[Mark-sf]

Are you sure about the models you are comparing? The CX100 is a passive speaker and the 4000 is active.

[Mark-sf]

Hope your son appreciates it!

[Mark-sf]

I would check the 7V power supply section around TR19 and C10. If the fuse that was bad was T1A for the 5v supply there may be and issue with IC4 circuit or its zener.

[Mark-sf]

I don’t know what you mean by “servo noise”. If you mean 120hz buzz then it’s likely a power supply cap problem. As for the 45 sod are you seeing a variable freq on pin 1?

[Mark-sf]

If you have access to an oscilloscope you should find a 500Hz sine wave on P1 of the motor connector when the speed is set to 33. It’s possible that the motor control chip has been damaged. Check the schematic available at https://beomanuals.com/manuals/Beogram/Beogram%202402/Beogram_2402-Schematics.pdf. While its a different model it uses the same motor control circuit.

[Mark-sf]

Your problem is not likely an electronic one but a mechanical one. There is a muting switch under the tonearm that is activated by the arm movement. It likelly needs its contacts cleaned. The service manaul is at https://beomanuals.com/manuals/Beocenter/Beocenter%207700/Beocenter_7700-Service_Manual.pdf. The part is 1567 in the parts list but the diagram marks it as 1557. You open it by removing screws in the rear and it hinges from the front.

[Mark-sf]

I would not hold my breath given that B&O is out of the turntable business. You might try contacting Rudy over at https://beolover.blogspot.com/2015/01/beogram-40024004-apple-remote-controls.html and see if you can convince him to come up with an 800x version.  I have the one for my 4004.

[Mark-sf]

Your BeoSound stage manages remote commands only via BT, HDMI or Ethernet and your 8002 needs a wired datalink signal coming from a Master system. From my knowledge your BeoSound does not have a source Master system interface nor do those ML and MCL components.  The Master system is what decodes the output of your Beoremote One IR commands into the datalink control signals the 8002 receives via its DIN connector.

The other issue you have is that you need to get the DL signal into a Master system component which do not pass through your phono preamp as they have their own DIN signal pins.

[Mark-sf]

Excellent work. Having done something similar for the Beogram 4002/4 series and GRado Signature carts(which I sold many in the 80’s),  I fully appreciate the time and effort. I am confused by your statement that the cartridge is sealed in the shell as from your pictures you have omitted the cartridge body and its 4 pins that plug into the arm and are only displaying the SP stylus shell. In my case I re-wired the tonearm and built a special socket receptor for the pins. I don’t see any cartridge pins in your pics, hence the question.

[Mark-sf]

95GU55 or 95GU56 should work fine as replacements for the PU51.

[Mark-sf]

In the bottom cover there are two holes that adjust the set down point for 7” and 12” records. It is easiest to place it on a stand or supports so that you can watch the arm without having to constantly flip it. If your bottom does not have the holes then you will need to remove the 4 corner screws and remove it first. These eccentrics should be marked and are in the from of the cam gear.

[Mark-sf]

That model has many electrolytic caps that by now have started to fail. That is usually the cause of it spinning backwards. You should start by replacing them in the power supply and motor/coil section. Once you’ve confirmed correct and stable voltages then you can see if there are other issues.

[Mark-sf]

I would continue to check for the proper power supply voltages to the different modules. Even though all the fuses are fine, a unit this old can have failed or failing electrolytic capacitors. I believe the tuner section has at least one rail dedicated to it (12v) and you also will need +-33 to the chip power amps.

[Mark-sf]

You have one foot still attached on the front right about 6″ in. I believe they are bigger than those for the Beograms but you can compare their part numbers in respective service manuals.

[Mark-sf]

While I have not done it myself, the screws as seen in the parts figures are not threaded but keyed. Since they depend upon gravity to drop down, they could be simply stuck and once in the proper release orientation be pried downward with a spudger.

[Mark-sf]

You may have not gotten an answer earlier because your question is confusing since the Beogram 8000 control panel is made of plastic so scratches do not reveal a different color. I know of no way to fill in and blend this that will not make it visually worse due to the matte finish.

[Mark-sf]

If you want to get rid of the hum then you have to take action.

1. Try the connection with/without the ground connection and report the results.
2. The ground wire needs to be connected to a solder lug on a screw terminal under the back right top plate that you can remove by pulling the wood trim forward.
3. From that same lug, there should be a connection to the black multi-pin connector.

Please see the excellent video by Beolover

[Mark-sf]

As I stated don’t even bother with sourcing a DIN cable. For the RCA one, they can either take quality bulk cable such as Mogami or Cardas and terminate one end with quality RCAs or you can buy a premade RCA-RCA cable and they can remove/cut the connectors on one side.

[Mark-sf]

Unless you are connecting the table to a unit with a DIN input you do not need to put back the DIN cable. While that is a cheap RCA cable it is one that B&O used on later 4004s and many others. If the hum does not change when using the ground wire to your phono inputs it’s likely that it’s not properly grounded internally. I have replaced many of these and it needs to be done correctly since the DIN cable has a double shield system. Are you comfortable with soldering? If not a competent tech can do this but I would simply use a higher quality RCA cable.

 

[Mark-sf]

Sorry, there was a typo in my response. I meant 88cm.

 

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