Beogram 5500 Type 5943: Operational Again

This Beogram 5500 turntable is playing records again.  I connected it to its Beomaster 5500 unit and fitted it with an MMC-2 phono cartridge.

The Beogram sounds great and the remote control functionality with the Beomaster works perfect.
These Beosystem 5500 components are ready to return home to their owner.

To get to this point from the previous post I had to go through the Beogram 5500 service manual adjustments.

The set down point and the platter speeds were the only adjustments that were out of range on this turntable.  However, there was a problem with the platter motor making an audible racket as it turned.
The sound is similar to Beogram 4002/4004 platter motors as they age and their oilite bearings dry out.

I am not setup to re-infuse the bearings right now the way Beolover restores the Beogram 4002/4004 motors. I will save this motor for restoration later and in the meantime use a spare Beogram 5500 platter motor.

Bang & Olufsen used this same 12VDC MMX-4H2RPB motor as the platter motor for a number of their turntables.  Both tangential arm and radial arm turntables from around 1984 and on. 

The replacement motor is nice and quiet so the platter rotates silently now.

For the speed adjustments there are two trimmer resistors on the Beogram 5500 controller board.

To check the speed setting I used the new Beolover RPM tool.
In order to put the Beogram 5500 into record play mode so I could measure the platter speeds I placed a 45 RPM record on the platter then paused record play.  The 45 RPM record leaves the edges of the platter with the markings exposed for the Beolover RPM tool to measure with.

The tonearm set down point for record sizes 17 cm (~7 inch) and 30 cm (~12 inch) were initially off the mark on this Beogram.  

The service manual specifies that the 17 cm set down point should be adjusted first, then the 30 cm set down point.

For the 17 cm set down point adjustment there is a black, plastic eccentric disc that moves the set down position in or out as shown in the following picture. The disc can be rotated with a flat head screwdriver.

For the 30 cm set down point adjustment there is a metal lever whose position is moved with a white, plastic (nylon) adjustment screw.  After the position is moved, a locking screw is tightened to ensure the lever position doesn't change.

Here is the 30 cm set down point after the adjustment.

Although I didn't have to adjust the Beogram 5500 record tracking sensitivity it is worth noting that I checked it.
That adjustment appears more difficult on this type of Beogram than the Beogram 400x and 800x turntables. On those turntables it is easy to disable the platter motor function and move the arm to a test track where the arm is lowered.  Once lowered, the platter is manually rotated to check the record tracking.

On the Beogram 5500 while the platter drive can easily be disabled by removing the platter belt, manually getting the arm to a test track to test the sensing of the arm position seemed difficult.
Manual operating the platter to control the arm movement and set down are rather unclear.

For this Beogram 5500 I put on a test record with the platter functional and observed the record tracking by viewing the servo motor advancement from the rear of the Beogram.

From this vantage point I was able to check platter revolutions with regard to the Servo Motor advancing the drive pulley.

I could see that this Beogram Servo Motor started advancing the arm within 2 turns of the platter after the initial set down. That is setting down on a music track...not setting down on the lead in groove.
Once set down, the Servo Motor advanced the arm every revolution of the platter.

The rest of the adjustments like the audio signal muting, arm alignments and suspension were all good so I was comfortable to install a good MMC-2 phono cartridge for the listening test.

Beogram 8000: Tracking and Tracking Force Adjustments

I am anxious to try this Beogram out playing records again. That time is almost here and tonight I took the next steps to get there.

First up is calibrating the tonearm tracking force. Most of the MMC cartridges have a recommended tracking force of 1.0 gram or a little higher. I like to calibrate the tonearm tracking force so the tracking force sliding scale is right on when the indicator is on the "1" position.

For these tracking adjustment procedures I use one of my old MMC-4000 cartridges. I fit it to the tonearm and checked the initial tracking force weight with the scale at the "1" position. It measured low.

The adjustments for the tonearm tracking force are made by calibrating the tonearm counter-weight with the tracking force sliding scale.

Here is the tracking force adjusted to within 0.01 grams.

I should mention that for these adjustments I want most of the Beogram functionality operating but I don't want the platter turning. Bang & Olufsen designed these turntables so you can disable the platter motor by itself. With the turntable power unplugged I pull off the P4 connector from the main board. I can now plug the turntable in and operate all of the other functions.

This is a good time to adjust the tonearm set down position. I set this one just before the middle of the record's lead-in section.

Now for the record tracking check. In this test the service manual instructs that the tonearm is lowered onto a record for playing while the platter is disconnected. The platter is then manually rotated and observed how many rotations of the record occur before the tangential arm motor advances the arm assembly.

Any necessary adjustments will involve using the small screw shown above to adjust the aperture of the tracking sensor light. That adjustment will speed up or delay when the control circuit advances the arm.  I check the arm tracking at several positions.

Now that the adjustments are done I reconnected connector P4 and gave the turntable a quick play test (without connecting the turntable to any amplifier). This is just to get a good feeling that it is ready to bundle up the Beogram case and give the turntable a real functional test.

That step will have to wait until tomorrow.