CD player with distortion. laser?

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grahamfocal

grahamfocal

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Hi I have a Orelle CD100 Cd player that I bought for a steal, with a fault. The unit has alot of distortion coming through the speakers, alot!!
The guy at the shop said that its likely to be the Laser assembly.

when inserting a disc it reads the TOC fine, but rather hideous distortion when played.
The eye has been cleaned and there is some slight improvement.

Can anyone tell me for sure if its the laser (its a CDM4 assembly) or if it sounds like something else.

Thanks :spin:
 
Mooly

Mooly

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Without hearing hard to say. Poor signal off the disc whatever the cause can cause distortion... if that's the right word... it's more of a rapid interuption in the music.

So yes it is possible to be the laser, but it's not distortion as most recognise the word.
If you have a working CD player and very gently try and "slow" the disc with a finger the same kind of "distortion" appears.

So without examination it's guesswork... you really need to check the integrity of the RF signal from the pickup assembly with regard to amplitude and jitter and take it from there. Does the distortion alter if you hold the player at different angles/upside down ?
 
grahamfocal

grahamfocal

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literally got the cd player home tonight, I will try those things that you suggested, I took a punt on it being the laser assembly and have one on order, as it was very cheap (i know the CDM4s are hard to get hold of) at £45 from Germany, and new.

I will try slowing the disc down and see if it makes the same distortion.

The only thing that I do know, is that the laser lens was cleaned and it improved, but not by much.
Just wondered if there were any definate 'ah that will be the......' answers.

:)
 
grahamfocal

grahamfocal

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Mooly said:
Without hearing hard to say. Poor signal off the disc whatever the cause can cause distortion... if that's the right word... it's more of a rapid interuption in the music.

So yes it is possible to be the laser, but it's not distortion as most recognise the word.
If you have a working CD player and very gently try and "slow" the disc with a finger the same kind of "distortion" appears.

So without examination it's guesswork... you really need to check the integrity of the RF signal from the pickup assembly with regard to amplitude and jitter and take it from there. Does the distortion alter if you hold the player at different angles/upside down ?
Click to expand...

So basically it could be the fact that the cd is running too slow, as a possibility, causing the gap in the reading of the disc?
 
poynton

poynton

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As the disk plays and presumably changes tracks, pauses etc, I would say the fault is unlikely to be in the laser or control section.

If the distortion is on both channels, I would tend to look at those areas common to both i.e. power supply, probably to the output or dac "analogue" sections.
I would guess PSU caps or a regulator.


Andy


.
 
Mooly

Mooly

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grahamfocal said:
So basically it could be the fact that the cd is running too slow, as a possibility, causing the gap in the reading of the disc?
Click to expand...

Not exactly... what I mean is trying to slow a disc on a good player can cause a form of distortion similar to how you describe. It's a fine line, to much friction and the servo will drop out of lock and throw a fit.
Now that "distortion" sounds the same as a laser pickup with a marginal or poor quality output... it can cope with track search and reading the TOC but not provide continuos high quality signal that's above the drop out threshold.

I can see where Andys coming from, caps are favourite failure items on many Philips based players.

It could be anything :) I'll still stick with laser problem on this, based on your description. Cleaning a laser that is providing a good signal shouldn't change the symptom... and you say it does.
 
grahamfocal

grahamfocal

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Thanks guys, that is a real help indeed, I am no genius with electronics, but know the basics, and like to try to fix things if I can. I replaced a few laser assemblies. Hopefully the laser will arrive in the post over the next few days so will let you know the outcome.

Thanks again
 
grahamfocal

grahamfocal

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Darn it, its not the laser, so time to try other options.

My Dad, an electronics whizz also, thinks as its common to both, its probably the power supply end, dont have a scope so is there a simpler way of checking, other than buy all the caps, although this wont be expensive I suppose.
 
Mooly

Mooly

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Looks like Andy could be on to a winner then :)

Caps are favourite failure items for sure.

Not sure if it applies to this model but there is a 33uf cap that causes problems according to many on here on the servo PCB ?

Edit... is the fault 100% unchanged ?
 
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Mooly

Mooly

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That's a pity... it seemed hopeful.

I'm not sure what the servo is based on in your player. Philips had so many variations on the go, even in the same models sometimes. The cap mentioned I think lives on the board under the RAFOC (laser)... I'm sure someone will correct me on that if not.
Changing all the caps is OK if you know it's going to work... but is it ?
 
grahamfocal

grahamfocal

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I did spot a small cap under the mech, will test it tomorrow.
Still all good fun and I am learning by the day, so its good, I like to know how to fix, as opposed to chucking a perfectly good CD player for the sake of (hopefully) a component worth pence.
Thanks mooly I am learing a lot from you guys, hopefully I will be able to help someone in the future once I find the problem.

One thing is, I will not give up.
 
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