Pioneer Speaker Package subwoofer transformer.

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

Hey Guys,

I have opened up the transformer end cap and cut away the tape and insulation to find the thermal fuse. See photos attached.

I checked with my DMM and good news is that the fuse is definitely open. However, I checked direct onto the primary windings past where the fuse is soldered and I get an open circuit there too

The only way I get anything in range at all is to go to the 2M Ohm setting on the meter so I am pretty sure that's not right.

madan1, I will take the pics you asked for and upload them next.

Thanks again.

[madan1]

Re: Pioneer Speaker Package subwoofer transformer.

Make some pics of the bottom of the main pcb and the amplifier component ( from the pins look like a single-chip-solution ).

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

Thanks for the tip Khron.

I figured that might have been the case. 'Adventure' is my middle name so I will give it a go. Absolutely nothing to lose by trying that out.

I checked online at my local electronics outlet and they have thermal fuses at 77 and 133 degrees C. The transformer lists 105. To me that seems a little on the low side. Any opinion about moving to a higher fail temp ?

Thanks again. I will post the outcome of my 'open transformer surgery' when I have it on the operating table.

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

Thanks madan1.

The big caps are 50v 4700uF. I thought that too but at 50v it probably still leaves options of 12-0-12 to 48-0-48 so I didn't rely on that.

Yes, it sits in standby until it receives a low frequency signal and then it turns on. Feature of convenience I guess. Makes troubleshooting a bit more difficult though.

I agree with you, not a big fan of power saving. Have seen it cause many problems.

[Khron]

Re: Pioneer Speaker Package subwoofer transformer.

If you have no continuity on the primary, odds are pretty good the thermal fuse went "poof".

If you're feeling cheap and/or adventurous, you could try gingerly cutting through the outside insulating tape, around the area the mains wires are - the thermal fuse is usually not buried too deep. Either bridge it, or replace it with a similar-rated one.

Do note that if you choose to replace it, the connections will need to be crimped, not soldered (due to it being a THERMAL fuse, y'know? ).

[madan1]

Re: Pioneer Speaker Package subwoofer transformer.

+/-12V stand by which should not be affected by the big transformer fail
check the main caps ratings.. for sure the V is somewhere there, but not more

My guess is that the big transformer is used only to power the amp section. Everything else is powered constantly by the "stand by" board ( screw the power saving ).

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

Thanks for getting back to me eccerr0r.

1. The dimensions of the transformer are: W80mm x H70mm x D95mm. Weight is about 2kg.

2. Photos are attached. If you need anything in more detail please let me know. I have a shot of all components for reference, power board and amplifier board.

3. It is rated at 180w with a 6.5" down firing speaker.

Thanks again.

[eccerr0r]

Re: Pioneer Speaker Package subwoofer transformer.

Three things... first off if you can measure the size of the transformer, you can get a good guess at the volt-amps or watts the transformer can handle.

Then the other thing is show a good picture of the rest of the board, maybe someone can stare at the board a bit and make an educated guess at the voltage of the transformer. The 24V is a good guess from the relay, but maybe more clues can be gotten from the topology of the board, capacitors, zeners, etc.

With the voltage and the volt-amps a current rating can be estimated.

Third thing is how many watts this amp/speaker rated to handle? What's the rating written on the panel?

[bamix]

Hey Guys,

I wasn't sure whether to post this in Audio or in Power Supplies.

Looking for some advice on a failed speaker package subwoofer. This Pioneer unit from a cheapo S-HS50 kit that came with my AVR dropped its lunch a while ago. I have pulled it apart and carried out some basic checks and it looks like the main transformer has failed.

I have 240VAC going in and nothing at all coming out. It has 3 wires coming out, 2 Yellow and a White at centre. I figure it is a centre tapped transformer but it has no marking or labelling on it at all that indicate what it is. I even pulled the end covers off and there was nothing inside there either. I have attached a picture for reference.

It only has an SF logo in a diamond with a part number below, SF-76E/282128E. Beneath that it says (Thermal Fuse Fitted 0115C).

According to my DMM I have no continuity on the primary (240V) side and I do have continuity on the secondary side between each Yellow and the central White wire.

So my question is, if there is no output and no labelling, how do I work out what the specification of this part is ?

I can't locate a repair manual on the subwoofer, the board number draws a blank too. I checked for anything screen printed on the board that might help. The only thing that was of any worth was a Bestar IC Relay BS-115C that is running a 24VDC Coil. Might this indicate that the transformer I need would be a 24-0-24 ?

I know it's a cheap, low level, poor performing sub but I just want to get it working again. So if anybody could humour me with some advice I would appreciate it