Friday, 18 January 2013

CD52 MKII Mods part 1


This is one that I've not had a play with at all yet. I've had several goes at the CD50 which uses the TDA1541 dac, CD850 and I owned a CD850MKII from new for about 18 years all of which use the later swing arm type laser assembly from philips, the CDM4.

I thought i'd start this thread to show the mods progress and explain some of the rationale behind some of the changes that will be made. I'll lay my cards on the table now, I've no intention of keeping the player at the end and I will offer it up for sale (in the appropriate forum section) for a sensible price that reflects the cost of the parts plus a few beers. I'm not looking to spend hundreds but I do expect to make significant improvements within a reasonable budget.

Hopefully the thread will be informative and therefore my approach acceptable to the community. As previously stated in other threads, I do this because I can and I really enjoy it! If I can fund my obsession by selling at the end of the project then happy days 

There is plenty of information relating to these players on the internet. The player is Pre the KI Signature badge. That doesn't mean "he" wasn't involved! Indeed all of the SE range are his work. From experience I can tell you that in general, the SE versions are mainly about a few capacitor changes and bracing the actual cases. I have read that in some SE models the transformer is constructed using higher quality materials but I cannot confirm this. Certainly in KI models, the mods are SE plus a toroid transformer most likely of a higher VA plus copper chassis plating and a shiny badge!

Since I'm likely to change and improve most of what the SE would offer, I've started with a basic CD52MKII as the only reason I can see for using an SE would be for perception.

I've got hold of a reasonably priced player that works other than the drawer loading cog which is a common problem on all CDM4/19 transports. A replacement made from a more modern plastic is readily available for £6 on ebay. This is one time I'm glad our friends from the other side of the world are happy to 'clone' everything! The original part went out of production many years ago! For a test listen, the drawer can be manually operated. 

I'm not going to washy word audio reviews at every stage of this project but I will give a very brief overview at the start and finish of the project. To start I need to verify that everything work as it should and that there are no actual faults with the player (other than the loading cog). I have a couple of test CD's I know very will with a mix of tracks on them so having listened to them to verify functionality I can also comment generally on the sound. What I will say at this point is that the sound is quote flat compared to what I'm used to. Its quite a warm sound but lacks sparkle and accuracy. Something I'm sure I can improve to a reasonable degree. Don't get me wrong, I'm sure the standard sound would suit many, its just not good enough for me out of the box and I know it can do better.

Here's the player in the flesh during test this morning. I've already removed the offending loading cog and ordered a replacement which will come with a new belt too.




Here's the offending cog. As you can see, its stripped most of its teeth. The theory offered on the internet is that the grease philips used has reacted with the plastic and made it go soft. I can tell you it feels more like hard wax now than plastic although I'm not convinced by the theory about the grease! Having owned an 850MKII from new, I can tell you that you push the drawer to close. This is bound sure to stress the gear as its work ratio means that the motor spins hundreds of times to move the drawer from end to end. just pushing the drawer 1 cm is likely to require the motor to spin 3 or 4 times. This will put far too much pressure on the fragile teeth of the old cog. Armed with this information, even with the new cog, I'd recommend using the play button to close the drawer.


Next up will be some investigative work in the core power supply to see what can be done to improve things immediately before and after the voltage regulators............



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