I just checked the SM of CDM-1, I believe the CDM-0 is similar. There is a 4x op.amp NE5514 that amplifies the current of the 4 detector diodes. Its output pins 7, 8, 1, 14 are at 0V when there is focus and the laser is on track. I would monitor these outputs during playing. Their output is matrixed, forming two signals for the radial servo. That is a bit complicated, but there should be a DC offset adj. TP and a radial offset trimmer to adjust 0V on the TP during play.
That's another of those fixes that can be open to debate... if resoldering had 'fixed it' would that because of an unseen dry or the would it be because the heat somehow temporarily 'fixed' an issue with the diode array.
Laser power we know. More current = more RF. So that should not need altering at all.
Focus gain as far as I recall won't alter the DC conditions but if it is low the player will be prone to jumping in response to physical shock and vibration and if it is high the focus coil in the RAFOC can be noisy and hissy as it gets fed a lot of high frequency content as well as the basic lower frequency focus voltage.
Focus offset... having looked at the typical nightmare of all the Philips versions and methods I'm going to say adjust for best quality of RF. Sometimes the meaning of what they say doesn't always tally with what you expect and so if by chance adjustment of this pot does not alter the RF quality then I would set it empirically for best playability i.e. see where things go wrong in one direction and where they go wrong in the other and set it in the middle.
I like Philips stuff but a lot of the procedures are very convoluted.
Hm, none of these trimpots are for radial adjustment. Please check the SM from here, especially page 23:
Philips CD-204 Service Manual
It seems there is no trimpot for the radial adjustment, unlike in CD-74/84* that I am more familiar with. Try the usual "heating test": is there any component overheating? If there is anything suspect, try a freeze spray. Also try carefully heating the ICs (6211 ... 6218).
BTW the check method is described on page 32 (G and H). Perhaps worth going through it.
*CD-74/84 Marantz I mean
Philips CD-204 Service Manual
It seems there is no trimpot for the radial adjustment, unlike in CD-74/84* that I am more familiar with. Try the usual "heating test": is there any component overheating? If there is anything suspect, try a freeze spray. Also try carefully heating the ICs (6211 ... 6218).
BTW the check method is described on page 32 (G and H). Perhaps worth going through it.
*CD-74/84 Marantz I mean
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I question the need for this effort, as hardly any units are still in service, CD and DVD formats are long gone from use, streaming and memory stick have long made those formats obsolete.
It is impossible to get blank CD-R here, the ones in stock are old stock from no-name brands, or super expensive. Even blank DVD-R is a take it or leave it situation, not much choice, and you have to search for stock.
Music is sold on line, some movies are sold on memory stick, the sale of CD for music or as a free item with computer magazines is negligible, as is their circulation here, I have not got them for almost 15 years (I still have my old Byte magazines).
So the chance of somebody coming along after say 15 years and trying to repair a CDM mechanism is negligible.
It is impossible to get blank CD-R here, the ones in stock are old stock from no-name brands, or super expensive. Even blank DVD-R is a take it or leave it situation, not much choice, and you have to search for stock.
Music is sold on line, some movies are sold on memory stick, the sale of CD for music or as a free item with computer magazines is negligible, as is their circulation here, I have not got them for almost 15 years (I still have my old Byte magazines).
So the chance of somebody coming along after say 15 years and trying to repair a CDM mechanism is negligible.
"CD and DVD formats are long gone from use"
Whilst that may be true in some parts of the world, it does not seem to be the case everywhere. There are probably millions of silver discs happily spinning and making music. I for one will continue to expand my disc collection. I've found that second user discs are fine and allow musical exploration at a very reasonable cost. But, as always, each to their own. Just as with Class A, AB, D, Valves, sensitive speakers with large bass cones, etc etc. Freedom of choice is great
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I broke a rib falling on ice just before leaving Canada, had today off work and had a bit of time, so;
I'll PM you @eschenborn
Richard
- Confirmed my stock (original captive mains and RCA leads) CD204 works fine except for the disc tray belt needing replacement (you need to assist the tray to close with a disc in). I've played 5 CDs without issue today
- Replace the 4 22uFs and 1 33uf on the control board on the heavily modified 204 - 33uF was high ESR, the 4 22uFs (according to my cheap Chinese cap meter) were either a single diode with capacitance, or dual diodes Replacing all has thing working and sounding wonderful again with the external Abbas valve clock;
I'll PM you @eschenborn
Richard
Thanks again to everyone here for the wealth of assistance and input. In light of the time and costs required to go ahead with fault finding even in the best of circumstances I resolved not to take this repair project further ahead. I won't pour any more resources – neither time nor cash – into my CD-204 for the time being.
At the end of the day, I agree since there is a limit beyond which patience/forbearance ceases to be a virtue. (-Edmund Burke)
You will use your energies for further projects and you will finally be satisfied with another love.
It is also a quality to know when to stop...
You will use your energies for further projects and you will finally be satisfied with another love.
It is also a quality to know when to stop...
Do you have the CDM 0 transport or CDM 1 ?
In case of the CDM 1 you will have to check the plastic bearing screw as it has a dip from wear. Polish it or replace it if possible.
https://dindiki.com/?cdm1-laser-service
In case of the CDM 1 you will have to check the plastic bearing screw as it has a dip from wear. Polish it or replace it if possible.
https://dindiki.com/?cdm1-laser-service
Please check if there is a small dent in the clamp (created by the metal ball bearing over the years). this needs to removed or just make sure the ball can't make it to this dent while playing (shift the clamp a little). Also check the wear of the plastic bearing on the spindle (the one that can adjust the height of it) It too is probably worn and needs to be sanded.
These are the main reasons why the player behaves like described.
hi @Lampie519 , thank you. I thoroughly checked the clamp but might check again (cd player is in deep storage now). a photo would help me.
As I wrote in the thread, my player has a CDM-0 drive. most of the CDM-1 hints do not apply there.