on it(Power PCB Relay) which i suspect triggers on/off depending on whether that 10v line is present. I need someone to tell me if I'm right and if its possible to bypass this component to allow me to have it ON as soon as i plug in the power cord in the wall(without the dvd present)

I can't take pictures of the PCB's atm but if the need is there i can get some. Thanks

Here's a PDF i found on tyco electronics website.
http://www.tycoelectronics.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Customer+Drawing%7F7-1419125-9%7FC%7Fpdf%7FEnglish%7FENG_CD_7-1419125-9_C.pdf


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PostPosted: 16 Oct 2009, 11:39 
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Joined: 08 May 2009, 08:20
Posts: 918
Location: Duesseldorf, Germany
Hi Datenshi and welcome!

Yep - the relay on the pcb could be a "remote power on" circuit. Is there any "power on" switch at the subwoofer? Can you switch "on" the amplifier without the DVD connected? Can you see if the amplifier transformer has more than 2 secondary output leads?

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 16 Oct 2009, 14:12 
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Joined: 16 Oct 2009, 01:18
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Hello! and thanks for the welcome.

There's no On switch on the subwoofer, btw the Sub and Amp share the same "box", all the other speakers connects to the back of the subwoofer(making sure there's no confusion). I believe it only powers on if the dvd is powered on, the amplifier pcb says "B+/10v" on one solder point below the 9pin miniDIN socket in which you plug in the DVD. There's a green LED which indicates if the amp/sub is On, it never goes on if i just plug in the amp/sub to the wall socket. The transformer has 3 cables in it, on the TOP of the coil there's 1 cable(red+white+red wires) in the front, and 1 cable(yellow+black+yellow wires) in the back, then at the BOTTOM of the transformer there's 1 blue cable(2 blue wires) leading back to the pcb, tracing one of the blue wires going back to the pcb, it leads into the OEG SDT-S-109LMR, and the other blue wire leads to the blue wire on the power cable connected to the wall socket.


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PostPosted: 19 Oct 2009, 15:27 
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Joined: 08 May 2009, 08:20
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Location: Duesseldorf, Germany
Oh my, sry for the late response!

OK, you can bridge (shorten) the relay. That shouldn't be a heck. You have posted the relay datasheet... This shows a "Connection diagram". Take a look onto this scheme and you'll see a "coil symbol" and the "switch symbol" with an arrow, pointing to the switch (that's what you'll need).

What you could do now, is to cut off the "remote on" to get a "standalone" amp circuit:
Solder out the realy - and connect a power-switch (a mains capable type) , via wires, to the "mains HT" holes that are left. The "mains HT" connections are the two pins that are shown in the upper section on the "connection diagram" (datasheet - switch and arrow symbols). That would be the best way and you don't have to change the complete mains input section. The switch then is used as "on/off" switch.

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 07 Feb 2012, 18:35 
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Joined: 07 Feb 2012, 17:57
Posts: 1
Hi, I have a Sony MHC-S3 Hifi which no longer comes on. There's even no standby light at all. I can hear the hum from the small transformer so its not a fuse problem. I opened the unit and tested the power supply the other time. Power goes into the small transformer alright but there's no power going into the main transformer. I believe the small transformer activates the relay. I suspect the problem is with the relay (OEG SDT-S-109LMR) but I'm not entirely sure. Should the standby light come on even if the relay is not working?


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