bang olufsen beomaster 4500 no power

[freakaftr8]

Hello all. Im repairing this unit for a friend. He states that the receiver wont*power*up at all.*I have dc 5v standby to the glass panel and can use my camera phoneto see the ir working under the unit near the ir remote pickup butno*lights whatsoever and buttons will not respond. I only have the receiver and*no*speakers or accessories. When I plug it in I get a click from the*power*supply relay. Thats it.*I'm assuming I'm getting DC filtering from the bridge rectifier or I wouldn't be getting 5 volts to the glass panel or be able to see the IR working underneath the unit. when I receive the unit the glass panel was removed in there were some grounds coming off the main transformer disconnected. When I reconnected them to the frame of tge chassis and plug the unit in I finally have a clicking on the relay. Do I need to have the components connected to this unit in order for it to achieve stand by and us power up by hitting the button.
Any ideas would be greatly appreciated.

[freakaftr8]

Re: bang olufsen beomaster 4500 no power

There are two bridge rectifiers in this unit. Im not gettung any 33 or -33v off the filters.

[budm]

Re: bang olufsen beomaster 4500 no power

Any pictures? It sounds like the standby power supply is working but the main power transformer primary side may not be getting the 120vac feeding it through the relay, cannot tell much until we can see the pictures to know if that is the way this unit is setup. You should be able to turn it on without any speakers or anything connected to the unit beside an AC power.

[freakaftr8]

Re: bang olufsen beomaster 4500 no power

Thanks for the tip.

I ok dug into the thing a little further and I have ac voltage on one side of the r1 but the 9 Volt energizes up on plug in then deenergizes right away so the 9 Volt disappears the coil does not stay latched. The four rectifier diodes on that circuit look like at one point they got extremely hot as the board is very brown around that area but the diodes test good.

[budm]

Re: bang olufsen beomaster 4500 no power

This may help:
http://elektrotanya.com/?q=showresul...oria=&kat2=all

[freakaftr8]

Re: bang olufsen beomaster 4500 no power

Thanks bud. Im suspecting the 4700mfd 16v cap at the moment. It looks unhappy

[freakaftr8]

Re: bang olufsen beomaster 4500 no power

Found it. Main processor eeprom. Removable. When removed 9v completes circuit. Eeprom must be corrupted somehow. Battery is good.

[freakaftr8]

Re: bang olufsen beomaster 4500 no power

Anyone ever sewn the eeprom get wiped clean before?

[ReeceyBurger123]

Re: bang olufsen beomaster 4500 no power

Did you ever sort this buddy ?

[stj]

Re: bang olufsen beomaster 4500 no power

sounds like his eeprom was shorted out.

[rhomanski]

Re: bang olufsen beomaster 4500 no power

Really? A two year old thread? He may have been killed by the cops by now. He lives near the prison you know.

[ReeceyBurger123]

Re: bang olufsen beomaster 4500 no power

He is on here frequent and I speak to him often. Im just checking is that ok with you ?

[rhomanski]

Re: bang olufsen beomaster 4500 no power

Have at it. Maybe he'll come back.

[ReeceyBurger123]

Re: bang olufsen beomaster 4500 no power

Hopefully lol

[Longbow]

Re: bang olufsen beomaster 4500 no power

I'm suspicious about the shorted eeprom part. The troubleshooting on this was non-existent. About the only way you could identify a faulty eeprom is if it is actually shorted + to - or if you happen to have a spare one. This was not a part that B&O servicers kept in stock. Typical of this series of offerings, (beomaster, beocord, beogram, etc) they packed a lot into a small attractive cabinet. The heat alone smokes every electrolytic in a short time. Add to that the usual suspects like under rated bridge rectifiers and noisy transistors. Just getting some of these things into the service position takes an origami master.

[stj]

Re: bang olufsen beomaster 4500 no power

He is on here frequent and I speak to him often. Im just checking is that ok with you ?

PM the guy - maybe he's got email notifications set.

[rhomanski]

Re: bang olufsen beomaster 4500 no power

He is on here frequent and I speak to him often. Im just checking is that ok with you ?

Heh, Heh, he was a little testy with that one. Guess he got in a better mood a little later.