Continuing on from this project's previous post, I needed to install a Beolover SyncDrive platter motor and a Beo4 Remote Commander.
However, there were still some other follow-up tasks like checking the 21V supply voltage (to make sure it doesn't have any noise), adjusting the TR3 collector voltage with the new R26 trimmer, installing a Beolover platter detector lamp replacement, installing Beolover RPM indicator LEDs and running the platter speed calibration.
Here is the 21V measurement check. The inset oscilloscope screenshot is zoomed in on the 21 V line so I could check the ripple. The measurement looks very good.
Next, I installed a Beolover platter detector lamp module so I could check (and adjust) the platter detection signal with the 1TR6 trimmer I installed (in an earlier post).
Once the 1TR6 trimmer was properly set, I moved it over to the component side of PCB1.
I changed the speed indicator lamps in the Beogram 4004 RPM indicator panel to Beolover LED modules.
Now I could install the SyncDrive platter motor, run its speed calibration and test the platter detection functionality of this Beogram 4004.
SyncDrive speed calibration...
At this point I was able to calibrate the Beogram 4004 record tracking.
I removed the platter belt for this calibration procedure so I could rotate the platter by hand and check the Beogram 4004 servo motor performance when advancing the tonearm.
While this procedure is usually a repetitive adjustment and measure series of steps, I was pleasantly surprised that I was able to lock in the correct setting only using the coarse screw adjustment shown in the picture above.
Usually I get the setting close using the coarse adjustment, then dial in the final setting with the Beogram 4004 eccentric screw adjustment and/or the Beolover tracking lamp trimmer.
Now for a quick check of the platter detection signal and the position sensor run-out groove detection.
The empty platter detector signal looks good.
Previously I had adjusted the position sensor to output 5V when the clear part of the position scale was in front of the detector. Note that when the blacked out part of the scale is blocking the sensor, the voltage is around 10 V. Those can be checked and adjusted (using PCB1 trimmer 1R88) without the platter motor if desired.
The last section of the position scale has a series of narrow black bars. This is so the position sensor will generate a series of pulses that the detection circuit on PCB1 can interpret as the run-out groove of a record. Each run-out pulse adds to the voltage level that capacitor 1C33 charges up to in the detection circuit until the detection threshold is reached. At that point, the run-out detection circuit initiates a stop and return to end the record play.
This picture shows the position scale bars entering the position sensor area. The inset oscilloscope screenshot shows what the run-out sensor signal looks like when the tonearm is moving through the run-out groove. In this case the run-out detection circuit triggered on the third pulse.
Note: My measurement point here was at the node for 1D41, 1D42, 1C33 and 1R82 on PCB1.
Last, but not least, was to install the Remote Commander...but first, I still had to clean the old oxidation off the Beogram 4004 control panel button contacts. I applied some Deoxit fluid on the cleaned contacts.
While checking the button panel I discovered that one of the buttons was badly damaged and would not work. I replaced the plastic button with a spare.
With the button panel restored and tested, I install the Beolover Remote Commander.
This version of the Remote Commander is designed to operate using a Bang & Olufsen Beo4 remote control.
Also...note that the Remote Commander installation is using the Beogram 4004 options.
Using the Beolover Remote Commander with a Bang & Olufsen Beo4 remote control can be a little bit tricky. That is because the Beo4 remote control is configurable and may not be ready to work with controlling a Beogram right out of the box.
This was the case I ran into with this Beo4. It did not have the Phono option in its list of supported components. Adding that to the Beo4 menu list is not difficult but it wasn't intuitively obvious.
Beolover describes the setup in this video.
This Beo4 had one additional wrinkle however. It did not have a Phono named function in its memory to add to the list of components. It did have "N. Radio" which, it turns out, is another function name that works as a phono selection.
My next step will be to reassemble the rest of this Beogram 4004 and do some record play testing.
