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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 25th May 2020, 11:53 am   #1
chroma04
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Default Sony CDP-101 Replacement Keypad

Hi,

This first generation Compact Disc player now perhaps just about qualifies as vintage, and may also serve as a cautionary tale for any person undertaking restoration of this type of equipment dating from the early 1980's.

The player had been lurking in the corner of my 'to do' pile for a number of weeks, and I fancied having a go at something a little different from the usual radios.

Now, it's well documented (both on this forum) and elsewhere on the internet, that these machines suffer from a stuck drawer, due to the grease of the mechanics turning to goo and generally binding the moving parts. This example was no different, and after a couple of hours cleaning and generally removing all of the old grease, the mechanism was back to full operation.

The machine failed to play a disc when loaded. Fortunately, a gentle clean of the KSS-100A laser lens with a moist cotton bud brought about a vast improvement, with the machine now playing most discs thrown at it.

Now at this point, I should have boxed up the machine and called it a day, but......... I noticed that the display window of the machine was looking somewhat grubby and in need of a clean. I therefore removed the six screws holding the fascia to the chassis (this machine is substantially built!) and removed the keypad and LED board for access. Now some people will know that these machines have a 'touch-sensitive' keypad. There is a 'click' when a key is activated, but this noise is actually produced by a relay within the machine, which gives the keys their 'click'.

The touch sensitive keypad is basically a pressed membrane, which is glued to a steel backing plate, and two tails emerge from the keypad, which are connected to two sockets on the PCB of the flourescent display vacuum tube. The construction is quite similar to that of the ZX Spectrum (and similar) computers of the era.

Anyway, the cleaning of the panel was straight-forward, however, upon re-assembly, I noticed, on testing, that one of the keys was inoperative. Opening the fascia once more quickly revealed the issue to be due to the membrane.

Two layers of plastic are glued together, with the conductive strips sandwiched in between. Over the years, the glue must have dried out, and the two sections were now coming apart due to the movement, and were taking the conductive strips with them!!

I subsequently attempted to repair the item but it was fruitless, in fact the more the tails were flexed, the worse the issue became, until there were now only four of the fourteen keys now operative!

I searched for a possible alternative (including placing a message in the 'Wanted' section of this forum, however no replacement was forthcoming, and my options were becoming limited. If only I'd left the thing well alone in the first place.......

In the end, and as the damage was already done, I decided to attempt the construction of a new keypad, using tactile switches. I already have the service manual for this machine, which is pretty comprehensive, which contains all the schematic diagrams. Looking at the diagram, it was a straightforward task to identify the keypad layout and their conductors. I then decided to purchase some Vero-board (with individual pads) and solder the switches directly to this, using wire links to the various switches for the various combinations of key presses. I decided to colour code the wires for ease of connectivity, as I quickly realised that there were going to be many conductors criss-crossing and it could easily become confusing if not. Then, after planning it all out on paper, I set about the process of construction.

Positioning the switches so that they aligned exactly with the correct parts of the keys was critical, and the PCB had to be spaced back slightly, as the plastic keys (due to the depth of the tactile switches) now sat proud, giving sufficient clearance for the key to be pressed. However, with some perseverance, this was managed, and finally assembled back into the fascia.

The PCB containing the indicator LED's has to sit directly behind the keypad and, as the overall height was around 1mm more than originally intended, I was concerned that I might not be able to fit the fascia back in place. However, although it is extremely tight, there is just about enough room for everything to fit back together.

All that remained was to solder the individual leads to the relevant pins of the display PCB and fit everything back together. Thankfully, everything progressed smoothly, and I now have a fully functioning keypad once again!!

I decided to leave the original ribbon connectors of the keypad in place. Also, I have not modified any other parts of the assembly in any way, so that, in the unlikely event of me finding the correct membrane, the machine may one day be returned to its original form as intended by Sony.

In summary, it's not a particularly elegant solution (as you can see from the wiring in the photo), but it has returned the machine back to a usable condition once more, at least for the time being. In fact, I actually now prefer the 'feel' of the keys, as I always thought that, as originally intended, the keys were a little nondescript, and had to be pressed with some force, and in exactly the right place, for them to operate.

This has certainly been a lesson learnt, and something I will remember for the future!

The machine is a little fussy with particular CD's, however, I intend to leave it well alone and enjoy it for what it is.

Adrian.
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Old 25th May 2020, 3:02 pm   #2
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Default Re: Sony CDP-101 Replacement Keypad

Nice one
It is a long while since I have seen one of these machines.
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Old 26th May 2020, 12:35 am   #3
hamid_1
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Default Re: Sony CDP-101 Replacement Keypad

That's a pretty impressive repair job! Even if you were to obtain a NOS keyboard membrane, it might also be brittle and likely to break when being installed, so I think you took the best course of action, though not the easiest.

There was an article "Saving the CDP-101" which gave some modifications to improve reliability and replace obsolete parts. It's worth a read:
http://tronola.com/html/sony_cdp-101.html

I also have one of these machines. I found it by someone's dustbin about 8 years ago, soaking wet (it had been raining heavily.) I knocked on the door of the house where I found it and asked if I could have it. The guy said yes, and even gave me a couple of amplifiers to go with it! After leaving it indoors for 3 weeks to dry, I tested it. It seemed to play but there was no sound on one of the channels. Using my finger as a signal injector, I traced the fault to a NE5532P op-amp chip. It looked rusty, so I replaced it and was rewarded with a working player.

It's still hard for me to think of a CD player as vintage technology, but I suppose it is now. The Sony CDP-101 was the world's first commercially available CD player, making its debut in 1982.

Like you, I've found a few CDs that it doesn't like playing. I'm aware that some modern CDs have copy-protection or don't exactly conform to the original Compact Disc standard. Often these discs do not have the Compact Disc Digital Audio logo on them, but some still do, even though they are non-compliant. I found a couple of "NOW That's What I Call Music" albums from this century that it couldn't play, but it did play "Amy Winehouse - Lioness Hidden Treasures" from 2011 so it's not allergic to all modern discs.

To be honest, I don't really use my CDP-101 much, it's more of a museum piece. Ironically when I asked permission to take the CDP-101 I found by the dustbin, I was given a more modern Pioneer VSX-405RDS tuner-amplifier with it, along with another Sony amplifier which I subsequently gave away to another forum member. Then somebody else gave me a matching Pioneer CD player to go with the Pioneer receiver and that became my main hi-fi system, along with a Garrard AP76 turntable and Shure M55E magnetic pickup acquired non-working for 2 from a car boot sale, so the whole lot cost me practically nothing except time to fix it!
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Old 26th May 2020, 10:11 am   #4
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Default Re: Sony CDP-101 Replacement Keypad

SWMBO bought a very old Sony CD 'ghetto blaster' from a charity shop recently, nice machine but it got handed to me when she discovered it would not play all the way through one of her CDs. I took it completely apart expecting to find that the laser head was refusing to travel all the way along its track, but in fact it was running so sweetly and freely I didn't have to do a thing to it.

Back together, played about 10 of my CDs no problem, handed it back, still problems getting all the way through certain CDs. After some analysis it seems that the player just doesn't proceed beyond a certain fairly high number of tracks - it's almost as though the firmware never expected to see so many tracks on a CD.

Are there such things as dual-layer CDs in the same way as there are dual-layer DVDs?
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Old 26th May 2020, 10:34 am   #5
McMurdo
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Default Re: Sony CDP-101 Replacement Keypad

Great repair. I always view these old membrane keypads as having a finite life particularly when users press them far harder than they need to. Isn't the plastic used called 'lexan' or some other trade name?

In my experience, if a disc is going to be difficult to read, it's on the higher track numbers. Whether its anything to do with the slower disc speed and effect of disc wobble/warp on the servos at the periphery, I dont know. I'm not aware of any dual layer CDs, only the slightly extended 80min versions of CDRs they started making.
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Old 26th May 2020, 10:55 am   #6
Ted Kendall
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Default Re: Sony CDP-101 Replacement Keypad

SACDs generally have a CD layer.
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Old 26th May 2020, 12:54 pm   #7
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Default Re: Sony CDP-101 Replacement Keypad

There are some 'hybrid' CDs which have two layers, audio CD plus something else. A couple from my collection Sting - Sacred Love and The Brit Awards 2006
In the case of The Brit Awards dualdisc, there's a note on the cover saying it may not play on all CD and DVD players.

There were also some non-standard recordable CD-R discs that could go up to 99 minutes. I had a few of these, but only found one CD-RW drive that was compatible with them. The usual limit is 80 minutes of audio and 99 tracks. The 'Now' albums that my CDP-101 couldn't play had over 79 minutes of music on them, very close to the limit, but the disc didn't play at all, not even at the beginning.

I think the keyboard membranes were made of mylar film. There are people selling reproduction ones for the Sinclair ZX computers so it must be possible to still produce them, but I suppose it's only worth doing if there's enough demand, which there wouldn't be for something like the CDP-101.
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Old 26th May 2020, 2:58 pm   #8
chroma04
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Default Re: Sony CDP-101 Replacement Keypad

Hi,

Many thanks everybody for the positive comments!

I'm certainly more than happy with the repair from a functional point of view, and it has at least brought the machine back to life once again!

Many thanks hamid_1 for the link. There appears to be some useful information there which I will certainly have a look through. You are also correct that a replacement original membrane (even if one could be found) is more than likely to have the same issue, caused by removal / installation. I therefore think that my machine is probably best left as is.

The machine has seen some hours' usage now, and doesn't appear to suffer from the jumping / skipping issue, caused by the focus / tracking drive op-amp IC's (IC204 / 304), which are also a known issue with these machines.

I now have two 101's, and this machine is definitely the fussier of the two. I, too, have a couple of 'Now......' CD's, and this machine refuses to play either of them - not even from the beginning. Others produce quite a loud knocking noise when searching for the TOC, which sounds as if it's coming from the focus/tracking coil of the KSS-100A. Other discs play fine, all the way through to the end.

I have double-checked that the sled motor gearing is free to run all the way along the track. To be honest, my gut feeling is that the machine is either in need of setting up, or a component is probably past its best after all these years. However, as I don't have the required test CD / test gear (or experience for that matter!) to go through the service procedure, I feel that it is probably best left alone, at least for the time being.


Adrian.
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