Beogram 4002 (5514): Restoring the Plexiglass Hood

The Beogram 4002 (5514) that I just restored had a pretty badly scratched hood. Here is an impression:

Whenever the damages can be felt with a fingernail the initial step for the restoration is a sanding step with 220 grit paper to planarize the surface before it can be polished back to translucency. This shows the surface after the sanding step:

Looks a bit like wood at this point, doesn't it? About 10 polishing steps later using ever finer paper and then micro-mesh polishing cloth restores the surface:

Most Beogram hoods had rubber bumpers installed at the front corners to soften the impact when the hood is closed. They are usually gone due to age-related deterioration of the rubber. This is an easy restoration. They can be replaced with 2 mm O-ring snippets that then need to be cut to length (~1 mm above the plastic).

I outfitted a 2 mm drill bit with a plastic handle for removing the deteriorated rubber from the holes in the hood:

Then the O-ring snippets can be glued in with some super glue gel:

And then it is time to cut them to length. I do this with a 3D printed spacer and a razor blade:

And this is the end result:

Allright! Looks like this restoration is over! Time to send this Beogram back to its owner!

Beogram 4002 (5514): Final Adjustments and a Test Drive with Chico Hamilton on Auto-Repeat!

It was time to do the final adjustment on the Beogram 4002 (5514) that I am restoring right now. It is always a delightful moment to adjust the platter and sub-chassis, the arm lowering limits and then finally the tracking force. Since after that it is the moment when the deck gets its first post-restoration play, and I nervously watch the beautiful electromechanical ballet unfold that so nicely brings out the best in vintage vinyl!

This particular Beogram posed an unusual challenge with regard to the sub-chassis and platter adjustment: The platter was too close to the right-front side of the cutout of the aluminum plate that encloses the platter. Usually the platter may be a bit too close to the motor end of things and this can easily be countered by bending the adjustment rod of the sub-chassis spring on the back right side of the enclosure. Not so here. In this case the counter force on the left back spring needed to be increased a bit. Since I am not really a friend of the service manual mandated rod bending procedure, I decided to come up with a more elegant fix.  Bending rods of delicate mechanical equipment with big adjustable pliers is not really Beolover's cup of tea. I like things to be precisely tunable and reversible.

So this is my solution: I designed small 3D printed parts that stick on the blade springs and that allow to pull the metal 'strings' that levitate the sub-chassis from the springs laterally:

This shows one of them in action on the left-back spring assembly:

The 'ramp' integrated in the bottom part pulls the levitating string a bit back generating the right amount of counter-force that results in a centered platter:

There are two videos on my YouTube channel that show the basic procedures how to adjust the platter bearing and the subchassis (in a Beogram 4000, but the process is very similar in the 4002). After that it was time to do the tracking and arm adjustments. This shows the adjustment of the tracking sensor sensitivity using the light intensity trimmer of my LED based tracking sensor light source:

A good opportunity to present my new least liked record: Henry Mancini's movie score of 'Gaily, Gaily'. I bought it as a combined-shipping $1.50 add-on to another vinyl order. Big mistake. While I am usually a Mancini fan, this is just too much! So it is perfect for the tracking sensor adjustment procedure where sometimes the needle gets dragged across the record if one is not careful.

After that I went on to adjust the arm lowering limit:

An important adjustment that makes sure the stylus misses the platter ribs in case of a sensor malfunction. There is another video on my youTube channel that shows how to adjust the lowering limits. Once the arm is adjusted the tracking force can be calibrated. I usually use a B&O tracking forge gauge:

There is also a video about the tracking force calibration process.

And then it was finally time to give this deck a spin. I selected a recent acquisition, the 'El Chico' titled release by Chico Hamilton of 1965:

I was able to get it as an early Impulse pressing. I simply like my covers without barcodes...;-)!!

Unfortunately, it was not really 'near-mint' as advertised. Instead it was maybe 'very good' with some audible scratches. The ebay seller, however, was very cool about my complaint and simply refunded the money and let me keep the vinyl. So I am still enjoying it after a thorough clean with my CleanerVinyl ultrasonic cleaner attachment. The scratches somehow even emphasize the awesome raw emotional power of this record. This music is just a prime example why one wants to listen to analog sources. My favorite track is 'People' on the A side.  Guitarist Gabor Szabo is just at his best on this track:

This photo is from the gatefold cover of this great record! I am enjoying this record right now on auto-repeat, courtesy of the Beogram 4002 Commander MkII remote that I just updated with an auto-repeat function.

The final step is to polish the hood of this lovely Beogram 4002. And then it will be ready for its trip back home! This is Beolove!

Beogram 4002 Commander MkII: Remote Control for Beogram 4002 Now With Integrated Auto-Repeat Function

The Beogram 4002 (5514) that I am currently restoring was supposed to receive my 4002 Commander Remote control system. A great idea, since the keypad is still near-pristine and the Commander remote will allow using the deck without touching the precious keypad. Check for demo and installation videos here if you are interested in upgrading your 4002. The Commander board plugs into all DC motor models. 

I decided to use this occasion to develop an updated MkII version of the 4002 Commander with an auto-repeat function, similar to what is found on the later Beogram 8000 and 8002 turntables. I realized that my long term goal may be to transform the 4002 into a deck that has the functionality of the 8002. Sort of a beautiful all-metal 8002....;-) 

This shows the 4002 Commander IR receiver board together with the red auto-repeat indicator board that utilizes the 4-channel "4-ch" indicator in the control cluster to indicate whether the single or the multi-repeat functions are active:

The 4-ch indicator was used in a few 4002s that have the CD-4 decoder board installed, which essentially turned them into a Beogram 6000. Most 4002s do not have this upgrade, and so one rarely sees this indicator in action. Well, now there is a way to enjoy it!...;-)

This shows the indicator in action:

And here an impression of the very simple installation process:

The indicator assembly plugs into the 4-channel indicator illumination slot in the aluminum panel and it is secured in place with the screw that is used to bolt down the keypad. My goal is always to keep the design of the Beogram intact that my upgrades can be removed without a trace if desired at a later point.

This shows the deck in action with the auto-repeat function engaged:

The 4-Channel indicator is on permanently if just a single repeat has been selected. If multi-repeat is active (up to 10 repeat plays) the indicator blinks in a 1s interval. As the plays are executed sequentially the indicator switches back to permanently on when only one play is left.

The repeat functions are selected by pressing the 'up' key on the included paired Apple remote at any time before or during the playing of a record. Each time the 'up' key is pressed the number of plays increases by one. I set the maximum plays to 10, thinking about a situation where the deck is set into action but then forgotten. So a mechanism that automatically turns it off after some time is a good idea. The 8002 has a similar restriction, and I think for the same reason. This is Beolove!

Beogram 4002 (5514): Installation of a New DIN5 Plug With Gold Coated Terminals

The Beogram 4002 (5514) that I am currently restoring is making progress. In my opinion a Beogram restoration is only complete with a modern all-metal DIN 5 plug that has gold coated contact terminals. The original plugs are usually corroded and that is not a great thing for transmitting the precious signals from the MMC cartridge. Here is an impression of the original plug with oxidized terminals:

This shows the soldering job inside the new plug:

And here the final result:

Pretty, isn't it?? This is Beolove! On to adjusting the platter and sub-chassis...

Beogram 4002 (5514): New Transport Lock Bushings

Before I was able to adjust the platter and sub-chassis of the Beogram 4002 (5514) that I am restoring right now I needed to replace the disintegrated transport lock bushings. This deck had the orange type bushing and so it was not a surprise that they were gone:

Since the fragments were all over the place I took out the sub-chassis to make sure that there were none left underneath:

Rogue bushing fragments are sometimes an issue since the sub-chassis floats fairly close to the bottom of the enclosure, and if there are bushing splinters lodged between the chassis and the enclosure the chassis cannot float freely anymore, which impairs the vibration insulation of the turntable mechanism. 

After cleaning things up I installed my 3D printed replacement bushings :

There is a video about installing new transport lock bushings in my Beogram 4002 playlist. The bushings can be ordered directly from my Shapeways store. This is the link to the part. Two parts are needed per transport lock.

The next steps will be adjusting the platter and the chassis, and then do the tonearm weight calibration and arm lowering limit adjustment.

Beogram 4002 (5514): RPM Performance Measurement after Restoration of DC Motor and Control System

After rebuilding the DC motor and the control system of the Beogram 4002 (5514) that I am restoring right now, it was time to do a RPM performance test. I set up my BeoloverRPM device that allows the long-term logging of the platter RPM, and then did a 24 hrs test:

After the data was logged on my computer, I graphed it relative to a measurement that I took when I initially received the unit for restoration. This shows the two curves in comparison:

The red curve shows the performance before the restoration. The typical telltale sudden negative RPM spikes are visible that indicate failing brass sleeve bearings in the DC motor. This is very common for DC motor Beograms. In this case the spikes are still fairly moderate, but would have been audible since they are in the 1% range. The black curve shows the performance after rebuilding the motor and the installation of new RPM trimmers and RPM relay. The large spikes are gone and the variations are much smaller. There are still some variations, which are related to the intrinsically slightly erratic performance of the analog motor control system, which is affected by temperature changes and probably the moon phase (that was a joke...;-). Some Beograms show them others do not. At this point I do not have an answer why they sometimes occur. The good news is that they are fairly slow over time and also small enough that one cannot hear them. The short term 'wow and flutter' RPM changes (the high frequency 'noise' on these curves) are within the spec given in the service manual (0.05%).  So this Beogram is back in business.

Beogram 4002 (5514): Replacing all Electrolytic Capacitors and Rebuilding of the Platter RPM Control System

After rebuilding the DC motor of the Beogram 4002 (5514) that I am restoring right now it was time to update the electronics. I usually replace all electrolytic capacitors, install new relays to further reduce RPM variations and give the RPM control circuit modern 25-turn potentiometers that the RPM can be adjusted reliably. It is important to replace the aging Ta capacitors since they can fail via short circuit and go literally up in flames. This shows the main board in its original condition:

After the rebuild it looked like this:

the extracted parts are on the left. This is a detail shot of the 'RPM section':

The old Siemens relay was replaced with my custom designed replacement relay based on a modern encapsulated Japanese SMD relay and a breakout board that precisely matches the pinout of the original Siemens relay. This shows the part in detail:

I have a similar part available for the National relays that can be found in certain 4002 units. They are available to other enthusiasts. Just send me an email of use the contact form.

After doing the main board I moved on to replace the reservoir capacitor. This shows the original can:

the two contacts at the front are the positive ends of two capacitors that have their common ground on the back:

Such double-capacitors are no longer available, and I usually replace them with a custom designed 3D printed fixture that holds two modern 105C grade capacitors in place and that fits to the mounting strap of the original capacitor:

This shows it installed:

On to PCB#8 (the 'output board'). This photo shows the original condition:

The output relay is also a Siemens version, i.e. can be replaced with the same relay as the RPM switch relay above:

I also added a grounding switch that allows to connect signal and system grounds in case there are humming issues when connecting to a amplifier with RCA inputs.

Beogram 4002 (5514): Rebuilding a Noisy DC Motor with Oil Infused Bearings

Most Beogram 4002 with DC motor need the motor rebuilt at this point in time. Sudden RPM drops or a noisy motor performance are signs that the time has come. In this particular Beogram 4002 (5514) the motor was fairly noisy when running without load. I rebuild all DC motors when I restore a 4002 since these problems will sooner or later hit all of these motors. The main cause for these performance issues are drained oil infused brass sleeve bearings with 'permanent' lubrication. these bearings are made from porous brass, which are infused with oil under vacuum. This type of bearing is good for many years until the infused oil runs out. While the motor is running the infused oil continuously replenishes the oil film on the bearing surface. The spinning shaft slowly distributes the oil to locations outside of the bearing, eventually depleting the oil.

Since such low voltage DC motors with appropriate inductive tacho control feedback appear to have vanished from the marketplace, the only solution is to replenish these bearings with oil to give the motor another lease on life. The extraction of the bearings requires a complete disassembly of the motor. Otherwise it is not possible to get the bearings back in properly. This shows the motor disassembled. The bearings are the two small round items in the 'front row':

Once I had the bearings out I immersed them in a mason jar and pulled a vacuum with a FoodSaver pump. Immediately, air bubble started emerging from the bearing indicting that the infusion process had started:

After 24 hrs the process had abated and no more bubbles could be noticed:

I read that about 20% of the weight of such a bearing is the infused oil.

I extracted the bearings from the jar and reinstalled them. This shows the bottom bearing installed in the brushes carrier:

The top bearing needs to be installed by clamping the holding ring down on the spring that holds the bearing in place. This shows the bearing with the spring:

After slightly bending the tabs of the holding ring,

I used my special tool with adjustable pliers to clamp the tabs fully down:

This ensures that the bearing is held in place snugly as it was before disassembling the motor.

Then I put the motor back together:

After soldering the PCB back on it was time for a test with my bench supply:

A properly assembled motor should draw less than 30mA at 5V. If the current is higher the brush career plate needs to be loosened and the screws carefully tightened in several small steps in sequence around the motor (as you would tighten a vacuum flange).

These motors are very sensitive to improper alignment of the shaft with the bearings and they will not run well if this is not done properly. Another frequently encountered issue is that the motor runs in the wrong direction after assembly (or it runs not at all). This is caused by the brush carrier plate being mounted at the wrong angle relative to the permanent magnets in the motor. If that happens remove the screws, rotate the bottom plate by 120deg and try again. If it still not works properly, do another 120 deg and then it should run int he right direction. Generally, it is a great idea to make an alignment mark with a Sharpie pen before taking the motor apart...;-).

Alright, it seems this motor is running well again...the grinding/screeching noise went away. I will give it a RPM test with my BeoloverRPM device after I rebuild the main PCB with a new RPM relay and RPM trimmers. These items are the other leading trouble spots causing unstable RPM performance of DC motor Beogram 4002s.

Beogram 4002 (5514): Rebuilding the Arm Lowering Mechanism and the Tracking System

This Beogram 4002 (5514) had a completely stuck arm lowering mechanism. The lubricants had hardened to a degree where I needed to use a screwdriver to pry the linkages from their pivot pins. This is a frequently observed phenomenon, which is easily fixed by cleaning and lubricating the mechanism. This shows the solenoid and damper with linkages before I took everything apart:

This shows the parts spread out on my workbench:

This video shows how to rebuild the tone arm mechanism in detail. After putting the mechanism back together with fresh lubricants, I moved on to the damper to arm linkage. This shows the arms from the back. The linkage sticks out in the back under the yellow paint  marking:

To lubricate its pin the sensor arm needs to be extracted:

This linkage was also stuck and it can off including the pin on which it pivots:

After separating the pin from the linkage I glued it back in with a bit of epoxy and then reinstalled the linkage with a bit of silicone grease. This video shows how to get to the damper to arm linkage and re-lubricate it. Then it was time to put the sensor arm back in and align the arms to be parallel to each other and perpendicular to the carriage rods:

This concluded the restoration of the arm lowering mechanism, allowing me to move on to the tracking system. I usually install my SMD LED based light source to replace the original incandescent bulb assembly, which is not available anymore. LEDs are very long lived, so this promises trouble-free carriage operation for a long time.  I also replace the usually wobbly and/or cracked plastic carriage pulley with a precision turned aluminum unit, which can be had from Nick of Beoworld. I'll be happy to get other aficionados in touch with Nick, just send me an email. This shows the original parts in place:

After removal of the original bulb housing the tracking system aperture is visible:

This shows the 3D printed replacement part together with the original bulb housing:

My part has an integrated intensity trimmer, which enables a straight forward fine tuning of the tracking feedback sensitivity.

Here is an impression of the installed parts:

Pretty, isn't it?? I will adjust the tracking system sensitivity after I rebuild the PCBs.