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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 8th Aug 2011, 6:55 pm   #1
zooterman
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Default Low Volume on CD Player help.

Hi Folks.
Been going through some of my hoard today, got a Phillips CD 104 CD player, everthing works fine except that the volume is very low, cleaned the laser but no improvement, any suggestions ?.
Wal
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Old 8th Aug 2011, 8:58 pm   #2
tri-comp
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Default Re: Low Volume on CD Player help.

This has to be only speculations. Without a scope and access to the player it can't be anything else.

I remember these players having issues with the power-supply 3-terminal stabilizing-IC's. Re-soldering will most likely solve that.

If the printed circuit boards are with thru-plating also resoldering these will cure the odd behaviour.

There is a power-on muting circuit that mutes the output using a small relay #1510.
Defective electrolytic caps in this circuit will obvious cause problems.
This circuit resides on the Decoding-1 board consisting of transistors 6536 & 6537 with components.
Electrolytics 2517 & 2518 is what I would go after besides dirty relay contacts.

Do you have the schematics. If not, PM me.

rgds,

/tri-comp
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Old 8th Aug 2011, 9:28 pm   #3
Red to black
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Default Re: Low Volume on CD Player heeeelllllllpppppp

Hi Zooterman,

Quote:
cleaned the laser but no improvement, any suggestions ?.
Being a digital system, this part either works or it doesn't, ie. it can either read the data, or it cannot, what Iam trying to say is, it does not 'fail gracefully' or when you get low emission (dirty lens or otherwise) you don't get low sound.

Skipping and/or erratic track reading yes, but low sound definitely not.

Tri-comp has posted some useful information, I would just like to add the following.

With this being a digital system both the left and right, and the loudness is coded and decoded together (interleaved) in the same digital data stream, it is only seperated out into L & R analogue in the final stages (D-A converter) much further downstream from any of the digital processing, so any faults of this nature are likely to be confined electrically very near to the output of the player.

I hope this helps.
Cheers,
Baz

Ps. I may have a diagram for this
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Old 8th Aug 2011, 10:22 pm   #4
julie_m
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Default Re: Low Volume on CD Player help.

If this is the player I'm thinking of, with the tiny voltage regulator on the huge heatsink, replace that regulator. They are run hard and can fail. Use the thinnest layer of thermpath you can get away with.

If it's not, ignore me ..... But the others are right, the fault must be on the analogue side, which is easy. Scope the output if possible, you should see a good volt or so on loud passages. A distorted, asymmetrical waveform indicates a power supply problem. Work backward from the sockets and look for the usual suspects: dry joints, bulging electrolytics and overheating ICs.
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Old 9th Aug 2011, 10:05 am   #5
mark pirate
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Default Re: Low Volume on CD Player help.

I have had a similar audio problem with a 104, they suffer badly from dry joints, a good going over with a soldering iron cured it 100%.

Mark
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Old 9th Aug 2011, 6:44 pm   #6
zooterman
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Default Re: Low Volume on CD Player help.

Thanks All,
I will have a go at it and will update with progress.
Wal
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