CD player LCD backlight bulb needed

Discussion in 'Digital Sources' started by onanysunday, Jun 22, 2017.

  1. onanysunday

    onanysunday AK Subscriber Subscriber

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    While recapping my Akai CD-A30 I managed to blow this LCD backlight bulb in the process. When I shine a bright light behind the dim screen you can see it illuminates just fine. I don't know anything about what bulb this is except for what you see in the photos. If anyone has one of these spare bulbs from an old parts deck, or has a part number so I can purchase a new one, please let me know as I would be most grateful. Thank you.

    bulb.jpg bulb2.jpg bulb7.jpg bulb3.jpg bulb6.jpg bulb4.jpg
     
  2. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Can you measure the voltage on the contact pads with the lamp socket removed?

    You will need to get a bare lead lamp and fit it into the old socket. Look close, see how the actual lamp leads go through the socket and wind around the housing and tie on?

    You take the old one out and put the new lamp in, re threading the wires.

    AKer dgwojo has lamps, MCM sells them. Probably on Ebay. You need to know the voltage and diameter. Voltage will read higher without the lamp pulling it down.

    It is probably 6, 8 or 12v
    Looks like a 4mm but maybe 4.5mm
     
    John James likes this.
  3. onanysunday

    onanysunday AK Subscriber Subscriber

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    Electrified PCB traces for bulb socket = 12.33 volts DC and bulb is 4mm in diameter.
     
  4. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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  5. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    I'd bet on a 12V/40mA or 12V/60mA, 14V/80mA is also common in that size but that might be too bright. Dave should have some or all of those ratings on hand, though.

    John
     
  6. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Should be cheap enough to get one of each.
    Postage is/was $4.
    Dave is good people.
     
  7. onanysunday

    onanysunday AK Subscriber Subscriber

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    I emailed Dave, we'll see what happens. Also, I found some 4mm bulbs at a local electronic junk surplus store. They "looked" identical to what I need so I bought 5 of them. But, they must've been rated at a lower voltage or something, because as soon as I connected them to the pcb traces, they all burnt out without even lighting up for a split second, unless of course they were all just burnt out to begin with. I tried an led in there as well with the same result- no light coming out of any of them whatsoever. Of course I checked them all for continuity only After connecting them all and of course none had any continuity. They could be peddling junk there, I suppose that is why they were only 20 cents apiece. Also, I don't know what amperage I need as I sifted through close to a dozen, similar Akai cd player service manuals. None mentioned this part on any of their diagrams.
     
  8. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    You could probably tack a high value resistor in there and measure the voltage drop to get a better idea of the current supply available to drive the lamp, but may be easier to just pick up one or two or all three of those values from Dave and see what works best. These are not expensive lamps and those three values are probably the most common in the voltage range you mentioned.

    John
     
  9. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Dave will fix you up.

    MCMelectronics has them to buy postage is higher.

    Surplus lamps could be anything from 1.5v to 28v

    LED need a resister on the negative side to work. You need to drop to about 2-3 volts. There is a web site with a resister calculator but it asks about LED specifics. It does offer typical specs but surplus could be weird. You could try 470 to 1k ohm and see, if the LED is actually still good.
     
  10. Eastham

    Eastham More Class A than ever! Subscriber

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    Looks like a standard automotive dashboard lamp to me. The kind that would Illuminate the dash gauges and such. See if you can pull the bulb out, if you can you can replace it with a T5 type bulb.
     
  11. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    It's a bare lead lamp.
    The leads wrap around the socket.
     
  12. Eastham

    Eastham More Class A than ever! Subscriber

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    Oh. Quite a strange bulb isn't it.
     
  13. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Not really. I've seen that style in a lot of vintage stuff.
    I'm sure that when parts were available, you just replaced the whole thing.
    Now we rebuild stuff because we can't get the parts.

    Pioneer SX-9000 function lamps are tubular cartridges that must have been intended to be replaced in whole (if they even thought about replacement), but now we have to take the cartridge apart, replace the lamp and rebuild the cartridge.

    Dial indicator lamps are sort of built in too.

    I've spent more time fixing lamps than it took to fix the amps.
    One Sansui 4000, took 2 hours to fix the amp and 3 hours to fix the lamps.
     
  14. Eastham

    Eastham More Class A than ever! Subscriber

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    I know how it feels, I had to replace the Axial lamp for the "Computer Drive" logo in my SU-V505 which involved removing the board it's soldered to, then removing the plastic light guide that goes around it which meant unsoldering each of the 7 led's for the computer drive satus indicators because they where clipped to it. Kind of a PIA but worth it in the end.
     
  15. onanysunday

    onanysunday AK Subscriber Subscriber

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    Thanks, all fixed up now thanks to Dave and his specialty bulbs. He had a 14V 100mA replacement bulb with correct socket already attached- very helpful!

    Akai CD-A30.jpg
     

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