Beogram 4004 Type 5526: Second Beogram 4004 from Texas service manual checks to playing records

I reached the home stretch of this Beogram 4004 turntable. It was almost as pristine as the first one but did require a few adjustments per the service manual.

Running through the service manual checks I started with checking the sensor signals from the carriage position sensor and from the fixed arm. Because the LED lamp was changed for the carriage position sensor I needed to make sure the voltage on the sensor, 4IC1, is 5V when the sensor is on a clear part of the moving position scale.

That sensor and new LED lamp are now adjusted where they should be.

For the new Beolover lamp assembly in the fixed arm for the record detection the voltage on the collector side of 1TR3 should be a steady 4V when a record is present or the platter is off.

That measurement was initially low so I had to raise the collector voltage using the new 2MΩ multi-turn trimmer I installed in place of the original, fixed 1MΩ resistor 1R26.  The reason for that is described in this Beolover post.

Now that the voltage level at the collector of 1TR3 is set I checked what the actual pulse signal looked like when the platter is installed and turning.

A nice healthy detector arm signal from an empty platter. I think it is safe to press the fixed arm's sensor assembly back into the arm.

On to the platter to tonearm mechanical height adjustment. The platter was a little low on this Beogram. It should be 23mm from the deck of the platter to the top of the fixed arm.

The platter height (and levelling) is done with the platter main bearing assembly. The large nut is loosened so the threaded bearing can be rotated up or down as needed for the adjustment.

In this case I needed the platter to be lowered a little bit.

I check the height at the edge of the platter and at the center.

That is right on the money.

During the platter height check I determined that the platter needed a little levelling so I adjusted those screws as well.

The next mechanical type check is for the arm lowering limit. For this check the stylus should be about 0.5mm above the low rib of the platter. That provides a little bit of cushion should the arm try to drive towards the center of the platter without a record. The stylus hitting the high rib of a rotating platter could easily shear off the stylus.

The stylus/tonearm distance check is done with a string from the center spindle of the platter to the edge of the turntable. I can use the string to make sure the travel of the stylus remains on the center line.

The cartridge tracking force check showed it needed some recalibration so I adjusted the tracking force gear position to bring it into line. I calibrate it for 1 gram.

This Beogram 4004 restoration installed a new tangential tracking sensor lamp assembly (a Beolover custom part) so I figured I would have to go through that whole adjustment procedure and I did.

The platter belt is removed and the adjustment calls for manually rotating a test record with the platter engaged and observing when the tangential drive motor advances the arm assembly. On initial lowering of the tonearm on a record the platter should go through two rotations before the arm assembly is advanced. After that it should advance on every rotation.

The following pictures show the adjustment screws.

It always takes a few iterations but eventually it was set per the service manual.

I attached the platter belt again and performed the platter motor speed adjustments.

It is very nice to have the Beolover RPM measurement tool and both speeds adjusted easily with the new multi-turn trimmers I installed on the controller board.

The final adjustment steps were strictly cosmetic, mechanical adjustments. I made sure the cabinet deck and platter were level and the floating suspension worked.

The Beogram 4004 turntables still look amazing!

The first real record play was next and I fully expected it to play great as all of the tests passed. No problems. I moved the Beogram to my office and put on an MMC-20CL cartridge followed by some seventies big band music.

The dust cover on this Beogram 4004 could use a little polishing so I will have to do that as the last step...but first I am going to reward myself with a nice, long listening break.