Adding PC-Link to MDS-JE640 (like MDS-S50)

[BearBoy]

Going by the specs on MiniDisc.org (I don't have any of these machines), the MDS-JE770 is both PC Link and PS/2 keyboard compatible. The MDS-JE470 has PC Link but no PS/2 keyboard port.

[NGY]

40 minutes ago, BearBoy said:

Going by the specs on MiniDisc.org (I don't have any of these machines), the MDS-JE770 is both PC Link and PS/2 keyboard compatible. The MDS-JE470 has PC Link but no PS/2 keyboard port.

Good point, actually.

Normally, if both functions are supported on a given (very seldom) model, then those are sharing the same PS2 port. The 470 does have a PS2 port, but on the rear panel (and w/o the keyboard functionality implemented).

[kgallen]

OK you clever people here is my latest cut-and-shut based on the insight from @M1JWR and @BearBoy

Per @NGY's comments, the PC-Link (raw I2C) is not buffered in the 770 (despite the block diagram suggesting it is, below).

The key here is that if the unit has a keyboard interface, then the I2C (IIC DATA, IIC CLK) also needs to be available raw on the DIN connector. The Keyboard interface has this 5-transistor circuit between the uC and the DIN. Also the PC-Link has these two extra connections IIC BUSY and IIC POWER.

I believe that @sfbp has all these connections in place on his 640, however I need to review the details (but need to pop off for now for a work meeting, so be back later...)

Sorry this is a pdf - exporting as png/jpg/gif didn't have the resolution (however I'll also upload a png just so you can see what's in the pdf, so you don't get too excited...)

Keyboard_PCLink.pdf

[BearBoy]

@NGY, ah, okay. Thanks! I was getting a bit confused because the implementation on the Japanese MDS-JB940 seems to be different, at least it is according to MiniDisc.org

MiniDisc.org says that PC Link on the MDS-JB940 works via the digital optical input (for audio transfer) and can also be controlled from a PC (via Control A1(II) or via the keyboard PS/2 port?)

Unfortunately the English manual I have for the MDS-J940 makes no mention of PC Link as it looks like it was a Japan only function.

Looks like the implementation on the MDS-JE770 was different with everything going through the PS/2 port on the front?

[NGY]

2 minutes ago, BearBoy said:

MiniDisc.org says that PC Link on the MDS-JB940 works via the digital optical input (for audio transfer) and can also be controlled from a PC (via Control A1(II)?)

I admire the enourmous amount of information on minidisc.org, but learned over the years that I have to take those "facts" with a grain of salt.

The quote above is a bit ambiguous. Using the PC-Link, the audio signal can be transferred either via TOSLINK digital or analogue RCA. Controlling the device from a PC normally happens via the PS2 port (and the PC-Link device), but, the Control A1 has very similar commands/functionalities to that, and - in theory, I have not yet seen this documented - it can be used for the same purpose, as the PC-Link.

[BearBoy]

The page for the PC Link kit (PCLK-MN10/MN10A) says:

Quote

Kit includes: Software CD-ROM, USB cable, TOSLink cable, USB to TOSLink/Control-A1 adapter box

But all the photos I can find of the PCLK-MN10 show it having a mini-DIN connector, rather than the 3.5mm jacks used by the Control A1 system.

Probably best we rely on first hand knowledge from people who have used the system rather than what I am scrabbling together from, potentially inaccurate, web sources and my own speculation ;-)

[NGY]

10 minutes ago, kgallen said:

I believe that @sfbp has all these connections in place on his 640, however I need to review the details

Looks like we are doing a "rat race" here ;-) .

Even I had not posted all my steps and findings here, I feel being somewhat ahead (as been all there already, I even see now where Stephen's solution went wrong), and if you were given me some time to consolidate my knowledge and finally put into practice, we could probably lift all the clouds here at once.

Yes, out of sheer vanity :-) I wanted to come up first with the ultimate solution, in a completed, polished format. But as it is just a pointless luxury that both of us are wasting precious time to discover basically the same thing :-) , maybe better approach is to wait until you also conclude with your findings, then we consolidate the stuff later. I go back to my 640 in the meantime, to do the final step.

[NGY]

1 hour ago, BearBoy said:

But all the photos I can find of the PCLK-MN10 show it having a mini-DIN connector, rather than the 3.5mm jacks used by the Control A1 system.

I trust you mean by "mini-DIN" the standard PS2 plug, dont' you?

I never saw the PC-Link mentioned as to be used via the Contorl A1 jacks/lines. I think it is possible - to a certian extent, as the command set of the - sort of standardized - Control A1 seems limited compared to the - sort of Sony proprietary - PC-Link bus command set.

 

EDIT:

I wanted to add this note, although it might be obvious: I think the ambiguity around "PC-Link" is coming from the fact, that the deck is connected to the PC-Link device on two lines. One for the (either digital or analogue) audio transfer, and nothing else happens there, but the audio signal flow. The other line is the actual digital control of the deck, that covers controlling the deck operation (record, play, pause, etc.), transferring digital information (track/disc info, etc), as well as some editing functions, etc. The same time, the PC-Link device connects to the PC only on one line, that is the USB. It is possible to transfer audio to a non-PC-Link enabled device via the CAV box, but it lacks the control and info part (ultimately, the communication between the deck and the PC).

[BearBoy]

Yes, I meant PS/2 style plug.

[kgallen]

18 minutes ago, NGY said:

Yes, out of sheer vanity :-) I wanted to come up first with the ultimate solution, in a completed, polished format. But as it is just a pointless luxury that both of us are wasting precious time to discover basically the same thing :-) , maybe better approach is to wait until you also conclude with your findings, then we consolidate the stuff later. I go back to my 640 in the meantime, to do the final step.

But on starting this, I did not know you were doing this so embarked on my own investigations per the initial request from @sfbp. I realise you want to present the perfect solution, but even if you share some thoughts then we can collectively learn and collaborate on the way. My reading of your comments was you still had issues to solve. If you want to present the ultimate solution and have all of the answers but are not ready to share, then that "heads up" to us is useful. i.e. I can butt out if this is all old news and there is a known solution yet to be shared.

That said, I don't think I've wasted my own time since I've learned more about an aspect of these machines I hadn't investigated before. However if I'm presenting old news at the frustration of others then I can stop.

Above reads bitter, it is not meant to! Greatest respect to you all here, you are great friends if such can be stated given this is an open forum.

[BearBoy]

Like this:

[NGY]

@kgallen, I never meant you'd stop doing your stuff as you do it very well [respect]. All I was trying to hint (from the beginning) was that there is a certain amount of work that had already been covered in the background (that could have - besides my vanity of course ;-) - saved your time), and waits only for the actual implementation.

@sfbp's photos assured me I am on the right track - but of course I can still fail with it. For this, surely, if you enjoy the 'discovery', please keep going on :-) ! I will also keep my eye on this thread, and if you find something I obviously overlooked, I will take that happily.

"Four eyes see more than two".

[kgallen]

@NGYAre you able to share (without major document preparation on your behalf!) the next step that I feel you know the answer to? I realise you want to fully validate your findings but of course this may depend on having a suitable deck and "vandalising" one's main machine is never to be taken lightly, so there could be a significant timeframe involved here. You are teasing us with the answer ;-) Is there anything next you need help with to bring this to a conclusion in our minds? I cannot help with the soldering iron, since the lead on mine will not reach to your workshop :-D

Maybe you just want some space in your mind for this, without the chatter in this thread, in which case I abate!

[NGY]

17 minutes ago, kgallen said:

Maybe you just want some space in your mind for this, without the chatter in this thread.

Exactly - I admit it  is just a question of different style (me feeling uncomfortable put into writing that I could not yet finalize or could not prove beforehand).

17 minutes ago, kgallen said:

@NGYYou are teasing us with the answer ;-)

No, it is very simple, no secrets: my theory is that both from HW and FW persective everything should be already there on all three versions (1 - PC-link only, 2 - kbd only, 3 - PC-Link and kbd). However, there are differences amongst the revisions of the same board, that need to be looked after in each and every case. To give you and example - just exchanged PMs with @sfbp on this: his keyboard pcb is different from mine, and both differ from what is documented in the SM. (Also, I have information on at least three different "universal" JE640 MB boards, that seem to be the same...) Once I can confirm it with 100% certainty (I think this is what you feel "teasing", but I am simply not yet ready) what is supposed to be there on all versions in order to get this PC-Link thing going, I can move over and test whether or not the firmware supports it. There is a slight chance it will not - see the note on the different MCU versions in the S50 and the 640. It might be just an economical decision as you explained, and hopefully it is.

[sfbp]

55 minutes ago, BearBoy said:

The page for the PC Link kit (PCLK-MN10/MN10A) says:

But all the photos I can find of the PCLK-MN10 show it having a mini-DIN connector, rather than the 3.5mm jacks used by the Control A1 system.

Probably best we rely on first hand knowledge from people who have used the system rather than what I am scrabbling together from, potentially inaccurate, web sources and my own speculation ;-)

Dunno if I am going to get a significant amount of sleep, up again (something to do with pollen in April I suspect).

The point about the protocol used by:

a. The IR controllers
b. Control-A1
c. SIRCS
d. PCLink

Is that it is the same in all cases. This I recall being steered towards by Jim Hoggarth. One of the reasons it is so badly documented is (most likely) the variations which cause silly incompatibilities. One of the reasons that M-Crew seems a bit slow at transmitting commands is that they are sent at the speed of a person pressing buttons on a remote

The only point in all this is it's not unreasonable to expect the signals being used by keyboard and PCLink to be effectively the same. The commands, that is.

[kgallen]

I believe I made (at least!) one incorrect assumption or statement earlier in my voyage of discovery. In reviewing/perusing my pdf attached above for 770, I realise that for a keyboard, the deck is an I2C slave (SCL is input to the deck, albeit with flow control from the deck using transistor Q34[770]/Q5[640], SDA seems input to the deck only). For PC-Link the deck is I2C master (or indeed could be master or slave) (SCL is output or bidirectional, SDA is bidirectional). This means that to support PC-Link, the "keyboard pcb" cannot have any active circuitry that would prohibit driving out either SDA or SCL. Active circuitry could of course allow this, but if the deck was intended keyboard-only then the active circuitry may be unidirectional as detailed above.

[NGY]

Exactly. See Q5 - this is there also to shut down the keyboard comms if and when a CAV device wants to talk to the MCU.

Part of my hypotesis was that PC-Link has to have priority against the keyboard. And having Q5 there tells me - cross our fingers - the FW will "know" it once the connections part is sorted out.

 

18 minutes ago, sfbp said:

The only point in all this is it's not unreasonable to expect the signals being used by keyboard and PCLink to be effectively the same. The commands, that is.

It certainly depends on the version of the MCU. The 640 and the family members do have separated, dedicated ports on the MCU for the I2C and the keyboard signal lines.

 

[kgallen]

52 minutes ago, NGY said:

Exactly. See Q5 - this is there also to shut down the keyboard comms if and when a CAV device wants to talk to the MCU.

-My apologies, on which schematic is this Q5 transistor you speak of.- <Hey, where has "strikethrough" gone when doing Edit???>

Ah, on the 640 schematic, I was on 770 where it's Q34. This can be used in I2C for flow control - the slave holds SCL low to tell the master to extend the I2C cycle (I2C spec $3.1.9). But also you are right, this can also be used in multi-master I2C topologies as a means of bus arbitration (I2C spec $3.1.7).

My second apologies, I am still commenting and disturbing your peace despite my assertions to the contrary :-(

[NGY]

5 minutes ago, kgallen said:

on which schematic is this Q5 transistor you speak of

Yeah ... it is "Q34" in the 770. Funny, because both in the 640 and the 940 (and in some others) it is "Q5".

[NGY]

On 4/8/2021 at 11:58 AM, kgallen said:

You are teasing us with the answer ;-) Is there anything next you need help with to bring this to a conclusion

OK ... thanks to the "persuasion" by @kgallen , I dropped all my present tasks and spent last night and today on completing my journey.

A PA will follow shortly ... stay tuned. Allow me a short break and a few hours to sleep, then I get back to you.

@sfbp, don't close your 640 just yet ;-) !

[kgallen]

I'm saying nothing more on the subject otherwise I will get told off! :-P

[sfbp]

49 minutes ago, NGY said:

OK ... thanks to the "persuasion" by @kgallen , I dropped all my present tasks and spent last night and today on completing my journey.

A PA will follow shortly ... stay tuned. Allow me a short break and a few hours to sleep, then I get back to you.

@sfbp, don't close your 640 just yet ;-) !

Especially since with my incompetent big thumbs I probably made an error in soldering........... waiting with bated breath

[sfbp]

On 4/8/2021 at 3:43 AM, kgallen said:

-My apologies, on which schematic is this Q5 transistor you speak of.- <Hey, where has "strikethrough" gone when doing Edit???>

 

It appears to be a bug of some sort, since if I quote a post the S for strikethrough is still there. However you should still have the HTML option to surround the text with <s>text</s>

[NGY]

On 4/7/2021 at 3:02 AM, sfbp said:

hmmm if you can figure out how to add PC-Link to the 640 I for one would be eternally grateful.

Here is the thing then: the 640 does work now with PC-Link and M-Crew. (See my uncut, lame video at the end - "Welcome to Paradise" :-) .)
Yes, it is done, and I feel this is a breakthrough, after all those unsuccessful tries in the past, including my previous attempts back in 2017 or so. The icing on the cake is the 640 has kept all its keyboard functionalities too !

I guess what you are mostly interested in is how this was made possible, and what's needed to replicate it on your machines - the shiny, polished, step-by-step guide and documentation I originally wanted to post here can wait.

The beauty is that it's like Columbus' egg. Plain and simple, and all of you will now say "gosh, I should have done this easily".

[I had not reinvented the wheel either, really. What I did was I took the recently purchased S50's main board I did not fear to sacrifice and began doing actual measurements of what lines/signals go where, what connections, pull-up resistors, etc. are there, and compared the thing to the SM-s. The big surprise came when I realized none of the SM-s (640, S50, PC3, etc.) tell you the true story, because this or that is different here and there, from what is on paper and what is actually on the board. Looked too complex, and I got misled quite a few times when working only from the SM-s.]

I distilled all this information down to a simple, clean solution. No matter which version you have (EU, US/CAN, etc.), just follow this:

[In a nutshell: there is nothing special required, everything is there already in the machine (this was my theory afterall, and it finally stood). Very minor things must be checked and supplemented, but nothing that could not be done DIY.]

Check this silly drawing:

These are the lines (marked with green) that must be there, all the way from the PS2 socket down to the MCU (other lines are all there, nothing to do with them). Follow these lines on your actual boards/wires one by one and see if you can get there all along. If there are jumper wires and/or 0 ohm resistors and/or inductances in series, leave them there. If you see some pull-up (typically 4k7 or 10k) and/or pull-down resistors (typically 100k) or parallel capacitors, you can also leave them all there. If the continuity breaks somewhere, look after what is missing.

What must be there in order to get this working, i.e., must be supplemented in case they are missing (and normally are - see my photos with the details below):

- R36 and R37 (very tiny 0 Ohm resistors) are not populated on the main board (@sfbp, you have been this close, all the rest you did well!),

- two wires  are missing, from CN820 on the MB up to the keyboard pcb (as seen also on @sfbp's photos), making sure you solder them in proper order (do not accidentally swap them), and

- two 100 ohm resistors need to be soldered on the keyboard PCB in the positions marked "L805" and "L806" (well, plain jumper wires would also work, but in some PC-Link models these serial resistances are there, for a reason I guess).

(Warning:
- when measuring traces on and wires between pcb-s, don't just use your DMM directly in resistance or continuity mode. See more on this here.)
- make sure you and your device are properly ESD protected, and never work on a powered up machine.)

This is it, and you're done.

I would love to see then the feedback from people who succesfully replicated this on their machines.

- - -

Next steps that now are also doable using the same approach:

- for "technical maximalism": build the I2C extender circuit mentioned above (good news: the keyboard PCB is already prepared just needs to be populated, and only THT parts are required),

- probably the "most wanted" one: make the 940 work like the Japanese version, PC-Link and keyboard,

- a "side effect": make the keyboard work on the S50 (and on the 470 too) - similary to the I2C buffer, the MB pcb already has this area, just unpopulated,

- and an "opportunity" for the low end machines: make the 440 (!) work with PC-Link and even accept a keyboard too.

And some mandatory, due thanks:

- @kgallen - I value your attitude for getting things done quickly (like in the case of the copybit killer stuff). This pushed me out of my "laziness".

- @sfbp - your photo gave me the final "kick" that my hypothesis was right, and that I had to finish my research and do the soldering part at last. When I saw your 640's main board, I immediately realized why your attempt was unsuccessful. (And I asked for some new photos because this very part was hardly visible caused by the bright spot of the flash, but then I came across finally even without them.)

- @Sony - having these features already built in (only disguised for certain markets ...)

[kgallen]

Well @NGY sterling work indeed. We treasure you for it, even if we (I) drive you to distraction! However I do not own any of these machines so I will leave the fun to those who do!

The only contribution I can make here is to help out with a couple of comments above regarding 100R resistors and 10uH inductors (ferrite beads)...

Often you will see 100R resistors inline to a digital connection. Why so? Is there a significance to where they are drawn in the schematic? Indeed there is. Often you will see a small value series resistor in a digital line. On the schematic it is shown near to the driver of the signal - the output of an IC usually. This is a series termination and on the PCB it should be placed physically close to the source (driver) rather than the sink of the signal. This resistor helps match the electrical impedance of the driver to the electrical impedance of the PCB trace. It is there to give a better wave-shape to the digital signal - to help avoid transient overshoots and minimise signal reflection and ringing (refer to transmission line theory). As well as helping signal integrity, this helps minimise the generation of high frequency harmonics due to these transients. This reduces the emission of unwanted radio frequency signals from these high speed digital circuits. This helps with EMC compliance which has been part of equipment design requirements and international standards since the 1990s. The purpose of EMC compliance is to minimise how much electrical interference (emission of spurious radio frequency signals) a piece of equipment can generate such that it does not disturb the operation of another piece of nearby equipment.

So what about these inductor/ferrite bead things then?

Well this is a similar story. Have you seen those fat bulges or clip-on lumps on some cables - often seen on VGA cables and laptop power supply DC cables. Well these little inductors - or ferrite beads - we see on Sony schematics are there for the same reason. You will generally see these components in the power supply lines, +5V and GND for example, to internal components - often the TOSLINK transmitters/receivers - but also in supply signals going out to external connectors - like the PS/2 DIN connector we're interested in this thread. An inductor (or ferrite bead) has very low impedance (resistance) to a low frequency - or DC - signal, like a +5V power rail. But it has a very high impedance (a high ac resistance) to a high frequency signal (which is why you won't usually find them in signal lines - for this purpose anyway) - like these radio frequency signals that are generated inside our equipment. What these ferrite beads do, is restrict the amount of this RF energy that "leaks out" of our equipment into cables that connect our equipment to some other piece of equipment. These external cables can act as aerials (antenna), spraying our internal electrical noise outside of the equipment. This leads to EMC compliance failures during equipment compliance testing because these noise signals can disturb the operation of other equipment.

So what about when we are doing "user hacks" to our equipment?

Well if the intended circuit has these components in the design but they are not populated on our board what do we do? Well this depends on if you intend to sell the equipment. And if you do, will there be any "come back" on you if your modified equipment disturbs the new owner's pace-maker (example!).

So let's summarise and say - if you want to "do it properly", then ideally you will source and fit these ferrite beads per the original design. This means the modified equipment would be expected to comply to the EMC regulations of that piece of equipment - with that function - when it was built at Sony's factory. (Note: There is considerable variability shown across designs and we see a range of implementations in this area even from Sony - from inductors, resistors to plain wire links - there is no definitive answer. Economics and profit margins are always at play - saving 5 cents on a component will always be asked from the engineering teams on consumer products. Note2: The "do it property" was in no way intended a criticism or "sleight" on @NGY's comments above, I was more commenting on approaches we may take to our own modifications.)

Conversely, if you don't give a damn and the equipment is only for your own use, then you are probably going to put a wire link or 0R resistor there instead of the ferrite bead - i.e. something you already have in your spares box. The function of the design won't be any different, you'll just be spraying a few more radio waves about inside your house.

Regarding the 100R series terminators - similar to above, but in most cases you will get away without these. Not fitting them is likely to mean internal signals can be a little more "dirty". In extreme cases this can lead to errors in digital signals (interpreting a 1 instead of a 0 and vise-versa). In many cases this may go unnoticed (would you be able to hear a 1-bit error in your music?). On signals related to the microcontroller, this may cause the machine to crash or hang.

Jeez, I thought I was going to write a couple of lines. Don't invite me here again... But aside, maybe you learned something new about electronics and some of those squiggles in the schematic diagrams we speak about so often are step-by-step a little less mystifying.

Let us know how you get on...

 

Example of 10uH ferrite beads in an external connection (like L805/L806 referenced above):

Example of 100R series terminator on high speed digital signals:

[kgallen]

For those anal like me, if you have need for any SMT inductors like I describe above, for a Sony mod [note in @NGY's project above, the headphone board uses through-hole components] I came across these on eBay (UK) the other day:

https://www.ebay.co.uk/itm/Bourns-CM322522-100K-SMD-Inductor-10uH-1210-Pk-of-10/202771742580?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

(I already bought a batch for my intended 440 optical out mod...)

He's got lots but if this thread is read in the future or somewhere else on the planet without eBay UK access needs some, you're looking for 10uH 1210 SMD (1210 is the size, which is a spec you'll need along with the inductance value of 10 micro-henry).

[NGY]

On 4/9/2021 at 10:45 PM, kgallen said:

Well @NGY sterling work indeed. We treasure you for it, even if we (I) drive you to distraction! However I do not own any of these machines so I will leave the fun to those who do!

The only contribution I can make here is to help out with a couple of comments above regarding 100R resistors and 10uH inductors (ferrite beads)...

Often you will see 100R resistors inline to a digital connection. Why so? Is there a significance to where they are drawn in the schematic? Indeed there is. Often you will see a small value series resistor in a digital line. On the schematic it is shown near to the driver of the signal - the output of an IC usually. This is a series termination and on the PCB it should be placed physically close to the source (driver) rather than the sink of the signal. This resistor helps match the electrical impedance of the driver to the electrical impedance of the PCB trace. It is there to give a better wave-shape to the digital signal - to help avoid transient overshoots and minimise signal reflection and ringing (refer to transmission line theory). As well as helping signal integrity, this helps minimise the generation of high frequency harmonics due to these transients. This reduces the emission of unwanted radio frequency signals from these high speed digital circuits. This helps with EMC compliance which has been part of equipment design requirements and international standards since the 1990s. The purpose of EMC compliance is to minimise how much electrical interference (emission of spurious radio frequency signals) a piece of equipment can generate such that it does not disturb the operation of another piece of nearby equipment.

So what about these inductor/ferrite bead things then?

Well this is a similar story. Have you seen those fat bulges or clip-on lumps on some cables - often seen on VGA cables and laptop power supply DC cables. Well these little inductors - or ferrite beads - we see on Sony schematics are there for the same reason. You will generally see these components in the power supply lines, +5V and GND for example, to internal components - often the TOSLINK transmitters/receivers - but also in supply signals going out to external connectors - like the PS/2 DIN connector we're interested in this thread. An inductor (or ferrite bead) has very low impedance (resistance) to a low frequency - or DC - signal, like a +5V power rail. But it has a very high impedance (a high ac resistance) to a high frequency signal (which is why you won't usually find them in signal lines - for this purpose anyway) - like these radio frequency signals that are generated inside our equipment. What these ferrite beads do, is restrict the amount of this RF energy that "leaks out" of our equipment into cables that connect our equipment to some other piece of equipment. These external cables can act as aerials (antenna), spraying our internal electrical noise outside of the equipment. This leads to EMC compliance failures during equipment compliance testing because these noise signals can disturb the operation of other equipment.

So what about when we are doing "user hacks" to our equipment?

Well if the intended circuit has these components in the design but they are not populated on our board what do we do? Well this depends on if you intend to sell the equipment. And if you do, will there be any "come back" on you if your modified equipment disturbs the new owner's pace maker.

So let's summarise and say - if you want to "do it properly", then ideally you will source and fit these ferrite beads per the original design. This means the modified equipment would be expected to comply to the EMC regulations of that piece of equipment - with that function - when it was built at Sony's factory.

Conversely, if you don't give a damn and the equipment is only for your own use, then you are probably going to put a wire link or 0R resistor there instead of the ferrite bead - i.e. something you already have in your spares box. The function of the design won't be any different, you'll just be spraying a few more radio waves about inside your house.

Regarding the 100R series terminators - similar to above, but in most cases you will get away without these. Not fitting them is likely to mean internal signals can be a little more "dirty". In extreme cases this can lead to errors in digital signals (interpreting a 1 instead of a 0 and vise-versa). In many cases this may go unnoticed (would you be able to hear a 1-bit error in your music?). On signals related to the microcontroller, this may cause the machine to crash or hang.

Jeez, I thought I was going to write a couple of lines. Don't invite me here again... But aside, maybe you learned something new about electronics and some of those squiggles in the schematic diagrams we speak about so often are step-by-step a little less mystifying.

Let us know how you get on...

Thanks Kevin, for the invaluable input, I am sure it will be very educational for a lot of people. (And I see nothing wrong whith educated people seeking for technical perfection.)

Maybe not for me, though. You could already realize, I am trying to use a "simplified" language when it comes to technical terms and explanations, for the sole reason I want it be readable for those too, who are not necessarly graduated EE-s, but still interested. I am sorry, if, for this reason (and maybe with my above work too) I look like somebody who is totally an outsider and does not know, what he was doing, just hacking left and right until gets some results by chance, and he is then so proud of this luck. No. I make serious efforts to make my posts valid, true and factual. I also did put serious work into this result above (just to pick this one as an example), regardless its Columbus's egg nature eventually (that always turns out afterwards, does not it?), and I also do have a very basic knowledge to be able to differentiate, what is allowed and what is a no-no when designing electronic devices, even if it is not reflected in my wording (that is, as I said, on purpose). You can read with a few posts above, I am keen on having all my statements based on proven facts (for example, the question of whether or not the I2C extender was a non-negligible item in a circuit like this).

Matter of fact, and particulary to the point you raised, with the 100 ohm resistors I simply followed the Sony engineers, how they implemented this in another, factory stock, PC-Link enabled deck. In other words, if there had been inductances there, I would have definitely placed those instead (although none of them would be SMT devices on the keyboard pcb). The same time, I can show you another machine, when there is only a wire link there, also by design, by the Sony engineers... There are lots of examples I could also post here from Sony SM-s, but I don't feel I have to prove anything more.

In the other hand though, the inductances you are (rightfully) looking for are already there on the keyboard PCB - just please take a closer look ...

Please don't take this as a battle - I wanted to come up with a clean, pure solution for those who are only interested in the ultimate result to use in their machines, and even if it does not look like as a well established solution, it is thought over in all details, trust me. If you find anything you could do better (i.e., technically perfectly), then all right, but I guess not even Sony's engineers wanted to do that anyhow, so I feel totally unguilty. My solution is safe and sound.

Now, with all these long posts we managed to cover dust on the main thing, for what the thread was originally created. I hope there will be just a few people who will find that post with the thing interesting and useful, and I can consider it as a little "heritage" from me, in a question that has long been unsolved (by very smart people).

With that, I also want to say good bye to all these great folks here on this forum I met over the years, it is time for me to look for other adventures.

MD forever.

[BearBoy]

Amazing work NGY!

[sfbp]

6 hours ago, NGY said:

With that, I also want to say good bye to all these great folks here on this forum I met over the years, it is time for me to look for other adventures.

MD forever.

That is the sad part... we shall miss you very much indeed. Hopefully whatever it is that took you away will relent or retarget you in our direction.

I'm still puzzling over what I didn't do right. And I definitely went through all the same contortions with the MXD-D5C (US/Can model) and with the same result. So will be wonderful to have that machine fully fixed and with optical output which I already added.

[sfbp]

Here is the picture you needed, which I couldn't face doing when asked (been sleeping rather badly as you have noticed this week). I see there is absolutely nothing joining R36 and R37. By absolute bad luck the flash went off in that exact spot. Today I used my new handydandy phone and it took picture without flashing anything (I guess it has a better grade of light sensor)

So that's all I needed, to add a blob of solder between each of those two connection points? (forget the 0 ohm SMT resistors for this poor schmuck!)

[sfbp]

BTW this is quite mysterious - that those two "jumper points" don't even exist on the schematic in the Service Manual that I have. Not that surprising I didn't know to jumper them.

I definitely noticed that the board in the D5C didn't match the schematic, but that certainly would be true given that the one I recall looking at for clues was the Japanese one.

I cannot begin to understand how you pieced it together! And I will be looking to see if I can work out what's going on with the D5C, too.

[sfbp]

Problem solved! The R36 and R37 are clearly visible in the diagram for the MDS-S50. Maybe what happened is that they altered the 640 board enough to make the S50, then retrofitted the new board (minus a couple of zero ohm resistors at least, who knows what else!) to 640's. And why not, indeed?

Where's the same spot in the JB940, I wonder? Or was that always enabled? I've never had a JB940 in my hands though a couple of times was tempted to order one from Japan - until I saw the horrendous shipping cost for something so heavy.

[M1JWR]

nice expeimentation, the bummer is, that if sony added a usb system like on the 980 earlier then none of this would be needed,all good stuff all the same, no wonder 980's cost mega bucks,its all about that usb, dispite its much poorer internal build quality

[sfbp]

Not quite - M-Crew is a much better tool than SonicStage, for editing. Once USB came along, everyone was focused on the computer and transfer therefrom. No PC-Link, no accurate remote editing. You have to transfer the file somehow to the PC and edit it there.

[M1JWR]

true stephen, thing is the usb was/is convenient even though sonic stage was rather crap, still handy for titling discs though, otherwise i found that with sonic stage transfer to pc can only be done with the player the pc transferred to in the first place, now i wonder where that mz n1 portable is that i had, did loadsa discs with that before i got the 980, i have a feeling that it is with an old mate in luxembourg, drat !!

[sfbp]

The reason for that is that all that gets transferred back is the rights (library book checkout). NetMD cannot be transferred to PC***. Pre-RH1 limitation in USB speed (hardware/firmware). RH1 by design****. They didn't want to proliferate copies generated by NetMD transfer. For HiMD a lot less restriction because they're normal files.

***I don't think you can get anything OFF an MZ-N710 for example.

****The ability to upload MDLP bitwise built into the firmware. The ability to upload SP, if i recall correctly (and doubtless someone's gonna jump all over me with hobnailed boots) simply generates 16bit toslink output and makes a wave stream. You can capture it but it won't be as good as the SP because it's not bit for bit.