i am doing a full electrolytic recap on this philips cd-204,
im very happy as i found some that were way off the mark, two were really bad ,
any way i recapped the the laser pcb,while i was working i noticed that the 47k pot (which is for focus offset i have read) was maxed out clock wise,
this player was not reading discs before i started ,does any one know why this would be adjusted in this manner?
it does not seen like it would ever be set like this in the factory,is it posible that it was adjusted like this at some point as the caps were way off?
i fear leaving it like this after the recap in case it damages the laser now that things might be working better,
im still waiting for some 68uf caps for the control pcb,this will give me a day or two to work out if it needs to go back to half way,
some pics,its dark here at moment so pics are not to good, ill post better ones in morning,
thanks in advance
mike
im very happy as i found some that were way off the mark, two were really bad ,
any way i recapped the the laser pcb,while i was working i noticed that the 47k pot (which is for focus offset i have read) was maxed out clock wise,
this player was not reading discs before i started ,does any one know why this would be adjusted in this manner?
it does not seen like it would ever be set like this in the factory,is it posible that it was adjusted like this at some point as the caps were way off?
i fear leaving it like this after the recap in case it damages the laser now that things might be working better,
im still waiting for some 68uf caps for the control pcb,this will give me a day or two to work out if it needs to go back to half way,
some pics,its dark here at moment so pics are not to good, ill post better ones in morning,
thanks in advance
mike
Attachments
well i got it back together ,i left the pots as is,
well the recap is done,i have checked it and looks right,
before the recap the the disc would enter and spin up for 2-3sec and stop with no read out on screen,
now i put disc in ,it shins up and reads TOC very fast, however the disc carries on spinning at a normal speed,the play ff rew buttons show no sign of live,
however if i use the program system to pick a few songs before the draw is closed it will play those songs ,but rew ff play seem to be dead ,the stop button is working along with all others it seems
once i have pushed stop the disc does stop but the play ff rew will not activate the disc till it is ejected and the disc reinserted,
when it will play it sounds very good,its some kind of control related problem it seems
i will clean the switches out again and see if that may help
do you have any ideas?
mike
well the recap is done,i have checked it and looks right,
before the recap the the disc would enter and spin up for 2-3sec and stop with no read out on screen,
now i put disc in ,it shins up and reads TOC very fast, however the disc carries on spinning at a normal speed,the play ff rew buttons show no sign of live,
however if i use the program system to pick a few songs before the draw is closed it will play those songs ,but rew ff play seem to be dead ,the stop button is working along with all others it seems
once i have pushed stop the disc does stop but the play ff rew will not activate the disc till it is ejected and the disc reinserted,
when it will play it sounds very good,its some kind of control related problem it seems
i will clean the switches out again and see if that may help
do you have any ideas?
mike
It is impossible to say on the preset without you actually going through the set up procedure and seeing if anything is amiss.
The only adjustment that will damage the laser is the 'laser power' setting and again that needs to be checked, however Philips players often have rather convoluted set up procedures making things a little more difficult and open to interpretation.
A good scope and a look at the RF (eye pattern) is the first step and will allow a determination of laser power to be made by confirming the output is around 1.2 to 1.5 volts peak to peak in amplitude.
The official procedure with Philips is normally to look at a small DC voltage across a resistor in the photo diode array circuit of the pickup which can be done in conjunction with visual confirmation using the scope.
The logic problems again might need a scope... you need to look at the inputs to the processor dealing with the 'keyscan' from the front panel as the various buttons are pressed and make sure that the switches connect the appropriate lines together when pressed.
The only adjustment that will damage the laser is the 'laser power' setting and again that needs to be checked, however Philips players often have rather convoluted set up procedures making things a little more difficult and open to interpretation.
A good scope and a look at the RF (eye pattern) is the first step and will allow a determination of laser power to be made by confirming the output is around 1.2 to 1.5 volts peak to peak in amplitude.
The official procedure with Philips is normally to look at a small DC voltage across a resistor in the photo diode array circuit of the pickup which can be done in conjunction with visual confirmation using the scope.
The logic problems again might need a scope... you need to look at the inputs to the processor dealing with the 'keyscan' from the front panel as the various buttons are pressed and make sure that the switches connect the appropriate lines together when pressed.
thank you very much for your input,i do not have a scope so im guessing ill get one,can you think of any tests i can do with my digital multi meter to narrow things down abit for me?
i am glad you have given me some advice,i have read lots about these players on this site and you are in alot of them
thanks again
mike
i am glad you have given me some advice,i have read lots about these players on this site and you are in alot of them
thanks again
mike
All you can do with a meter is look for changes in voltage as you press the various keys.
The keys are scanned in a matrix type array and when a button is pressed it connects the appropriate data to the system control chip inputs.
This is from a CD304 but I think it is very similar. For example pressing FF links pin 24 to pin 26 via a diode.. The voltages on these pins are not a static DC voltage but are a 5 volt data signal and so all you can really do is look for change in the voltage as the connection is made and compare results to buttons that work.
It is always worth looking things over really carefully after changing lots of caps as it is so easy to have blobbed some some solder somewhere or fitted an incorrect value or polarity cap.
The keys are scanned in a matrix type array and when a button is pressed it connects the appropriate data to the system control chip inputs.
This is from a CD304 but I think it is very similar. For example pressing FF links pin 24 to pin 26 via a diode.. The voltages on these pins are not a static DC voltage but are a 5 volt data signal and so all you can really do is look for change in the voltage as the connection is made and compare results to buttons that work.
It is always worth looking things over really carefully after changing lots of caps as it is so easy to have blobbed some some solder somewhere or fitted an incorrect value or polarity cap.
i have checked all the pcb's to the diagrams and i have done the recap with no faults, further more before removing a cap i marked the neg with a black dot,also i replaced a cap for a cap one at a time,
i checked the ribbon cables and they passed, i will try to test the micro buttons on control pcb ,
i do know that the player was put away years ago for not working ,this could very well have been the problem at that time,but who knows,
raining here today and its welcome as i have planted some ferns and flowers ,its warming up nicely for spring, i live in a alpine zone so i have a small window to get garden planted out,
i also need to get as much done about the house that Sylvia my wife will have problems with,
on Tuesday i am off to Auckland for a trip to pick up some more audio gear that i accidentally purchased lol
mike
I suspect the fault will probably not be easy to diagnose without test gear and also experience I'm afraid. One comment would be that in the majority of cases issues like these tend toward something simple rather than 'the big chip' but sometimes you have to go down the road of 'replacing just to prove it isn't that'.
Good luck with the trip 🙂
Good luck with the trip 🙂
i have an update,
i removed the control pcb,plugged it in naked so to speak,it works very well,
the pcb has a bend in it stopping some buttons from operating,this i think i can sort out with some playing about ,this is good as it means the job i did is good,
however it still has a problem,it plays till song number 4 and will good no further ,is it normal for the disc to slow down as the laser moves out to the edge of the disc?
if i leave my finger on the search ff it well go to almost to end of cd but skips like crazy,bear in mind that have not maintained the transport at all yet ,
this is very exciting as its getting closer every day,thanks so much for your positive help you have given me,
ill spend some time with the button problem and get back to you when fixed
mike
i removed the control pcb,plugged it in naked so to speak,it works very well,
the pcb has a bend in it stopping some buttons from operating,this i think i can sort out with some playing about ,this is good as it means the job i did is good,
however it still has a problem,it plays till song number 4 and will good no further ,is it normal for the disc to slow down as the laser moves out to the edge of the disc?
if i leave my finger on the search ff it well go to almost to end of cd but skips like crazy,bear in mind that have not maintained the transport at all yet ,
this is very exciting as its getting closer every day,thanks so much for your positive help you have given me,
ill spend some time with the button problem and get back to you when fixed
mike
hi there
i have sorted the buttons out,i unsoldered the switches that were not making contact, pulled them out by about .75 mm and re soldered them,working great now
just the transport to go,do you have any advice regarding this last step,
i have watched the disc as the swing arm progresses over the disc,the motor sounds like it labors the more it moves to the outer edge,
i have noticed one other thing,
its making a sqeeking sound,the sound seems to be coming form the swing arm or laser it self,
i have read that the laser will make a noise if adjusted incorrectly? this brings me back to the 3 pots on the laser pcb
i might lube the transport and check the thrust bearing but im not to keen on powering it up again till i find out why that 47k pot is maxed out clock wise
mike
on the bottom of the motor that powers the disc there is a fly wheel of sorts,this fly wheel has a cage or thrust bearing mount,this i removed ,the shaft has worn a dimple in the wear pad or grub screw ,
the shaft has a nut on it to hold said fly wheel on,
i removed this along with fly wheel,it turns out it is the motor,
upon removing these things i found a clip,this removed ,some disassembly was needed at the top of shaft for shaft removal ,
shaft looks good but dirty ,cleaned it with scotch bright ,
reassembled with the smallest amount of very light weight oil wiped over shaft,
now it seems to be playing well
but time will tell
the sound that i mentioned has now gone,but i still worry why that pot is maxed out,
i may wait till i get a oscilloscope to test it before i start using it full time,is this a good idea?or is it the old story of if its working leave it alone?
was my method correct?
if it is not please do say ,was i meant to use oil? this oil is way lighter than wd-40 ,its almost just solvent with a touch of lube,
if i have done it wrong ill just redo it
thanks for your help
to think all those years working at power stations playing about with those big old steam turbines has lead me to working on these little things 🙂 just as much care is needed for both types of machines it seems🙄
im thinking of resurfacing that thrust bearing ,
but resetting it looks interesting as it seems to set height of disc to laser,
im guessing i can use feeler gauge to see what the distance is now and just set it back to that?
but i ramble
mike
it seems i went off subject a little,
it turned into a repair rather than adjustment,
i hope some one will make use of some of my suggestions in the future
mike
it turned into a repair rather than adjustment,
i hope some one will make use of some of my suggestions in the future
mike
Pleased to hear you found the 'logic' issue. Those things usually are something straightforward rather than something like an IC...
Yes it is normal for the disc to slow as the laser tracks outward. The CD system is 'CLV' or constant linear velocity rather than 'CAV' or constant angular velocity like a turntable. CLV means the data rate coming off the disc is constant at all times.
'Twittering' noise can be coming from either the focus coil of the laser or from the platter motor and tbh we are back in 'scope territory because unless you can actually see what the RF looks like then it all becomes guesswork.
As you say, the height of the platter is going to be altered by the motor thrust washer and there is a procedure in the manual for doing this. The mechanical adjustment will alter the voltage the focus coil needs to bring the lens into the correct position.
CD players that are in good mechanical and electrical adjustment tend to have a very wide range of tolerance on any individual setting. If the player has a problem such as a weak laser or leaky photo diode array... or something mechanical amiss... then adjustment becomes ever more critical and it shouldn't be like that. A good player should literally fall into alignment as you go through the set up procedure. If something seems super critical then there is often an underlying issue.
Again from a CD304 manual:
Yes it is normal for the disc to slow as the laser tracks outward. The CD system is 'CLV' or constant linear velocity rather than 'CAV' or constant angular velocity like a turntable. CLV means the data rate coming off the disc is constant at all times.
'Twittering' noise can be coming from either the focus coil of the laser or from the platter motor and tbh we are back in 'scope territory because unless you can actually see what the RF looks like then it all becomes guesswork.
As you say, the height of the platter is going to be altered by the motor thrust washer and there is a procedure in the manual for doing this. The mechanical adjustment will alter the voltage the focus coil needs to bring the lens into the correct position.
CD players that are in good mechanical and electrical adjustment tend to have a very wide range of tolerance on any individual setting. If the player has a problem such as a weak laser or leaky photo diode array... or something mechanical amiss... then adjustment becomes ever more critical and it shouldn't be like that. A good player should literally fall into alignment as you go through the set up procedure. If something seems super critical then there is often an underlying issue.
Again from a CD304 manual:
Attachments
You're welcome 🙂
You might find this interesting, totally different player and optics but the theory is similar:
Sony CDP790 and KSS240 Restoration Project
You might find this interesting, totally different player and optics but the theory is similar:
Sony CDP790 and KSS240 Restoration Project
hi there
its a good read,i see some one on first page bringing up that a sony dvp-s9000es can be made to sound super good,
i have one and is my daily driver ,it sounds good now so i wounder how much better it can get?
ill sit down and take some notes as you gave lots of good tips
mike
its a good read,i see some one on first page bringing up that a sony dvp-s9000es can be made to sound super good,
i have one and is my daily driver ,it sounds good now so i wounder how much better it can get?
ill sit down and take some notes as you gave lots of good tips
mike
Yes !!
Seems to be a focus / servo problem. Try fiddling with the pots one at a time & one degree to each side. When You press fw or rew, it should jump to the right track and instant play without much skipping. Start by cleaning the lens. Check for good sled movement / lubrification / broken gears etc.