Beogram 4002 (5513): Another Beogram From Houston - Mechanical Work

The restoration work on this Beogram 4002 (Type 5513) begins with the various mechanical restoration tasks.

Those include cleaning out the debris from the cabinet base and some disassembly of the floating chassis components for cleaning and lubricating.

The arm lowering & raising lever is attached to the fixed arm.  The pivot for that lever can occasionally get gunked up so we typically remove it for a clean and lubrication.

The arm lowering damper is also cleaned.  The rubber washer on the end of the plunger gets replaced with a new washer and the metal part of the plunger is lightly lubricated with a silicone lubricant.

The tangential arm spindle parts are removed for cleaning and lubrication.
I don't immediately re-install the spindle however as I find it easier to make a few Service Manual mechanical adjustments with the tangential arm assembly free to slide back and forth.

Before making any Service Manual mechanical adjustments I like to move the four set screws that sit underneath the two metal rails the tangential arm assembly rides on.

These set screws are for adjusting the height of the rails but the slotted end to make the adjustment with sits underneath the floating chassis.  I remove them and re-insert them from the top.  This allows any change in their height to be made from the top side of the floating chassis without having to remove the floating chassis from the cabinet.

Here is a photo of one of the re-inserted set screws.

That gives a little peace of mind in case some change in the tangential arm assembly height is necessary.  Normally it shouldn't be but the set screws allow about 3 mm of height adjustment.

Next I reassembly the tangential arm assembly and go through the adjustments to make sure the arms are perpendicular to the back rail, parallel to each other and have the proper distance to the platter.

The Service Manual says the distance between the Fixed arm and Tonearm is 7.7 mm.

The top of the Fixed arm to the top of the platter (metal) surface has to be 23 mm.

After that is set the tops of the two arms (Fixed and Tonearm) should be even.  If they are not, the Tonearm height can be adjusted. 

With a phono cartridge mounted I check that the Tonearm and cartridge vertical alignment (azimuth) is good.

I set the Tonearm lowering limit so the stylus of the cartridge is about 0.5 mm above the lower platter rib.

I calibrated the tracking force of the Tonearm/Cartridge so that it measures 1.0 gram with the tracking force knob set at 1 gram. 

After that calibration I set the tracking force knob to 1.2 grams.

Before installing the Beolover Tracking Sensor Lamp component to the Beogram 4002 Tracking Sensor Assembly, I checked and adjusted the metal aperture so it is 1 mm above the Tracking Sensor.

The Beolover Tracking Sensor Lamp was then installed followed by the Tangential Arm Assembly spindle parts.  The plastic pulley on the spindle was replaced with an aluminum pulley.

When the spindle was installed I lubricated it with a mixture of grease and oil.  Not too thick and not too thin.

The floating chassis components can now be re-installed in the Beogram 4002 cabinet base where the suspension will be adjusted so the top of the platter is even with the cabinet aluminum deck.

Along with that, the platter motor and reservoir capacitor assemblies will be installed.

I'm pleased with the mechanical adjustments so far.  The re-installed floating chassis aligns good with the aluminum deck plate so it is on to the rest of the electronic restoration tasks.

Those include the restoration work on the main PCB, the output (audio muting) PCB, the LED lamps for the speed indicators, the arm detector lamp (in the Fixed arm) and the contact cleaning on the Beogram control panel buttons...Plus all of the related adjustments.

Beogram 4002 (5513): Another Beogram from Houston

The Beogram 4002 Type 5513 is turning out to be a popular Beogram in Houston.
Here is the initial assessment of another one in need of restoration.

The dust cover is functional and can be kept for now as the supply of newly manufactured Beogram 400x dust covers have become scarce for the moment.

Cosmetically this Beogram clearly has a problem with the condition of the keypad buttons.

On the bright side...the wood trim on this unit is in great condition.
The deck panels, platter and tangential arm assembly also look good.

This keypad though, will need replacing.

The rim of the sub-platter has some sort of residue on it.  I will try to clean that off.

Inside the Beogram 4002 cabinet is pretty typical.
There is debris from the disintegrated transport lock bushings everywhere.

The photo shows the DC platter motor already removed.  I already extracted the platter motor and sent it to Beolover for restoration.

Here is a picture of the Beogram 4002 cabinet with most of the components removed.
I will vacuum the cabinet base out to get rid of all of the loose debris.

Here are the removed components.

The floating turntable chassis, boards, control panel and display panel.

The two boards (main board and output audio signal board) look normal...and ready for restoration.

I opened up the servo motor case to check what the damping material looked like.  Often the foam padding is deteriorated and crumbling into little pieces.
This one is still intact and fine.

I removed the arm lowering damper for cleaning.  It also looks it good shape.

Here is the tangential arm tracking detection sensor opened up.  It will be replaced with a Beolover replacement part.

The SO (stop) and ES (end stop) switches look to be in good physical condition.  They will be functionally tested later along with the arm position sensor and infrared lamp.

The tangential arm assembly itself appears to be in good condition too.

While I have everything apart I will clean and lubricate where necessary and perform some early service manual adjustments.

Other restoration tasks will be electronic restoration work on the two circuit boards, switch contact cleaning.

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 5500 Type 5943: Replacing the Transport Chassis 1106 Base

 In order to get this Beogram 5500 functional again the bottom part of the tangential arm assembly chassis (1106) must be replaced.

At the end of the previous post I showed photos of this Beogram 5500 chassis and the photos revealed a broken tab necessary for the arm control string to connect to.  Without that tab the Beogram 5500 tangential arm assembly cannot operate.

The first step in replacing the bottom section of chassis 1106 is to remove the arm assembly from the guide rails.

There are two rails that I lifted up on one end and slid out to remove.

A view of the back of the arm assembly shows a spring (for arm lowering and raising) that will have to be removed.

Having removed the guide rails, the tangential arm assembly can be lifted and turned to access other parts that will have to be disassembled.

A nice part about this design is that the phono audio cables can be detached from the base of the arm assembly without having to de-solder or disturb the phono cable connections.

As this photo shows, the phono cables are fitted around the chassis 1106 base so they just need to be maneuvered out of their slots.

There are also two screws at the base of the chassis that must be removed so the bottom piece of 1106 can be removed.

...and here is the tangential arm assembly ready for the bottom (white piece) to be pulled off.

You can see that the phono cables are out of the way.

Here is the bottom piece of chassis 1106 removed.

Again, here are the old and the replacement chassis 1106 bottom pieces to show the mounting tab for the tangential arm guide string.

Reassembly with the new arm assembly base was just the reverse steps of the assembly.

With the proper chassis 1106 base installed it was easy to attach the tangential arm guide string.

I installed a new servo belt and tested that the tangential arm assembly is operational.

The set down points of the tonearm for 17 cm and 30 cm records are a little off.
I will be going through the service manual adjustments for this Beogram 5500 next.