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guytou 9th June 2005 02:18 PM

Does somebody know the purpose of YM3613B?
...It's located between the decoder (YM3616) and the digital filter.
I can't find any datasheet , except resumed characteristics on servicemanual of my YAMAHA CDX 810 CDP .

My idea is to well understand what does this device , and eventually bypass it , since the decoder already supply a dataflow (Dout , SDSY , BCK ) . Thanks in advance !

P.S. : I've already dypassed the DF .

scottnixon 9th June 2005 02:43 PM

That's a a 'digital audio interface transmitter' which will output a biphase from the demod chip to the outside world. It's inputs were likely parallel with the filter chip and should really only feed a digital output on the player.

Chris Daly 9th June 2005 02:47 PM

As luck has it i have a schematic for a CDX920
containing this very chipset , the YM3613B
appears to convert the 3616 word lengths into
Wordclock Bitclock and data , it also has the purpose
of clock generation and digital out.

It appears to me to be essential for the players operation
signals originating from the 3616 are vastly different
and need the YM3613B to correlate Wordclock Bit clock
and Data further downstream. You cant simply bypass it
doing so will make the player stop as it has no common
word lengths to work with, and would have no clock
generation. Frequency arising from the 3613b is
16.9344 MHz

Cheers / Chris

guytou 9th June 2005 03:13 PM

Thanks for replies , scoottnixon and chrisdaly , what i don't understand yet is that the 3616 seems (from the pinchart & block diagram) to have a real dataflow , not biphase : pin66 : SDO . pin 67 : SDSY . pin 68 :o2 (I think BCK) . For chrisdaly ,in case of bypassing 3613B I would obviously transfer the xtal from 3613 to 3616 , What are you thinking ,I mean what's exactly the interface purpose of 3613B ? Thanks .

guytou 9th June 2005 03:16 PM

Sorry chris , I forgot : 3616 can receive XTAL at pins 79,80 .(XO , XI .)

scottnixon 9th June 2005 03:28 PM

Pin 7 is DDO which outputs a biphase signal. I built stuff using these in early 90's and it's a basically a digital transmitter.

Chris Daly 9th June 2005 03:41 PM

The 3616 is the main processor ic for the player
it has word lengths and data flow quite different to
what the chips further downstream require.

Put simply it is speaking a totally different language
that has no similarity to what occurs later.

If you try and make the 3616 do this on its own
I consider the player will instantly stop, you risk
the processor ic stopping as well, with possibly no way
of its starting again. Its a bit like riding a pushbike
down Londons subway... it makes no sense at all !!!

Define what you are trying to achieve, if you think
for instance that clock timings are ragged or similar
use a schmidt trigger such as 74AC14 to square
leading edges up. You can come to little harm from
using these devices which are always beneficial
in logic transfer. generally speaking any digital
waveform benefits from tidying up. Read up about
Schmidt triggers and look up a pinout for the device
you intend using. Bypassing ic's that are essential
for the players function can only lead to having to
buy another player.

Cheers / Chris

Chris Daly 9th June 2005 04:09 PM

Just confirming The 3613b is essential for the players
operation it cannot simply be bypassed.

From the schematic I am viewing it is well implemented
to convert the 3616's wordlengths into data bitclock and wordclock ( Yamaha equivalents ).

Likewise its clock generation circuit is well thought out
and engineered.

Im sorry there is little tweaking in this part of the circuit
however Schmidt trigger implementation may prove
beneficial , Im happy to suggest which lines may
benefit, but may need your schematic to confirm

Hope this is of help.
Cheers / Chris

guytou 9th June 2005 09:35 PM

Thanks guys for the very complete replies . In fact I am quite newbee with that stuff and i thought the 3616 was working the way a CXD 2545 works , i.e. it feeds directly the dac . I have to learn more on datas transfer formats , by following this marvellous forum , for the moment my old CDP sounds well , except lot of skipping , but the pickup (TAOHS-JP3) costs about 150 USD here in france !

Here is the sheme of the aforementioned part (digital section of
YAMAHA CDX-810) , how sounds for you ?
My attempt came from that i use to have another CDP with same DF/DAC (ym3433/PCM56) , but not the same mechanic/decoder (KSM213/CXD2500) , and I can't regain the same accuracy , definition with my YAMAHA . So I suspect wether mechanism or decoder/digital path .

guytou 9th June 2005 09:54 PM

Sorry , i am not able to separe a page from the pdf.servicemanual , but I can send the entire servicemanual for those who are interested .
For scottnixon : do you think the 3613B provides only the biphase for Digital out ? ( I don't have any use of it ).

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