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Old 25th May 2020, 9:46 am   #1
Edward Huggins
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Default HELP: CD does not Start

I think this is my second ever Help! Posting.

I've never needed to do any repair work on my Rocksan, Marantz and NAD CD players as they have worked faultlessly. So far anyway....

However, my Wharfedale WPC-398 Portable is another matter.

It will read and scan the disc, the motor runs, it displays the total playing time and number of tracks, I can select each track - but it will not play.

I've used a proper CD (brush type) lens cleaner and also used iso-p on a cotton bud. I can see no visible trim-pot/s. I'm reluctant to dismantle this too much as it certainly does not look too service-intervention friendly.

Highly Esteemed Members, any ideas?
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Old 25th May 2020, 12:01 pm   #2
Edward Huggins
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Default Re: HELP: CD does not Start

Sorry to all - ROKSAN!
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Old 25th May 2020, 12:29 pm   #3
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Default Re: HELP: CD does not Start

This appears to be a boombox rather than a pocket portable.

The first thing to check is the power supply, either the built in mains one or the batteries. These players pull a lot of current on occasions, and behave oddly when the voltage dips.
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Old 25th May 2020, 12:57 pm   #4
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Default Re: HELP: CD does not Start

I second the caps in these budget range players
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Old 25th May 2020, 7:06 pm   #5
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Default Re: HELP: CD does not Start

You don't actually say if the disc spins when you select play. It obviously spins up to show track number and time etc which also means it's finding focus so when you press play does the disc continue spinning (I presume it does or some sort of error would show) and presumably when you selct track numbers towards the outer edge, the disc slows down? If it does all that it implies that the servos and everything are working fine so it could be a muting problem (I've had muting transistors go short) or a problem with the DAC. As suggested, check supply voltages and decoupling electrolytics.
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Old 25th May 2020, 7:50 pm   #6
Edward Huggins
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Default Re: HELP: CD does not Start

Thanks for these prompt responses. I had rather assumed it might be some sort of logic control failure to the motor. The small Boards inside are very densely packed. I'll try to locate the relevant electrolytics and take voltage readings. I am not getting an ERROR display. I might also take out the mains lead and just try it on Batteries.
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Old 26th May 2020, 9:38 am   #7
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Default Re: HELP: CD does not Start

As sideband said, the laser and control circuits relating to that all work. So the control processor is also OK - or you would not get anything regarding track information etc.

Again agreeing that it could be a mute transistor shorting, or a DAC problem.

The difficulty is that it is probably all surface mount parts, so difficult to problem diagnose and fix.

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Old 26th May 2020, 11:21 am   #8
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Default Re: HELP: CD does not Start

Edward, are any of the buttons (play, stop, pause etc.) stuck down, or do they all click down and spring up nicely?
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Old 26th May 2020, 12:26 pm   #9
Edward Huggins
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Default Re: HELP: CD does not Start

No, they are all fully functional and positive in action. And spray cleaned. I'm a bit daunted by the dense packaging on the Boards and those miniscule discrete components.......now, where's me x12 magnifier? Thanks to all so far.
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Old 28th May 2020, 9:56 am   #10
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Default Re: HELP: CD does not Start

If the toc has been read, there's a good chance that the servo and decoder are basically OK. One trick is to request the last track on the disc, then press play. This will force the sled servo to move the pu. You should be able to hear the sled motor run for a second or so. Conversely, manually put the sled at the edge of the disc, switch on and the sled should hit the in switch, then TOC is read.

On these type of units, the electronics don't normally fail, it's nearly always, spindle motors, sled motors, split plastic gears, dirt in the guides, or of course the PU itself.

Very often the little motors will 'carbon-up' the commutators, if the motor is disconnected from the servo, the old trick of putting 6v across the terminals and letting it free run both directions, will act as a temporary clean-up.

From what you written, I'd be surprised if this was a surface mount/servo electronics fault. But I could be wrong!!!

SJM
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Old 28th May 2020, 10:40 am   #11
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Default Re: HELP: CD does not Start

Have you checked that the play button is actually working? Even if it clicks, it may not be making contact or might have a cracked solder joint. Try shorting its pins with a bit of wire or paperclip.

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Old 29th May 2020, 11:06 am   #12
Edward Huggins
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Default Re: HELP: CD does not Start

Quote:
Originally Posted by samjmann View Post
If the toc has been read, there's a good chance that the servo and decoder are basically OK. One trick is to request the last track on the disc, then press play. This will force the sled servo to move the pu. You should be able to hear the sled motor run for a second or so. Conversely, manually put the sled at the edge of the disc, switch on and the sled should hit the in switch, then TOC is read.

SJM
Thanks for this. Yes, the TOC is being read everytime. All the push buttons are positive in action.
Are you suggesting that I should MANUALLY slide the lens to the end of its slider track (where it would read the last track) put on the CD, close the lid and press play? It's a top opening mechanism.
I am double checking as I've never needed perform this procedure before.
BTW, this (Chinese) "Wharfedale" badged unit has a far better build quality than one might expect.
Many thanks for all the suggestions to date.
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Old 29th May 2020, 12:03 pm   #13
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Default Re: HELP: CD does not Start

If you manually move the CD laser assy to the last track position whilst off and then apply power, the laser assy will simply return to the beginning and re-read the TOC, because it won't know where it was. If it comes up with error, then the motor drive that moves the laser assy laterally has a problem. Most systems don't store track info after power removal. What you need to establish is firstly does the disc spin when play is selected and secondly with the chassis out does the laser assy move laterally when a track number of 3 or more is selected. If the laser assy is moving laterally and the disc is spinning, I would blame either the motor that spins the disc or the laser assy. If the laser assy is not moving laterally then look at the motor that drives it along, usually on a worm drive of some sort, it might even be a slipping drive belt.
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Old 29th May 2020, 12:20 pm   #14
Edward Huggins
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Default Re: HELP: CD does not Start

Many thanks for this prompt and detailed reply. The disc spins when I close the lid and reads the TOC. If I raise the lid quicky, I can see the disc coming to a rest. Now, I cannot hand-move the laser assembly along its track at all. In fact I never thought one could do this as I assumed that its linkages would always be engaged......
Obviously I only applied minimum lateral force. Does this suggest a fault with the Sled Motor or its Cogs/Linkages?
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Old 29th May 2020, 12:50 pm   #15
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Default Re: HELP: CD does not Start

No that does not suggest a problem, you have to bear in mind that the laser assy is driven by a variable slow motion drive system, so the part that engages with the laser assy will be stiff to move manually. You mention that the TOC is being read but not if the disc spins when in play mode, they are 2 different stages. It is possible for a laser assy to read TOC but not play the disc, this is why you need to check my points above. The laser assy not only has to to be able to achieve focus to read the TOC (vertical movement) but also has to be able to move it's lens slightly from side to side, in order to follow the tracks on the spinning disc. Once the lens starts to loose the track with it's side to side movement, a signal to the motor that does lateral movement is sent. This moves the whole laser assy to a new position where it can then carry on reading the track. This action happens all the way to the end of track or disc, depending on what was selected at start of play mode.
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Old 30th May 2020, 8:56 am   #16
Edward Huggins
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Default Re: HELP: CD does not Start

Noting content in Post #10. I selected the last track - and it actually played! But on trying to start from the first track again, it just failed to play. This at least suggests the sled motor runs and, quite obviously, the disc spins in Play mode. Maybe there's some elusive intermittency somewhere?
I feel I cannot keep prevailing on your good support for now, so it'll will have to go in the roundtoit pile. My thanks to all. At least it's PLL Tuner still works superbly well.
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Old 30th May 2020, 12:21 pm   #17
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Default Re: HELP: CD does not Start

No problem Edward, glad I could offer some advice.
If it will select a track, then play EVERY time, then there must be some odd control keyboard type fault. But if it's still fussy about playing that way, then you're looking at sled/gears/motors etc.

I once did have a very expensive Danish CD player to look at with much the same problem as you have. In the end it was nothing more than a split in the sled gear, but most of the time it would play normally. Despite the £800.00+ price the sled was a standard Sony type mech

Best regards, SJM.
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Old 30th May 2020, 1:08 pm   #18
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Default Re: HELP: CD does not Start

Are the bars that the laser pickup moves laterally on clean and not stuck up with old grease?
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Old 31st May 2020, 6:06 am   #19
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Default Re: HELP: CD does not Start

Just a thought, does it happen on all CD's ? perhaps the one in question is damaged at track 1.
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Old 31st May 2020, 11:58 am   #20
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Default Re: HELP: CD does not Start

It sounds like it may be the Spindle Motor.
Strangely, even with a failing Spindle Motor the TOC can sometimes be read but ask the Player to actually play.....no thanks!!!

It has to spin at it fastest at the centre of the Disc where the TOC and 1st Track are located on the Disc and slows down as it plays through.
The fact that you say it plays the last Track indicates to me that it may be the Spindle Motor not quite up to the joib of spinning the Disc at the correct speed constantly for actual Playback.
As I say, it seems strange that it reads the TOC but I have come across (and been fooled by) this symptom before.

Try checking the Supplies to the Motor Drive circuit/s first, making sure they're getting a good and clean DC Supply. There will always be a slight ripple observable here, they use the bare minimum of reservoir Caps in these things.
But I suspect the Motor itself to be honest.

James.
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