[Dan_ed]

Hi all,

I have just finished assembly of my new Chime kit last week. Well, the Chime is playing beautiful music but it is not complete. I have it setup in a jig so that I can get to it if I need to probe, fix, modify, etc. This is really an excellent sounding component!

So on to my issue. The transport of my Marantz 63SE is currently supplying the Chime, but I have been working on another project which is a CD transport modification. I have this new transport working as far as reading TOC, displaying the tracks, and it seems to actually play a CD. But no music is coming out. I see the SPDIF receiver led go green, but not the PLL reclock led.

I'm not real experienced in the digital audio realm so I'm trying to fumble my way through trouble-shooting this.

My assumption is that the SPDIF led is an indication that some signal is seen at the DAC input but is not an indication that the signal is correct.  I am seeing, and I need to double-check this when I get home this evening, a 2vpp SPDIF signal. A few folks have told me that this is too much amplitude for this signal. Can anyone confirm this or have any other ideas on what may be causing the PLL not to lock?

Thanks!

[Dan_ed]

After reading the HagDac manual, again, I think I've answered my own question. 

If things still don't work after getting SPDIF down to .5vpp, I'll be back with more questions.

[hagtech]

Maybe you have 2Vpp unterminated.  With the 75 ohm termination on the CHIME you're down to 1Vpp, which is probably ok.  On CHIME there are three LEDs.  The back one indicates power.  Left side is I think the SPDIF receiver data ok indicator.  It turns green when valid data is present (even at 48k or 96k).  The right LED is from the reclocking circuit.  It is green only with 44.1k input data.

jh

[Dan_ed]

Thanks Jim,

I re-measured the DOUT from this transport again last night. I get a 4.8Vpp sinusoidal when I probe DOUT without grounding the probe. When I ground the probe I measure a .5v signal, which is directly from the DSP's DOUT.

The left side led always turns green when I play a CD. The right side never does, so I guess this means there is no valid 44.1k data when the CD is playing.

Not sure what this is telling me. 

[Dan_ed]

I borrowed a better probe. 

My Marantz is putting out a .6Vpp signal and this experimental transport is putting out .4Vpp. I think I'm not hitting the threshold.  aa

[hagtech]

I think you have enough signal.  The problem must be with timing?  You have to be within 100ppm of redbook timing.

jh

[Dan_ed]

I'm sure you're right. Bumping up the amplitude to .6V didn't make it work. It's got to be timing.

[Dan_ed]

I'm getting a nice 1.4+MHz spdif signal. The transport crystal is a Citizen 300-8441, 16.9MHz, +/30ppm. Maybe data is just not coming out? Or, the frequency is outside of the lock range for clock recovery/dejitter?

[hagtech]

Timing sounds ok.  I wonder if encoding is correct.  Or maybe something is causing the HAGDAC to mute?

jh

[Dan_ed]

Thanks for sticking with me on this, Jim. I'm having fun and hope you are as well. 

Maybe these traces will help explain what is going on with this transport?

Marantz after TOC

Marantz with CD playing

Transport after TOC

Transport with CD playing

These make me think that the HagDac cannot detect the individual bit streams.

[hagtech]

Is your custom transport sending out normal SPDIF?  Do you have any schematic pieces of it?  What does SPDIF output stage look like?

jh

[Dan_ed]

I assume it is normal SPDIF.  I'm taking the signal right from the DSP DOUT pin.  I've been looking for the service manual for the Marantz so I can see what they do with SPDIF between the DSP and the rca connector.

Found this today. I have the chip spec for the DSP on the transport. The format for DOUT says EIAJ. Also found that the decoder on the Marantz is putting out biphase mark as the source for the coax and optical. The coax circuit has a small r/c circuit just before transformer output.

[hagtech]

You can make that Marantz waaaay better by replacing that output tranny.  It has horrible frequency response (from your scope photos).  Use the one in the HAGUSB if you can.  I upgraded my CD player and it made a difference.

jh