Beogram 4002 (Type 5513): Full Functional Restoration

This post describes the functional restoration work done on a Beogram 4002 (Type 5513) from a customer in Florida. This post discusses the initial assessment of the unit.

This is the unit with the panels off:

It was in pretty much original condition, except that someone had already done some work on the platter motor, as was evident from the upside-down installed pulley:

I extracted the motor and took it apart to get the bearings out for oil-infusion:

The bearings are the two small donuts up front on the black pad. Most of these DC platter motor need fresh oil in their bearings at this point in time. This can be done by immersing them into motor oil under vacuum:

The bubbling represents air drawn from the porous bearing material. This allows oil to inter diffuse into the material. These bearings were partially 'thirsty'. It took about 4 days until the bearing stopped, and they were ready for prime time again.

So in the meantime I focused on the rest of the functional restoration. A critical point that needs to be done for all Beogram 400x is to take all the mechanics on the carriage apart. This includes the arm lowering and the lateral translation systems:

This shows the parts after disassembly:

And after a through cleaning process involving ultrasonic cleaning and some chemical helpers:

Beo-sparkling-lovely! I finally found some suitable rubber washers that can replace the occasionally worn washer on the damper plunger:

A new rubber washer for sealing the plunger is essential for reproducible and reliable arm lowering.

This shows everything re-implanted:

One more item needed to be addressed: A frequent trouble spot in the arm lowering system is the linkage that connects damper to arm. you can see it here poking out above the "V" shaped cut in the lever that is bolted to the end of the arm assembly:

If one wants to get to the pivot point of the linkage, it is required to remove the sensor arm fixture:

As usual, the small copper plate that helps the arm slide in up position came off:

It is glued to the base with a usually degraded double sided tape. I epoxied it back into place after cleaning the tape residues off:

Then I removed the bulb-based tracking sensor light source to replace it with a LED based component. This shows the original setup:

and with bulb housing removed:

This reveals the aperture that is used by the mechanism to measure the arm movement. Here are the original bulb and the replacement part shown together:

I installed the replacement. The small white item on top is a potentiometer that allows adjusting the light intensity. This can be of great help when calibrating the tracking response:

The final 'act' of the carriage restoration was to replace the as usual cracked carriage pulley:

In practically all Beograms that I have encountered so far there is a hairline crack in the shaft collar that makes it impossible to fix the pulley to the shaft properly. I replaced it with a nice precision machined aluminum replica:

Beolovely! On to replacing two more light bulbs in the RPM trimmer panel above the keypad. This shows the panel removed and with the bulb covers off:

I removed the bulbs. This shows the two Beolover replacement drop-in ready LED replacement assemblies prepared for installation:

They solder directly to the solder points where the bulbs were connected:

On to restoring  more of the electronics. This shows the original reservoir capacitor of the control system:

They often leak and/or are out of spec and should definitely be replaced. This shows the Beolover replacement in place:

Then I replaced the final light bulb, the one that is in the sensor arm for detecting the absence of a record to prevent arm lowering. This shows the bulb compartment pulled out with the Beolover replacement parts next to it:

I unsoldered the bulb and installed the LED setup:

This shows it in action. The warm-white LED ensures that there are enough red photons to properly illuminate the B&O logo at the end of the arm:

Then I focused on the main PCB. While it is still installed, it is a good moment to replace the two power Darlingtons on the solder side. This shows the original TIP120 that was in charge of regulating the 21V system power rail:

I replaced it with a contemporary unit:

Sadly, I forgot to take a picture of the PCB component side before getting 'down to it'. So here just the result of my labors...;-):

I usually replace all the electrolytic capacitors, the relay, the power transistors, and the sensor transistor which often lost some gain, making record detection unstable. After the board was retired I calibrated the sensor transistors biasing to get 4V at the collector.

Then I moved the trimmer below deck to the component side

and measured the sensor response:

It passed with flying colors showing a whopping 9V amplitude. Each drop on the trace above represents the passing of a black rib under the sensor. This is used by the control system to detect if there is no record on the platter, and if so, to disable arm lowering.

I also restored the output PCB. This shows it in original condition:

And after replacing the relay, the relay time constant capacitor and installation of a (red) switch that allows connecting signal and system grounds (this is often a very effective remedy if there is some degree of ground hum):

This concluded the work on the electronic system.

Like many DC motor Beograms, this unit had degraded transport lock bushings:

This shows one of them after removing the upper part of a lock:

When this is encountered, it is best to remove everything from the enclosure that bushings fragments can be vacuumed out. Otherwise they can get stuck under the floating chassis and impede its motion. This shows the empty enclosure:

This are the replacement bushings:

They are composed of two parts, which makes the installation a snap:

Then I focused on the plinth guidance washers. This unit has already metal ones installed, but one was missing up front:

I replaced it with the one from underneath the keypad, which I then replaced with a nylon replacement:

Then I focused on the badly corroded RCA plugs:

This unit seems to be a 'factory RCA' issue. I replaced the old plugs with new all-metal types with gold plated terminals:

This shows the red and black inserts identifying right and left channels:

Then I did a 24 hrs RPM stability test with the re-assembled motor, which is a must after restoring DC platter motors. This shows the BeoloverRPM device that can log the RPM over long periods of time:

This is the curve I measured after ~24 hrs:

This is as good as it gets with the Beogram 4002 DC motors!

Before finally playing this deck for the first time, I needed to do all the adjustments. After adjusting platter height and level, getting the sub-chassis to float freely and the platter line up with the aluminum platters, it was time to adjust the arm. This shows the arm lowering limit adjustment completed. This is an important one, since it will prevent a catastrophic needle event in case the record detection circuitry malfunctions:

Then I replaced the flimsy circlip that holds the counterweight in place with a nut, which can be tightened. This makes the calibration stable enough for shipping:

Then I adjusted and calibrated the tracking weight with a digital scale:

Then it was time to give the aluminum panels a deep clean and put the deck together for a first celebrating spin! I selected a wonderful record from Ian Carr's Nucleus: "Out of the Long Dark". He is definitely one of my favorite trumpet players! He recorded this album in 1979 on Capitol Records (ST-11916).

Of course this record had been ultrasonically cleaned on a CleanerVinyl ProXL Ultimate Kit together with a UC-3360 multi-frequency cleaner, restoring it to its original glory. A beautiful combination!:

So far this deck plays very nicely again. I will now test it for a couple of weeks, trying to make sure that there are no intermittent issues. Unfortunately this deck still has a couple cosmetic issues: The plinth has a strangely 'bleached' area in the center of the front part, and the keypad has the usual use-pattern:

I hope these issues will be alleviated while I test this Beogram, and then it will be time to send it back to its owner!