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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 30th Mar 2017, 8:07 pm   #1
marsbar
Triode
 
Join Date: Apr 2011
Location: Stavanger, Norway .
Posts: 38
Default Finally, figured out my Bang Olufsen LX 2800

Was supposed to work outdoor today, but had to find indoor work instead.

I looked at my previous post regarding my Bang Olufsen LX 2800, and went trough all the tips again.

It simply appeared that R111 had to be adjusted

This decides whether the picture get stretched at the bottom and top, so this has to be tuned so letter in top, middle and bottom of teletext are the same size.

Made a map over what function all the pot meters nearby had, and adjusted the picture in. A test card would have been nice, but had to cope with normal picture and teletext.

I also replaced a 470uF capacitor in the audio part as the internal resistance was slightly high, and also in previous posts it was suggested to replace all red capacitors. Some hum in the background of the sound disappeared.

So this is what I did:

-Changed Zener diode 5.2V on PSU board
-Changed ALL electrolyte capacitors on main board
-Changed 470uF capacitor on sound amplifier board
-Cleaning on HV cable and transformer
-Changed mechanical on/off switch

TV is fed from decoder is set at:

RGB
YUV off
AUX Scart CVBS
Format 4:3
HD Activation OFF

Picture and sound is impressive

For the retro experience I also have a fully functioning C64 and Panasonic VHS

BTW, Think I posted this in the wrong section, can someone move it so "success stories"?

Thanks
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Old 31st Mar 2017, 9:41 am   #2
marsbar
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Default Re: Finally, figured out my Bang Olufsen LX 2800

Here are some pictures over the job done.

Main PSU board: All caps except the big yellow one is replaced.

Picture driver board: There are several pot's. These all correspond to

the various picture adjustment, vertical and horizontal.

Marked with a screwdriver is pot R111.

However, pots are not clearly listed in the manual with correct symbol.

In other manuals, like Japanese, there is a symbol stating what each pot does...

If you attempt to adjust these I suggest making a map with location of pot and a figure what the pot does.

Also, a good idea is to measure R with power off using a multi-meter before you start fiddling so you have something to go back to if you need.
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Old 4th Apr 2017, 9:19 am   #3
flyingtech55
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Default Re: Finally, figured out my Bang Olufsen LX 2800

Well done saving one of these. They are capable of giving really good results when they are working correctly. I went on the B&O course on these when they first came out. It was pretty comprehensive and intensive. I think it was a three day course. They are a 'proper' B&O design.

One thing I do seem to remember was that on the power and scan board the actual PCB material would darken with heat and age. In some cases where the darkening was particularly bad, B&O would issue a complete replacement PCB. I think we had two replaced by B&O but it is a long time ago and my memory fades with age.

On the other hand I used to scrap off the (I think) MX sets whenever I could as they were those horrible Thomson things. Unfortunately at that time, B&O sets were generally bought rather than rented and the owners normally wanted them repaired. Whenever I could I just sent them back to B&O and let them repair them...serves them right!

Tim
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Old 6th Apr 2017, 2:42 pm   #4
Welsh Anorak
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Default Re: Finally, figured out my Bang Olufsen LX 2800

Hi
Nice to see one of these again. I would be tempted to address the dark areas of the line stage and fit the components further from the PCB, lengthening the wires if necessary. Maybe the 3W wirewounds could be up-rated to 5W and positioned where they can do less damage. This would help future reliability.
Those MX sets mentioned by Tim were not great - Thomson ICC3s if I remember, with a big mains transformer, numerous dry joints and an unreliable LOPT. Plus the tinted front meant that the picture was dull, especially when the Thomson tube had started to lose emission, usually after a year or so.
Thomson then brought out the ICC5 and we ran for the hills, screaming.
Glyn
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Old 6th Apr 2017, 3:11 pm   #5
flyingtech55
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Default Re: Finally, figured out my Bang Olufsen LX 2800

Hi Glyn

Glad you also liked the LX chassis. You had to know the 'trick' to get them to start under fault conditions but once you were in the know they were fine.

On the subject of the MX sets, I don't know anyone who had a good word for the ICC3 and ICC5 chassis. They were 'orrible. I pity the poor TV engineers who worked for the Thorn group rental companies. Tx9 and Tx10 good! ICC3/5 bad. ISTR the Salora IPSALO chassis could be pretty taxing too but not as bad as those Thomson things

Tim
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Old 7th Apr 2017, 5:39 pm   #6
Michael Maurice
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Default Re: Finally, figured out my Bang Olufsen LX 2800

I still use an LX2802. It is our main TV. It has been repaired a few times and around 15 years ago, I fitted a new CRT and today the picture is very good.

B&O also used Philips chassis, notably the CP90 in the MX1500 and a later chassis which I cant remember for the life of me which chassis it was, something 2.2.

These were better than the Thomson chassis, though anything is better than a Thomson chassis.

B&O's later offerings were also quite good.

Couldn't afford one now though
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Old 9th Apr 2017, 8:01 pm   #7
Welsh Anorak
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Default Re: Finally, figured out my Bang Olufsen LX 2800

I think that was an MD2.2. I wonder if they were somehow chosen to be a cut above the usual Philips sets? They seemed more reliable, but that's probably because the Philips TV was far more common than the B&O.
I still have a genuine B&O 32" 3-32 which is working perfectly and is going begging - PM me if anyone's interested. The screen surround (black) is damaged but easily repaired.
Glyn
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