Magnavox cdb560 hum +music at output

Discussion in 'Digital Sources' started by UncleBingo, Feb 13, 2018.

  1. UncleBingo

    UncleBingo AK Subscriber Subscriber

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    506
    Howdy,
    Looking at this CD player for a friend. He said it was humming along with the music. (Perhaps it doesn't know the words?) Both channels.
    I don't usually work on these, but thinking it was possibly a bad ground on the output RCA's I agreed to crack it open and have a gander.
    Short story is that the hum is somewhere else. I've pulled and measured the power supply (filter caps) and they're within 20%. I even subbed in a couple new caps there to zero effect.
    Swapped out the LM op-amp chips and still... hum
    Lifted 1 leg of the main diodes and they test good.
    I am suspicious of the 78XX series regulators in here, but not crazy about going full rabbit-hole without some assistance (or at least a shove in a meaningful direction).
    Anyone conquer this hum on a similar unit? (Phillips/Magnavox).
    I have Multimeters, oscilloscopes and function generators available and probably a frequency counter somewhere. Thanks.
     
  2. CT Jim

    CT Jim AK Subscriber Subscriber

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    Location:
    Branford, CT. 06405
    I have a cdb465 which suddenly developed some static during playback. I have not pulled anything yet, but will be watching this thread for additional tips for when I get it on the bench. I did find the Philips cd-465(same model) service manual, but I'm not impressed with it, I suppose I could just replace 20+ caps and hope that solves it?
    This model has a super motorized tray system, I'd like to get it back up and running.
     
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  3. UncleBingo

    UncleBingo AK Subscriber Subscriber

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    Odd that nobody has had or fixed this problem on this or a related model. Anybody?
     
  4. markuus3889

    markuus3889 Diatom, what's that?

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    262
    Location:
    Braindead, Minnesota
    Hi UncleBingo,

    You may have better luck over at DIY audio. Search for "CDM2" info since that is the transport and some variation of "Philips CDM2" and/or your model. Quite a few units from Philips/Magnavox and other various manufacturers used the CDM2 and its variations. I think there are three variations of that type transport. There were known problems with electrolytic caps on the transport I think it was a 33uf but the blue electrolytic axial caps with thin blue shrink wrap are all problematic in those units. Though I don't know if that's your issue. There should be a lot to read. You should find manuals for the Philips CD560(same as Mag CDB560) and Philips CDM-2(under Philips General Documents) at Hifi Engine.

    Good luck,

    Mark K.
     
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  5. UncleBingo

    UncleBingo AK Subscriber Subscriber

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    Thanks! I have the manuals, but they're a little thin...
     

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