DVD player won't load dvd

[Circuitous3]

I have a Samsung dvd v3500 VHS/dvd combination player. I realize the most likely issue for this continuous loading problem is a dirty laser lens. I was able to remove the back and front covers of the player, retract the dvd tray which allowed access to the optical assembly, and remove the optical assembly. But I didn't see anything that looked like a lens. I cleaned the only component that seemed in a position to be able to read the dvd from underneath, but the cleaning didn't fix the problem. I found a picture of the component housing the lens online, but I didn't see anything like that when looking at the optical assembly. I saw a thread mentioning that a lower piece containing the lens was "unsnapped" from an upper piece, but it didn't look to me like anything could be unsnapped. Any help with this would be appreciated.

[drussell]

It actually is rarely a dirty laser diode.  Malfunctioning, misadjusted or damaged, yes... but dirty... very, very rarely, in my experience.  Generally if someone who doesn't know exactly what they're doing tries to "clean" it, they will damage the very, very fragile positioning mechanism and you will be SOL without replacing the whole assembly.

The vast majority of the time, a "no-read" is actually something with one of the motors, like the stepper that moves the coarse carriage assembly or the cheap toy motor that is spinning the disc itself rather than the laser diode assembly.  If you have an X-Y capable oscilliscope, you can attach it to the positioning system for the diode and re-align things IF it hasn't been permanently damaged by someone jabbing it with a Q-tip or something.

Perhaps start here, for some basic preliminary information to help you understand the mechanism:

https://www.repairfaq.org/sam/odfaq.htm
https://www.repairfaq.org/REPAIR/F_cdfaqd.html

One stabby-jab can tear the laser diode part off the positioning system mechanism or damage it in some way and render it permanently useless.

[drussell]

Here is a link to the service manual which contains much of the information you seek if you have or can beg/borrow access to the necessary equipment to service your unit:

https://elektrotanya.com/samsung_dvd-v3500.pdf/download.html

[Circuitous3]

Thank you very much for this helpful information drussell. I'm obviously an amateur when it comes to electronics repair. After googling the problem I saw a number of references to a dirty laser diode causing this no read problem and assumed that was the most likely cause. I was careful about the cleaning, and would still like to locate the laser diode to give this possible fix a shot. But based on your information I realize there may be a number of other problems involved. The unit is about 16 years old, so it really doesn't owe me anything.  .

[drussell]

Yeah, it certainly doesn't hurt to take a shot at it! 

Hopefully the diagrams in the service manual can help you disassemble the transport mechanism enough to get to the laser diode lens thingy.  It will be a small little clear blob, maybe 4-5 mm diameter usually, that is mounted on a springy servo mount.  Be careful when you try to clean it of any dust or residue since the positioning mount is fragile.  Tobacco reside is probably the worst thing that can be on it since it is difficult stuff to clean off.  Hopefully you don't have anything like that on there!     (Though if there is, then cleaning it might well improve things.)

Also, does ever it read ANY discs at all?  Like will it still read a good, non-scratched CD?

That unit happens to be new enough that it doesn't have much in the way of "adjustments" like the older units do, so other than adjusting the SKEW, there isn't much that can be done short of a new diode assembly or whole transport mechanism.

[rhb]

Look for solder flux residue, especially on the logic lines and clean it off..  I fixed my CD player by cleaning it with isopropyl alcohol.  It started reporting "no disk" .   I could tell from the lack of the normal squeak when the disk started spinning that it  was not spinning the disk.  I cleaned it 2-3 years ago and it still works fine.  I've repaired a number of other devices by doing the same thing.  Flux is hygroscopic and this becomes a real problem in humid environments.

[MyHeadHz]

The repair manuals posted should have you covered, though it can be a bit daunting to find out where to start.  I've repaired a lot of optical drives, and the most common problems I've found are:

laser- setting the pot to allow a bit more power, as they lose power over time.  those pots are sensitive- a small movement goes a long way.  set it with a multimeter

motor drive belts (on older drives like yours)- they dry and crack, the only solution is to replace them

disc clamping- when drives close, there are usually two magnetic pieces that clamp to keep the disc in place, and over time they can get too weak/strong to hold the disc properly.  Since your drive opens, it could be on the weak side.  if you hear/feel vibration or scraping, this could be the problem

hair and grime can get in pulleys and small gears as well.  you could go through to clean and grease the components if you like.  just use a rubber-safe grease.

some pictures of the drive you have would be nice.

[Circuitous3]

Yeah, it certainly doesn't hurt to take a shot at it! 
Also, does ever it read ANY discs at all?  Like will it still read a good, non-scratched CD?

The problem doesn't seem to be disk-specific. It happens with DVDs in good condition. But a few times months ago I was able to get it to load and play a DVD after repeated attempts, but as I remember display problems developed during the playing and I had to eject the DVD. So it sees that this issue had been brewing for awhile. I'll continue trying to locate the laser diode, but that will have to wait until the weekend. I'll let you know how it goes. Thanks again for the manual and your advice.

[Circuitous3]

Look for solder flux residue, especially on the logic lines and clean it off..  I fixed my CD player by cleaning it with isopropyl alcohol.  It started reporting "no disk" .   I could tell from the lack of the normal squeak when the disk started spinning that it  was not spinning the disk.  I cleaned it 2-3 years ago and it still works fine.  I've repaired a number of other devices by doing the same thing.  Flux is hygroscopic and this becomes a real problem in humid environments.

When I was working on removal of the optical assembly, I noticed that the disk was spinning. But which are the logic lines and how would I recognize them? The circuit boards were dense with circuits. A magnifying glass would help. Which ones would I look at for solder flux?

[edavid]

I hate these cheapo Funai DVD/VCR combo units.  They are very unreliable and unpleasant to work on.  Anyway, I had one with the same symptom, and it turned out that one of the power supply filter caps had gone bad (I think it was the 2.5V supply), but fixing that didn't cure the problem, so I guess the DVD drive had gotten damaged.

I would check the power supply voltages, but I wouldn't be too optimistic about fixing this...

[rhb]

The logic devices  have lots of traces going to them.  However, just look for solder flux anywhere and clean it off.  Dry with a hair dryer and repeat if there is any left.  I use a soft toothbrush or a wide artist's brush.  You want to be gentle.  IIRC I discovered the flux issue when I tore apart a Funai VHS player looking for usable parts and saw flux everywhere.  I was living in Houston and had two VHS players  fail after about a year of very light use each.  Not sure of the other brand.  I didn't try to fix it, but I made a mental note to test the flux hypothesis. 

The first test was the remote for Mother's DVD/VHS player. I took it home cleaned a big blob of flux off and took it back.  It worked fine until the unit died.  It was so difficult to disassemble that I put it in a container and poured 4 bottles of alcohol in until I reached the level of the main board.  I sloshed it around, saved the alcohol and let it dry.  That got it working for a while.  I tried a couple more times, each time with temporary success before i got tired of fiddling with it.  My CD player was my 3rd test of the hypothesis.  As it as functioned reliably ever since I think the hypothesis confirmed.  Flux residue is bad for electronic devices.

[drussell]

The problem doesn't seem to be disk-specific. It happens with DVDs in good condition. But a few times months ago I was able to get it to load and play a DVD after repeated attempts, but as I remember display problems developed during the playing and I had to eject the DVD. So it sees that this issue had been brewing for awhile.

It is interesting to note that the symptoms seemed to come on slowly, so that points to a more gradual degradation of something rather than outright breaking or jamming of a physical, mechanical part.

I am still interested if you can get it to read a CD since the whole optical system will align itself differently when reading a CD than when reading a DVD.  The information is recorded at a different physical depth into the disc in a CD vs. a DVD.

[drussell]

I hate these cheapo Funai DVD/VCR combo units.  They are very unreliable and unpleasant to work on.

What makes you suspect that this unit was manufactured by Funai?

I believe this unit is an old enough combo that it was actually made by Samsung in Korea.  Not that all Funai stuff is crap, but for a Japanese company, they certainly have produced a lot of very, very low end stuff for various OEM "names" that used to have a decent reputation like Sanyo or Magnavox.  They do actually know how to build some good stuff too, though, even if that's not the things from Funai that you're accustomed to seeing.

To the OP, out of curiosity, where does your unit say it was "Made in ...," anyway?

[edavid]

I hate these cheapo Funai DVD/VCR combo units.  They are very unreliable and unpleasant to work on.

What makes you suspect that this unit was manufactured by Funai?

I believe this unit is an old enough combo that it was actually made by Samsung in Korea.  Not that all Funai stuff is crap, but for a Japanese company, they certainly have produced a lot of very, very low end stuff for various OEM "names" that used to have a decent reputation like Sanyo or Magnavox.  They do actually know how to build some good stuff too, though, even if that's not the things from Funai that you're accustomed to seeing.

If you look at photos of the Samsung, you'll see it's identical to the Sanyo DVW-7200 and Magnavox MWD2205.

[Circuitous3]

Thank you for the suggestions.

The repair manuals posted should have you covered, though it can be a bit daunting to find out where to start.  I've repaired a lot of optical drives, and the most common problems I've found are:

laser- setting the pot to allow a bit more power, as they lose power over time.  those pots are sensitive- a small movement goes a long way.  set it with a multimeter

Would I be looking for a trimmer or slide type pot? Could you direct me to a source of instruction for the procedure?

motor drive belts (on older drives like yours)- they dry and crack, the only solution is to replace them

 

I will need to locate them first!

disc clamping- when drives close, there are usually two magnetic pieces that clamp to keep the disc in place, and over time they can get too weak/strong to hold the disc properly.  Since your drive opens, it could be on the weak side.  if you hear/feel vibration or scraping, this could be the problem

I don't recall hearing any funny noises, but I'll listen for them.

hair and grime can get in pulleys and small gears as well.  you could go through to clean and grease the components if you like.  just use a rubber-safe grease.

Is plumber's valve grease ok? It's safe for rubber washers.

some  pictures of the drive you have would be nice.

I'll post a picture or two the next time I get a chance.

[Circuitous3]

It is interesting to note that the symptoms seemed to come on slowly, so that points to a more gradual degradation of something rather than outright breaking or jamming of a physical, mechanical part.

I am still interested if you can get it to read a CD since the whole optical system will align itself differently when reading a CD than when reading a DVD.  The information is recorded at a different physical depth into the disc in a CD vs. a DVD.

I didn't realize that a dvd player could read a cd.  But I put in a cd and the player read that it was loading for a minute or so, then I got the message "this disk can't be read, please check the disk." Then I put in a dvd, which loaded for a minute or two, and I got the same message.  Just for the heck of it, I loaded another dvd, and after a minute or so it loaded and I got the navigation screen for the movie! I was quite surprised.  I selected to play the movie and it played!  I'll try to play some other dvds, but it seems that the player is behaving erratically.  The first dvd, following the cd, should have played, but it didn't.  Don't ask me why the second dvd played.

[rhb]

That was precisely how things started when my CD player failed.  At first I saw the problem just with CD-Rs.  When it did it with replicated disks I took it apart and cleaned it.

The flux can be *anywhere* and cause problems.