Hello everyone! I've been a member on this site for quite a while now, but never posted in the forum before. Maybe i will write something in the new member section later.

And to make a long story short:
A couple of years ago i brought this player (along with some discs) used from a auction site, and it was then damaged during the shipping. (It wasn't packaged properly) And recently i was thinking about however it was possible to repair it, when it seemed to be a somewhat easy problem

But now let's get to the core of this thing.

This D504 that has some sort of mechanical trouble loading/starting the disc, error message U1 appears. When you put a disc into the player, the big platform (or whatever you might call it) that can move slightly up and down at an angle won't go all the way, but when i carefully lift's it up with my fingers when the motor is struggling with it, it then moves into place and the disc starts running. However the player is then during playback quite noisy, but the noise then fades away and disappears around 5-10 min into the feature. But it then comes back when it starts over from the beginning of the other side.

Does anybody here know what this problem might be?

Noise during playback is normal.
The disc spins at high rounds per minute and gets slower after 5 - 10 minutes. This is the same for both sides. Of course, noisy playback could also be warped discs.
The only thing I can think of is the motor belt or the famous M-holder which has a weakness and has been superseded by a better part.

Thanks! Then i know that this type of noise is normal. After all, this is my very first (somewhat working) LD player


"motor belt or the famous M-holder"

Ok, so how do i disassemble this thing further in a safe and correct way? How does these parts look like? And exactly where are they located? Is there a disassembly guide/pictures somewhere?

I have been walking in your foot steps some years ago. In the beginning there are so many questions that arise.
I cannot guarantee motor belt or the m-holder, but this m-holder (a plastic part holds the laser optics, pickup and motor in place) is known to break in pieces and this results into several problems.
The belt is a generic replacement part which you can find at eBay for a low price, part SCQ4.0.
First of all, unscrew the 4 screws at the sides and then unscrew 6 - 7 gold screws at the back. Then you can remove the chassis cover. Power on the player and open the tray (if possible). When the tray is fully opened, there should be two black plastic tabs or hinges at the end of the tray. When you gently push both of these inwards, you can slowly pull the tray backwards and away from the player.
With the tray removed, you should have better access and working space. I can't come up with any disassembly guide or pictures for this model, sorry. Hopefully someone else can contribute.

Ok, but now sadly the problem has gotten worse! The tray won't open and it displays the E3 error message. So how am i supposed to get to the two black plastic tabs if i cannot get the tray to open!

If the tabs that hold the gears in the M-holder are completely broke then it can cause pickup movement issues and the pickup cannot go to the rest position to allow the tray to open. You need to look inside and see where the pickup is and move it a little and see if that helps it find the rest position.

I've now tried to carefully move the pickup into the rest position like krbahr said, and the tray did then open again like normal, great! But now i cannot seem to find those "two black plastic tabs or hinges" that laserpaal mentioned earlier. Are they visible in this picture? Could somebody please point them out to me, sense i am a real newbie when it comes to these players.

They are located in the picture. The release tabs are the long black ones you can see near the steel bar on both sides. Gently push them towards the center between the steel bars while you simultaneously pull the tray away. The motor belt should now become visible. Good luck!

So, it was that easy! I have just taken the tray out now and the belt looks fine, not broken, sticky or anything. But could it be that the original tension has been lost? After all it seemed to be just a little to loose (not very much) Or could it after all be this famous m-holder? If so, where do i go from here?

Maybe it would be a good idea to first get a new belt to test it with before trying anything else...

If you have to lift the assembly up then it needs a new belt. If you have to move the laser into place then the m-holder needs to be replaced.

This loading belt should work with the D504.
http://www.ebay.co.uk/itm/Pioneer-Rieme ... 5d34785d2b
As for the M holder you can get it from here.
http://www.donberg.ie/catalogue/audio_s ... c_199.html

In many cases, the belt is the cure. Better start off with it from there.
Doesn't hurt if you lubricate dry spots where there is movement (plastic and metal parts). Sticky lubricate residue or lack of lubrication can also make problems.
As of assembling the disc tray. The plastic tabs should be equally lined up before you gently push the disc tray into place. You should hear a click and the tabs will lock the tray in place. Power on the player and the tray will be automatically closed - no adjustment needed.

I have now ordered that new belt to begin with. And while waiting for that to arrive i will try laserpaal's tip to lubricate some of the moving parts a little. Would silicone spray be a good lubricator to use? Or is there something else you would recommend?

I will come back later to report as soon as the new belt arrives.

I don't know if silicone spray would be efficient. I bought this from ebay: http://www.ebay.co.uk/itm/280939083691 - made my player much smoother and more quiet in operation. Over all, you should choose a lubricant compatible with plastics and metal.

I just saw that on the back of the silicone can it actually says that it works on both metal and plastic. So i guess it will do just fine. I also think that i have been using it successfully before on some electronic gears, and cannot remember it to have caused any problems.

Anyway thanks for the link!
Maybe i will get some if the silicone fails to work.

Today i got the new belt, and i just had it installed. So now the assembly doesn't need help anymore to get into the starting position! So that is one problem solved!

However when you turn the player on, the pickup motor spins like crazy, but it doesn't always move the pickup around as it supposed to. I even had to give it a gentle nudge in order to get the tray out again. And one time the error message E4 turned up on the display.

So does this mean that it also is the M-holder that is broken? And if it is, how do you further disassemble the player to get to it?

And yes, i have now also used the silicone for a slight lubrication, and i really think that i could see a big overall improvement in the mechanical performance.

I published a Swedish guide on Segalovers some time ago on how to replace the M holder. Will see if I can get it for you.

Glad to hear that one problem is solved. According to this site, your player may have a problem with the slider and while it tries to clamp the disc before the spindle motor engages. Since the player was damaged during shipping, those parts could be out of alignment.
From my perspective, I can only guess what the problem may be, but swapping out the existing m-holder won't cause any harm. Hope nissling can provide the link.

Have you found it yet?

Tried to locate the page for you, but it seems like it has been done unavailable to guests so a created account is needed.