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Dead NAD???
Dead NAD???
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Old 13th October 2017, 09:19 AM   #1
giblets is offline giblets  United Kingdom
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Default Dead NAD???

Hey there,
picked up a NAD as bargain basement (15) and to be honest a bit of a risk.

Its a NAD C542i, and had some power issues, which I had down as a bit of dry solder on the connector from the transformer to the main board.
Managed to fix that, and device powered up properly.
However, stick in a CD and... well nothing, doesn't spin up, the laser does nothing. I've got a copy of the service manual which suggests that it's either the u101 (chip on the m/board) or the connection/ pickup.

So the question is whether it is worth bothering and trying a new mechnism, or simply put it down as a risk taken and lost?

Cheers for your thoughts
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Old 19th October 2017, 09:01 AM   #2
Mooly is offline Mooly  United Kingdom
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Dead NAD???
Does the lens move up and down three times when the drawer is closed (no disc inserted) ?

If it does then the laser should also be lit during this brief period.

Before pointing the finger at any IC's you must check the basics such as all rails being present and correct.
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Old 19th October 2017, 09:49 AM   #3
giblets is offline giblets  United Kingdom
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Hi, thanks for the reply, once the door shuts absolutely nothing happens, no spin up and the lens does not move or light up (or anything else). The LED display lights and simply blinks.
Where would the best place be to check the rails? (sorry if I am a little inexperience in this!).
cheers
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Old 19th October 2017, 11:59 AM   #4
Mooly is offline Mooly  United Kingdom
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Dead NAD???
The platter won't spin until the laser focuses onto a disc, so no spin is normal.

The very first thing to check is to confirm that when the drawer shuts, it does so fully and that any subsequent mechanical loading of the mechanism finishes. I'm not familiar with the NAD but slipping loading belts (if it uses them) can cause such problems.

There will be some form of micro switch to detect the drawer is closed. If that isn't happening then the drawer motor will keep running. So make sure that is OK.

Also check that the laser assembly is correctly positioned at the centre of the disc. It can be a useful check to manually move the pickup outward (turn the sled motor by hand with the player off) and then reconnect power and turn on. The sled should instantly return to the centre again.

If it all checks out mechanically then you have to measure all the main voltage supplies produced by the power supply. The manual will show them all. Typically there will several such as +5 +9 perhaps a - and a + 15 and assorted display related rails such as -28 (depending on the type of display).
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Old 19th October 2017, 12:10 PM   #5
giblets is offline giblets  United Kingdom
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Thanks, I've tried to ensure the tray is fully in ( tried to look for the micro switch), I've also moved the laser to the start position to no avail.
Good to know the motor waits for the laser, I've heard the laser assembly is sensitive to static so hoping that is the cause.
I'll look for the voltage,
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Old 19th October 2017, 12:42 PM   #6
giblets is offline giblets  United Kingdom
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Not sure if relevant, but every few closes the tray doesn't manage to close properly.
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Old 19th October 2017, 02:08 PM   #7
Mooly is offline Mooly  United Kingdom
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Dead NAD???
It could be very relevant. If the loading cycle doesn't complete then the system control will not proceed any further because the logic is effectively in a non valid state.

Mechanical issues like this are a number one cause of issues.

When the tray doesn't manage to close, can you still hear the tray motor running ?
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Old 19th October 2017, 02:29 PM   #8
giblets is offline giblets  United Kingdom
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Thanks for keeping with me, when it fails to close fully on it's own (i.e about halfway), it just reopens. If I try to stop if opening/ closing then it does carries on trying to close/ open the tray, and there is a reasonable amount of force created by it (and the band seems to have a half decent grip), thats not to say it could be an issue as I've got nothing to compare it too.
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Old 19th October 2017, 02:34 PM   #9
Mooly is offline Mooly  United Kingdom
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Dead NAD???
It could be the belt slipping although it usually the final stage of loading that cause trouble, not just half way in.

You should be able to stall the motor by holding the tray but be careful its not good to do that for any length of time. Make a judgement call. If you can apply force and still hear the motor spin then the belt is slipping.

Beyond that and you need to see if there is any obvious obstruction... belt is most likely at this point though.
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Old 19th October 2017, 02:49 PM   #10
giblets is offline giblets  United Kingdom
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Hi,
I' can't hear much when I hold the tray, but one thing I did notice when looking online is than in many cases closing the try has a mechanism that lifts up the spindle and the laser. On mine, the spindle never lifts up to engage the CD.
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