Nad 522 optical assembly problem

[Time]

After a failed lens cleaning attempt our 522 stopped working. It wouldn’t
recognise CDs or if it did would just display 99.99 as track length and
still not play.

So, after a trip to the repair shop and being told to throw it because
repair would cost more than a new one I decided to have a go myself. I
took it apart, noted the pickup assembly (Sanyo SF-P101 5/8P) and ordered
a new one from the UK (I'm in NZ). I removed the old one and replaced it
exactly with the brand new unit; I removed the temporary solder bridge and
turned it on.

Still wouldn’t work…
not exactly the same thing, this time it would just try to spin the CD a
tiny bit clockwise, then spin it backwards about one rev (I'm guessing
this is how it would try to slow the CD, had it been spinning correctly?)
then ‘Er” would display on the display. I've tested all connections, and
everything seems fine. I also tested some of the components such as the
main spinup motor, and during this testing the CD spun up properly! I
don’t get what happened, and I can't accurately reproduce it but the cd
spun up, the display flashed --.-- a few times and attempted to play track
one, but after all these good signs it still ended up with ‘Er’ in this
attempt it also showed 16 tracks (the max that can show on the display at
once) even though the CD in it only had 8.

Does anyone know why this new unit isn’t working, or recognise these
signs? I head somewhere that it might need calibrating/aligning, does what
I described sound like this could be the problem?

Sorry for the long post, but hopefully this way I wont have to post
additional info.

 

[Jerry G.]

The factory alignment for the laser tracking has to be done. This is a
procedure that requires the service manual, scope, DVM, and the calibration
CD for your unit. For some models, there may be an interface and software
required. I have no idea for your particular model. The best bet would be to
contact Denon, and order the service manual, just to start with.

When adding up the technician's time, and the value of usage of the parts,
and the instrumentation, the service shop would have told you that it is not
worth to do the repair.

--

Jerry G.
=====

After a failed lens cleaning attempt our 522 stopped working. It wouldn't
recognise CDs or if it did would just display 99.99 as track length and
still not play.

So, after a trip to the repair shop and being told to throw it because
repair would cost more than a new one I decided to have a go myself. I
took it apart, noted the pickup assembly (Sanyo SF-P101 5/8P) and ordered
a new one from the UK (I'm in NZ). I removed the old one and replaced it
exactly with the brand new unit; I removed the temporary solder bridge and
turned it on.

Still wouldn't work.
not exactly the same thing, this time it would just try to spin the CD a
tiny bit clockwise, then spin it backwards about one rev (I'm guessing
this is how it would try to slow the CD, had it been spinning correctly?)
then 'Er" would display on the display. I've tested all connections, and
everything seems fine. I also tested some of the components such as the
main spinup motor, and during this testing the CD spun up properly! I
don't get what happened, and I can't accurately reproduce it but the cd
spun up, the display flashed --.-- a few times and attempted to play track
one, but after all these good signs it still ended up with 'Er' in this
attempt it also showed 16 tracks (the max that can show on the display at
once) even though the CD in it only had 8.

Does anyone know why this new unit isn't working, or recognise these
signs? I head somewhere that it might need calibrating/aligning, does what
I described sound like this could be the problem?

Sorry for the long post, but hopefully this way I wont have to post
additional info.

 

[Mark D. Zacharias]

After a failed lens cleaning attempt our 522 stopped working. It wouldn't
recognise CDs or if it did would just display 99.99 as track length and
still not play.

So, after a trip to the repair shop and being told to throw it because
repair would cost more than a new one I decided to have a go myself. I
took it apart, noted the pickup assembly (Sanyo SF-P101 5/8P) and ordered
a new one from the UK (I'm in NZ). I removed the old one and replaced it
exactly with the brand new unit; I removed the temporary solder bridge and
turned it on.

Still wouldn't work.
not exactly the same thing, this time it would just try to spin the CD a
tiny bit clockwise, then spin it backwards about one rev (I'm guessing
this is how it would try to slow the CD, had it been spinning correctly?)
then 'Er" would display on the display. I've tested all connections, and
everything seems fine. I also tested some of the components such as the
main spinup motor, and during this testing the CD spun up properly! I
don't get what happened, and I can't accurately reproduce it but the cd
spun up, the display flashed --.-- a few times and attempted to play track
one, but after all these good signs it still ended up with 'Er' in this
attempt it also showed 16 tracks (the max that can show on the display at
once) even though the CD in it only had 8.

Does anyone know why this new unit isn't working, or recognise these
signs? I head somewhere that it might need calibrating/aligning, does what
I described sound like this could be the problem?

Sorry for the long post, but hopefully this way I wont have to post
additional info.

I've fixed many cd players, including some NAD's but the one area where I
always seem to blow it is when replacing Sanyo-Fisher pickups. For some
reason, on problems that would ALWAYS be a bad pickup on other brands,
replacing the Sanyo pickup does not fix my problem, and by that I mean the
symptom remains exactly the same.

Jerry is wrong, most modern pickups function pretty well right out of the
box, provided the "solder blob" is cleared. At least well enough to run, and
do the adjustments for radial / tangential, etc.


Mark Z.

 

[Tim Schwartz]

Hello,

While I'm not sure that this is the answer, there is a service note
about "CD will not read in, CD is spinning on high speed." from NAD for
the 522.

Cause: 5V to the RF amp/laser is too low; D505 is defective, regulator
U506 (78L05A) can also be defective.

Solution: Replace D505, zener 4.3V, 0.5W with 3.3V 1.3W type. Replace
the regulator U506 from 78L05A (TO-92 case) by a 7805 in a TO-220 case
(MC78M05 or equivalent).

This change was done in production at some point, but I don't have
serial number info. It should be easy enough to check the voltage of
the zener diode and the size (case) of the regulator.

Unfortunately, there is a laser tilt adjustment that is mechanical as
well.

Regards,
Tim Schwartz
Bristol Electronics

 

[Sam Goldwasser]

The factory alignment for the laser tracking has to be done. This is a
procedure that requires the service manual, scope, DVM, and the calibration
CD for your unit. For some models, there may be an interface and software
required. I have no idea for your particular model. The best bet would be to
contact Denon, and order the service manual, just to start with.

When adding up the technician's time, and the value of usage of the parts,
and the instrumentation, the service shop would have told you that it is not
worth to do the repair.

Do you actually know this for a fact for this model? At least some
come prealigned.

Did he remove the solder short, if any?

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[Gareth Magennis]

I am assuming you are not going to go out and buy a service manual,
calibration disc, scope and DVM to fix this.

Have a look at the main pcb and see if there are any presets on it. Mark
the position of each one so you can get everything back to where it was
before you started messing with them, then mess with them. Load a CD and
have the player try to play it. While it is doing its spinning, hunting,
failing kind of thing you can adjust each preset in turn and see if it
helps, leaving them in the position that helps most before moving on to the
next one. I have done this before with old tossable units and rescued them.
You don't seem to have anything to lose by trying this so I would say have a
go. If it doesn't work, you may have a fault elsewhere, or the new laser
assembly is faulty or damaged.



Good luck.

 

[True american Zero]

Are you Tim from Emu ?

 

[Time]

Thanks for all the replies,

The reason I went ahead and got this part was because I understood that it
wouldn’t need any adjustment, I wasn’t sure about this but I had read it
was so in a few places.

Yes Sam, I have removed the temp. solder bridge.

Gareth Magennis; There don’t appear to be any adjustable settings on the
main PCB, all I see is the one on the pickup PCB itself and I think I read
that that’s for laser power.

Mark Z; you don’t think its related to the pickup?

Tim Schwartz; both components are the latter that you said. What did you
mean by: “Unfortunately, there is a laser tilt adjustment that is
mechanical as well“
Is this one of the screws on the pickup unit, the one that isn’t thread
locked? Why is it unfortunate?

Thanks again

 

[Mark D. Zacharias]

Mark Z; you don't think its related to the pickup?

Wish I could tell you for sure. As good as I think I usually am with cd
players, my batting average with Fisher pickups seems like .000 (not really,
just seems like it.) After replacing was the symptom identical to what it
was previously?
I think I would defer to Tim on this one - he has more experience with NAD,
and his long history of helpful posts here on the Group shows his obvious
technical talent (really NOT sucking up, just the truth!).

Mark Z.

 

[Gareth Magennis]

I replaced a laser assembly in a Denon once, and like yours it made no
difference and I gave up. A while later I fitted the new laser in another
Denon and again it made no difference. It wasn't until some time later I
discovered the new laser was faulty. Doh.

 

[Tim Schwartz]

Hello,

As I don't have any idea who Emu is, I'm not Tim from Emu.

Regards,
Tim Schwartz
Bristol Electronics

 

[Tim Schwartz]

Hello,

As I don't have any idea who Emu is, I'm not Tim from Emu.

Regards,
Tim Schwartz
Bristol Electronics

 

[Tim Schwartz]

Hello,

As I don't have any idea who Emu is, I'm not Tim from Emu.

Regards,
Tim Schwartz
Bristol Electronics

 

[Tim Schwartz]

Hello again,

The reason I call the tilt screw unfortunate is that it is only
mentioned in passing in a service bulletin. The service manual does not
mention it at all. The service note covers the problem of the "player
does not read discs, skips, produces scratching noise only on some
specific CD's", so this might not even apply to your machine. The
service note says:

"4) Adjust TILT-screw on the laser unit for minimal Jitter with the
help of a jitter meter. This is the lower mounted screw at the yellow
metal plate in the corner"

"5) If the laser power is above 24mW the unit will malfunction
after playing for some hours. A Laser power meter is required here.
Adjust laser power down to 18-22mW.

So, you need a jitter meter and a laser power meter, which few people
have. My experience with these is that I only change the entire
mechanism as an assembly, and only buy them from NAD, which is more than
most people want to spend on these machines now.

Regards,
Tim Schwartz
Bristol Electronics

 

[Sam Goldwasser]

Hello again,

The reason I call the tilt screw unfortunate is that it is only
mentioned in passing in a service bulletin. The service manual does not
mention it at all. The service note covers the problem of the "player
does not read discs, skips, produces scratching noise only on some
specific CD's", so this might not even apply to your machine. The
service note says:

"4) Adjust TILT-screw on the laser unit for minimal Jitter with the
help of a jitter meter. This is the lower mounted screw at the yellow
metal plate in the corner"

"5) If the laser power is above 24mW the unit will malfunction
after playing for some hours. A Laser power meter is required here.
Adjust laser power down to 18-22mW.

mW? You could burn the coating off a CD with 20+ mW. No normal CD player
uses that much power.

The maximum power of the lasre diode in a typical CD player is 5 mW and
maybe 1 mW makes it out the objective lens.

So, you need a jitter meter and a laser power meter, which few people
have. My experience with these is that I only change the entire
mechanism as an assembly, and only buy them from NAD, which is more than
most people want to spend on these machines now.

Perhaps to get absolutly optimal performance but you don't need them to
get it working. Just keep the laser power down (or better yet, don't
touch it!).

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[jakdedert]

Hello,

As I don't have any idea who Emu is, I'm not Tim from Emu.

Methinks he doth protest....

 

[True american Zero]

Hello,

I knew a great guy named Tim Schwartz from a company called E-Mu
Systems in Santa-Cruz (USA). He wazs the service manager.
It would heve been funny !

Cheers
Georges

 

[Time]

The symptoms weren’t exactly the same. As I said, the CD player originally
stopped working because I was too rough while cleaning the lens, and that
seems to be exactly how the old unit acts; it spins the CD up, takes quite
a while looking and eventually just shows 99-99 on the display, it can
detect the CD (it also knows when there is no disc inserted) but just not
properly, as if the lens is damaged or scratched.

With the replacement; it usually doesn’t even spin the CD up, it just
gives a pathetic little spin and then says ‘Er’ as I said.

I don’t like the idea that this new unit could have been DOA, i went to
quite a lot of effort (not to mention the $$) to get it, how could I rule
this in/out?

-I am quite sure the laser is getting power a red light shows up on my
digital camera display, so I think ill stay away from adjusting laser
power.

-I think the unit is mechanically sound, it moves through all the right
axes, although I'm not sure why it doesn’t spin-up CD's correctly.

-And the unit at least attempts to focus; the lens bobs up and down under
the CD.

Do these symptoms make any sense?

 

[Thomas Sedlemyer]

Did you look for the presense of a small drop of solder on the laser board
across two small pads. This is done to short across the laser diode to
protect from static discharge damage. If present it is removed after
installation by touching it with a hot soldering iron(grounded tip
prefferably).

Tom

..com...

 

[Time]

Yes, I already removed that.