DVD repair question

**Budget DVD players are usually throwaway items. Normally, you will replace the entire laser and associated mechanism. Called 'the loader'. Unless you can find a donor mechanism from another cheap player, you will probably need to buy an OEM part. Naturally, you should check power supplies, as electros are a common failure mode.

Trevor Wilson

And, if it uses a rubber belt in the loading mechanism, a worn or broken belt could prevent it from going into the reading position.

My guess based on the history of this thing is that it is a mechanical problem from abuse.

--- sam | Sci.Electronics.Repair FAQ:

Repair | Main Table of Contents:

+Lasers | Sam's Laser FAQ: | Mirror Sites:

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

The most common things for the mech failing to come up under the disc correctly, are either misalignment of the mechanics, which usually means that the tray rack has slipped a tooth or two on its drive gear, which is usually related timing-wise to some kind of cam or anular gear that handles the deck lifting, or a slipping belt. Normally, if it is a timing issue, you will never get the deck to come up and lock, even if you try to help it. On the other hand, if the deck does come up when helped, then that is almost certainly a slack drive belt issue, assuming it uses one. When the motor has to crank the weight of the deck up, after the relatively easy task of sliding the tray back in, this brings the drive train under a lot of load, and that is exactly when the belt slips. With direct drive systems, I have had a similar problem caused by weak drive to the motor, but if that turns out to be the case here, you might struggle to locate the cause without schematics.

As an aside, your observation that the laser was not homing, is probably as a result of the loading sequence not completing. When the deck comes up into place, a switch is made, which tells the system control micro that it can start the disc evaluation procedure, the first part of which is to check that the laser is home, and if not, to drive it there.

Arfa

Thanks gentlemen for your replies, I shall attempt further inspection of the unit this week. To address one mans concern - I fully realize this may not be worth repairing - price wise - I mentioned that in my initial post. But it is the grandkids - so I thought I'd give it a whirl.

Thanks to all for your replies.

Lou

Knowing that children use it and the "littlest one" innocently causing some hardship on the mechanics my educated guess is that the mechanism is out of alignment. Get it in some bright light, put on your reading glasses and get familiar with how the mech works, drive belt or worm drive whatever is there. It's not that complicated if you are handy with a screwdriver.

Therein lies the problem - got to put er in some "bright" light. Trying to see what is going on in dim light - doesn't help! But - thought I'd tap the resources of those of you here for some additional ideas, being this is my first "internal" DVD repair.

Reading glasses? Hells fire - I wear glasses and see that stuff better with them "off". Even the bi-focals don't help. But whatever it takes, we'll give er another glance.

Thanks!

I don't know if you have a Maplin store near to you (you sound like you're UK), but if so, you might like to get yourself a white LED. I have a couple of these on the bench, one set in the end of an old Biro pen tool, and one just soldered and sleeved to a pair of stout-ish wires. I connect them externally to a set of NiCd batteries from an old cordless phone.

Those white suckers burn so bright, that I find them endlessly useful for looking inside mechs, just as you are trying to do now. The one on the Biro pen body, can be slid in where you can get straight in, and the one just on wires, can be manouvered around 'corners'. Don't forget to check the specs of any white LED that you get. They need a bit more voltage to drive them than reds or greens etc. Also make sure that you limit the current.

Arfa

No Bud, I'm in the U.S. and no Maplin Store here. But, if I look around, I might have some of the LEDs floating around. I'll have to look and see. Never thought of something like that. I use something else at current on my bench, but I want to give that a whirl to see if it can help. If nothing else, it might flood the immediate area - whereas my other method may not. Thanks!

Nothing beats lots of light and a comfortable, clutter free working environment free of interruptions. You should be able to remove the mech from the chassis. Do that so you can get a good 3 dimensional view of all the workings and manipulate it manually as if it was loading/unloading a disc.