CD player cannot read CDs

[norf]

Hello everyone

I have an Exposure player from 1997 and when I place a disc the message on the display is "no disc". The laser assembly is Philips CDM12 and that had been replaced but still the same problem; the laser mechanism moves up and down. The player does not spin the disc to read the TOC but there is not a problem with the motor itself - it is spinning when given voltage.
Any ideas what should be checked next?

Thanks

[Simon]

yea, get yourself and old pc drive that has a play and stop button, they last forever. I refuse to own a "cd player" because they are such for 3 months before randomly breaking down !

[Mechatrommer]

Exposure player from 1997 ... Any ideas what should be checked next?

china brand dvd player or blue ray that cost $50.

[poptones]

Spend 50 bucks on an mp3 player and download your music like everyone else

[Tube_Dude]

Hello everyone

I have an Exposure player from 1997 and when I place a disc the message on the display is "no disc". The laser assembly is Philips CDM12 and that had been replaced but still the same problem; the laser mechanism moves up and down. The player does not spin the disc to read the TOC but there is not a problem with the motor itself - it is spinning when given voltage.
Any ideas what should be checked next?

Thanks

Have you already clean the lens?

[Tube_Dude]

I refuse to own a "cd player" because they are such for 3 months before randomly breaking down !

Really!? I have a Philips CD 202 from 1983, with CDM-0 transport, and a Philips CD 160 that are still going strong. The last one even read strongly scratched CDs that any othe player can read. God bless the CDM2/10 transport... 

[poptones]

CD202s are worth bucks. The Philips converters used on this things are highly prized. I had two sets of samples from Philips and sold them a few years ago on ebay (long after Philips had stopped making them) and I got like 120 bucks a set for the filter and converter pairs!

Maybe when I get my amp built I'll worry about getting a higher end signal out of my pc. But I've always hated CDs. When I had them I bought a 200 disc changer because I hated having to change them all the time, then I discovered what a nuisance it is to keep track of 200 empty cd jackets and, worse still, to have to reload the player! If I had 1000 CDs today I think I would rip them all to flac and sell them on ebay.

[David_AVD]

The laser assembly is Philips CDM12 and that had been replaced but still the same problem; the laser mechanism moves up and down.

Did you remove the anti-static solder blob (or clip) on the new laser when installing it?

[poptones]

Doh! Good call.

[Tube_Dude]

CD202s are worth bucks. The Philips converters used on this things are highly prized. I had two sets of samples from Philips and sold them a few years ago on ebay (long after Philips had stopped making them) and I got like 120 bucks a set for the filter and converter pairs!

Yes, its true! The CD 202 use the TDA5140 one for each channel, the CD 160 use the TDA1541 STEREO chip. Still multibit converters... 

[Tube_Dude]

Did you remove the anti-static solder blob (or clip) on the new laser when installing it?

I don't think the PHILIPS CDM12 come with it, but I can be wrong...

[norf]

Thanks for all your replies. I don't remember if the laser pick-up had an anti-static clip; if it did then it's been removed. Any other suggestions?

[Tube_Dude]

All the voltages in the power supply ok?

[David_AVD]

Does the laser emit any light during the initial scan process?  If not, double check for solder blob.  If so, maybe check capacitors around the servo chip.

[6502nop]

The player does not spin the disc to read the TOC but there is not a problem with the motor itself - it is spinning when given voltage

Am I the only one here that sees a problem with this statement?

1) Norf, how are you "giving voltage" to the motor? Is it the same way the MPU of the player is? If not, trace the motor control back through the lines - probably a MOSFET/Darlington driver, a 2N2222 buffer, and then back to the "MTR_ON" pin of the MPU. Anything in there could be burned out.

2) If the MTR_ON tracing checks out, then the MPU isn't detecting an insertion (DISC_IN). You need to figure out how that happens. Tray switch? Opto interrupt? Laser bounce? Hub clamp?
The most common no-op conditions I've seen repairing CD/DVD drives on computers have always been traced back to the user abusing the tray (and earlier cartridges used on NEC units). Misalignment and breakage of the tray position switch/lever was almost always a result.

nop

[David_AVD]

The player does not spin the disc to read the TOC but there is not a problem with the motor itself - it is spinning when given voltage

Am I the only one here that sees a problem with this statement?

That's why I asked about the laser emitting light.  If there's no light (and hence no reflection from a disc), the motor won't even try starting.  Also check for the lens moving (focussing).

[6502nop]

The laser assembly is Philips CDM12 and that had been replaced but still the same problem; the laser mechanism moves up and down.

Actually, David, Norf did say it was traversing for focus.

However, my point was that just because the laser isn't turning on doesn't mean it's bad. Remember, this is from 1997 - when lasers were still pretty pricey. Some manufacturers would put a simple IR LED reflective sensor under the tray opposite from the laser sled to check for the disc, so they wouldn't have to fire up an expensive laser every time the tray closed. Some even kept doing this after the prices dropped, just to keep the laser lasting longer. I can attest to this based on personal experience, but don't believe me:

From RepairFaq.ece.drexel.edu:

What the CD player should do when a disc is inserted:

   1. Drawer closes (or with portables, lid is closed manually) and CD is clamped to spindle.

   2. Interlock (if present, always in portables) engages. In others, there may be an optical sensor or the optical pickup may act as its own disc sensor assuming a disc is present when it detects reflected light from the disc's reflective information layer.

   3. Pickup resets to starting (index) location toward center of disc usually found with limit switch or optical sensor.

The following three steps may or may not be performed concurrently:

   4. Laser is turned on and focus search routine is started to position lens at correct vertical position. Once correct focus is achieved, focus servo is activated to maintain it.

   5. Disc starts spinning up to 500 rpm and Constant Linear Velocity (CLV) servo is activated to maintain correct speed. CLV servo uses a PLL to lock to clock transitions derived from data read off of disc. (A buffered version of this signal can be monitored at the 'RF Test Point'.) A partially shorted spindle motor can result in the disc spinning but never quite reaching the required 500 rpm.

   6. Tracking servo is activated to maintain laser beam centered on track.

At this point, data is available for digital processing.

   7. Disc directory is read and displayed.

If any of steps 1 to 7 fail, then the laser is turned off and the machine will display some kind of error/no disc message (typically, it may display Error, Disc, or go blank) and return to idle mode, or in the case of a changer, load the next disc and try again.

(Emphasis mine - I also forgot about that limit switch on the sled!)

Now, you're completely right if this is the "just use the laser" design. So, if Norf can determine that the laser is lighting up, then the problem lies in the motor, driver, power to motor, or the laser can't focus.

It's also entirely possible that the new (?) part is defective, too. I've seen a youtuber who had a Sony unit shipped to him defective.

nop

[David_AVD]

The laser assembly is Philips CDM12 and that had been replaced but still the same problem; the laser mechanism moves up and down.

Actually, David, Norf did say it was traversing for focus.

Well he says "the laser mechanism moves up and down" which I took to mean the mechanism, not the lens.

Hopefully he finds the root cause with a little more digging.   

[6502nop]

Huh. I hadn't thought of that. One person's up/down is another's left/right or in/out.

So, if Norf is still in this thing, here's a cleaned up version of the laser detector from the repairfaq forum, translated from the ASCII art, with some added notes. I built this thing and tested it using a remote, but I was out of IR diodes, and threw in an IR interrupt sensor I had. Thing is, the sensor's "+" terminal, which I figured to be the anode of the diode, had to be swapped to get it to work. Another circuit I found online also had the diode wired this way, so I'm guessing my sensor isn't what I thought it was.

nop

[norf]

Thanks for all your help! I will try again to find the problem with the player.

[TorqueRanger]

Tell you what if you can change the motor out and tell me what happens  Please....