My bang and olufsen 7002 wont select the phono stage

Check the 3 amp Slo-Blow fuse in the 3rd fuse holder (bottom right corner) of the phono junction box. I had a similar problem with my AMI F-80 (1954). The turntable continued to turn and would not detect the end of the record to return it to the rack, nor could I cancel the record. Power through this fuse goes to the mechanism junction box and on to the carriage junction box where all the control contacts are. So without that power, it doesn't know what to do next. Also, there is a way to modify/fool the credit unit so it thinks it always has credit (free-play!). Basically you put a jumper on the contacts, but I made the jumper go through a simple flip switch, so I could choose free play or not. I hope this helps.

Things to check:
1. is cart connected to arm, or are wires loose?
2. Is turntable connected to rest of system, or are wires loose?
3. Did this ever work, or is this a new connection? If new:

A. Does rest of system actually have a 'phono" input? If not, you may need a "pre-amp" to boost phono signal.

What you have is a record changer; and malfunctions today are probably more likely that in the past--even after the prestigious Fisher name and price had been largely supplanted in the post war years--before mfg quality control as a customer fault under protection (for sellers) by Warranty dodges had come to the fore. (In actuality, while record changers would would have been favored by record producers--for the rapid rate at which they destroy records--they would have been looked upon with disdain by pro disc jocks as well as high-end audio equipment producers (including Fisher) in favor of single play turntables that don't destroy records that must be played "on the air," repeatedly, hundreds of times per week in successsion.)

1. Did you unclip the tone arm from its resting post?
2. Remove record and turn off platter (name for a turntable record support) drive motor, and unplug the player machine.

1. While manually rotating platter in PLAY direction (that's CW), actuate PLAY lever to its extent, release, and watch for tone arm movement as you continue platter hand rotation.
   1. (Oh yes, make sure the record hold-down arm is up and rotated outward to prevent hold-down-arm drop from causing changer to return tone arrm to stow post and dis-actuating START lever...such features once accurately called "self stop,: today inaccurately called "auto stop."
      1. ...by the way, could your problem be that you did not lower hold-down arm onto record(s)? ...making the changer mechanism below the platter "think" that all records had been played...so that it swung and stowed tone arm and then Self Stopped the player rather than repeat-playing the top-of-stack record (in order to save changer and record wear and tear)? Is your problem now solved? Just in case not, continue...
2. As you hand rotate and watch, the tone arm (and release spindle with no record on it) should "recapitulate" its normal, record changing and playing motions--you are simply "handing" in for the platter motor.
3. If there is a "hitch in the changer's stride" (that means a jam) it will also occur and be felt operating the changer manually. At that point, you will have "set" the changer mechanism in conflict-fault position for facilitating inspection to find the specific problem.
4. Note that since record-changer-/turntable-type players are permanently confined to level-only use, that means the turntable/changer platform need not be affixed to its base (some are--some aren't) so it might be possible to simply lift the turntable/changer platform assembly up off the base to inspect underneath. Some (possibly most) turntables/ changers, on the other hand, are apt to be fastened to the base (lest the furniture be bumped into...but those typically did little more than prevent tone arms from skating some ot the time) in a suspension arrangement (if not rigidly) that incorporates helical thrust springs and hold-down screws at each hold down point, typically 4 in number. Detaching the platform is apt to involve simply looseing and then over loosening the screws...or by some other obvious or not so obvious means.
   1. Being mindful of any hard-connected wires, unfasten, lift, and invert changer platform to inspect underneath.
   2. Take appropriate corrective action at point of jamming.
   3. Revert and refasten platform and re-run manual-unpowered operation to confirm corrections.
   4. Return power to player and test using a record.
   5. Thank yourself for posting your question...if all or some of the above works.

If the sound is affected on all systems then yes something has gone inside. Try a pair of headphones, if the sound is still bad, then either the pre-amp has failed or the power amp.

Just turn up the weight on the arm slowly bit by bit till the problem stops. The weight should have numbers on it - set it at 2 and increase it. You will have to stop the record playing each time you increase the weight. Also look around to see if it has an Anti-skate control, if it has again increase that in stages. It's all down to trial and error setting up a turntable, there's no correct way and it depends also on the records too and quality of them.

I am not familiar with the model but a high quality turntable and tonearm needs special care.

The turntable should be adjusted to be as level as possible - the classic method uses a circular "spirit" level that has a blob of mercury instead of a bubble.

The tone arm can be moved manually but great care must be exercised especially if it is fluid damped, though it is better not to if the mechanism is functioning.

It is important the stylus tip is in good condition and the playing weight is adjusted to the required value using a stylus balance.

The correct playing weight is specified by the cartridge manufacturer and the adjustment method will be described in the instruction manual.

Move the tone arm off the rest on to the record and it will start to spin. There is a switch that turns the player off when the tone arm is on the rest.

take the turntable arm by your hand and place it above the record,then use the up and down lever to lower arm on record!!

Check to see if there is a cueing lever that is holding the arm in the up position.  If no cueing lever and it has worked recently then something has happened to the changer mechanism.  Open the bottom and look to see if there is an obvious problem like something stuck or broken.  You may be able to make the mechanism go through its cycle slowly by rotating the platter with your  hand so you can see where it is getting stuck.

possibly some kind of obstruction inside.
I had something similar with my turntable, and it had a dirt dauber nest inside it!
no kidding.