Sorry for another CDM question. I have the laser current adjusted and coarse/fine focus offset as per Philips' service manual. I've verified the adjustments and they perfectly hold to within Philips' recommendations. Regular CDs play fine.
I have a decent variety of CDRs, made with different burners and are from different vintage. TOC and first two tracks of all CDRs are read and played back perfectly. Track three on all of them starts to skip and there's static like noise/distortion. By track 5, nothing is read or played back at all.
Any ideas on what this may be?
No position on the focus offset potentiometer helps to track pass track 3. One end to the other. Laser current is at 50mA and I've went as high as 58mA, but nothing changed. I don't feel comfortable going higher.
I have a decent variety of CDRs, made with different burners and are from different vintage. TOC and first two tracks of all CDRs are read and played back perfectly. Track three on all of them starts to skip and there's static like noise/distortion. By track 5, nothing is read or played back at all.
Any ideas on what this may be?
No position on the focus offset potentiometer helps to track pass track 3. One end to the other. Laser current is at 50mA and I've went as high as 58mA, but nothing changed. I don't feel comfortable going higher.
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A healthy cdm1mkii laser should have no difficulty with any but the worst cdr's. It sounds like you may have slight radial arm motion resistance, as it's more sensitive to such things with cdr's. Check that a)the ball bearing on top & under pivot point of the radial tracking arm is present, siting in the right spot in moving & stationary parts, and has loose, slippery grease(i.e., that hasn't turned to glue), and that nothing is interfering with the flexible circuit tape as it moves with the laser.
Nothing is catching the ribbon and the arm is floating perfectly smooth. I can't really see the ball bearings.
I guess I could take the arm out, clean off those spots, relube, and put it back together. But then I'm risking some misalignment?
As long as you make *sure* to get the bearings into the pivot points properly, there is no risk of misalignment at all.
It is possible, though odds are small, that the laser is weak. Happily, it's precisly the same laser as the cdm4/19, used in lots of inexpensive Magnavox/Philips players from late 80's, easy to find cheap on ebay.
It is possible, though odds are small, that the laser is weak. Happily, it's precisly the same laser as the cdm4/19, used in lots of inexpensive Magnavox/Philips players from late 80's, easy to find cheap on ebay.
Thanks for a great suggestion. Just to clarify, is the entire swing arm from CDM4/19 compatible with CDM1 mkII, or the laser itself needs to be harvested and the ribbon wire desoldered?
Okay, I took the entire thing apart. Ball bearings look like new. I cleaned everything to perfection. Relubed with silicone 1000CST lube as per Philips service manual. Put it all back together. The arm floats like a feather.
Took the lens apart. Cleaned both lenses.
However, it still will not play CDRs pass track 5. Any other suggestions?
It's maybe a hair better. It now reads track 5 on some CDRs, but is severely distorted/skipping. But anything after track five, it doesn't read at all.
This is on every single CDR of a large variety. Even expensive Mitsui and Mama CDRs.
A bit more info. So after disassembling everything, cleaning, and lubing... I get different focus offset voltages. It plays all of the regular CDs just fine as before, but focus offset is now averaging 100mV on track one and 350mV on the last track. This is consistent with most CDs.
Before, the difference between track one and the last track was much smaller. Any ideas?
Only thing I can think is that upper or lower bearing ball is not quite set in the divots, or perhaps you might just need to loosen the bottom plate holder screws & make sure the plate is totally centered/straight. Not something I've encountered before, after working on hundreds of cdm4/cdm1mkii units.
Yup, some of those caps were indeed bad. All electrolytic caps were replaced with new similar types recently.
This is a Micromega transport. I've asked three separate owners of Micromega transports with CDM1MKII (Duo, Trio, Meta Research) and all three reported that CDRs don't play, or play extremely poorly.
I think I'll just have to accept that these players don't play CDRs.
Most of the cdm1mkii-equipped units that I work on are Museatex CD-D(LOTS of them)and Proceed PDT/PCD1/2/3, with the odd vintage Micromega now & then. All of these use the stock Philips servo board, and I *never* have trouble getting them to play even my most see-through and scratched cd-r's all the way through. After replacing the one & only non-Nichicon lytic cap on the servo pcb(the notorious 33uf ld power filter) and dealing frequently with worn clamper bearing plate, they sail through every cd-r perfectly, 99% of the time. On very rare occasions, one will have trouble playing or searching past a certain number of tracks on cd-r, and this has always been due to a sub-optimal laser. Install a good used laser/radial-motor assembly from a cheap cdm4/19 unit, tweak the settings, and problem solved. Every time.
I fixed it! I kept adding layers of tape to a CDR until the machine read it. It needed to be raised 0.2mm. Since CDM1mkII (unlike CDM1) does not have the Teflon set screw which raises the spindle as it wears out, I had to be creative...
MKII has a sleeve bearing and the shaft rests on a plastic bottom cover. Over time it makes a divot in the plastic and spindle lowers. I took a piece of Teflon jacket (0.4mm) thick, cut out a tiny piece of it, and placed it at the bottom of the sleeve bearing. The shaft now sits on the Teflon instead of directly on the plastic cover's bottom.
I put a good amount of lube there. So far it's playing every single CDR perfectly.
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Played a couple of dozen CDRs and all worked perfect. Even the few regular CDs that skipped before, on the last track or two, now play fine.
Maybe the actual problem is somewhere else and this fixed it indirectly? It's possible the CD base slid down on the shaft a bit. Although my first attempt to raise the plater was to move it up the shaft, but it was on so solid that I didn't want to break anything. It could have been glued on a little low (0.2mm) at the factory. I don't think CDRs existed back then to test or worry about.
Maybe something else?
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