ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi all,
I have a Beolink 7000 that seems to have a backlight power supply issue a step beyond most others described on the forum.
The power supply to the screen (from the black and brown wires) is around 30v AC (and across the coil).
One of the PNP transistors had obvious signs of heat stress, so I sourced some BD436 replacements and replaced both on PCB 1, as well as the 220uF capacitor just adjacent to the wires terminating on the board hoping that might be the solution.
So far it hasn't made any difference to the low AC issue for the supply out to the backlight.
Otherwise the remote is working quite well - with battery renewal and IR capacitor replacement the two-way comms to my Beocenter 9500 is functioning correctly, and the motor drive/start up behaviour of the remote is all good, as are the menu functions of the remote - it's just annoying needing a to shine a torch at the screen to see what I'm selecting
Thanks,
Dan
Hi,
the voltage should be something around 110V AC.
Sorry, there is absolutly no circuit plan for these boards available... at least i have never seen something like that, just the normal service manual, which contains no circuit description.
The only thing i can say: replace all transistors on this cooler.
You have checked the coil and the signals with an oszilloscope? If one halfwave is missing, the voltage on the output is decreasing to 30-50V... exactly what you found.
Martin
you can perhaps take a high quality top/bottom pictures of the board to help us to make a back engineering of the schematic :)
I love when a plan comes together
Beogram 4002 / Beocenter 9000 / Beocenter 9500 / RL140 / Beolink 1000 / Beolink 4
maybe this will help...
Thanks for the posts - I've got a bit of lead time for the NPN transistors to turn up, but this is all great supporting info.. I'm on the right track hopefully - I'll update how it goes
Hi, did you ever get this working ?
Im having a totally dead voltage(0) on black/brown wires, and I cannot hear any humming from the coil at all, otherwise the remote is working perfektly, just like yours :)
I have checked the 1A250v fuse, and it is fine..
Any great ideas ?
Sorry to report that I have not had much good luck with this unfortunately - as well as new NPN and PNP transistors, I tried a whole replacement PCB1 board, and it still made no difference.
The fault finding flowchart in the manual recommended both PCB 1 and 2 be replaced for this issue, and I decided to cut my losses where they are and just sourced a fully functional BL7000 - even with the backlight inoperative it's OK as a #2 unit handy elsewhere in the room to adjust volume etc.
There must be a switching function driven by PCB2, but I'm even less sure where to start with that.
Hi, thanks for your reply, that actually helped me a lot, I have the Service Manual, but did not think that it could be from PCB2/3 the control of the trafo could be located :)
In my case this makes a lot of sence, since I measure 0V at the trafo, so the circuit is not even powering up... I have exchanged PCB2 in my 2 BL7000's, and both processor boards are actually working in my "working BL7000", so the fault could be on PCB3 or 4 also, don't know if the display board is exchanging data with the processor board, and should return "ok" for the processorboard to turn on the backlight..
But, I have a friend at B&O and he has the BL7000 now, he will try to do some measurements on it and see if he can do something :)
I will let you know..
/Weebyx
And..... My friend has just gotten back to me, he has changed TR37 / C15... and now it works like a charm again :)
One more thing ...
Have you tried changing the backup battery on PCB2(processor board) ? Sometimes a low voltage there, can cause side effects..
hello weebyx, thanks all here for the great info. im having a challenging time with the same symptoms, where is c15 tr37?
thanks very much!
It is the one with the black circle :) I also changed the capasitor C15 (10nF) also in the black circle, but I think that the transistor is the problem if you are having 0v like me...
fantastic, no wonder i couldn't find it! thanks and thanks to die_boegner. es i have 0v, so will get onto it in the morning!
thank you very much
I used 50v in mine, but really don't know what the correct voltage should be..
How do you access the PCBs in the bottom half of Beolink 7000, meaning how does that part disassemble? Wanted to ask before I break something trying to open it. People on this post have opened it with success, obviously.
Many thanks
toptip: How do you access the PCBs in the bottom half of Beolink 7000, meaning how does that part disassemble? Wanted to ask before I break something trying to open it. People on this post have opened it with success, obviously. Many thanks
You need to pull out the battery and desolder the wires, then remove 4 black plastic caps, and unscrew the 4 bolts that hold the mirror assembly in place.
Many thanks for the reply.
I presume the rechargeable batteries are 1.5V each as it was probably to early for Li-ion?
toptip: Many thanks for the reply. I presume the rechargeable batteries are 1.5V each as it was probably to early for Li-ion?
Yes, you can buy a new battery pack with correct batteries from BeoVienna on a certain auction site. Dont try to use the wrong ones, they will only cause trouble.
One last question.
The elastomeric or "Zebra" connectors for re-attaching the LCD panel... That is the part that is giving me the "heebee-jeebees," so to speak! I read many internet posts and spoke to friends who have fixed calculators and alarm clocks with these connectors and I understand many a times you could end up losing digits or entire segments of the display if the connection is not tight. One person said he wiped the connector surfaces with isopropylene alcohol and that made things worse. Any good reading on this about what to do?
toptip: One last question. The elastomeric or "Zebra" connectors for re-attaching the LCD panel... That is the part that is giving me the "heebee-jeebees," so to speak! I read many internet posts and spoke to friends who have fixed calculators and alarm clocks with these connectors and I understand many a times you could end up losing digits or entire segments of the display if the connection is not tight. One person said he wiped the connector surfaces with isopropylene alcohol and that made things worse. Any good reading on this about what to do? Many thanks
The best way is to do some measurements of the location of the 2 connectors. Measure the distance each of them are from the edge of the PCB, or take a good picture of it before removing the LCD.
Dont clean with anything, just remove at replace them and test. If pixels are missing, then remove LCD again, and move the connectors a bit and try again. Nothing will die forever, it is just a matter of testing and moving until display is fine again.
You can test without connecting keyboard and glass. Just connect power to battery and see if the display looks good. If all text is fine, assemble and do final test.
Thank you. Will try and report. Waiting for this to arrive:
https://www.adafruit.com/product/625
I was reading that cutting these to size may reduce their life due to oxidation and other contamination. I thought maybe I should apply something like clear nail polish just to the edge to prevent that from happening.
toptip: Thank you. Will try and report. Waiting for this to arrive: https://www.adafruit.com/product/625 I was reading that cutting these to size may reduce their life due to oxidation and other contamination. I thought maybe I should apply something like clear nail polish just to the edge to prevent that from happening.
I have not yet seen any problems with cutting them, but... I hope it glows more white than it appears on the screen. The LCD is blue itself, so with blue background light, the text will be blue on blue.
It looks very nice. Where is rest of this diagram??? Very important. Thank You....
Nice wiring diagram but where is the rest of this diagram??? Thank You
Hello,, can You send bigger part of this wiring diagram?>?? Thank You