BeoWorld Bang & Olufsen Forum

Hi all,

          before I start delving too far I was hoping someone may give me a couple of pointers as to the most likely fault with this.

The problem is that it blows the T4 amp fuse (hidden behind the transformer) as soon as power is swithced on. I haven't done any testing as yet which is pending any help given here.

 

Chris.

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The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.

Chris,

If it blows as soon as the mains plug is inserted into the wall outlet, it could be the mains transformer that has shorted windings.

If the fuse first blows when taken out of standby it's probably a shorted output stage.

Martin

I had the same symptom with a BM6500.  Of course, that doesn't mean it was the same problem  .  For me, it was the vertical silver can-type capacitor near the fuse.  (On page 10 of the service manual you'll find this to the right on the rectifier D3).  Page 19, lists it as a 4700uF -10 + 50% 16V Cap.  However, as it's an older receiver and that is a large electrolytic capacitor, you may want to check it first.

 If you have the service manual (available to Gold Members) you should be able to isolate the issue fairly quickly.  Since you know the fuse is blowing instantly, start from there and check every potential path to ground.  

 Good Luck!

 -Rob 

That's great stuff guys,

                                the mains transformer was one of my suspects (yes Martin it does blow as soon as power is supplied) and the info' on the capacitor to check first is great.

 

Chris.

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The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.

Yes, the large PCB mounted cap ! I also remember replacing one of these. If that is indeed the problem, you should also check (or replace) the associated rectifier.

Martin

Yep, I replaced the rectifier too - forgot to mention that.

 

Thanks Martin!

 

-Rob 

Brilliant!

I'll keep you posted

Chris.

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The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.

Right,

         I've checked the power supply/transformer which is fine and removed the board and identified the problem to be the Cap as suggested. Next question is where to get the replacement capacitor & bridge rectifier from.

Chris.

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The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.

Hello Chris, I'd suggest you get yourself down to Farnells or RS, just the road from you.

Do you have an account with them, if so you can order and then collect, otherwise you'll have to wait for delivery - in 24 hrs.

Thanks Dave,

                     I've found what I need at Farnells but may have a look at RS and see if they have owt.

 

Chris.

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The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.

Well - here's how it went.

Been babysitting the grandkids over the past week, but in the meantime I ordered the parts (didn't realise my next door neighbours wife worked for Farnells so they cost me a grand total of £3.00 - happy days).

Got back home toady at @ 10am and the beomaster was up and running perfectly by 11am, I even replaced the mains lead which had been cut by the previous owner.

So all in all I reckon you guys have saved me at least an evenings work diagnostics wise so thanks a million you're real stars

 

Chris.

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The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.