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One full line of pixel missing suggests that indeed one electrical connection to the driver chip was lost, so ordinarily I would jump to the conclusion that the zebra strip is responsible for this, but Guy’s experience tells another story !
I am not aware of other common failure modes for this, although damage to the conductive track on the LCD could explain this behavior.
Now I’m getting really curious about this issue ! If you still have one (or more) damaged screen in your possession, and are willing to ship them to France, please PM me.
Hi Pilatomic, In my experience Beo4 screens do fail, but replacement is actually quite straightforward because connection to the PCB is via a little rubber ‘contact strip’ – a replacement strip is provided with the new screen.
Can you describe me how the screen fails ?
I think there is a good chance the screen are actually fine, just not making proper contact.
The “contact strip” is called a zebra strip, it is commonly used for connecting LCD displays, but the drawback is you now have to keep it under mechanical pressure to ensure a proper electrical connection.
Failure to maintain the correct mechanical pressure is, as far as I know, the most common failure mode for those kind of displays.
Si vous n’avez pas pu obtenir cette information ailleurs, je possède un meuble similaire, les tubes mesurent 15 mm de large par 25 mm.May 20, 2022 at 8:30 am in reply to: BEOLAB 6000: looking for DC voltage for DIY Bluetooth #5167
@Pilatomic: thnx! This sounds really helpful. One question. Is it correct that the +/-35v at the C5 capacitor is always available? So also when the BeoLab 6000 is in stand-by/Red LED on?
The voltage across C35 will only be present when the LB6000 is turned on. ( Relay RL1 closed )
If you need a permanent voltage, you can find it across C31. It will probably have quite a lot of ripple, but the DC/DC converter should be able to deliver a stable output voltage nonetheless.May 18, 2022 at 8:19 pm in reply to: BEOLAB 6000: looking for DC voltage for DIY Bluetooth #5122
I checked out the schematic you posted, and at first the circuit around the 5V point was not make any sense. I believe it is rather a 34.5V point ! ( A2 and A5 are definitely 8.6V and -8.6V according to this schematic )
IMHO, your best option is to use the +35V present across the C5 capacitor ( it is the leftmost large red circle on the drawing ). You can find the negative side ( 0V ) by identifying the large white band on the capacitor.
Then use an isolated DC/DC to get a clean isolated 5V (you don’t technically need an isolated supply, but it makes things a lot easier to avoid noise and some issues with different reference potentials).
I would recommend the TMR 4-4811WI, as it accepts inputs from 18 to 75V.
Last advice : You might want to find a bluetooth module with a good quality audio output. Many of them are sub par, and would probably sound like a disappointment on those speakers.
Best luck with your project !
ERRATUM : Bad wiring diagram in installation manual.
There was a mistake in the section 6, about the signals connections on the MHS CPU. The RST pin was incorrectly placed.
I apologize for this mistake !
If you ran a jumper wire to the wrong pin in an attempt to make the connection according to this diagram, it does not seem to cause any issue, but it is better to remove it.
The installation manual v1.1 contains the correct diagram.
- This reply was modified 3 months, 1 week ago by pilatomic. Reason: Changed formulation