Pioneer Speaker Package subwoofer transformer.

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

budm,

I tried the test using a 60W incandescent lamp in series. I think perhaps my connections were not solid enough but it didn't seem to work, that is the lamp did not appear to light at all.

I checked with my meter and found that I had 240v available at the Blue and Brown wires but nothing showing at the winding ends again.

I was worried that the windings had failed and was packing up the test gear when I noticed that the incandescent light globe was quite warm to the touch. So I substituted it for the lower wattage Philips LED lamp and tried again and it worked. I attached a small video as a 'rar' file for reference.

From this result can I presume that, for now, the transformer will be OK if I proceed with replacing the Thermal Fuse ?

Thanks in advance. I do realise that you must be very busy and appreciate your kind efforts.

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

budm,

Apologies but I missed your post regarding the sub model. I don't know that it has a model number. It was part of the Pioneer Speaker Kit boxed up as S-HS50 that was bundled with the AV Receiver I purchased, a VSX-522.

I can only find any information on line where people tried to sell them off, nothing either from Pioneer themselves or any technical data. Here's a link as an example.

I have since changed the centre speaker for a larger Klipsch unit and although it is all entry level gear it does alright for my application. Mind you, all my kids think I am going deaf .......

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

madan1,

It is TDA7293.

Hope that helps.

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

Thanks budm.

Yes, so in series as:

* Blue Wire -> Lamp -> Blue Wire -> Winding End 1
* Brown Wire -> Winding End 2

and Thermal Fuse is no longer in the circuit.

Lamp on the neutral side should be OK I think. DC is my favoured current.

[budm]

Re: Pioneer Speaker Package subwoofer transformer.

What is the actual model number of this Pioneer sub woofer?

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

You are right madan1.

I couldn't see anything with my naked (failing) eye but I looked at the original pic and can make something out. I will try and get a better image to confirm.

Give me 20 minutes

[budm]

Re: Pioneer Speaker Package subwoofer transformer.

The incandescent lamp will limit current, if the transformer has shorted winding the lamp will light up brightly. 60W incandescent lamp will be fine, it has to be incandescent lamp.
The lamp is connected in SERIES with the primary winding of the transformer.

[madan1]

Re: Pioneer Speaker Package subwoofer transformer.

Well, that's a surprise... I've heard about companies erasing the chip labels, but did not expect it from pioneer.
Anyway, from the pinout and the form factor, this looks like tda7294 to me and according to the documentation - everything supplying between 10 and 40 volts should do the work.
My guess is that they have been aiming at 40 volts after the rectifier bridge.


ps. just got a second look at the image and I swear I can see the ST logo and some part of the TDA label. Can you check again what's the label?

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

madan1,

Please see attached pictures.

I hope they cover what you are after. There is basically one IC connected to the heat sink. I took the holding bracket off too but there was no information on that side of the IC. The board is only screen printed there as IC21.

Let me know if there is something else you would like.

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

budm,

I have a test socket that takes bayonet cap lamps but smallest I have available here is 60W. Is that going to create too much current draw for the test and potentially damage the primary side ?

I also have one of those Philips LED replacement globes for bayonet socket but it is 11W only.

Will either of these suffice ?

[Agent24]

Re: Pioneer Speaker Package subwoofer transformer.

Don't worry about what I said, since the primary is fine, the fuse probably just failed from old age.

[madan1]

Re: Pioneer Speaker Package subwoofer transformer.

You are welcome , but I still insist on the pictures of the amplifier.. call it curiosity .
To me it looks like stk or something.. and since it is power directly from the main caps, the V will be easy to find in the documentation.

[petehall347]

Re: Pioneer Speaker Package subwoofer transformer.

them damn things confuse me .. well they did for a few minutes .. i do this to find secondary voltages to order a new transformer .. new thermal fuses work sometimes if transformer is good ...
other factors blow them too like over-current on secondaries . thermal fuses are to protect against fire ... sometimes they wear out with old age same as regular fuses ...
always safety first .. use a current meter whilst testing and test for a few days ...

[budm]

Re: Pioneer Speaker Package subwoofer transformer.

Leave the secondary of the transformer not connected, then use 40W lamp in series with the primary to power up the transformer (the thermal fuse bypassed) and see if the lamp will light up brightly or not.

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

Thanks so much everybody for your kind consideration.

petehall347, you were right.

This time I checked at Blue and Brown and then used an alligator clip to join the 2 legs of the fuse together. Clip off = Open, Clip on = OK.

I will order 5 of these as replacements.

Hopefully the issue doesn't go any deeper than this one problem. I was concerned too as agent24 made mention about a consequential failure. madan1, if I still have any issues I will post the pics you made mention of. In that area I found some suspect solder joints on the board under magnifying glass so I touched them all up with the iron. I trust they are OK.

Thank you

Благодаря

Kiitos

[madan1]

Re: Pioneer Speaker Package subwoofer transformer.

madan1,

Pics requested of underside of the Power Board (IMG_3251_small.jpg) and Amplifier Board (IMG_3252_small.jpg) are attached.

Thanks.

and some of the components attached to the radiator

[Agent24]

Re: Pioneer Speaker Package subwoofer transformer.

Maybe the transformer went shorted in the primary winding and blew itself as well as the fuse.

Or it could have been failing open-circuit, which would generate excessive heat.

[petehall347]

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.

maybe it confused you like it does to me ..twist fuse wires together then check blue to brown wires ohms ..

[budm]

Re: Pioneer Speaker Package subwoofer transformer.

Since filter caps for the +/- supplies are rated at 50VDC, it is probably safe to say that the it may be running on +/-35VDC, so that means the transformer will be 24-0-24VAC.
24V x1.414 = 34V.

[bamix]

Re: Pioneer Speaker Package subwoofer transformer.

madan1,

Pics requested of underside of the Power Board (IMG_3251_small.jpg) and Amplifier Board (IMG_3252_small.jpg) are attached.

Thanks.