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 Post subject: CLD-59 shows NO DISC
PostPosted: 03 Jul 2022, 20:35 
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If I insert a CD or LD it will show 0 time for a few seconds then NO DISC.
Is there a common part failure for this or can someone explain how the discs are sensed?
I have a service manual for the 100 series (590). Not sure how similar they are.

The spindle never turns. I am seeing about 4V AC instead of 5V DC on the VWR1260A board motor connector when the motor is disconnected and nothing when the motor is connected. The motor resistance is about 5.5Ω.

My assumption would be a power board problem but there are 2 inputs "DRIVE A" and "DRIVE B" that I can't seem to get to. They appear to switch the drive voltage to the motor.
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 04 Jul 2022, 02:58 
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It senses the disc w/ the laser pick-up.

Have you opened up the player to see if a red light is flashing from the pick-up and if the pick-up even moves on the track?
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 04 Jul 2022, 04:00 
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Thanks for the reply.
With no disc or CD in machine, the pickup moves in and I see a faint red glow in the laser. It then moves out and back in and I see nothing light up. It does the same movement with a disc in the machine. Is there more than 1 "red light" on the pickup?
How bright should the light be?
Shouldn't the spindle motor start b4 the pickup moves?
I am not really familiar with these laser discs, but from what I can see the spindle motor reverses direction to play "side B" under control of the mechanism control. Is that right?
I just can't figure out what drives that IC control and how to nail down where the problem originates.
With no voltage on the motor, I am assuming the motor isn't the problem.
I tested most of the diodes and transistors on the power board and they appeared to test OK, but that isn't definite.
I am interpreting this from a 590 service manual that appears very similar.
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 04 Jul 2022, 04:02 
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As ldfan stated your player is not even getting to the point of trying to spin the disc. The laser has to sense a disc being loaded before it will turn on the motor to spin. If the laser moves to the correct position to detect a CD or LD and gives you the "NO DISC" message then the most likely candidates are the laser pickup being bad or one of the voltages going to the main board is bad.
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 04 Jul 2022, 04:09 
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But the disc must be spinning b4 the pickup can sense it, right?
So, I guess I have to verify the PSU is generating the motor voltage first.
If the voltage is there b4 the switching circuit, then the control signals are not being applied to drive the motor, since I have no voltage on the motor.
I just haven't figured out what inputs cause the motor to start.
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 04 Jul 2022, 05:47 
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ruggb wrote:
But the disc must be spinning b4 the pickup can sense it, right?


Actually that is not the case.

The CLD players first have to decide what type of disc is on the tray. If you insert an LD, it will literally pick it up instantaneously as the pick-up quickly flashes it and then prop up the LD indicator (no disc spin at all). If you insert a CD, the pick up will flash the disc and if it doesn't think it's an LD it will then move the pick up closer to the spindle motor to flash again to detect the CD. If it determines a CD is the disc in question, then the machine will direct the spindle motor to perform a quick spin up to read the TOC and then be ready to play the disc.
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 04 Jul 2022, 14:53 
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Yes, with the CD out, it moves into CD range and the Laser comes on/off, then it moves outside CD range and it comes on/off again. Then moves back under the CD and stops.
There is another device about an inch to the left (from the front). Is that the tilt sensor?
Which sensor is triggering the motor start?
I videoed it with my phone and can see the red light but I have no reference for its brightness.
Will varying the tracking and/or focus gain give me a clue?
Also, there is a current adj pot on the carriage. Which should I try first?
One other thing, it won't switch sides, but I am assuming that is because it does not see the disc on side A, right?
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 05 Jul 2022, 15:20 
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ruggb wrote:
There is another device about an inch to the left (from the front). Is that the tilt sensor?

Yes.

ruggb wrote:
Which sensor is triggering the motor start?

An IC triggers the motor start, not a sensor.

ruggb wrote:
Will varying the tracking and/or focus gain give me a clue?

You could try adjusting focus gain, but it should be done as outlined in the CLD-D406 service manual.

ruggb wrote:
Also, there is a current adj pot on the carriage. Which should I try first?

I wouldn't touch it.

Have you verified your belt is ok?
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 06 Jul 2022, 00:10 
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Last edited by ruggb on 06 Jul 2022, 00:15, edited 1 time in total.
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 06 Jul 2022, 00:13 
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ruggb wrote:
Which sensor is triggering the motor start?

An IC triggers the motor start, not a sensor.

I am trying to trace the signal. Something tells the IC to start the motor.

ruggb wrote:
Also, there is a current adj pot on the carriage. Which should I try first?

I wouldn't touch it.

If the laser is weak wouldn't tweaking this pot verify that?

Have you verified your belt is ok?[/quote]
Everything loads and moves fine, so I assume there is no issue with the belt.
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 06 Jul 2022, 01:01 
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ruggb wrote:
I am trying to trace the signal. Something tells the IC to start the motor.

Yes, when focus is locked. CLD-D406 service manual has a block diagram of the focus servo towards the end. It will show test points. Just make sure the ICs are the same in the CLD-59 (they likely are).

ruggb wrote:
If the laser is weak wouldn't tweaking this pot verify that?

Possibly, but I still wouldn't touch it unless the issue has been determined to be the pickup with absolute certainty.

ruggb wrote:
Everything loads and moves fine, so I assume there is no issue with the belt.

While it is loading, help the mech raise by gently pulling it upwards.
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 Post subject: Re: CLD-59 shows NO DISC
PostPosted: 06 Jul 2022, 02:21 
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With laserdisc players as stated above it needs to determine what type of disc in inserted, CD or LD. Once it received an reflection back in the CD or LD position then the IC turns on the spindle motor. It you receive "NO DISC" on the display you did not get a reflection so the player just stops at that point.

You have to debug if you can see an RF pulse in the electronics when the laser is checking the CD or LD position. Just because you see the laser lite that does not mean the laser pickup is good. You have to connect an oscilloscope and trigger on receiving a pulse. Forget about what you have been thinking and just follow the RF signal to the IC and verify a pulse is present. Again, no pulse, no work!!
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