beolover: Beogram 4002 (5513): Complete Restoration of a Recently Acquired Unit from California

I recently bought a Beogram 4002 (Type 5513) in nice cosmetic condition. It safely arrived in a Beolover shipping container. The seller did a great job packaging it following my video to the dot.

Here is a picture of the final result of my efforts:

Let's see what it took to get there!...;-):

This shows the unit after I put it on the bench:

The hood was pretty scratched as usual for Beograms coming out of storage:

Luckily there are new exact reproductions of these dust covers available from the dksoundparts store in Denmark. I removed the hood. The cosmetic condition of this Beogram is pretty good.

But the keypad had the usual smudges from using it:

I removed the aluminum panels and platters and had a look below deck:

It looked mostly original, always a good starting point for a restoration!

As usual, I started with the DC platter motor. This shows it extracted:

I took it apart to get the dry Oilite bearings out. They are the two small donuts on the black pad:

I immersed them in synthetic oil in a jar in my vacuum chamber. After pulling a vacuum strong bubbling started:

The bubbling indicates air being drawn from the porous Oilite material. As the air leaves the material, oil can diffuse into it and replenish the oil reservoir. This process can take up to three days. It is complete when the bubbling has stopped.

While this process was going on I focused on the remaining restoration tasks. First came the cleaning and re-lubricating of the carriage and arm lowering mechanisms. This hows the carriage after all moving parts had been removed:

This shows the old lubricant encrusted parts ready for the ultrasonic cleaner:

When I disassembled the damper I found someone had used teflon lubricant on the plunger:

After seeing this I thought I'll drink one to human creativity after I am done with this Beogram!...;-).

While the parts were cleaning in the ultrasonic I looked into the solenoid assembly. This shows it extracted:

I removed the plunger

and checked its magnetism. Like most this one was able to attract a ferrous setscrew:

I treated it with my tapehead demagnetizer until the setscrew did not get attracted anymore. This is an important part of any Beogram restoration. When the plunger is magnetized it can result in delayed arm raising during the auto return at the end of a record. It can be a hair raising experience when the new $800 stylus scratches across the record during the carriage return!!...;-)

Next I focused on the circuit boards. It is a good idea to replace the two power Darlingtons on the solder side of the main PCB before removing it. This makes it easy to place the replacements properly that the bolt holes match up. This shows IC1 (TIP120) that regulates the 21V rail:

I replaced it with a TIP102, its stronger cousin:

New TIP devices need a bit of capacitance on the emitter to quench a high-frequent oscillation that can develop in this circuit configuration. I usually solder in a 100 nF multi-layer cap (yellowish package) between the emitter and a conveniently located nearby GND patch. After replacing IC4 with a TIP107 I removed the board. This shows the original state of the board:

I replaced all the electrolytic capacitors, power transistors, RPM relay, RPM trimmers and the sensor arm transistor and its biasing resistor:

The relay was replaced with a Beolover Siemens Relay Replacement for Beogram 4000, 4002, and 4004.

After I was done with the main PCB I removed the output PCB from under the keypad:

In the 4002 this PCB only contains the output muting relay and its delay circuit. This shows the original condition:

I replaced the output relay with another Beolover Siemens style replacement relay, and I also exchanged the electrolytic capacitor that defines the timing of the relay delay:

As usual, I also installed a switch (red) that allows connecting signal and system grounds. Connecting the grounds usually quenches any humming issues, especially when connecting a Beogram to RCA input via a DIN5 to RCA adapter.

In the meantime the carriage parts had cleaned very nicely in my ultrasonic cleaner:

I usually install a new gasket in the damper plunger:

This is an important aspect of any full Beogram restoration. The original gaskets are often hardened and/or warped. This can result in inconsistent arm lowering behavior. Very un-beolovely when the arm drops without damping occasionally!

This Beogram also had an already starting to crack spindle nut holder (right):

The Beolover replacement part is shown on the left. This shows it installed:

I also installed a new Beolover Aluminum Carriage Pulley for Beogram 4002 and 4004:

This shows everything back in place with new synthetic lubricants:

Beoshiny! On to replacing the incandescent bulb in the tracking sensor with an LED assembly. This shows the original setup:

I removed the black bulb housing. This shows it next to the Beolover Tracking Sensor LED Light Source (Beogram 4002 and 4004):

I implanted the new part:

One more restoration task on the carriage assembly was cleaning and re-lubricating the damper to tonearm linkage. It is hidden between the tonearm and sensor arm assemblies. You can see it stick out in the back from the v-cut in the small metal plate that is bolted to the back of the counter weight:

To get to the linkage the sensor arm assembly has to be unbolted. This shows it with the linkage already removed:

I cleaned the pivot point and re-lubricated it. Then I reassembled everything and also glued the small copper plate that aids the lateral arm movement (while the arm is up) back into its place:

Then I bolted the assembly back next to the tone arm:

At this point everything had been removed from the enclosure except the floating chassis. I disassembled the transport locks, which revealed that the transport lock bushings were completely gone:

I removed the floating chassis and vacuumed out the enclosure:

Then it was time to put everything back together. But first I installed a new Beolover Transport Lock Bushing Set for Beogram 4000, 4002, and 4004. These transport lock bushings have been designed for easy installation. Each bushing consists of two halves:

Installation is easy: Simply put one half in from the bottom

and the other from the top:

Note that the orifices in the chassis can vary slightly. It is a good idea to put a bit of superglue gel on the vertical parts of the bushing halves to hold them securely in place if they sit a bit loose. This shows one of the lock orifices with the lock bolt already inserted:

After re-installing the floating chassis I replaced the old reservoir capacitor. This unit was set up with a dual-capacitance capacitor can combining a 4000uF and a 1000uF capacitor in one package. This is evident from wiring being present on both ends of the can:

I replaced it with a Beolover Main Reservoir Capacitor for Beogram 4002 and 4004 (Types 551x/552x):

This part can be used in both single and dual capacitance setups. This shows the removed parts:

The small round device between the orange and black wires is a rectifier that uses the 1000uF capacitor for powering the output board. The Beolover part has an integrated rectifier, i.e. it can be discarded along with the old capacitor.

There were still a few more light bulbs that needed replacing with LEDs. Two of them are in the RPM adjustment panel above the keypad. This shows the panel already removed and flipped over:

The light bulbs are behind the two bulb covers:

The Photo also shows the two green Beolover RPM Panel LED Backlights for Beogram 4002 and 4004 (Types 551x/552x) ready for installation. This picture shows them installed:

Here a detail shot of one of them:

The LED boards essentially function as extensions of the small PCB that features the solder pads for the bulbs. The LED boards do not interfere with the bulb covers, which can be re-installed after the swap:

On to replacing the final bulb: It is in the sensor arm. This shows the small compartment at the end of the sensor pulled out:

This reveals the bulb. The Beolover Sensor Arm LED Light Source (Beogram 4002, 4004 and 4000) is shown on the cloth below to the left. This picture shows it installed:

At this point I remembered that my customer wanted the carriage motor upgraded with a new Beolover Carriage Motor for Beogram 4000, 4002, and 4004. This custom-manufactured state-of-the-art modern coreless DC motor runs much more quietly with less vibration than the original motors. It also draws less current for the same performance, which gives the H-bridge power transistors some relief (they often burn out with the original motors if their internal friction gets too high). This shows the new motor inserted in the motor housing:

It is a few mm shorter than the original motor but has the same diameter. The supplied EPDM O-rings help further reducing the motor's vibrations. This shows the motor assembly re-installed:

At this point it was a good moment for aligning the arms. I did this with my recently developed alignment tool. It makes it a snap to get the sensor arm base perpendicular to the carriage rods after which the sensor arm can be parallelized:

Once the sensor arm is perfectly aligned, the tonearm can be adjusted to be parallel relative to the sensor arm.

At this point the oil infusion of the platter motor bearings was complete. I extracted the bearings from the oil and put the motor back together. Then I installed it in the Beogram for a 24 hrs RPM stability test using the BeoloverRPM device:

The BeoloverRPM has two operational modes. In 'slow' mode (shown above) it measures the RPM in 10 sec intervals and sends the data to a serial port of a computer where it can be recorded with any generic terminal software. This allows plotting the RPM over long periods of time using Excel or similar software. This shows the result of my 24 hrs measurement:

'Beolovely' looks different!! The occasional large RPM drops indicated that this motor had at least one bad spark snubber that occasionally short circuited. Such shorts result in momentary torque loss of the motor causing the platter to slow down until the snubber recovers. In my experience snubber failures start intermittently until they permanently short out and then the motor runs very irregular, if at all.

I extracted the motor and opened it up to get to the rotor. This shows the rotor with its commutator end up:

On the black pad to the left the three new bidirectional TVS devices are shown prepared for installation.

I unsoldered the spark snubber 'ring' and put it next to the TVS devices:

This shows the TVSs implemented across each of the windings:

I put the motor back together and ran the 24 hrs test again. This time I got a much nicer graph:

Replacement of the spark snubbers seemed to have fixed the problem!

Next I collected some high resolution data in the 'fast' mode of the BeoloverRPM:

In this mode the device sends an RPM measurement every time a platter rib passes through underneath the sensor. This gives 24 RPM measurements per platter turn (there are 24 ribs). This allows visualizing short term RPM changes caused by the feedback-based motor control circuitry. This graph contains the data covering ~35 platter turns (~70 sec):

The prominent zig-zag pattern is a measurement artifact that comes from the fact that the spacing of the platter ribs around the platter is slightly irregular due to manufacturing imperfections. This generates a repeating pattern for every platter turn (sort of a 'platter fingerprint'), which is superimposed to the real RPM changes that are introduced by the feedback system that keeps the motor RPM stable over time. This real RPM change is essentially the sine-wave like pattern that modulates the zig-zag pattern. An evaluation of the wavy component yields a wow and flutter estimate of about 0.1%.

This is 2x of the 0.05% stated in the specs list in the service manual. This difference is most likely systematic due to the entirely different way wow and flutter was measured in the 1970s when these turntables were produced. I see it for all Beogram motors that I restore. Back then the measurement was carried out with a test tone on a test record. In these measurements deviations from the tone center were measured with an analog spectrum analyzer and then converted into a wow and flutter number. It should be pointed out that this discussion is pretty academic in the first place since humans start typically recognizing frequency fluctuations above the 0.7% threshold, i.e. the RPM fluctuations of this Beogram are well below this threshold, whether the number is 0.05% or 0.1%. This motor is definitely ready for duty again!

On to doing some adjustments! First I adjusted the bias of the sensor arm transistor on the 25-turn trimmer that I used to replace the fixed 1MOhm resistor that is typically installed. The bias should yield a 4V DC voltage at the collector of the transistor.:

After I adjusted the trimmer I moved it over to the component side:

Whenever work is done on the sensor arm it is a good idea to check the sensor response to an empty platter rotating beneath it. This shows the trace I measured on my oscilloscope at the collector:

Each dip corresponds to a platter rib passing under the sensor. The amplitude exceeds 6V, which is a perfect result. All good in the record detection department!

It was time to focus on the remaining adjustments. The first step is usually to align arms, platter and subchassis to achieve a 23 mm top-of-the-arms-to-platter distance and to get the platter and arms parallel, while leveling the subchassis to get the platter flush with the surrounding panels. This can be a pretty tedious and iterative process, depending on how out of alignment things are. I usually start with getting the aluminum panels properly aligned and settled on their alignment pins together with the keypad. Then I get the arms parallel and in 23 mm distance with the aluminum panels. Then the platter can be adjusted to be in the same distance. If everything is done right at that point everything is parallel and in the right distance.

Once this is squared away the tonearm adjustments can be done. First I adjusted the arm lowering limit to miss the lower parts of the ribs by about 1 mm:

This is an important adjustment since it is a failsafe in case the record detection circuit malfunctions and the arm lowers onto an empty spinning platter. The lower parts of the ribs are smartly placed in the three arm lowering positions for 7", 10" and 12" records.

Then it was time for calibrating the tracking weight. I usually start by replacing the flimsy locking washer that holds the counterweight adjustment screw in place

with a square nut and a washer:

This allows me locking the calibration in place so it can survive shipping of the Beogram. I adjusted the counterweight to get 1.2 g weight at the 1.2 g weight dial setting:

Since B&O cartridges need between 1 g and 1.5 g tracking weight, and most use 1.2 g, this calibration makes sense. The dial is somewhat imprecise over its entire range. Generally, I recommend using a digital weight gauge and set the dial to whatever position is needed to get the proper weight adjusted.

With the arm adjustments squared away, I focused on adjusting the tracking feedback:

Then I replaced the grubby oxidized original DIN5 plug

with a nice modern all-metal plug featuring gold plated terminals:

Beogolden!

I still needed to replace the work keypad with a newly restored one. This shows old (left) and new in direct comparison:

We offer keypad restoration kits for DIY. If DIY seems daunting, you can also send your keypad in for full service. See here for more info.

The original keypad had the usual cracked plexiglass parts that hold the RPM panel in place. Left:

And right:

This usually happens when one is not careful during extraction or replacement of the RPM panel.

Luckily, there are really nice replacement parts available at the dksoundparts store:

All one needs to do is transferring the metal spring clips from the old to the new:

This shows one of them installed and holding the RPM panel down:

Here a picture of the new keypad with the RPM panel in place:

Before I could install it I still needed to replace the original wood frame with a new CNC machined oak frame in the "4000c" style with splined front corners. I baked the original frame in the oven at 250 F for 30 min to soften the glue and then I used a carpet knife to cut the metal fixtures from the wood. After cleaning the glue off I applied 3M 300LSE double sided adhesive tape to the metal parts. This shows them prepared for installation together with the new oak frame:

I use two of the small aluminum panels for the installation. The panels have the exact thickness needed to guide the metal parts into the correct position. I use parchment paper to keep one leg of the fixtures from sticking while guiding the other leg into position:

After one end of the metal part has been glued in, the parchment paper can be removed and the other side pressed into place on. This shows the process for the left side:

After bolting the new frame in I replaced the original output board with a Beolover Internal RIAA Pre-Amplifier for Beogram 4002 and 4004. It is a plug and play process. The RIAA board has an identical form factor and the same connectivity:

This shows the board installed and plugged in:

My customer also wanted to upgrade his Beogram with the Beolover SyncDrive. This shows the SyncDrive installed in place of the original motor:

The SyncDrive is superior to the original motors since it has a digital control system which is only very weakly affected by temperature changes. It is also a synchronous motor, essentially bringing a DC motor 4002 up to the wow and flutter performance of the original 4002 with AC platter motor, while giving it a long-term RPM stability similar to the later digitally controlled Beogram 8000/8002.

And then it was finally time for a test spin! I selected one of my favorite Blue Note albums, "Point of Departure" by Andrew Hill (BLP 4167). It was recorded in 1965. I like the cool but edgy sound of Hill's piano play. Here an impression of the album playing:

Beolovely! A perfect match! The Beogram performed very smoothly, and so I focused on the remaining cosmetic task: Replacing the scratched hood with a new one. The first thing was removing the old plexiglass cover from the hinge assembly. It is easy to get to the mounting screws: Just push a razor blade in between the aluminum trim and the plexiglass, which reveals the screws:

After removal of the screws the hinge assembly is liberated. This shows the new cover with the new aluminum trim strip (the old ones cannot be reused if a smooth like-new look is desired - they always get a bit wiggly when one tries removing them) together with the hinge assembly:

There is one potential issue when installing a new hood: In some cases the hinges pivoting on the back piece can be a little bent, i.e. they have a tighter angle than normal and that can cause the new hood to chafe on the back piece when it is opened or closed. See here for a detailed description of this issue. This can happen even if the original hood did not chafe since the new hoods are slightly deviating from the original shape on the back end.

Since a lot of the later Beograms have pressed in dowel pins on which the hinges pivot, it can be difficult removing the hinges for checking their angle with my tool. So it is better to check first if there is a problem before going through the effort of pressing out the dowel pins. That is why I now always bolt in a new cover in for a quick test for its interference-free movement on the hinge assembly:

Once the new cover is installed I move the back piece, while watching the gap between the metal part and the 'stabilizer bar' that has been designed into the back end of the hood to prevent it from sagging. If there is interference it usually seems to happen close to the hinges. This hood passed the test nicely with an at least 1 mm gap across the entire movement range:

I removed the hinge assembly and used my 3D printed alignment pieces for centering the new aluminum strip across the back of the cover:

I usually use a strip of blue tape stuck to the hood for making a pencil alignment mark which will allow me placing the strip properly once the hood is bolted to the hinge assembly:

The new dust covers have another small design issue, which makes it difficult to get a precise and sharp bend of the trim towards the sides of the cover. There is a 'channel' in the plexiglass that runs from top to bottom on the sidewalls. This makes it difficult to bend the aluminum strip since there is a void under it and the corners come out rounded in the channel area. This is why I started glueing 3D printed plastic pieces into the top end of the channel:

After the epoxy has hardened I trim them with a razor blade to match the plexiglass precisely:

After this was done on both sides, I bolted the hood back in. It is not recommended to tighten the bolts much to prevent stresses in the plexiglass. That is why I put some white wood glue into the threads on the hinges to give the bolts an additional incentive to stay put: