Sony CDP-101 Introduction
Inside the Sony CDP-101
Remote Control
Clearly by adding an elegant infrared remote control handset to the CDP-101,
Sony were blazing the trail for the CD concept in every aspect! Like the
player, the handset is as futuristic as anything you could imagine! With a
slightly squareish profile by today's standards the handset is built tough with
a stylish painted brushed aluminum clad top and soft rubber buttons like any
remote of today, but it has a weight & feel that no modern day remote can touch.
On the sides of the remote, there are some Just like all remote handsets of today, the Sony RM-101 uses a modulated pulse position protocol to signal the CDP-101 player. The player looks for pulsing light in the area of the modulating carrier frequency which is 40kHz, and by looking at the length of each modulated burst, can detect binary 1's and 0's, so this too is a simple digital device that uses a kind of pulse position modulation. Referring to figure 1 below, this shows part of a PCRemote screen shot and is the display of the RM-101 Play button. As you can see, there is one wide pulse to start with, which is a synchronization start pulse, then 12 following pulses, some wider than others. The thin pulses represent a binary value of 0, and the wider pulses a binary value of 1. So going from left to right, the 12 bit value is 010011010001. By looking at the codes from all the other buttons, I have established two things: First, the data appears to be sent with the least significant bit first, but the PCRemote display is merely concerned with time going from left to right, so for us to read it as a number it needs to be reversed as 100010110010. Second, I can see that all the pulses start with 100010, so it is possible this is a 6 bit device code, and the remaining 6 bits 110010, are the button code, so this would give 64 possible devices with up to 64 buttons each. In fact, further research into this indicates that Sony uses (or used to back in the 80's) a 5 bit word code and a 7 bit data code. The total data packet is about 20 milliseconds long and there is another 20 millisecond gap at the end before the pattern is repeated. The repetition goes on and on for as long as a button is held down. Figure 1. PCRemote display of RM-101 Play button at scale 9 showing entire data packet
Looking more closely at the pulses in Figure 2 below we can see more detail about the pulse durations. The starting synchronization pulse is 2.4 milliseconds long and then each data bit is a 0.6 millisecond gap followed by a 0.6 millisecond pulse for a binary 0, or a 0.6 millisecond gap followed by a 1.2 millisecond pulse for a binary 1. So the duration of the shortest data packet with the value of 000000000000 would be 2.4 + ((0.6 + 0.6) x 12) = 16.8 milliseconds. The duration of the longest data packet with the value of 111111111111 would be 2.4 + ((0.6 + 1.2) x 12) = 24 milliseconds. Just for your information, the numbers on the top row of the PCRemote display are the pulse numbers starting from 0 and counting to the right, the second row of numbers is the actual count of the number of 40kHz cycles that is needed to fill the amount of time of the pulse or gap width. It is data at this level that PCRemote actually records and uses for playback of the pattern to emulate a button press. So in fact, PCRemote does not need to know anything about the details of the protocol we are discussing here, it just records and plays back the pattern of pulses it sees! This is in fact how all learning remotes work and why they use so much memory for learning something so simple! They are just not smart enough to learn the actual protocol like we are here! But at least with PCRemote the user can see what the application is recording and redo any recordings that are obviously wrong. That can sometimes happen if you have fluorescent and especially neon tube lights on in the same room as the receiver. Figure 2. PCRemote display of RM-101 Play button at scale 40 showing detail of pulse sizes
The following table shows the binary values of all the buttons on the RM-101 The codes are shown as 12 bit binary numbers and as described above (least significant bit on the right but first to be transmitted), this makes the code for play 10001 0110010 and they are divided into a bunch of 5 and 7 just to make them easier to see and are listed in order of numerical code. This information can be used to manufacture a new RM-101 remote or you can convert the data into pulse width times for entry into some kind of other intelligent remote control transmitter device to use with a CDP-101 if you have lost your RM-101!
CDP-101 Problems
After a quarter of a century of usage, it is only fair that a CDP-101 should have a failure or two. Having said that, mine failed in about 1985 which I didn't feel was that good at the time! It therefore effectively suffered the same fate as every other piece of Sony equipment I have ever owned including the first ever Video 8 recorder with digital audio the EVS-700 and the first ever small head Video 8 HandyCam camcorder the TR-55. While all of these items did indeed work at one point and continued to do so through their warrantee period and were purchased at a time when each of them was incredibly difficult to make, they all failed after a relatively short time compared with other equipment I have. While it was great to have such futuristic equipment at the time, it's a shame that it all busted so quickly! So while Sony clearly has a significant leadership position in design concepts, I can't say as I'm that impressed with the equipment. Even within the last month, I have found two items of Sony equipment just discarded in the garbage at our condo (yes, I'm rooting through the garbage again!), an STR-DE915 receiver and a CDP-297 CD player. How come I never see any Pioneer or Technics gear tossed away there? After a little research I find that anyone who has had the misfortune to own an STR-DE915 receiver will never have anything good to say about Sony again and I think it is a shame that Sony puts their name on such poorly designed equipment, although the CDP-297 is up and running straight out of the trash can and works with the RM-101 remote! As far as my CDP-101 is concerned, it sat for many many years just gathering dust waiting for a service manual to come along. Well, now I have one, so let's see what can be done! What was happening with the player back in 1985, was that it did start to play the disc, but then started to skip and jump around. Then a knocking noise starts to come from the focus servo and it is unbelievable how loud the noise gets, so I would unplug it before it exploded! Now, there is also another problem, the drive for the loading draw has failed so you have to take the lid off to get the disc in! So the two problems are: Disc skipping which gets worse and worse the longer the player runs; Second, the loading draw is stuck. From all I have heard about CDP-101's, these are the two classic and most prominent problems. If your CDP-101 has not had either issue yet, one day it will. The CDP-101 Troubleshooting Guide lists the problems shown in the table above and the sequence of actions needed to solve them. Problem is, neither of these things are listed. The section about "Sound Skipping" just tells you to clean the sled drive and to replace the rack if needed. Hmm, well I did hear from one guy in Germany who said that cleaning and lubricating the sled drive did work for him, so I guess that would be worth a try. But from the amazing knocking and banging going on under the hood, I can tell you that an oil change is not going to work in this case! STK6922 Causing Disc Skipping
Oil Change Needed to Free Loading DrawOK, I take back everything I said about this thing not needing an oil change! The reason that the loading draw was not working is that the grease used to lubricate the moving parts had dried up and actually gone solid in some places. In fact not only was the draw stuck, but I also noticed that the chucking mechanism that lifts the disc up and down was straining and slow. The best thing would be to go through the whole unit can change all the oil! Having said that, many parts do not really need oil and just cleaning them up with some Goo-Gone did the job for me. The particular part causing the draw to stick in my case is shown in the pictures below. You need to remove the bottom of the player and lift the bottom circuit board up to get access. This means removing the 5 screws that hold it and cutting some of the straps from the cabling above. That means removing the top of the player and removing the two screws that retain the top folding board. All quite easy though!
Current Usage
The Sony CDP-101 comes out for occasional usage to demonstrate some real
digital audio history, but when I tell people that it is over 25 years old
they just look blank... Try this: Setup a CDP-101 and tell people that you
have just bought a new high end CD player that you want them to listen to... It
works every time Pictures & Reference
Here are some extra CDP-101 pictures I found on eBay. Mint working CDP-101's go for about $100 to $300 depending if they have all the parts with them. Remember, if buying on eBay, ask if the player can play all day when it's hot, or you can expect to be changing IC204/IC304 as described above! The skipping caused by the focus servo chip problem is time & heat related and just playing a couple of tracks is NOT a sufficient test!
|
high-end Hi-Fi and digital electronics, my
first CD player ever, the first CD player ever, the Sony CDP-101
circa 1983! Before anyone in the U.S.A. even knew what CD stood for where
CD was not introduced until later in 1983, I had
my first CD system working in the summer of 1983 in England on August 5th! This then lead to the
purchase of my first 
edition
P10
Road in London as that is where all the top Hi-Fi shops in England are clustered
and I set about finding the best price. Well, I was amazed to find that
not one single store had a single CD player in stock and this was in August
1983. The sales guys in most stores just laughed and said "you will
never get one, and if you did, it would cost thousands"! I kept
looking around and in one store, Arena Electronics where I was getting the same
story, there were a couple of Indian guys behind the counter furiously talking
in Hindi and just as I was about to leave, they called the sales guy over and
changed his mind for him. They told me the the player would be waiting
there for me the next day! I showed the sales guy 4 CD's that I had just
purchased from the
When you open up the CDP-101 and compare it with a modern day player, the
first thing that strikes you is just how much of it there is! Even though
it contains the first LSI (Large Scale Integration) microchips in any consumer
electronics device that replaced over 500 ordinary integrated circuits in
prototype CD players, it is still stuffed full in there and it is a wonder it
ever worked reliably, but work it did. As the digital to analog converter
was of course one of the
most complex and costly components to produce back
then, the player was setup in such a way that the single converter was time
shared 
sliding covers that run almost the whole length of the handset and when you
remove them, they reveal nothing but the slot from which they came. I have
always presumed since first seeing this that Sony would soon make a receiver or
something with a similar design and provide a fluted slide that could join two
remotes together. As far as I know they never did and the design was
abandoned. When you press a button, there is a small light that blinks on
the player, just like a 1980's TV. There is also a switch on the bottom of
the player that when switched on causes a little "beep" sound at every
button press. The sound is actually quite smooth & cute and not like the
cheep sounding beep of modern electronics and shows just how hard Sony were
working on every detail. As one of the primary challenges in the integration of
the large audio & video setup's I have built over the years is the detailed
understanding of infrared remote control, it is fitting that I should describe
the detail of this handset first, as first it was indeed, although of course it
is no longer used in my primary system. This may also be vital information
if you are trying to build a replacement for the Sony RM-101 Remote Commander or
program some other device to use with a CDP-101! 
Looking at the
block diagram of the CDP-101 in the service manual and knowing that the knocking
noise is coming from the sled or the laser
assembly (or both), following back from the optical units focus & tracking servo
leads to IC204, the motor driver. Following back from the sled motor and
the chucking (the 4 lifting feet in the tray) motor leads to IC304, motor driver
again. Each of these chips is an STK6922 and
each has two drivers. The output pins for each are pin 2 and pin 16 (pin
numbers are on the back board) and the +ve and -ve inputs for each driver are 7
& 6 and 11 & 12 respectively as shown in the diagram to the right.
According to the service manual in idle conditions, all of these pins should
show 0 volts for IC204 and IC304. Once warmed up, my CDP-101 would just
start clicking and knocking of it's own accord with no disc loaded, so I just
had to be looking between the right two pins at the right time to see what was
going on. This test showed spurious voltages on the outputs of IC204 on
both pin 2 and 16. A couple of times I also noticed the sled motor twitch
but I never saw any confirmed results
on IC304. Either way, this looked like the problem area and searching the
net indicated others had changed both these chips, so I decided to replace them
both. Once both chips were replaced, the player ran fine, at least so far!
This is lucky, as I expected I would have to adjust the focus gain at the very
least, but it looks like
that was all that was needed. There are streams
and streams of other adjustments and checks in the service manual and in some
cases, other adjustments will be needed, so if you do this repair, just this may
not be all that is needed. I picked up my service manual on eBay and this
is where to look if you need one or I know that
