NAD C541 Tray Problem Repaired

Gary Indiana

Active Member
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EDIT: Important new info posted here.
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EDIT 2: This exact model NAD C541 has Sanyo laser SF-P101N 15-pin version. There is a 16-pin version of the same laser that does not work in NAD C541!
The whole brand new laser assembly with two motors, is less than $20 on ebay, just make sure to get the 15-pin version of Sanyo SF-P101N. Replacement procedure is realatively easy. No adjustments.
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This NAD C 541 HDCD player is my latest acquisition off CL. Cost me $25 with remote and original box.

This is a nice-sounding HDCD machine, positively reviewed here and here. Original price tag in 2000 AD was $500.

But…. Tray won't open, though you hear the motor whining.

Google says that this is a common problem for this CD player, so I'm posting details of my repair. Basic skills, common sense, steady hands, 59 cents o-ring and a Philips #2 screwdriver required for the fix.

Disconnect the power cable! 5 screws hold the outer case - take it off.

Remove 4 elevated screws in the bottom - they hold the black plastic transport assembly.

While removing the last of the four screws, don't forget the ruthless Laws of Gravity - make sure the transport doesn't drop ripping the ribbon cables with it.

Never, at any point, use excessive force in this repair.


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To remove the transport completely lift the back of it (like in the picture) and at the same time try to slide off the front plate of the tray. The oval decorative plate slides off upwards. You need to remove the plate to free the transport assembly completely and to gain access to the innards of the tray's motor, belt and pulleys.


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Notice two sets of cables and a ribbon running to the assembly. My recommendation is to leave them connected, but be extra gentle when flipping parts around, and keep the flipping to a minimum.


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Directly under the front part of the tray (when it's closed) there is a black plastic toothed gear - turn it with your finger to set the tray in motion, then move tray all the way out. Notice two little plastic tabs on the top of the tray - press them both outward and the tray can be removed. Now you see the motor and the rubber belt that became stiff and slack.


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I did not have a proper replacement belt, which should be square. I went to Ace hardware, to plumbing section and got a couple of different size o-rings for 59 cents apiece, hoping that one of them would work. And indeed! O-ring #29 works great.

The o-ring felt greasy out of the bag. It may have been treated with silicone grease. Wipe it with rubbing alcohol, and wipe it good! Then install.

This belt works only when the tray is operated, so it should stay healthy for a long time.

O-rings are made of very durable material:

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Cool, thanks for the tutorial!
I've got the same unit and it still opens the tray, but only reluctantly and most of all it won't close all the way any more. However, mine sounds like the motor is weak and can't get up to speed. Might still give the belt replacement a try though.
 
O rings do not have the same resiliency that a belt has. Order a belt of the proper size so you can replace it when it stops working in a few months. Been there, done that. MCM Electronics has belts. Use the link at the bottom of this page.
 
O rings do not have the same resiliency that a belt has. Order a belt of the proper size so you can replace it when it stops working in a few months. Been there, done that.
I agree, that O-ring is not exactly direct replacement for a square belt. However... it works and nicely pushes the tray in and out, it doesn't cost you $10 for shipping and it's available for less than a dollar at any good hardware store near you.

I'm not planning to replace it with anything else, and will update the info if it quits working next month (but I don't think it's going to happen ;)).

Looking for some extra info, I found that o-rings are suggested as capable replacements for square belts here (post #11) and here.

Those who don't mind spending extra $10 for shipping and would rather use a square belt, can find the info on how to measure the size of it in here. Just keep in mind that the old belt is stretched a little bit (by 1/8 inch?).
 
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I found out the hard way that for high torque applications (such as RTR drive belts) o-rings just don't cut it as a replacement for square belts. Back when I was a kid in the 90s and fiddled with my first RTRs interest in vintage audio gear was at an absolute low here and almost every repair guy would just tell you to scrap your vintage equipment "because spares are no longer available and besides, they aren't worth the labor to fix anyway!". So I used o-rings for my old Philips 4-speed 4 track deck... FF and Rew never worked properly.
 
... FF and Rew never worked properly.
It's not a rocket surgery: it either works or it does not. Proper length of the belt is always the key. This one works fine in the CD tray, that's why I posted the exact size of o-ring that fits.

All this is: a 15 minute DIY repair with easily obtainable part.

This player is a keeper, so I promise to update this thread with new info if that $ 0.59 o-ring explodes, incinerates, or defects to North Korea. :banana:
 
If you still have the old belt, try soaking it in a solution of Dawn dishwashing soap, some water, and some glycerin. Let it sit for a day or so then rinse off and dry. The belt should be soft and pliable again. I did this with a belt on a CDP and it's still fine two years later. YMMV.
 
If you still have the old belt, try soaking it in a solution of Dawn dishwashing soap, some water, and some glycerin. Let it sit for a day or so then rinse off and dry. The belt should be soft and pliable again. I did this with a belt on a CDP and it's still fine two years later. YMMV.

"Madge knows." I'll have to try that sometime.
 
If you still have the old belt, try soaking it in a solution of Dawn dishwashing soap, some water, and some glycerin. Let it sit for a day or so then rinse off and dry. The belt should be soft and pliable again. I did this with a belt on a CDP and it's still fine two years later. YMMV.
I saved the original old belt for sizing reference, and recommend doing it: tape it inside the CD player away from moving parts. But the original NAD belt looks really bad after 11 years of service; it's stretched and stiff, it is not like a typical good old belt that just lost a bit of its traction and slips.

I've seen vintage Sony CD players from 1980's that had much better quality rubber belts than this NAD. There are plenty of reports on the web of the NAD C541 tray going bad after about 10 years.

Upon using my fixed player for a few days, I can say with confidence that the o-ring will work better and much longer than original square belt in the NAD's tray transport.

People make mistake comparing disc tray to old tape decks, where indeed the size and shape of belts were crucial for proper operation and where substitutes never worked well. A CD/DVD tray is very different, it operates for less than 2 sec. at a time, and then limit sensors switch off the motor.
 
I saved the original old belt for sizing reference, and recommend doing it: tape it inside the CD player away from moving parts. But the original NAD belt looks really bad after 11 years of service; it's stretched and stiff, it is not like a typical good old belt that just lost a bit of its traction and slips.

I've seen vintage Sony CD players from 1980's that had much better quality rubber belts than this NAD. There are plenty of reports on the web of the NAD C541 tray going bad after about 10 years.

Upon using my fixed player for a few days, I can say with confidence that the o-ring will work better and much longer than original square belt in the NAD's tray transport.

People make mistake comparing disc tray to old tape decks, where indeed the size and shape of belts were crucial for proper operation and where substitutes never worked well. A CD/DVD tray is very different, it operates for less than 2 sec. at a time, and then limit sensors switch off the motor.

I have used O rings for a CD tray and they work for a month or so and then lose their resiliency and quit working. It isn't the fit or the tension, it's the wrong kind of rubber and it isn't made to stretch. In fact, you wouldn't want an O ring to stretch but to hold it's original shape.
 
Does anybody have experience with a Sony 508ESD cd player? The tray on mine is slow to close and needs a constant push for it to close. I just bought a replacement belt for %5.00 shipped(!) but I'd like advice as to if it is really the belt, and if I need to be aware of any issues when installing the replacement belt. thanks! Ed
 
"The tray on mine is slow to close and needs a constant push for it to close."
I had the same issue on my Yamaha cdx1030, and indeed it was resolved after I went ahead and changed the drawer belt.
Go for it!
 
Does anybody have experience with a Sony 508ESD cd player? The tray on mine is slow to close and needs a constant push for it to close. I just bought a replacement belt for %5.00 shipped(!) but I'd like advice as to if it is really the belt, and if I need to be aware of any issues when installing the replacement belt. thanks! Ed
I've got 507ESD. The tray belt was old and streched when I bought it (it was $4.99 at Goodwill :D). The replacement job was rather quick and simple, as far as I remember.
 
Thanks for the tutorial. Followed it and replaced it with the recommended o ring. I cleaned it with alcohol to remove the grease and it works fine. If it does go again,I will replace it again with another one out of the pack of 5 which cost all of £1.50! Will buy the original part if it does keep failing, but as you say the operation of the motor is small anyway.
I managed to replace the belt with the transport in place- remove tray and you can access the motor from either side ok.
Thanks again. I was convinced it was a deeper problem as it would load and eject cd's sometimes. It was worst when the player had been on for a while- maybe the belt was expanding slightly with the heat and loosing grip?
 
I managed to replace the belt with the transport in place- remove tray and you can access the motor from either side ok.
Yes, indeed!

I had another NAD C541 with bad tray belt and this time I removed the tray all the way out without removing the oval front plate or the 4 screws in the bottom.

It's a bit trickier job and a dental pick can help with pushing the plastic pins outward to free the tray, and then replace the belt.

It's important to clean with alcohol any traces of grease from the belt and the pulleys.
 
Restistor D701

Cool, thanks for the tutorial!
I've got the same unit and it still opens the tray, but only reluctantly and most of all it won't close all the way any more. However, mine sounds like the motor is weak and can't get up to speed. Might still give the belt replacement a try though.

This might be a little out of the box but I ran into the same thing: The belt has been replaced (by an original part from NAD) but the motor does not seem to have enough power to pull the tray all the way in and lift the laser unit. Then after a few seconds the display says No Disk and the tray comes crawling out again.
First I checked the power supply and replaced all the caps near the voltage regulators in the upper left corner of the pcb. No result. Then I suspected the motor controller (LB1641). I ordered a new one (about $3) and replaced it. No result. Still I suspected the motor controller, it was only putting out 3.5 volts to drive the motor, I do not know what it should be but it just seems low to me.
Now the 'out of the box' part starts
I looked at the schematic again and noticed resistor D701 (not R701 but D701). That resistor sets the output voltage of the motor controller. But the data sheet of the LB1641 says you should use a zener diode to set the output voltage :scratch2: . I then removed the resistor D701 from the board and found the symbol of a diode under it!. The pcb's silkscreen was designed to have a diode in that place!. I replaced the resistor with a 6.2 volt zener diode ( the symbol on the pcb shows you the correct orientation, very handy, thank you very much). And Success. The tray opens and closes strong, good as new! :thmbsp:
If you want to try this, I would advice to use a lower voltage zener diode first, maybe 4.3v or 5.6v first. If the motor was really designed to run on 3.5 volts then my value of 6.2 might be a bit high.. (the 6.2 zener diode sets the output voltage to 5.4 volts)
Bart
 
NAD C541 Sluggish Slow Tray Repaired

This might be a little out of the box but ....
WOW! Great work, Bart! THANK YOU for sharing your expert work.

Following your post I fixed today a couple of NAD C541 players with newly replaced belts and still somewhat sluggish trays. Now the trays work like brand new.

All credit for finding the fix goes to Bart!

Indeed, according to the manufacturer, the motor controller LB1641 should have a Zener diode hooked to pin #4 and not a 7.5 kOhm resistor. (Perhaps, I'm speculating, it was even meant to be a 7.5 Volt Zener, and someone srcewed it up at the production setup putting there a 7.5k resistor instead?)
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This is what D701 looks like on the board, right under the screw, next to LB1641 chip. It is a tiny 7.5 kOhm resistor.
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I did not want to remove the whole board, so I just cut the 7.5 kOhm resistor in half with pliers (not recommended ;)), and the diode symbol shows underneath.
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Your 6.2 Volts Zener seems to work very well, so I used the same value, but I used programmable TL431 regulator instead, which I bought off ebay in quantity of 30 for less than 2 bucks shipped from China. The good thing about the TL431 is that you can set any Voltage value up to 30+ Volts with a couple of resistors. I used 15k(R1) and 10k(R2) to get a 6 Volts regulator.
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I used the ends of the resistor, that I broke in half before, to solder the regulator to them (again, not recommended ;)).
The tray works perfectly well now, with normally expected speed and power.
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I looked at NAD's PDF Service Manuals for C541 and C541i (both of which can be googled up and downloaded for free) and I found that someone at NAD mistakenly marked D701 as a resistor and it was never caught: on the board they left the symbol of a diode marking it D but used a resistor instead.

Interestingly, C541i (newer version) has completely redesigned tray control. The chip is gone and they used four transistors instead. I wonder if the designers blamed the chip for poor performance of the tray's motor? That would be funny.

Picture of the PCB silkscreen shows diode D701
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C541 Service Manual has 7.5k resistor as D701, although the chip's manufacturer application has a Zener diode.
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The parts' list for C541 has D701 described as a 7.5k resistor
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C541i (newer version) went back to the old school with 4 transistors in the control circuit
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Hi, I came across this thread while trying to find info on this problem for this unit. I took the transport out after disconnecting the cables and took it apart a bit and this is what I discovered: The reason the drawer won't open sometimes is because the motor, rubber drive belt and linkage have to first overcome the magnetism of the spindle assembly that clamps onto the CD when it is inserted. This is especially true if there is no CD in the tray, as the CD provides some separation between the upper magnetic "Chucking Yoke" and the lower "Chucking Pulley", as they are referred to in the parts list for the C-541i (I don't have the service manual for the C-541). The Chucking Pulley has a ferrous washer embedded in it. This unit had this problem straight out of the box so I think the problem is a mis-sized belt rather than a stretched or worn belt, basically an design flaw. A tighter belt, as the #29 or equivalent O-ring seems to be, appears to be one solution from the experience of users here. I am considering placing a spacer of some sort on the upper magnetic "Chucking Yoke", either two or three layers of duct tape or possible a metal washer that will cling to the magnet in the upper magnetic "Chucking Yoke". This will make the magnetic bond easier to break when the drawer is closed. Oh, what fun we have!

Jack
 
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