Beogram 8000: Repair of a Scraping Sub-Platter with a 3D Printed Insert for the Main Bearing

The next item to look into with the Beogram 8000 that I am restoring right now was that the sub-platter scraped along on the chassis. This shows the interior of the 8000 with the sub platter still in place:

Somehow the platter was situated a few 1/10ths of a mm lower than usual, which made it touch the sub-chassis base plate in a few spots. This prevented the deck from maintaining a constant speed (it never showed 33.33 on the display, just 33, which is a signal that the RPM is off). Also it made an intolerable mechanical noise. Far from Beolovely! 

This seemed strange to me (there is no way to adjust platter height like one could in a Beogram 4002) and so I poked around a bit on the internet. I came across an uttering by one of the greats in this business, Dillen of Beoworld: "Typical symptom of a broken main bearing nylon insert. It happens often if the Beogram was transported with the heavy platter mounted or just put down too hard." (my customer confirmed that the ebay seller did not take out the main platter when he/she shipped it to him...).

He went on to say "The whole weight of the platter, hub and sub-platter rests on the very sharp pointy tip of the hub spindle. Only fix is to replace the nylon insert."

This shows the spindle after lifting out the sub-platter:

In the pic the tacho sensor is already out of the way (it swings away by moving the brass lever clockwise). In that position one can pull out the spindle:

The picture shows the pointy end of the spindle that rests on the plastic disc that Dillen mentions in his post.

The plastic disc can be pushed up using a small hex wrench or similar (there is a small hole on the bottom of the bearing that can be accessed from underneath the enclosure. This shows the white plastic (probably nylon) insert in the main bearing:

And after pushing it up:

First I tried to simply flipping it around, but there is no indentation on the back of the plastic part for holding the spindle in the center of the bearing. So my idea was to simply shimming the insert up a bit to lift the platter back to its normal height. The insert still seemed in decent condition, only the indentation was a tad too deep after the incident, causing the platter to be too low. 

I designed a small disk that I printed with my 3D printer:

After a few tryouts with different thicknesses it turned out that 0.7 mm was a perfect thickness to raise the platter just enough to not scrape anymore (test with the main platter and a record on top if you do that at home...).

The disc is easy to insert when the insert is up sideways:

Once the printed disc was next to the insert, it is straight forward to push the parts back to horizontal and down into the bearing.

Once I installed the spindle and the platter again, everything was fine. No more scraping, and the platter turned freely.

Beogram 4002 (5513): New Gold Plated RCA Plugs

Most Beograms have corroded DIN or RCA plugs at this point in time, and so it is a great idea to replace these connectors with new gold plated units. This particular Beogram 4002 (5513) was originally outfitted with RCA connectors.

I usually use modern quality big all metal plugs as replacements, but in this case an additional boundary condition was that the Beogram will be connected to a Beolab 5000, which has all connectors in a small compartment integrated into the bottom of its enclosure. While this is very elegant and hides the cables under the unit, it also is very restrictive with regard to what types of plugs can be used.

I finally settled on some all metal plugs made by Rean that are gold plated. They are short enough to fit into the Beolab compartment. However, like so many of these plugs they have gargantuan exit openings for the cables, which may be a concession to the modern trend to use very thick cables (which in my opinion is another snake oil concept to extract money from unsuspecting enthusiasts, but that is a different topic...;-). I did not like the looks of this, and so I decided to design small 3D printed inserts that would solve this issue and also allow me to color-code the plugs in an elegant way:

Then I soldered the plugs on:

This is how they look assembled:

Beolovely! Here is an impression of plugging them into my Beolab 5000:

A close fit, but leaving just enough room to get the cables out. The final job on this Beogram is to restore the hood which has a few bad scratches.

Beogram 4000: New Arrival from Italy

Exciting! Another Beogram 4000 found its way to my bench for a full restoration! TNT brought it over to the US in an amazing three days. I extracted it from the box. It was quite well packed and arrived safely. The exterior of the unit is pretty decent. No damages to the veneer and the hood is absolutely polishable:

The aluminum trim in the back of the hood came off on one side, but that can be fixed with double sided tape. After I opened it up and removed the aluminum plates (which are in dire need of a deep cleaning) I found that the carriage pulley had come off during transport:

Luckily the parts were easily found in the enclosure:

As usual the main key of the control pad extracted itself from the spring that holds it in place. This proves that it is absolutely necessary to tape the keys down for transport. I reinstalled the pad, switched the unit to 110V and plugged it in (keenly watching for potential smoke...;-). Nothing happened, so I pressed 'ON' and the carriage set itself into motion in search for a record. It stopped as expected at the set-down point for 12" vinyls. So far so good. However the solenoid did not engage. I moved the assembly a few times up and down by hand and then tried again, and there was a life sign. Very reluctantly the tone arm lift engaged after a tired motion of the solenoid plunger...

The unit came with the indication that the arm would not lower. It is clear that this unit needs a full clean and rebuild of the solenoid/arm mechanism. Also the solenoid looks strange and may be a non-B&O part. Other than that I found that the RPM switches are oxidized and do not work every time one presses them. The restoration will cure all that. On the good news end a working strobe light can be noted. 

In my opinion one of the intriguing features of the 4000. The position indicator, which is another remarkable design feature, was already broken once and glued back together. This indicates that this unit was in 'expert' hands at some point. The glue job is fairly well, done, though. 

Furthermore, the indicator light bulbs are dead. My SMD LED replacements will fix that for good. All in all I am pretty confident about this project. This Beogram 4000 is a good starting point for a full restoration, which will take it to near-new performance and looks.

Beogram 4000: Replacement of Incandescent Light Bulbs in Control Panel with LEDs

The Beogram 4000 that I am restoring right now had three broken incandescent light bulbs in the control panel. There are four bulbs, two for the position indicator and one each to illuminate the RPM trimmers. When I initially turned this deck on, no light came from any of the bulbs. Nonetheless, one of the position indicator bulbs was still o.k., but since the two bulbs that illuminate this indicator are in series, this did not help. At any rate, this is a perfect demonstration how fragile these bulbs are at this age, and that a replacement of them with LEDs is a great way to enhance longevity and reliability, and to make sure the unit survives shipping.

I recently developed dedicated SMD LED based replacement units that drop in for the position indicator bulbs. I assembled two and replaced the bulbs with them. I also replaced the RPM trimmer bulbs with high intensity red through hole LEDs fitted with appropriate 3.3k current limiting resistors. This brought them down to the proper intensity, making for a gentle but clearly visible low power illumination of the trimmer slots. 

Here are some pictures of the process. This picture shows the original light bulbs in place:

This picture shows the SMD LED PCBs that I used to replace the two position indictor bulbs:

and here after installing them and putting in the two red LEDs to replace the trimmer illumination bulbs:

After I was done with this I tested the functions of the keypad, and I had to realize that the deck does not switch to 45 RPM. Pressing the key did turn on the 45 RPM trimmer illumination, but the motor stayed at 33 RPM. This meant that the control system worked fine, but that there was an issue at the executive end of things. I traced the signal and found out that the relay that is responsible for changing the resonance frequency of the drive oscillator seems to have given up its ghost. It will be interesting to find a replacement.

Beogram 4000 Arrives From UK! Solenoid Oscillates!

I just received another Beogram 4000. This time from the UK. The unit is in decent condition, at least it has the MMC cartridge mount intact and the sensor arm insert is still there. The cueing/tonearm lift control panel came loose during transport. A great idea to tape them down. Luckily, the seller had the deck covered with a heavy duty plastic foil under the hood, so nothing bad happened. It will be straight forward to re-attach the panel.

Inside it seems everything is present:

But of course, like most units of this age it passed through some less-inclined hands and suffered a bit. I am not sure what attracts people to cutting off power cords, but this one, like the one I just obtained locally, had its power cord severed. So I bought a power plug and attached it to the cord:

Then it was time to plug it in. The first thing I usually do with a Beogram of unknown provenance, I measure if the voltage rails are present. At C1 one can measure the rectifier output for the 6V rail that drives the control system. It should be somewhere around 12V:

And on C2 one can measure the regulated 6V rail:

This looked pretty reasonable, so I went on to the 24V rail that is responsible for the power side of things. First I went for the rectifier output at C3:

And then for the regulated 24V rail at C4:

This seemed within spec, so these capacitors seem to have some remaining life left in them. I will exchange them anyway, but this was good enough for an initial turn-on of the deck.

I pressed the start button. Happy moment: The strobe lamp still works:

The carriage was also set in motion (good!), but then at the point where the tone arm should have been lowered into the lead-in groove of a 30 cm vinyl, a strange phenomenon occurred: The solenoid emitted a loud noise and its plunger oscillated rapidly. A 2 min video is more than a 1000 words, so I made one! Here it is. It demos the issue and shows how I repaired it.

Essentially, all it took to fix this was to reattach the lead that connects the emitter of TR4 to the current limiting resistor that is on PCB #7:

Let's see what else this Beogram has in storage for the Beolover!

Beogram 4000 Arrives! First Impressions!

Lucky Day!! Today a Beogram 4000 arrived in my driveway. It is a bit of a project, but came with a pristine MMC20EN cartridge (I am listening to Miles Davis 'Water Babies' right now with it! - Awesome!).

Also the exterior and the hood are in pretty good shape. And a really nice condition platter. Here are a few first impressions:

Nice control cluster (disregard the Sharpie marks under the position indicator for now...;-):

Lovely platter:

Here comes the sad part: The sensor arm insert is missing and the cartridge mount came off with the cartridge. It was not taken off for shipping and probably took a hit during transport. Actually I did not know that it had a cartridge on there...anyway, now I am really interested in making my cartridge mount replacement part perfect...;-). 

In fact it is interesting to see how B&O designed these first mounts. They were done with flex board, very similar to my approach, and the plastic part was simply molded in a shape that 'bulged' the PCB a bit at the end of the mount to press it into the cartridge contacts. Later designs are based on metal contacts and a rubber sub-structure that also renders the mount contacts flexible. All this makes me hopeful that I really might be able to get this mount replacement part going. Now for the sensor arm insert, well, I guess a 551x might have to bite the bullet and take one for the team. The mighty 4000 has precedence!

A few more impressions...real expert work on the RCA plugs,

and also on the power cord. Did they think this is an electric lawn mower??

All in all, I'd say not too bad! I am looking forward to getting this baby going again!