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Old 6th February 2006, 07:17 PM   #571
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Divide clock by 2...mmmmm

What is the prefered ic for doing this job?

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Old 6th February 2006, 07:19 PM   #572
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Quote:
Originally posted by rowemeister
Divide clock by 2...mmmmm

What is the prefered ic for doing this job?


d-type flip-flop 74hc74
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Old 6th February 2006, 07:30 PM   #573
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Do you have a schematic at hand or do I have to find one myself hehe

cheers
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Old 6th February 2006, 07:49 PM   #574
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Quote:
Originally posted by rowemeister



Do you have a schematic at hand or do I have to find one myself hehe

cheers
HI.

Something like this........................

Power on reset ( SET actually ) is possibly not required.

Use 74HC74 or 74AHC74 not CD4013 - available from Maplins.

Andy
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Old 6th February 2006, 07:56 PM   #575
Luke is offline Luke  New Zealand
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22mV nise seems quite high, thats about 1% of full output.
Can this player be reengineered to get rid of the noise?
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Old 7th February 2006, 12:36 AM   #576
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cheers Andy
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Old 7th February 2006, 03:20 AM   #577
Franz G is offline Franz G  Switzerland
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Quote:
Thanks Franz. I think the noise is there, but you'll have to set your volume to max. to hear it.
I am very sorry, I just tried it: full volume, >100dB/W speakers (see foto) attached: dead silence.

My hints:

First: The most critical voltage seems to be AVDD (pin 21 and 22 from the SM5872). It is recommended, to derive it from the 12V "audio" voltage.

Second: Try analyzing the ground layout...

Franz
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Old 7th February 2006, 09:17 AM   #578
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Quote:
Originally posted by rowemeister
..........I am changing every thing in the HF amp tomorrow with nice parts and then the RF later in week...............
HI.

Probably too late but .......

Before ripping YOUR cd-p apart, I had some thoughts last night re. the servo section / HF.

The servo is, of course, a linear, non-digital section (analog).
Looking at the PSU side, the +-10 feed does not require any mods, although splitting of the digital +5v would be beneficial. This is because it is a servo and therefore 'self-adjusting'.

EXCEPT, VRef, the reference voltage for the focus, tracking and radial servos is derived from the digital +5v. It is a simple 2.5v from a potential divider, R124 /R125, decoupled by a couple of caps. Any noise on VRef will be seen by the servo and WILL affect performance adversely!!

Can you measure the noise on the +%v at R122 / C122 / R124 junction.?

It may be worth feeding this point fron the 'cleaner' analog +5v and also deriving the VRef +2.5v from a more stable source, TL431.?


Andy
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Old 7th February 2006, 09:23 AM   #579
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Quote:
Originally posted by Franz G
........... Try analyzing the ground layout............

Franz

Hi Franz,

I have heard this before!

However, I, like many others no doubt, recognise that the pcb layout etc is done by a router with little regard for the sonic benefits of good grounding etc.

However, we do not possess the knowledge or tools to analise and then reconfigure the pcb.

Have you modified your Ground???
If so, please pass on the information.

Andy
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Old 7th February 2006, 09:32 AM   #580
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I changed C120 and C122 to 16V 3300uF Pana FC.

I changed these to give more headroom. I am also going to seperate the two 5V inputs to the servo has one is for analogue and the other digital.

The voltage between the two points is 4.983V in stop mode and 4.931V when playing. Tracking etc does not affect the voltage
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