Help with Cambridge Audio CD-500SE

Discussion in 'Digital Sources' started by hardtymz, Aug 28, 2018.

  1. hardtymz

    hardtymz New Member

    Messages:
    4
    Location:
    Ohio
    Hi all! I have a very weird issue with my CA CD player. It started a while ago and was intermittent here and there but now its really bad.

    I searched for hours on line and service manuals but kinda didn't even know where to start. So I press the power on button and the front blue screen lights up and shows the LCD numbers for a few seconds and then they go away and never come back. Leaving it plugged in over night can make it work for a few more seconds and same issue. The numbers go away but not the blue lights. At the same time, no button on the machine works. It's like it stored power in a capacitor for a few seconds and then drained completely. The drawer would open and and the laser and transport will sound like their working but then die. The problem is i can't find any information on this problem with ANY player, let alone a Cambridge. It worked fine for a while and got it super cheap and can't afford to replace it or send it away to professionally repair it either. Any hints or ideas?

    I like DIY and am pretty handy with a soldiering iron but not as well with schematics. I also LOVE how it sounds so that why I'll put in some effort for this.
     

     

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  2. Powertech

    Powertech Active Member

    Messages:
    445
    Location:
    South Wales, U.K.
    Only a guess at this stage, but I would start by checking the voltages around the 5V PSU voltage regulators. U1 & U2 would be good targets as these look to be feeding the digital circuits. These are 7805 regulators. Maybe one is either falling over when load is applied or something is pulling it down. The LCD and the control buttons are connected directly to the main control chip IC106. It looks like this may be losing power.
     
  3. hardtymz

    hardtymz New Member

    Messages:
    4
    Location:
    Ohio
    Thank you so much for looking into this! Would the regulators be the actual problem or the components before/after them? Also would the main control chip also be a culprit itself? 2018-09-06 03.07.53.jpg 2018-09-06 03.08.00.jpg
     

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  4. Powertech

    Powertech Active Member

    Messages:
    445
    Location:
    South Wales, U.K.
    The supplies to the backlight and the indication come from separate PSU regulators. I would check the outputs from these first as they are the cheapest to replace. It is possible that you have a failed rectifier, but all the PSU voltages need to be checked first. If it is the main control chip then you are in a difficult area as they are difficult to find and difficult to replace. Sorry, but I am only guessing here as I cannot measure the unit myself.
    It would help if you could takes some measurements around the power supplies (or get someone else to) and then report back. This may give us a better picture as to what is happening.
     
  5. cpt_paranoia

    cpt_paranoia Well-Known Member

    Messages:
    588
    Well, I've just bought one for £5, but it has a different version of the main (central) board; yours has Sony branding on it, but mine doesn't, and the front panel connectors on mine are in different positions. Differential diagnosis won't be so easy.

    Display fading after the cd mechanism starts does sound like a weak PSU; power comes up, display starts, motors start, take too much current, and you get a brownout.
     
  6. cpt_paranoia

    cpt_paranoia Well-Known Member

    Messages:
    588
    I could have sworn I had looked at a schematic of the D500Se as a result of reading this thread. But I can't find it anywhere...
     

     

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  7. hardtymz

    hardtymz New Member

    Messages:
    4
    Location:
    Ohio
    Thanks for the help so far! Here's a service manual site for it: https://elektrotanya.com/cambridge_audio_d500_sch.pdf/download.html

    Well I had parts lying around and went to town replacing old stuff like original 85 degree caps with 105 degree ones so they'll last a little longer. I also went ahead and replaced the main 7808 regulator on the heat sink and on the audio board, I replaced one 7905 and 2 7805 but left the 78m05 alone because online couldn't give me a clear answer if I could replace it with a regular 7805 instead. Turned it on without the top cover and still same issue. Audio board relay clicks like it should, the blue lights light up the front panel but that's it. I have a feeling it may be the logic chip/board. Also when powered up, no sound/movement from the laser sled. The laser isn't even on. Unplugged the ribbon cable from both ends and replugged it in again and no dice. The only thing I didn't do was pop that huge Sony copper shield off and see what's underneath. It's bolted down in all four corners by huge globs of solder. It might get messy... So for the most part caps and regulators appear to be out of the equation for now. Any other suggestions?
     
  8. hardtymz

    hardtymz New Member

    Messages:
    4
    Location:
    Ohio
    IMG_6157.JPG IMG_6190.JPG So if I keep the unit plugged in overnight (power off), it powers up just fine for 10 seconds before dying again. Powering on and off does nothing after that, except the blue lit screen. Every power cord/wire feeding each separate circuit board is only getting a few small mV. Not good I assume. I was expecting either 12 V or 5 V. So either the transformer is bad on every single output or the KH103M discs/caps are bad on the PSU board....? Do those caps go bad? If the transformer is bad, is there any place that would sell a replacement? The transformer reads ES-48-871-1895 (also printed is ES 48 x 40).
     
  9. cpt_paranoia

    cpt_paranoia Well-Known Member

    Messages:
    588
    That's a very strange symptom. Mains connected, but switch turned off means there's no voltage internally to charge flaky capacitors. So it's odd that it does come up briefly.

    The display backlight may use its own AC feed from the transformer.

    I would look at the AC voltage coming from the transformer to the power supply. And check all the solder joints on the mains input board, and the fuse connections.

    It does sound like it's a power supply fault, so start at the mains input, and trace it through. Take care with those voltages:, of course.
     

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