Are clocks always can shaped? - diyAudio
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Old 23rd June 2012, 07:06 AM   #1
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Default Are clocks always can shaped?

Opened up my new ONKYO cd player to have a looksy, and cannot see a tin can shaped item anywhere?
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Old 23rd June 2012, 07:26 AM   #2
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I presume you are looking for a crystal.

Not all CD players use crystal based oscillators, some use simple RC oscillators or ceramic resonators.
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Old 23rd June 2012, 11:06 AM   #3
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hmm.. specification I just looked up claims it has a crystal oscillator.. pcb's don't appear to be double sided.. Though I still wonder if it is on the reverse..

There's a strange looking IC with a metal square exposed.. not sure what that is..
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Old 23rd June 2012, 12:46 PM   #4
DF96 is offline DF96  England
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Microprocessor?

Most packaged crystal oscillators will be can shaped. Most individual crystals in the MHz region will be in smaller cans, but who knows what the electronic packaging industry will come up with next? It is possible that the crystal is inside a plastic package, perhaps looking a bit like a fat IC or a small relay.
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Old 23rd June 2012, 12:58 PM   #5
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Crystals will usually be in hermetically sealed tin cans. Not necessarilly cylindrical.

It's conceivable that they have used an oscillator module. These are genrally about 10 x 5mm steel cans with the frequency printed on the top.

Last edited by KatieandDad; 23rd June 2012 at 01:01 PM.
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Old 23rd June 2012, 12:59 PM   #6
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The crystal may be within an oscillator module.
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Old 23rd June 2012, 04:11 PM   #7
poynton is offline poynton  United Kingdom
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Post a photo(s) of the board.....

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Old 23rd June 2012, 05:51 PM   #8
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No metal can here either. I guess the oblong plastic package towards the bottom left of this poor photo is a ceramic resonator. It has a xtal symbol printed next to it on the very informative Elna board. Unfortunately I haven't found a cheap manual for this Kenwood DP770.

Where the Sony 20152 datasheet shows a crystal, the Kenwood has a transistor, which I assume is buffering the signal from the resonator.

The generation and transimission of clock signals seems to me a dark art. What's the advantage of a quartz crystal over a ceramic resonator? Could it be worth modifying the circuit to accept a crystal?

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Old 23rd June 2012, 06:13 PM   #9
DF96 is offline DF96  England
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Quartz has much higher Q so, other things being equal, it would give much narrower noise bandwidth. I don't know to what extent this is an advantage in audio clocks, as other things might not be equal. It is conceivable that a good ceramic might be better in some respects than cheap quartz, but I don't know. The circuit design matters too. Quartz is likely to have better long-term stability, but this doesn't matter for audio.

It is possible the ceramic resonator is simply a cost-cutter, judged to be good enough by the manufacturer.
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Old 24th June 2012, 02:26 AM   #10
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The blue plastic ceramic resonator is pretty darn certainly just the syscon clock, i.e., for the controller u-processor. The dsp clock is not apparent in the photo, but must be there somewhere. With a player old enough to use the CX20152(i.e., 1984-85), the crystal positively will be a metal can of a common sort, and definitely not a ceramic-cased SMD xtal nor a large rectangular 4-pin clock module.
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