CDM9 Tray Motor Overrun

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jonclancy

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Joined 2002
#1
Hi All,

I've had a look but can't find any archived info about the tray motor overrunning on a CDM9 unit when the tray is closing.

I have checked the limit switch and this seems to be working fine.

The problen occurred after I had re-capped the CDP with Pana FC and FKP caps (in the same values). 🙄

A look at the service manual didn't really help - the cap that is in the tray control part of the circuit is not one I changed.

Many thanks in advance for suggestions.

Jon 🙂
 
#2
Motor over run.. I assume you mean the motor keeps turning for 3 secs after the tray is closed and disc loaded in place?

My Theta Data obtained 2nd hand had a 10 ohm resistor fitted on the tray motor + motor terminal. Thought this was to slow the tray down and make it look more "deluxe".

I recently fitted a new tray gear to another Theta data and it had the motor over run problem... I cleaned the switch 10 times.... And reconditioned the belt, cleaned, sanded, cleaned gears etc...

There was no resistor on the motor on this one... Finally I put 10 ohms in series with the motor supply and the problem vanished.. Except now every 3 or 4th load it would not read toc.
Played with resistor values and got down to 3.3 ohm, no motor over run and reads toc every time a coconut.

I do not have a clue to the reason for the problem or why the resistor works. If anyone knows what the reason for the problem is I would be keen to know 2.

Jon, for now a resistor in series with the motor (fitted on the motor terminal) will probably solve your problem.

Keen to hear if anyone knows more....

regards
Guillaume
 
#3
Thanks Guillaume.......

.......... I'll give that a try.

I don't know it this makes any difference, but I mis-posted the problem - it happens when the tray is opening, not closing. It is for around 2-3 seconds, and I don't recall seeing any resistor when I had it in bits this weekend. I've now reassembled it, but it'll be open again soon to fit a Kwak Clock 7.

According to the scematic, as the limit switch is made, the +5V or -5V motor run voltage drops to zero and the tray stops. I can only think that a cap change I made is interfering with the motor run logic and it is thinking it needs to go for a few secs more. I replace Evox Rifa PFR with FKP and Rubycon with Pana FC - all like for like values.

Thanks for you suggestion. 😀

Cheers

Jon
 
#4
Update.... But no joy

Hi, I was hoping an update to bump this thread might just catch someone's eye out there.

I have finally got round to dismantling the player again and having a really close look at the schematic (with my limited electronics experience). The tray limit switch only seems to be employed while the tray is closing. I can short out the switch pins on the mainboard (simulating limit switch closing) and the tray stops dead. I am measuring +7V closing and -7V opening and the schema lists 5V.

Playing with the limit switch shorting has no effect on the -7V tray opening which seems to runn for a predetermined time (around 2 secs too long) and then the motor stops. I didn't get round to putting the resistor on the motor and am hoping that a fresh look at this might help. I am holding off putting back all the caps I replaced, but I have retained them all. I have a feeling that this problem will still be there when I have finished soldering and would prefer not to retrace my steps just yet!! 🙂

So, apart from the resistor on the motor (which I'll try anyway), does anyone have any other suggestions?

Most grateful for your thoughts.

Many thanks!

Jon

PS: I have a pdf service manual that I can email over if you'd like a look. The relevant part of the circuit is on sheet 4 "Alpha 5 CD Monoboard Circuit".
 
#5
Re: Update.... But no joy

jonclancy said:
Hi, I was hoping an update to bump this thread might just catch someone's eye out there.

I have finally got round to dismantling the player again and having a really close look at the schematic (with my limited electronics experience). The tray limit switch only seems to be employed while the tray is closing. I can short out the switch pins on the mainboard (simulating limit switch closing) and the tray stops dead. I am measuring +7V closing and -7V opening and the schema lists 5V.

Playing with the limit switch shorting has no effect on the -7V tray opening which seems to runn for a predetermined time (around 2 secs too long) and then the motor stops. I didn't get round to putting the resistor on the motor and am hoping that a fresh look at this might help. I am holding off putting back all the caps I replaced, but I have retained them all. I have a feeling that this problem will still be there when I have finished soldering and would prefer not to retrace my steps just yet!! 🙂

So, apart from the resistor on the motor (which I'll try anyway), does anyone have any other suggestions?

Most grateful for your thoughts.

Many thanks!

Jon

PS: I have a pdf service manual that I can email over if you'd like a look. The relevant part of the circuit is on sheet 4 "Alpha 5 CD Monoboard Circuit".
Click to expand...


Hi.

I take it that the problem is in an 'Alpha 5'?

Send me the pdf and I'll take a look.

Andy
 
#8
jonclancy said:
Hi All,

I've had a look but can't find any archived info about the tray motor overrunning on a CDM9 unit when the tray is closing.

I have checked the limit switch and this seems to be working fine.

The problen occurred after I had re-capped the CDP with Pana FC and FKP caps (in the same values). 🙄

A look at the service manual didn't really help - the cap that is in the tray control part of the circuit is not one I changed.

Many thanks in advance for suggestions.

Jon 🙂
Click to expand...


Hi Jon,

Thanks for the manual.


I have just checked my A6.

The motor voltage is almost the same as yours +-6.4v.
Looking at the schematic, I don't think that is anything to worry about. The driver chip is fed from the unregulated nominal +-10v.

On tray out, the voltage remains high for about 1 sec before returning to 0v.

On tray in, it returns to 0v immediately due to the switch.

The motor stops dead, by the way. No sign of run on after the tray is all the way out. [although as said there is voltage for a second after it stops]

If yours keeps running, try cleaning [degreasing ] the belt and pulleys, it may be greasy.

Alternatively, try the resistor.


Andy
 
#9
Hi Andy,

Thanks for following up my measuments on your own unit. It is feasible that the belt could be greasy. I changed the geared wheel on this unit and used a silicone grease. Quite possible that it went where it shouldn't have.

If that doesn't do it, I'll try the resistor to slow the motor down. That way the time and tray position might just coincide somewhere near the end of the tray travel.

Again, many thanks for your assistance here - I appreciate it.

Jon
 
#10
Success!!

Hi Andy and Guillaume

SUCCESS! I tried a variety of resistor values. Eventually settling on 22R5. The motor runs smoothly and doesn't overrun.

Thanks very much indeed for your help Gents - I'd be stuck without it. The forum doesn't show the large amount of PM traffic between us in discussing this problem and I appreciate your time.

Hopefully, anyone else with this particular problem can find a quick and easy solution in this thread.

All the best

Jon

Can't work out why it overran in the first place, though..... 😉
 
#12
brianuk said:
Hi Jon,

I have an A5

(as well as as an upgraded Marantz 😉 wonder who from)

Anyway the motor on my draw keeps running for about 2 seconds after fully opening - can this resistor change fix that?
Which resistor is it?

Thanks.
Click to expand...

Hi.

It is an additional resistor not an existing one.

Unsolder one of the wires going to the motor and solder the resistor to the motor and the wire.

Andy
 
#13
Hi Brian,

You won't need to remove the transport to get to the pulley and motor (at least on the A6) but you will need to remove the main PCB from the chassis as a whole. Open the lid, remove front and back panels, remove the DAC board, remove 4 x screws around the trafo and 1 x hidden screw at the rear of the transport. You can reveal this by opening the tray half way. The main pcb will now lift out of the chassis. Flip it over and the motor is fully exposed. I tried a few resistor values. 10R made little difference. 330R and 75R was too much and motor didn't run. So around 20R seemed to do the trick.

HTH

Jon
 
#14
CDM Tray Motor Overrun

I'm new to Arcam CD players having bought a (well) used A5 just before Christmas. I'd read threads here so although I couldn't audition the player I at least checked the tray mech before I bought it. £25 if you were wondering...

The tray always overran when it closed and even draws in slightly when the unit's powered up. I like the idea of using the solution described but it's 30 years since I've held a soldering iron and I'm nervous... (wuss)

However, that's not my main problem - the loading gear has now gone (quelle surprise) and in my attempts to make the drawer open, I'm pretty sure I've broken the belt too. I've not had the lid off yet but I've ordered the gear/"safe" grease combo and hope to do the job soon. Got the schematic and service manual too.

If I'm right and the belt's trashed, has anyone found a decent replacement for this?

I know this player is anything up to 13 years old but I'd hoped to get more than a month's use from the A5 before I got a problem. Would I take it back to the shop and ask for a refund? No, because it sounds ace and I love it.

Chris
 
#15
I doubt the belt is bust... Probably find all the gear teeth have now snapped off, once it starts it gets worse rapidly.

I normally just "nourish" the belt with some silicone based spray furniture polish (a belt drive turntable trick) that gets the rubber nice and supple again. With a sample or by measuring the diameter (that is how belts are sold, not circumference/length) of the belt you could probably get something from the usual suspects like Grandata/Donberg etc etc.
 
#16
CDM Tray Motor Overrun

tubenut said:
I doubt the belt is bust... Probably find all the gear teeth have now snapped off, once it starts it gets worse rapidly.
Click to expand...

Guillaume, you were spot on. As soon as I lifted the player from its shelf and moved it I could hear bits rattling around inslide. Sure enough, 10 teeth fell out and the belt was fine.

I was a bit confused because there didn't seem to be grease on the gear teeth or on the tray "rack" so it looks like these gears rot from the inside - is that right?

As a result of what I found I have only put the bare minimum of grease onto the tray "rack" when reassembling. I hope it will be enough.

Feeling brave now - might try fitting a resistor as mentioned because the wire from the main PCB to the motor is very easily accessible.

Thanks for your advice.
 
#17
Hi Chris,

Glad you got the diagnosis now - it's an easy repair to do.

The geared wheel and tray teeth would have been greased when new by the factory. Either someone has cleaned it off, or the grease has dried out or been absorbed (or whatever). The original gears just disintegrate and if your machine had not been factory lubed, then it must be that grade of material breaking down with age. Of course, common theory is that the original grease was aggressive. Whether this is right or wrong, I'd mitigate that with the use of a non-agressive silicone grease on reassemble. Maplin do a Servisol product, or, if you are really stuck, I can send you a blob in a bag in the post. PM me if you need any pointers to do the job - I've done it on my (from new) A6 CD and on my S/H D250 transport.

Cheers

Jon
 
#18
Jon

Many thanks for the offer of the grease. I bought the gear from a guy on eBay who seems to be pretty serious - I've sent him a few mails back and forth - and he supplies a syringe of clear grease with the new gear.

I cleaned as much of the old grease from everywhere as I could and reapplied the new grease - though I maybe should have gone a bit heavier on the "rack" itself. With luck I can partially correct that by opening the tray, switching the player off and carefully applying some on the teeth with a cotton bud.

I wish I'd read the A5 service manual more slowly - I managed to take out 5 of the locating pins from the back of the facia when I removed the lid. Oops! :xeye:
 
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