LC2 Repair

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  • #9570
    lausvi
    BRONZE Member
    • Helsinki - Finland
    • Topics Started 0
    • Total Posts 5

    I did had a quick search and found this: https://www.partco.fi/en/electronic-components/passives/resistors/flame-proof-resistors/12325-fres-05w-5r6.html … so I’ll either go for that or the TE Connectivity one that I linked to earlier.

    Ha, Partco is my local (finnish) component dealer and this is the exact part I bought and where I got the part earlier 😀 I guess they do ship abroad too, but it might get costly…

    (Again; I am not sure if this is 100% perfect part for this, but as the service manual doesn’t really give any details and the listing says flame-proof it sounded good to me and I used it for testing and was mostly astonished to find the LC2 working again with only this fix).

    #9588
    Die_Bogener
    BRONZE Member
    • Topics Started 1
    • Total Posts 107

    Caps make shorts and this depends on the voltage and temperature…

    You have heard about “selfhealing caps” with polystyrene caps? Some elko caps do the same … and trick you out. It will happen again.

    #9630
    Guy
    Moderator
    • Warwickshire, UK
    • Topics Started 11
    • Total Posts 588

    Update:

    Resistor R1 5.6 Ohm replaced (temporarily with ‘metal foil’ replacement for controlled testing, now aware of fire risk).  Correct T1.6AH fuse also fitted (incorrect one was fitted by previous owner).

    Tested LC2 again:

    • 5V now present including to IR board.
    • IR still not working.
    • Touch control is working – dimming/switching correctly with 60W bulb fitted.

    Obvious place to look next was the 2 x 22uF capacitors on the IR board.

    I replaced these with 22uF 16v Tantulum beads that were left over from my BL5000 two-way repair.  Easier to solder than SMD replacements!

    IMG_6354

    Now fully working with both IR and touch control 😀

    So a couple of questions before I place order with RS for correct fireproof resistor:

    • Any reason that I shouldn’t leave those tantalum bead caps in place?  I am happy to replace them in the future if the IR stops working again.
    • Any suggestions for replacing the (missing) little contact rubber between the PCB and the dome foil?  I was thinking of cutting a small piece from the Beo4 screen connection ‘rubber’.  Any better ideas, or is the part still avail from B&O?

    Thanks for everyone’s helpful comments so far!

    #9632
    Die_Bogener
    BRONZE Member
    • Topics Started 1
    • Total Posts 107

    Tantalum ist very expensive, big and very longliving… 🙂

    Tantalum hates spikes, overload and mechanical shocks. But this is here not the problem. Much better than this smd elko crap…

     

    the rubber is done because of mechanical tolerances. The screen rubber will also work, but not so long… silicon screen rubber oxidates faster, but will also work for this.

    It is also something like a fuse. Inside the case is a carbon paint for capacitive action. You should check it for cuts and breaks. It can be repaired with silver for windshields.

     

    #9648
    Guy
    Moderator
    • Warwickshire, UK
    • Topics Started 11
    • Total Posts 588

    Thanks Die Bogener – all useful info!

    However …

    IR control worked for a while, then worked intermittently, then stopped working 🙁

    Touch control is still fine, and 5v still being supplied to IR board.

    Not sure what to look at next!

     

    #9675
    Die_Bogener
    BRONZE Member
    • Topics Started 1
    • Total Posts 107

    You have cleaned the acid of the smd caps?

    #9702
    Guy
    Moderator
    • Warwickshire, UK
    • Topics Started 11
    • Total Posts 588

    You have cleaned the acid of the smd caps?

    I actually cleaned the IR board before changing the caps, because the area (3-pins) where it connects to the main board looked discoloured. I have now given it a further clean and there is no change.

    I have had to pack it all away now because 4-year-old grandson is staying this weekend, but I will have another play next week.

    Thanks again for your suggestions.

    #10136
    Guy
    Moderator
    • Warwickshire, UK
    • Topics Started 11
    • Total Posts 588

    So today I dug out the LC2 again.  Co-incidentally I had also found my Beoport (Beolink PC2) in order to investigate further for the Beoport thread.

    With the Beoport I had packed what I think is a Beosystem 3 sensor (I don’t think I had used it with the Beoport because I used a VX sensor instead).

    Anyway, just as an experiment I thought I would try replacing the LC2’s IR board with the Beosystem 3 sensor.  After a false start (where I got the IR and +5V wires reversed), I soldered it up and the IR control works very well.

    IMG_6375

    Just for interest, here’s the inside of the Beosystem 3 sensor:

    IMG_6373

     

    #10139
    Die_Bogener
    BRONZE Member
    • Topics Started 1
    • Total Posts 107

    Maybe a good idea… replace this smd c(r)ap with something more reliable…

    #15047
    Guy
    Moderator
    • Warwickshire, UK
    • Topics Started 11
    • Total Posts 588

    That new LC2 thread prompted me to dig mine out and have another go at fixing the IR sensor!  As previously mentioned I had been experimenting with a BS3 sensor – I even fitted a 3.5mm socket so that I could move it back to my Beoport for testing that!

    IMG_6522

    Anyway, today I first replaced resistor R1 with a ‘fireproof’ metal oxide 5.6 ohm resistor – this one from RS: https://uk.rs-online.com/web/p/through-hole-resistors/1870824

    I had to buy 20 so if anyone in UK needs a couple please PM me!

    Anyway whilst looking at the IR PCB I checked the continuity of the IR signal and realised that the trace was broken hence the signal wasn’t getting to the main PCB – I must have damaged this inadvertently when I replaced the caps.  I re-soldered the IR PCB in place, soldered a quick wire bridge to R9 and now it all works as it should.

    IMG_6523

    I am now going to experiment with finding something to replace that little contact piece that connects the touch sensor surface to the main PCB.

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