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CDX woes

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sonavor
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sonavor posted on Tue, Aug 19 2014 11:38 PM

Back in 2012 on the old workbench forum, I (kind of) got my first CDX working. The unit required the door hinge fix on the eject switch side and I was able to get the CD player working for a short while. Then it started acting up (working intermittently). Resolving that it was an alignment problem with the hinge switches, I put the CDX up and worked on other projects.

Later, I received a second CDX that had good hinges.

I spent the last week trying to get one good functioning CDX out of the two. I actually had the unit playing CDs for one night. The next morning, it wasn't working again.

So far, I have resoldered the griplets on the two main boards of the first CDX.  The second CDX looks to be a later version and has nicer looking griplets. For now I haven't touched those.

The problem I am having right now is the CD motor spins all of the time. When the lid is open, I checked all of the switches and they measure as expected. Yet the motor spins. Two days ago the CDX unit started functioning correctly.  I could turn power on, open the lid, observe the motor wasn't spinning, insert a CD, hit play and the unit would start right up. It sounded really good when it works. The next morning I turned the unit on, inserted another CD and was surprised the the motor was already spinning the platter. So it broke overnight. 

So at various times I have seen both of my CDX main chassis operate correctly while, right now, they both behave the same and will not stop turning.

That makes me suspect the problem is common to both so it would have to be in the common pieces of my latest tests...which are the lid components: eject assembly, lid door motor assembly and control panel assembly. The only thing is - I have seen it work with those same components. Maybe a loose wire somewhere?

As I said earlier, the two switches on the door open motor assembly and the one switch on the door eject assembly appear to be operating correctly. I can measure continuity and open on the switches as the door hinges go through their travel.

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sonavor
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Okay Jacques and Martin....Apparently, the griplet re-soldering fixed the CDX. I did just the servo board first, it didn't fix the problem.  Next I did the Decoder board. When I reconnected everything, there it was - the motor powers on stopped. The stopped voltage was less that a volt.  I put the cover back on and tried a CD. The CD played.

This is a goofy piece of audio equipment for sure. I wish I had just soldered one griplet then tested before I moved to the next one. It would have been nice to know which part of the circuit was actually causing the problem.

Another strange thing was that I have two CDX units that fail in the same way (motor wouldn't stop spinning), yet the problem must be two separate issues with the main assembly. I thought that was not a likely scenario and the problem must be something common to both. That theory started falling apart when the problem remained regardless of what lid I used.

So I still have the second (CDX 001 in my earlier references) unit that I will put away for now until I get a door motor gear for it. On that unit I had already reworked the griplets but I guess I will have to retry that again. Of course there could be an actual failed component on the unit...but it had worked as recently as last week.

I will see if this working unit (CDX 002) continues to work tomorrow.

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sonavor
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I tested powering on both of my CDX chassis disconnected from everything else.  I would have thought that without any connections to the switches or control panel, the motor would not spin the platter. But in both units, the platter starts turning. 


sonavor
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Here is the service manual schematic for the motor stop. The laser switch in my test is disconnected.  With power on the CDX, I measure 12 VDC between the two pins the switch closes.

 


sonavor
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In looking at the schematic and with the Laser Switch connector out, 63-2 and 63-1 are open.  I thought that would prevent the motor from turning.  With that connection off, I measure -5.8 to -6 VDC at 63-2 and +6 to +8 VDC at 63-1.  The closing of the door will close the Laser Switch which joins those two voltage points. So with it open, the motor should not spin, right?  I must be missing something here though...because both units measure the same here and behave the same.

Dillen
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Dillen replied on Wed, Aug 20 2014 6:53 AM

Sounds very much like a rivet via fault or a cracked solder joint in the power supply area.
It can sometimes be difficult to guess at what will happen in a circuit if one or more ground points are disconnected.

Martin

sonavor
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I'll have to just dig in deeper. I did measure some various signals and with nothing connected to the main chassis, I see a +6 VDC on the DO signal which is the state of the signal in Play mode. With everything disconnected, I would expect that signal to be low (not in Play mode). 

Can you tell me if the platter motor should be off if the CDX main chassis is turned on by itself (no connections to the lid motor control board or control & display board)?  If the connector for the laser switch inputs is removed, should a working CDX power up with the motor not running? 

chartz
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chartz replied on Wed, Aug 20 2014 9:06 AM

I agree with Martin John. And please do those ominous griplets. They are responsible for the strangest issues - from degraded or crackling audio to odd servo problems.

When you press PLAY, the motor will indeed turn immediately as the player is looking for the TOC. It will stop only if no CD is detected by the laser.

I say, do the solder job! Laughing

Jacques

sonavor
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I'm not sure what to make of this yet (will have to sleep on it) but I was able to manually coax the CDX into working. I suspected part of the problem is in the initialization of the laser head and the other logic that controls the motor.  When the CDX is failing, the platter immediately starts spinning and I can see some up an down movement on the laser head (light pen?).  To be able to put a CD in place, I have to disconnect power, open the door, insert the CD, then close the door.  After that I can turn power on. At this point the CDX tries to read the CD, detects nothing and briefly displays a question mark. I began running these tests with the bottom of the CDX case removed.  I have to add some support underneath so the laser mechanism isn't obstructed. This allows me to see what is going on since I have to have the lid in place to hold down the CD.  I was able to see that the laser head wasn't moving.  So I helped it along a little and that reset something.  The motor came to a stop.  I pressed play but the CDX didn't go into play mode. The motor also didn't turn. I have seen that before and it usually meant the worm gear controlling the door closed position needs adjusting. I did that, tried the play button as I adjusted and the CDX began playing.  I ran through a few tracks then tried a test of ejecting the CD and reinserting it.  That worked fine.  The next test was to turn power off the CDX, then back on.  I did that and the CDX started up okay.

The CDX is not fixed of course.  I have been here before.  When I had the CDX working a couple of nights ago it went through this same scenario where all of a sudden it got into the correct mode where it came up with the motor not turning and the laser head adjusting correctly to a CD. 

Maybe there is a problem with the laser head control. Something in the timing of things during start up? Could the laser sometimes stop in a position it can't start correctly from?  Is the problem a mechanical adjustment problem on the laser head?

One of my next steps is to repeat the test tomorrow with the same CDX chassis I got working tonight.  Then try the other CDX chassis and see if the same coaxing can get it playing again.  I know it also works because I also had it playing a CD a few days ago. 

sonavor
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chartz:

I agree with Martin John. And please do those ominous griplets. They are responsible for the strangest issues - from degraded or crackling audio to odd servo problems.

When you press PLAY, the motor will indeed turn immediately as the player is looking for the TOC. It will stop only if no CD is detected by the laser.

I say, do the solder job! Laughing

In one of my earlier posts in this thread I mentioned that I had reworked the griplets on the two boards of my first CDX unit. That didn't help.

Regarding the start up - Keep in mind, the motor starts turning with the CDX door open.  I don't think it should do that.  You can't insert a CD with the motor spinning.  When I have got the CDX into working mode, I can see the unit start with the motor not turning.  To help trouble-shoot the problem, I expected the CDX to start with the motor not turning if I turned it on with no cables connected (to the door motor, laser switch, load switch, control and display panel).  If none of those things are present, I would expect the motor to not start and the laser head not to look for anything.  That doesn't appear to be the case though as both of my CDX units behave the same.

Dillen
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Dillen replied on Wed, Aug 20 2014 9:44 AM

If it moves the laser lens up and down to seek focus, the lid contacts or related circuit is not working correctly.

Martin

chartz
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chartz replied on Wed, Aug 20 2014 12:00 PM

Dillen:

If it moves the laser lens up and down to seek focus, the lid contacts or related circuit is not working correctly.

Yes, it's a possibility indeed. But on both machines? What are the odds? Confused

Have you tried re-assembling the thing?

 

Jacques

sonavor
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I am using the same lid components on both CDX units during this testing.  Earlier, I measured continuity on the three lid switches (laser switch, lid switch and load switch).  I put my continuity meter leads back on the connectors receiving the signals and exercised the lid to see the switches open and close.  The first time (couple of days ago) that I got the CDX to work I had been probing around the load switch. So maybe that is the culprit. I don't think it is the laser switch because I can disconnect the connector for that switch and it does not prevent the motor from running or the laser from trying to focus. I have used deoxit on those switches and they look clean. On the side with the door motor, laser switch and lid switch, I did take that apart as I had to replace one of the gears. I didn't disassemble the eject mechanism as it works good (mechanically). 
However, I can go through them again. 

sonavor
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Update - as expected, the CDX is not working now after sitting for a few hours. It's very strange how it can kick into working mode and be fine for a while, then stop.  That kind of points towards something that warms up and cools down. I may have to just take one of the CDX chassis and re-solder everything.  That's also why I was wanting to know how the main unit should start up if none of the switches or control panel are connected. If it is switch related, then with the switches disconnected, shouldn't the main CDX unit think the door is open and start up in an "off" state?  Why does the laser head try to look for a CD when the laser switch is open (disconnected)?

Dillen
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Dillen replied on Wed, Aug 20 2014 4:40 PM

It's a goofy machine.
Maybe a little cooling spray could help locate an eventual thermal fault.

Martin

sonavor
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Dillen:

It's a goofy machine.
Maybe a little cooling spray could help locate an eventual thermal fault.

Martin

I agree, it is goofy. If I hadn't already heard it and liked its performance (when working), I probably wouldn't mess with it. But...I have heard it and I like the way it sounds and looks.
Do you know what the motor and laser head should do when the unit is turned on with the lid removed (no lid switches or control panel)?  If I knew for sure that the unit should come up with everything off, then I could troubleshoot just the main assembly electronics without the lid connected. it's kind of a pain with the lid in the way.

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