DIYbanter

DIYbanter (https://www.diybanter.com/)
-   Electronics Repair (https://www.diybanter.com/electronics-repair/)
-   -   Denon UD-M31 CD Problem (https://www.diybanter.com/electronics-repair/395489-denon-ud-m31-cd-problem.html)

rupert handford June 13th 16 06:01 PM

Denon UD-M31 CD Problem
 
Calling all CD repair experts!
This is my first in depth CD repair and I have the following questions:
I have the above unit, that won't play CD's. I have replaced the laser mech and still have the same fault.
The CD will 'twitch' but not run up to speed.
Using service mode I am monitoring the output from pin 62 IC802 and it never seems to go low (thus powering the laser).
Clock, data, CS and all Vcc lines are correct and the chip is being told to turn on from the processor.
I have also checked the operation of TR806.
Has anyone had experience of these IC's failing or is there another possible cause?
Please let me know if I have missed anything!
Regards,
Rupert

[email protected] June 13th 16 06:21 PM

Denon UD-M31 CD Problem
 
Are you sure the drive motor is good? If it is 'twitching' as you suggest, it just may be bad. I expect it is a Hall Effect motor with the speed fixed by the clock. So, either the motor or the clock should be on your list of suspects. Do you get output to the motor?

This is, after all, a mini-system, and so may not be as rugged or as easily serviced as a stand-alone CD player.

Peter Wieck
Melrose Park, PA

rupert handford June 13th 16 06:34 PM

Denon UD-M31 CD Problem
 
On Monday, 13 June 2016 18:21:11 UTC+1, wrote:
Are you sure the drive motor is good? If it is 'twitching' as you suggest, it just may be bad. I expect it is a Hall Effect motor with the speed fixed by the clock. So, either the motor or the clock should be on your list of suspects. Do you get output to the motor?

This is, after all, a mini-system, and so may not be as rugged or as easily serviced as a stand-alone CD player.

Peter Wieck
Melrose Park, PA


Thanks for the reply. I have replaced the entire CD mechanism and so have replaced the motor. I believe that the sequence is as follows:
1. Laser turns on
2. Focus adjustment
3. Motor will start if focus is OK, PLL is OK and RF output is present.
I have clock (from the chip). Focus is active (lens moves) but I have no RF and the APC of the chip is not going low.
Can happily email schematic and datasheet is it would help.
Regards, Rupert

[email protected] June 13th 16 07:34 PM

Denon UD-M31 CD Problem
 
Check the motor driver IC. I have had these go bad from faulty motors. With the mechanism replacement, you now have a new motor, but not a new driver IC.

Dan

Gareth Magennis[_3_] June 13th 16 07:38 PM

Denon UD-M31 CD Problem
 


"rupert handford" wrote in message
...

Calling all CD repair experts!
This is my first in depth CD repair and I have the following questions:
I have the above unit, that won't play CD's. I have replaced the laser mech
and still have the same fault.
The CD will 'twitch' but not run up to speed.
Using service mode I am monitoring the output from pin 62 IC802 and it never
seems to go low (thus powering the laser).
Clock, data, CS and all Vcc lines are correct and the chip is being told to
turn on from the processor.
I have also checked the operation of TR806.
Has anyone had experience of these IC's failing or is there another possible
cause?
Please let me know if I have missed anything!
Regards,
Rupert




Where did you get the mech from and how much did you pay for it?

I've bought many lasers from ebay that just don't work. That's why they
are so cheap and on Ebay.



Gareth.


rupert handford June 13th 16 09:16 PM

Denon UD-M31 CD Problem
 
On Monday, 13 June 2016 19:34:38 UTC+1, wrote:
Check the motor driver IC. I have had these go bad from faulty motors. With the mechanism replacement, you now have a new motor, but not a new driver IC.

Dan


Thanks Dan,
The motor is driven from the analog signal processor that I was asking about, but as the motor does move I guess that it is getting some signals?

rupert handford June 13th 16 09:19 PM

Denon UD-M31 CD Problem
 
On Monday, 13 June 2016 19:38:25 UTC+1, Gareth Magennis wrote:
"rupert handford" wrote in message
...

Calling all CD repair experts!
This is my first in depth CD repair and I have the following questions:
I have the above unit, that won't play CD's. I have replaced the laser mech
and still have the same fault.
The CD will 'twitch' but not run up to speed.
Using service mode I am monitoring the output from pin 62 IC802 and it never
seems to go low (thus powering the laser).
Clock, data, CS and all Vcc lines are correct and the chip is being told to
turn on from the processor.
I have also checked the operation of TR806.
Has anyone had experience of these IC's failing or is there another possible
cause?
Please let me know if I have missed anything!
Regards,
Rupert




Where did you get the mech from and how much did you pay for it?

I've bought many lasers from ebay that just don't work. That's why they
are so cheap and on Ebay.



Gareth.


Hi Gareth,
The motor was from ebay but from a supplier that I have used before and not had any problems with. What are the chances of replacing a unit and having exactly the same fault as the origional? Thanks for the idea though I am not ruleing anything out at the moment!

[email protected] June 13th 16 09:52 PM

Denon UD-M31 CD Problem
 

The motor is driven from the analog signal processor that I was asking about, but as the motor does move I guess that it is getting some signals?


Look at the BA6287F IC. This is hte motor driver IC and is separate from the signal processor. The signal processor will trigger the driver, but the driver itself may be the problem. If the driver has been weakened or damaged because of a bad motor, it may not be able to drive the new one either.

The way these work is that the CD needs to spin up to a certain speed in a particular period of time, before the focus takes place and an attempt to read the TOC happens. If you are just getting a short shake of the CD, I would start with the motor driver.


Gareth Magennis[_3_] June 13th 16 10:09 PM

Denon UD-M31 CD Problem
 


"rupert handford" wrote in message
...

On Monday, 13 June 2016 19:38:25 UTC+1, Gareth Magennis wrote:
"rupert handford" wrote in message
...

Calling all CD repair experts!
This is my first in depth CD repair and I have the following questions:
I have the above unit, that won't play CD's. I have replaced the laser
mech
and still have the same fault.
The CD will 'twitch' but not run up to speed.
Using service mode I am monitoring the output from pin 62 IC802 and it
never
seems to go low (thus powering the laser).
Clock, data, CS and all Vcc lines are correct and the chip is being told
to
turn on from the processor.
I have also checked the operation of TR806.
Has anyone had experience of these IC's failing or is there another
possible
cause?
Please let me know if I have missed anything!
Regards,
Rupert




Where did you get the mech from and how much did you pay for it?

I've bought many lasers from ebay that just don't work. That's why they
are so cheap and on Ebay.



Gareth.


Hi Gareth,
The motor was from ebay but from a supplier that I have used before and not
had any problems with. What are the chances of replacing a unit and having
exactly the same fault as the origional? Thanks for the idea though I am not
ruleing anything out at the moment!







Those chances are IMHO reasonable. There is a lot of fake ****e out there.

Think Occam's razor before suspecting pin blah blah on IC blah.



Gareth.




Gareth Magennis[_3_] June 13th 16 10:16 PM

Denon UD-M31 CD Problem
 
And I assume you have removed the soldered safety short that is shipped with
a new laser pickup before trying to use it?


Gareth.



All times are GMT +1. The time now is 03:37 AM.

Powered by vBulletin® Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright 2004 - 2014 DIYbanter