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Old 4th Jun 2024, 7:20 am   #1
Michael Maurice
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Default Bang & Olufsen MX6000

This TV comes on in standby (red light), when I try to turn it on, the light goes green for a moment then reverts to standby.

The line o/p stage does not start, the HT is around 22V, it rises to around 26V when brought out of standby whilst the green light is showing, then reverts to 22V.

I have changed the small electrolytics in the power supply, I have resoldered all known dry joints.

Where do I go from here?
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Old 4th Jun 2024, 10:53 am   #2
ben
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Default Re: Bang & Olufsen MX6000

what chassis?
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Old 4th Jun 2024, 5:59 pm   #3
Max Ripple
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Default Re: Bang & Olufsen MX6000

Can you put the set into "audio" mode,ie,press SHIFT-RADIO,assuming that you are using a Beolink 1000 handset?
If the set comes out of standby in audio mode and stay's on,it confirms that the problem is almost certainly in the timebase section.
"usual suspects"are C100 in the base drive of the LOPT transistorTR33.
The device itself is pretty reliable,and when it fails the set is usually completely dead,as it's stops the psu,which runs continuosly,but at low power,then as you say,ramps up on demand.
Other suspects-dry jointed C102,103,101,D80 and 81
C12 in the power supply is notorious too,if it's dry jointed,it seems to affect the power up of the supply.
Otherwise,you will need to explore more deeply,as what happening is the "powerfail" system is shutting the set down before full power due to fault.
The re is also a data check on the control bus at start up.
More info in the manual,without which,you are "dancing in the dark" somewhat.
Lots more info here if you need it.Super telly's,becoming popular again due to good performance with games consoles!
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Old 6th Jun 2024, 7:19 am   #4
Studio263
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Default Re: Bang & Olufsen MX6000

Unity 2 chassis.

The small electrolytics in the power supply are special types, start by putting those back. They don't give any trouble.

The symptoms you have are the 'power fail' circuit operating. The reason can be anywhere, but I'd start on the NICAM panel (clipped to the tuner / IF assembly) where there's a 330uF / 470uF electrolytic that plays up and stops the local SMPS here working. Its very common for it to fail, normally the board gets stained underneath. Note that if you just take the board out the set still won't work as the power fail loop will be broken.

These aren't sets for re-cappers and other chancers, you have to know what you are doing with them. Shame that so many of them go to computer game bedroom lurkers these days, they are far too good for that.
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Old 10th Jun 2024, 10:16 pm   #5
Michael Maurice
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Default Re: Bang & Olufsen MX6000

Just spoken to the customer, he says:

"When he first bought the TV everything was fine for a few minutes then out of nowhere there was what sounded like a snap crackle and pop and then the picture went off completely."

I cant couldn't find any shorted diodes in the power supply when I looked. Does this help in determining what might have gone wrong?

I'm goimng back to it next week.
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Old 10th Jun 2024, 10:37 pm   #6
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Default Re: Bang & Olufsen MX6000

I'd put money on it being the line o/p trfmr, based on that last info and the standby only symptom.
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