CDJ-900, the field manual

The five things on the CDJ-900 that change what happens next, if you are reading this in the booth. All five are explained in full further down this page.

Short answer. Format first, port second. The CDJ-900 reads FAT, FAT32, HFS+ and a multi-partition drive may not be seen at all.

Why this happens. A drive that mounts on your laptop proves nothing here. exFAT looks completely healthy on a computer and is documented as unsupported by this deck. A Mac GPT partition map is the other repeat offender, though AlphaTheta name a GPT refusal for the CDJ-3000 and the XDJ-AN and not for this deck, so MBR here is our recommendation rather than their published requirement.

Take the drive out properly before you try anything. The instinct is to yank it and try another deck, and the manual is blunt about what that costs: "Removing a USB device without following this procedure could erase the set’s management data and make it impossible to read the USB device." The procedure is one line: "Press [USB STOP] for over 2 second."

Fix it now. Then try another drive, then another player, which separates the drive from the deck in seconds. On a laptop, check the format and the partition map. Recover the music before reformatting anything, never after.

Two causes that are not the format. "USB hubs cannot be used." And firmware 4.11 exists precisely because a particular USB 3.0 device did not work properly on this deck, so on a unit that has never been updated the stick may not be the problem.

And if the deck looks dead rather than fussy. Check power management before you check the mains, because the deck ships with power management on, and stands by after four hours with nothing loaded, no PRO DJ LINK connection and no computer on the rear USB port. The manual: "The CDJ-900 is shipped with the power management function turned on." A deck idle since a long soundcheck reads as broken and is not.

Avoid it next time. Two identical FAT32 and MBR drives, exported fresh for the gig.

Related: The player will not read the USB Get the files off first

Short answer. The CDJ-900 shows POINT FULL, not the CUE/LOOPPOINT FULL the later NXS decks show, and the ceiling behind it is 100 cue or loop points per disc and 10 per track on a USB drive. Because this deck has no SD slot, there are no CARD messages at all: USB FULL is the only one, and it appears both when the drive has no free space and when the drive is write-protected, so read it as the drive refusing to be written to rather than as a capacity figure. Points that were saved can also stop appearing if the drive was pulled without being stopped properly, or if the power was turned off.

Why this matters. Both messages look like a broken drive from where you are standing, and both are fixable in seconds once you know which word means what. POINT FULL is the one people misread, because it sounds like the drive is full when it is the point count that is.

Fix it now. Read the word on the display before you touch anything. POINT FULL means delete some points, not swap the drive. USB FULL means either the write-protect tab or free space, so check both before blaming the deck.

Avoid it next time. Stop the drive properly before you pull it, every time, and let the deck finish writing before the power goes off.

Related: The CDJ-900 will not read your USB A disc will not come out

Short answer. The CDJ-900 gives you one way out and it is the pin. Unlike the CDJ-2000 of the same generation, this deck has no eject lock switch, so the manual's entry for a disc that will not eject has no check column at all: if DISC EJECT does not work, the pin is the answer. The hole is on the front panel and it is not something you would find by looking.

The pin, done safely. The pin is not a shortcut and the manual is specific about why. Turn the power off first and wait at least one minute before you use it, because a disc that comes out while it is still spinning can hit your fingers, and a clamp turning unevenly can scratch the disc on the way. Use the pin that came with the unit and nothing else. It is mounted on the bottom panel, and when it goes all the way in the disc moves 5 mm to 10 mm out of the slot, far enough to grip and pull.

The other way round. And there is an undo for the opposite mistake. If DISC EJECT gets pressed by accident on a CDJ-900, pressing PLAY/PAUSE immediately restores the deck to exactly the state it was in the instant before, which is a save worth knowing before you need it rather than after.

Avoid it next time. Take your disc out before the changeover rather than after, and if you play CDs on old decks, find the hole and the pin on one of them while nothing is at stake.

Related: Three things it does that are not faults Two error codes worth recognising

Short answer. The CDJ-900 ships with its power management turned on, and a deck nobody has touched for over four hours with no disc loaded, no USB drive connected, no PRO DJ LINK connection and no computer on the rear USB port puts itself into standby. A dark deck that was working earlier is usually this rather than a fault, and operating any control cancels it. The setting is AUTO STANDBY in the UTILITY menu, and OFF is what a permanent install wants.

Why this matters. This is one of the most common false alarms on old decks and it costs a soundcheck. A player that went to sleep during load-in is indistinguishable from a player with a dead power supply until you touch it.

Fix it now. Move the jog wheel or press a button before anything else. If it comes back, that was standby. If it does not, then look at the power.

Avoid it next time. In a fixed install, set AUTO STANDBY to OFF once and it stops happening.

Related: A UTILITY setting keeps reverting Start Emergency Mode

Short answer. When PRO DJ LINK will not come up on a CDJ-900, the manual gives four checks and none of them is the player itself. Player numbers first: set PLAYER No. to AUTO, or to a number nothing else on the network is using. Then whether the LAN cable is properly seated in the LINK terminal. Then whether the switching hub actually has power. Then whether something unnecessary is plugged into that hub, because the manual names an extra device on the switch as a cause on its own.

Why this matters. A booth network that half works burns time nobody has, and the instinct is to blame the deck that is showing nothing. Three of the four causes are outside the player entirely.

Fix it now. PLAYER No. to AUTO first, because a number collision is the quiet one. Then reseat the cable at both ends. Then look at the hub, both its power and what else is plugged into it.

One more thing on this deck. The manual warns against pulling the LAN cable while music or information is being shared, so stop the sharing or unplug at the hub instead.

Related: PRO DJ LINK, with the cable in the box Firmware, and what this site will not claim

Short answer. The CDJ-900 keeps a setting only if you give it time to write. The manual's own instruction is to wait at least 10 seconds after changing settings before turning the power off, and a change made in the last seconds before somebody hits the switch is the one that will not be there next time. This is the answer for a deck that keeps reverting a UTILITY setting somebody swears they changed.

Why this matters. It looks like failing memory on an old deck, which is an expensive conclusion. It is a timing rule that almost nobody reads.

Fix it now. Change the setting, back out of UTILITY, and leave the deck alone for a slow count of fifteen before the power goes anywhere near off.

Related: The deck is dark and looks dead Before you rely on one in a booth

What is in the record. Eleven dated versions, from December 2009 to 4.32 in April 2014, and nothing since. The ones that fixed something a DJ would notice are below.

4.11, July 2012

A particular USB 3.0 device did not work properly, and static noise was occasionally generated with a particular MP3 file. If a deck refuses a modern stick, this is the entry to check the version against.

4.10, January 2012

Sound quality and stability when playing with MASTER TEMPO on.

4.05, September 2011

The beat grid could sit about 50 ms out with MASTER TEMPO on, a one-frame loop artefact, and click noise on a specific MP3.

4.00, March 2011

Playback stopped if a loop was created across a whole CD, and a specific CD produced noise in loop playback.

3.20, November 2010

A rare fault accessing media devices, and an error after long play times that caused audio interruptions.

Do this. Note the version on any CDJ-900 you are handed, and treat a very old one as a unit that has not been serviced rather than one that never needed it.

Related: Every model, by firmware version The pre-gig checklist

The BPM. A BPM on the CDJ-900 that does not match the number printed on the disc, or the number showing on the Pioneer DJ mixer beside it, is not a fault. The manual states plainly that the measuring methods differ. Trust the deck you are beat matching on and stop reconciling the two.

After a static hit. Static electricity can put a CDJ-900 into a state that looks like hardware failure. The manual's own recovery is to turn the power off, wait for the disc to come to a complete stop, then turn the power back on. The waiting is the part people skip.

And the discs it refuses. The CDJ-900 refuses two kinds of disc by design and neither refusal is a fault. Non-finalised CD-R and CD-RW will not play, and this deck's list stops there because it is a CD player and not a DVD one, which is a smaller list than the CDJ-2000's. Nor will anything that is not a standard 12 cm round disc, and the manual is blunt about that one: forcing a shaped disc leads to damage or accidents rather than to a polite refusal.

Related: Two error codes worth recognising A deck out of a cold van will not play

Short answer. Two CDJ-900 error codes point at things the other codes do not. E-9101, MECHANICAL TIME OUT, means the disc mechanism did not finish loading or ejecting inside the time it is given, which is a mechanism problem rather than a file problem. E-8306, NO FILE, means a track is still listed in a library or a playlist but has been deleted from the USB drive, so the fix is on the computer that prepared the drive and not in the booth.

Why this matters. Both get filed under "the deck is broken" and only one of them is about the deck. E-8306 is a preparation fault that travels on the drive, so it follows you to the next player and the next venue until the library is fixed.

Fix it now. For E-9101, power the deck down and up, and if it repeats on more than one disc it is a service job. For E-8306, re-export the library from the computer that made the drive so the playlist and the files agree again.

The E-8302 family. E-8301, E-8302 and E-8303 are all PLAYER ERROR here, and this player’s own manual gives the causes as a disc or music files that cannot be played normally, with a cracked or dirty disc named separately.

Related: Error E-8302 Firmware, and what this site will not claim

Short answer. No. The CDJ-900 Operating Instructions list FAT, FAT32, HFS+ and the word exFAT appears nowhere in the document.

Why this happens. This is a 2009 deck and exFAT support came to AlphaTheta players much later. Most drives over 32GB arrive exFAT from the factory, so a new stick fails before you have put any music on it.

Fix it now. Format FAT32 with MBR. Never format a drive that still holds your only copy of anything: recover the music first.

Avoid it next time. The CDJ-2000 of the same generation answers identically, so one drive prepared correctly covers a whole 2009 booth.

Related: exFAT or FAT32 CDJ-2000

Short answer. The CDJ-900 manual says: "If multiple partitions are set for the USB device, the device may not be recognized."

Why that wording matters. Later units read the first partition and ignore the rest. This generation says the drive may not be recognised at all, so the symptom is a dead-looking stick rather than a partly readable one.

The other limits. Files deeper than 8 folder levels cannot be played, and beyond 10,000 folders or files inside a single folder the rest are not displayed.

Avoid it next time. One partition, FAT32, MBR, shallow folders.

Related: The player will not read the USB Preparing a USB for club players

Short answer. The CDJ-900 ships with a LAN cable as a listed accessory and joins a real PRO DJ LINK network over Ethernet, sharing rekordbox data with other players and a compatible mixer.

Why it is worth saying. Several much newer all-in-one units use the phrase PRO DJ LINK for a cable to one computer and state in their own manuals that they cannot connect to a PRO DJ LINK player. A 2009 CDJ-900 does the thing those units cannot.

Fix it now. If the network drops mid-set, do not pull the cable: the manual warns specifically against disconnecting it while music or information is being shared.

Avoid it next time. Carry a spare LAN cable. It is the cheapest item in a booth and the one nobody packs.

Related: CDJ-2000 XDJ-RX

Short answer. This page is the CDJ-900 released in 2009. The CDJ-900NXS is a 2013 deck and has its own page here.

Why it matters. Three letters separate the names and both are still working in clubs. Reading the wrong page means reading the wrong compatibility answer for the machine in front of you.

How to tell. The NXS badge is printed on the front panel beside the model name. No badge, this page.

Common mistakes. Assuming the two share firmware, display behaviour or media support. They do not.

Related: CDJ-900NXS CDJ-2000

Short answer. A CDJ-900 that just sits there when a disc is loaded is usually auto cue doing its job. Auto cue parks the deck at the first sound rather than at the physical start, so nothing happens until you press play. Hold AUTO CUE for at least one second to turn it off. The same function explains a track search that takes an age on a disc with long silences between tracks, and the manual adds a detail worth knowing: if the search cannot finish within 10 seconds, the deck sets the cue point at the beginning of the track and stops looking.

Why it is there. On a prepared library you want it, because it strips whatever silence the mastering left at the front. On a disc somebody handed you thirty seconds ago it is the thing that makes the deck look stuck, and that is when people start pressing buttons.

The detail most people never learn. That 10 second ceiling is the part worth carrying. A very quiet intro can run the search out of time, and the point the deck settles on is not the one you would have chosen. If a cue lands somewhere odd on a quiet track, this is why.

Related: Cue points will not save Before you rely on one in a booth

One drive covers a 2009 booth. The CDJ-900 and the CDJ-2000 give the same file-system answer, so FAT32 with MBR and a single partition works across both.

Photograph HISTORY before you leave. Past 999 tracks the deck deletes its oldest entries, so this is not an archive and on a busy house deck it may already be missing the start of your set.

Pack a LAN cable. One comes in the box, which means the one in the booth has had fifteen years to disappear.

Keep folders shallow and the drive single-partition. Both limits are invisible until the moment a track will not load.

Related: The pre-gig checklist CDJ-2000

Short answer. 999 tracks fit in HISTORY, and the deck does not stop there. The manual: "When a 1 000th track is recorded, the oldest item in the playing history is deleted."

Why that is worse than a ceiling. A list that stops recording loses the end of your set, which you would notice. A list that rolls loses the beginning, and it still looks full. On a house deck that nobody has ever cleared, you can walk away with a HISTORY that starts an hour into your own set.

Why it matters. HISTORY is what a lot of DJs rely on afterwards to reconstruct a set, for a tracklist, a radio submission or a royalties form.

When professionals use it. Long residencies and back-to-back gigs on a house deck, where the count accumulates across sessions rather than one set.

Common mistakes. Treating HISTORY as an archive. Export it or photograph it while it still matters to you.

Related: CDJ-2000 The pre-gig checklist

Short answer. A CDJ-900 carried from a cold van into a warm room can stop working for reasons that have nothing to do with the deck. Water forms inside the unit, on the moving parts and on the lens, and the manual states outright that the unit will not operate properly and will not play while it is there. The instruction is to leave it standing at room temperature for one to two hours without turning the power on, which is exactly the opposite of what a stressed crew does. It happens in summer too if the deck sits in the direct blast of an air conditioner, and the answer there is to move it.

Why this matters. It presents as a dead player at exactly the moment nobody has an hour, and the reflex, turning it on to see whether it works, is the one thing the manual tells you not to do.

Do this. Get the cases inside as early as you can and open them, so the gear warms with the room instead of after it. In summer, keep decks out of the direct path of an air conditioner.

Related: Disc care, and the cleaner not to buy Three things it does that are not faults

Short answer. Most CDJ-900 disc faults are the disc. Wipe from the centre outwards with a clean cloth, never in circles, and never with benzene, thinner, record spray or antistatic agents. For heavy dirt, water on a soft cloth wrung out well, then dry. Do not play cracked or warped discs, and do not put stickers or paper on a disc: the glue warps it. The manual singles out rental discs for this, because a label's glue can ooze out at the edges, so check the rim of a rented disc before it goes in. And a disc brought in from the cold can carry water on its own surface, which wipes off before loading.

The lens. AlphaTheta advise against lens cleaner discs for the CDJ-900, which is not what the shelf they are sold on suggests. The manual's position is that the lens should not become dirty in normal use, that a genuinely dirty lens is a service job, and that some commercially available cleaners may damage the lens. So the cheap disc that promises to fix a skipping deck is a risk the maker does not endorse.

Storing them. Cases, stored upright, away from heat, damp, direct sun and extreme cold. A warped disc is a permanent loss and warping is what all four of those do to it.

Related: A deck out of a cold van will not play Three things it does that are not faults

Go to AlphaTheta for the files themselves. We link their pages instead of hosting a copy, because a manual copied here is a snapshot of release day and theirs is the one that stays current.

Does the CDJ-900 read exFAT?

No. Its Operating Instructions list FAT, FAT32, HFS+ and exFAT appears nowhere in the document. Format FAT32 with MBR.

Is this the same as the CDJ-900NXS?

No. The NXS is a 2013 deck with its own page. Check the front badge.

My USB works on my laptop but not on the deck. Why?

Usually exFAT, which is documented as unsupported here, or a GPT partition map left behind by erasing a volume instead of a device on a Mac, which AlphaTheta do not name for this deck but which we recommend against anyway. Both look fine on a computer.

Can I use a drive with two partitions?

Not reliably. The manual says the device may not be recognised at all.

How many tracks does HISTORY hold?

999, and then it starts overwriting: "When a 1 000th track is recorded, the oldest item in the playing history is deleted." It is a working list, not an archive, and the part it loses is the oldest.

Does it have PRO DJ LINK?

Yes, over Ethernet, and a LAN cable is a listed in-box accessory.

How deep can my folders go?

Files beyond 8 levels cannot be played, and beyond 10,000 folders or files in one folder the rest are not displayed.