Finally, an affordable CD Transport: the Shigaclone story

[audio1st]

The second is from a Phillips CDM4 (swing-arm) transport (I can hear the screams from here) It was not working.!!!
This again needing the 22mm shaft. This will need a weighted puck.

[kevinkr]

Originally posted by audio1st
I have found a couple of different clamps recycled from other units.
The first is from a TEAC computer drive, which I have fitted to a motor with a 22mm shaft .

Have you run with one of these clamps yet, and if so what if any improvement have you noted? I'm thinking of doing the same thing, I was very disappointed with the clamp/puck assemblies I bought - it was a good effort but more difficult to achieve the required results than I imagined.

I'm running an RCEZ32 based version for which spare parts are almost non existent so I am hesitant to run the risk of wrecking a motor doing these experiments.. I'm going to get some spare parts soon from overseas.

[audio1st]

Hi kevinkr, I haven't tested yet because I'm in the process of building a new unit. I was also a bit disappointed with the screw clamp..
I'm thinking of mounting the transport at a slight angle (10 to 20 deg') to add some gravity to the sledge..

[Dan_ed]

Ok. I'm almost ready to admit defeat. But I can't help thinking that I've missed some basic step to getting this transport to work. Or, perhaps, I've somehow mangled both 31 transports in the same fashion. That seems kind of unlikely.

Still no music. Even from a stock transport that has only the R4 inductor removed and external 8v supply added. Everything on both transports seem to be working. Led (including light), TOC, laser motion, platform spin. Just no music. I do have the resistive network on the SPDIF output, 380/91.

Maybe I should hook the stock transport back to the original boards and PSU and see if it still plays in the boombox?

I'm not real experienced with digital audio equipment so I have quickly run out of ideas. I don't have access to a digital analyzer so I can't really see what SPDIF is doing. Is it possible that some DACs and transports just will not work together?

[audio1st]

Hi Dan_ed, are you sure you are not connecting to the 5V out and not the D ground. 5V is between D-out and D-gnd. My boards seem to output 2.2v at the D out and 0.5V after network..

[jonners]

Dan_ed - Which dac are you using? Presumably it works ok with a different transport, and you have checked the integrity of the digital connecting cable?

John

[Dan_ed]

Hi audio1st,

Yes, I have double checked the DOUT connections. Nearest the TOC connector is ground, then 5v, then DOUT.

However, and this really raises my eyebrows, your posting of the drop across the resistor network that you see is much greater than what I believe I'm seeing. I'm seeing ~2vpp after the network. I'll double-check this again when I get home this afternoon. I even went to the trouble of making a 75ohm load with a resistor and female rca connector. I placed this on the end of the 6' coax so that I could measure both my 31 transport output and the digital output of the Marantz I'm using now. They appeared to be close, with the Marantz perhaps a bit more.

Anyway, thanks for mentioning this. I'll recheck the signal again.

Edit:

Hi John,

I have just finished assembling a Hagerman Chime kit and used my old Marantz 63SE as a transport to make sure the Chime was working. And it does, beautifully, with the Chime. Jim Hagerman designed this kit with a led for indicating SPDIF receiver ok (green light) and another led to indicate PLL reclocking is ok. When I try to play with the 31 transport I get a green light on the SPDIF receiver but not on the PLL reclock, and no music.

It does seem to point back to the SPDIF signal. I'll check with Hagerman but I bet that SPDIF led only indicates that a signal is present. So if it is overloading the circuit, that may drown out the information.

[kevinkr]

I'm wondering what the pull in range of the vcxo in the clock regenerator circuit is on the chime dac .. (You might want to ask Jim this question.) Are you using the recommended crystal or the original resonator?

And unloaded your digital out should be just over 1Vpp and loaded around 500mVpp based on my experience with those values. (I was one of the ones who made the recommendation for those values based on the spdif standard requirements.)

If you are not too far away you are welcome to come down sometime and I will check out your transports and see if I can find any issues. (I sent a pm a couple of hours ago to this effect.)

[Dan_ed]

HI Kevin,

I just saw your email. Thanks for the offer! I'm just north of Salem, N.H. so driving down your way would certainly be a possibility. Hopefully, we can figure this out online. But if not I'll send you a note.

I have sent some questions off to Jim regarding the clock issue.

I also see from a post of mine a few days ago that I reported seeing 4vpp at SPDIF. Based on this and that you guys are telling me this should be a .5vpp signal I would say I really need to concentrate on this output. It is sure sounding like I'm saturating. First, I need to get my facts straight on what this amplitude really is.

The stock transport is still using the original oscillator. I have a second transport that I have done all of Peter's recommended mods to, so it has the Citizen crystal. I suppose the only common things between the two transports is the outboard psu and this SPDIF output network. Both transports are in the same situation. That is, everything seems to work but the music (PLL).

[kevinkr]

Hi Dan,
Some input receivers don't handle being overdriven gracefully so this could well be the problem.. The spdif (DO) from the DSP chip is around 4.5 - 4.8Vpp prior to applying the ~ 10mA load the voltage divider represents - IIRC loaded it is significantly lower.