Beogram 4004 (5526): Partial Restoration and Installation of Beolover Commander Remote Control Module

After I repaired the hood of the Beogram 4004 (5526) from Florida, its owner decided to let me do a partial restoration. The unit had shown some platter RPM inconsistencies in the past, indicating that the DC platter motor bearings started to run dry of their oil reserves. This shows the unit with the aluminum panels and platter taken off:

As usual, the first step was to extract the DC platter motor

and disassemble it to get the bearings out for oil infusion:

The bearings are the two small donuts on the black pad upfront. I immersed them in motor oil and pulled a vacuum. Immediately, strong bubbling started:

These bubbles are the air drawn from the porous Oilite bearing material. This makes room for oil to inter diffuse into the bearing. This process usually takes 2-3 days, and so I put the motor aside and focused on the other restoration tasks.

Like most Beogram 4004s, this unit also had degraded transport lock bushings:

While one can ignore their degradation as long as the deck is not moved, the fragments can cause the floating chassis to get stuck if they make it underneath during the rigors of transport. So it is essential to remove all the little bits and pieces when the bushings are finally replaced:

For this it is best to remove the 'guts' of the unit and then put a vacuum cleaner to it:

After removal of all the debris and dust it was time to install the 3D printed replacements. They come in sets of two, where each bushing is replaced with interlocking top and bottom parts for easy installation:

This shows the bottom part in place

and the top part added:

Then the lock mechanism can be reassembled:

After the transport locks were done I replaced the reservoir capacitor of the unit. These big 'cans' often start leaking and then they lose their capacitance causing operational issues due to an unstable power rail. This shows the original capacitor:

And the modern replacement:

Since the unit has a keypad that is still in pretty good condition, my customer decided to get the Beolover Commander remote control module installed:

The Commander allows controlling the deck entirely without touching the precious keypad via a paired Apple remote control. Which is a great idea since the coating that is on the keypads degrades over time due to the acids and fats from the skin when touching the pads. Read more about the Commander here.

The next step was to replace the cracked plastic pulley of the carriage spindle with a precision machined aluminum replica (send me an email if you need one, too. I'll be happy to get you in touch with the B&O aficionado who took it upon himself to create these beauties)

Then it was time for all the adjustments. First I aligned the arms with the platter and then the platter with the aluminum panels that surround it. Once that was all up to spec, it was time to calibrate the tracking weight. I usually install a M3 nut on the screw that is used to adjust the counter weight. This makes the calibration much more stable over time and it can easily survive transport that way. This shows the original circlip that holds the screw in place:

And here after replacing it with a square M3 nut and a washer:

I use a digital gauge to calibrate the spring based tracking force mechanism scale to be accurate around the usually used 1.2g for B&O cartridges:

Another important adjustment is the arm lowering limit:

Basically the needle needs to be able to go beyond the record surface when the arm is lowered, but not far enough to hit the black ribs on the platter. This is a safeguard against electronics malfunctions that may cause the arm to be lowered without a record on the platter (when everything is in order, the Beogram recognizes the absence of a record and the arm lowering mechanism is disabled).

Then it was time to adjust the tracking feedback sensitivity to make sure the arms remain about parallel when a record is tracked:

After I was done with the above tasks, I had a look at the bearings and the bubbling had stopped. This indicates that the infusion process is complete. So I broke the vacuum and extracted the bearings:

I reassembled the motor and installed it for a 24 hrs RPM stability test with the BeoloverRPM device. The BeoloverRPM allows logging the RPM in 10s intervals over extended periods of time. Perfect for the detection of intermittent RPM issues. Another great function of this little device is that one can adjust the RPM precisely:

This is the curve that I measured:

This is pretty good as far as Beogram DC platter motors go. The slight choppiness of the curve is observed with some of these motors after restoration. It usually goes away after playing the deck for a while as the bearing surface is polished by the rotating shaft due to the torque exerted by the drive belt. At any rate these small fluctuations are far smaller than what the human ear can detect. So it was time to clean the aluminum panels and put the deck back together for a test drive.

I selected a vintage vinyl that I recently bought, "Softly...but with that feeling" by Herb Ellis. This near-new condition Japanese pressing was of course cleaned ultrasonically with a CleanerVinyl ProXL setup before listening.

Here is a picture of this beautiful Beogram together with this lovely record:

A perfect combination. The deck performed admirably during this test spin. I will now play it a bit more and then, if nothing else comes up, it is time for it to be picked up by its owner!

 

Beogram 4004 (5526): Repair of Cracked Hood Hinges

I recently received a Beogram 4004 from Florida for some TLC. The first order of business was the repair of a cracked plexiglass hood. My customer decided to have it fixed since it is in a pretty decent shape except the cracked area. As usual, the crack was around the area where the hinge gets bolted on:

Luckily this was a fairly clean break, and all the fragments were still present:

After I removed the hinge and the aluminum strip side parts it became evident that the other side of the hood also had the same issue, but the parts were still loosely together:

After removing all traces of the old contact cement that held the aluminum strip to the plexiglass, I glued the parts back together with Weld-On #4 acrylic solvent. It can be used if the parts still fit together very well, which allows capillary forces to suck the solvent into the cracks. Once the solvent is in, simply press the parts a bit together and hold for a few seconds. That is it:

On the other side I just bent the cracked off part a bit to enlarge the gap slightly, and that was enough to let the solvent in to mend the parts back together:

Then it was time to install my hinge patches. They are pressed into place with 3D printed clamps that allow the application of significant force on the patches. This basically 'immerses' them into the plexiglass of the hood, as is evident from the dissolved material that gets squeezed out on the fringes:

After letting everything harden for 24 hrs, I removed the clamps:

I drilled out the mounting holes and restored the flat head recesses with a counter sink. Then I was able to bolt the hinge back in:

The final step was to glue the aluminum strip sides back to the plexiglass with contact adhesive. this shows the left side of the hood:

And the right side. Unfortunately, a small amount of solvent was sucked under the blue tape that I used to protect the hood. This left a minor pattern on the plexiglass next to the aluminum strip. If this hood were polished it could probably be removed.

Finally, I replaced the worn rubber pumpers at the front of the hood. Their material degrades over the years. They can be replaced with a small piece of 2mm Viton O-ring. The first step is to drill out the remnants of the decayed material with a 2mm bit:

Then the O-ring bit can be glued in with super glue gel and trimmed to 1mm length:

Beolovely! This hood will close gain with a nice soft 'thump' when the bumpers hit the plinth.