Identifying Part from Schematic

[budm]

Re: Identifying Part from Schematic

BTW, where did you get the diagram from? Are there any more info or more pages of the service manual?

[budm]

Re: Identifying Part from Schematic

Boy, you sure run into bad transformers. This may be hard to get.
Any label or sticker on the Transformer?
I wonder if it is truly 55V-0-55V, that would make the +/-77VDC (55 * 1.414) power supply for the power amplifier section, the filter caps are only rating at 80VDC and since it is not regulated power supply, that Voltage can easily goes over 77VDC.

[mikay786]

Re: Identifying Part from Schematic

Alright looks like I'm going to need a replacement transformer

Did what budm suggested in another thread, disconnecting the transformer from the main board and fault seems here. Is literally exploding fuses.

Theres no spec on the unit itself, but I have gathered from a quick google that's its a

600VA Shielded Transformer (http://www.widescreenreview.com/news_detail.php?id=6387)

5 Primary Side Cables (115-230v)
6 Output Cables

From the marking on the board thankfully its gives values.

2 x 55ac
2 x 12vc
2 x GND

2 X 12vc going to 2nd bridge rectifier RB154 (BD2 on schematic)
2 X 55ac going into the main bridge rectifier GBPC2504W (BD1 on Schematic)
2 X GND going into ground

Any advice on a replacement?

[budm]

Re: Identifying Part from Schematic

For R3 100K resistor to burn up like that I would check ZD1, D1, Q23.

[mikay786]

Re: Identifying Part from Schematic

http://uk.rs-online.com/web/p/bridge...fiers/2278643/

something like this better? (I'm going to put back in 10000uf 80v caps too)

[paulstef]

Re: Identifying Part from Schematic

Thanks, ill test the one fitted to see if it still works.

just noticed in the schematic the main caps are supposed to be 10000uf 80v, and the ones fitted (which owner said were the originals) are 4700uf 80v!!

and the bridge rectifier fitted is a KBPC2501, which is 25a 100a, so wrong part again?

Yes this rectifier has 100V peak reverse voltage.
You could remove the bridge rectifier and measure the output voltage of the transformer if you are uncomfortable with it. From the voltage ratings of the other caps it may not be a problem.

[mikay786]

Re: Identifying Part from Schematic

Thanks, ill test the one fitted to see if it still works.

just noticed in the schematic the main caps are supposed to be 10000uf 80v, and the ones fitted (which owner said were the originals) are 4700uf 80v!!

and the bridge rectifier fitted is a KBPC2501, which is 25a 100a, so wrong part again?

[CapLeaker]

Re: Identifying Part from Schematic

sounds like a 25A 400V bridge rectifier.

[paulstef]

Re: Identifying Part from Schematic

http://media.digikey.com/pdf/Data%20...5,25,35(W).pdf Maybe similar to this one.

400V, 25A.

[mikay786]

Got this Monitor Audio FB212 subwoofer, which unfortunately the previous owner has absolutely butchered the power board. Never seen such negligence

Problem started out as a hum and original owner proceeded to change main caps with some ebay jobbies which blew spewing guts out all over board. That and hes changed the bridge rectifier as the one fitted is not the original. After the replacement main caps blew he took them out and put back in the old ones.

So as it stands only the bridge rectifier isn't original (he says its the same specs but don't really trust anyone who has done this to the board)

Visually as far as i can see there is a blown resister, which I've identified as a 100k Resistor from schematic. (Position R3)

So what I'm trying to figure out is what the original bridge rectifier was from the schematic but following / reading them is a bit beyond me at present.

Looks like its maybe "BD1 BD254", not sure if that's a part number or what?