Beogram 400x: Cleaning and Re-lubricating the Tone Arm Lift Mechanism

The Beomaster 4002 (5513) that I am currently restoring exhibited the usual issues with the tone arm lift mechanism: The mechanism occasionally failed to lift the arm up in time before the carriage started moving back (scratch & ouch!) to its home position after pressing the 'Stop' button, or at the end of the record. Also, the relay sometimes clicked before the arm was completely lowered. All this pointed towards time-hardened lubricants in the lift mechanism. The cure for this type of behavior is to take the mechanism apart, clean the old lubricants out and re-lubricate it with a suitable grease. I use a silicone grease. This type of grease is well-suited due to its generally non-corrosive behavior, its compatibility with rubber and plastic parts, and its long-term stability.

The restoration process is straight forward, but requires a bit of insight into the mechanism. For this reason I took the opportunity of this restoration to add a short video about the process to my Beogram 400x YouTube playlist. The video also shows how to adjust the arm lowering time to achieve precise coordination with the output relay activation. Here it is:

Beocord 5000 (4715/4716): Exchanging the Belts

Once the tape mechanism was extracted from the Beocord 5000 (4715) that I am currently rebuilding it was time to replace the limp decaying original belts. I pretty much followed the procedure that I am showing in my YouTube video:

I improved the procedure in one point, however: I realized after doing it the first time that the alignment of the eject lever relative to the tape mechanism is crucial to get the proper action point when pressing the eject key once the unit is completely reassembled. Last time it took me quite a while to get this properly readjusted, since I only marked the position of part #256 ("lever") with a pencil, which was not precise enough. This time, I put a couple dabs of white paint where the part connects to the drive mechanism. Here is a picture:

This resulted in a much more accurate reassembly once the belts were in.

Here are a couple pictures of the newly installed belts:

I did the bottom belts first:

Here is a shot of the belt that drives the spindles and the free-wheeling mechanism. I also put a new light bulb in there - the old one looked pretty black, indicating little remaining lifetime:

After I put the drive back together and plugged it in, it turned out that the take up spindle would only occasionally feel like doing its job, usually after a making a clicking noise. It turned out that the retaining ring that holds the spindle assembly together (part #173 on the schematic below) was not seated properly. This caused the axle to have to much play at the top (top part of sequence #168), which resulted in random disconnects from the second part from the top in #168. Since this part engages with the cassette tape, this caused the tape not being wound anymore during play. A crumpled tape was the result. Luckily, I expected such issues, and used an old unwanted tape that has already a bunch of crumply regions...;-).

Here are a couple pictures of the part taken when I extracted it for inspection:

The small wheel at the bottom drives the counter, and is below the center plate of the mechanism. The above picture shows how I extracted the part after removing the retaining ring that holds the counter wheel in place, and the entire mechanism together. 

After I put everything back together a second time, the mechanism started to work normally. On to the recap of this unit.

Beocord 5000 (4715/4716): Extraction of Drive Mechanism

Experience makes life easier! This is my second Beocord 5000 restoration, and so I further streamlined my 'tape mechanism extraction' procedure that I outlined in my earlier post about replacing the belts in these units where I also posted a YouTube video about this process. The first step is to open the unit up. This time I took the plexiglass cover off since it needs to be polished anyway. This makes it much easier to extract the tape mechanism. I also lifted the preamplifier and radio amplifier boards up, since this unit will receive a full recap. Here is a picture of the 'unfolded' unit:

Inspired by earlier comments by 'chartz' of Beoworld.org that one can leave the solenoid in the enclosure when extracting the mechanism I realized that one does not even need to loosen the solenoid fixture if one takes out the screw that holds the bottom cover of the drive in place before taking the mechanism out (I wondered last time why there are three access holes in the front of the enclosure, but did not realize the purpose at that point - live and learn...;-).

That way one does not loose any of the alignment, except for the height of the tape mechanism. This issue was tackled by putting some small dabs of white paint on the two screws that hold the mechanism up relative to the solenoid bracket. Here is a picture of the right screw, and the screw that holds the bottom cover (that is the one that sits in the square cutout of the solenoid bracket):

When I took this picture, I was still of the opinion that I needed to move the solenoid a bit forward to get the tape mechanism out, so I marked the position of the bracket relative to the enclosure at the bottom, too. But as said above, this is not necessary. All that is needed is to mark the position of the screws that hold the mechanism to the solenoid bracket (the slightly rusty screw near the center of the photo). 

So, in summary, all one needs to do to get the drive out is to take these three screws out at the front, unplug the plug that connects the heads. After driving the counter screw at the back all the way out the drive can be lifted up and unplugged from the connector at the back and taken out (this pic shows the solenoid bracket loosened - I was still in the learning process...;-):

The next step is replacing the belts.

Beocord 5000 (4716/4715): Removing the Drive Mechanism

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Note: This post is 'historic'. There is a much easier way to extract the drive from the enclosure without lifting the Pre-Amplifier board (PCB #1) and removing the solenoid linkage as is described here. Check out my subsequent post about this process, which discusses the updated procedure.
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Per advice by 'chartz' and 'sonavor' of Beoworld.org (here is a link to the thread) I started working on replacing the belts of my Beocord 5000 (4716), which are all out of spec...they expanded over time and have too much slack. 

The first step is to take the drive mechanism out. In order to do that one needs to first flip up the board on the left to be able to get to the solenoid linkage. Chartz suggested to bolt the operating panel in reverse orientation back to the bottom of the enclosure with three screws. A great idea! This helps preventing breaking leads off when manipulating the expanded mess. Here is a pic:

The next step is flipping up the board on the left. This board is held in place by one screw in the back right corner, as well as a screw into the bottom of the enclosure next to the red DIN socket in the front part of the board. After removing the board one can move it a bit to the right to pull it out of the slits in the two brackets on the left that hold the board in place. 

A great thing is that there are two more slits that point upwards where one can secure the board in upward orientation. At this point it is a great idea to protect the plexiglass cover with an old T-shirt or the like from scratches. In my pic this was not implemented yet, as I was still ramping my learning curve...;-):

So far so good. Now it was time to get the drive out. 

The first step is to remove the solenoid linkage:

This requires removing the retaining ring that holds it on the shaft it pivots on. This requires a retaining ring removal tool. since the ring is seated flush with the linkage, this is a bit painful: I was able to get it off unscathed by carefully prying it open with the retaining ring tool, while jamming a small screwdriver in-between the ring and the linkage, thereby pushing the ring up. This enabled me to get the tool further in, which then allowed me to remove the ring just by prying it open and moving it further upwards.

Once the ring is gone, the linkage can be rotated 90 degrees, and removed:

the next steep is to remove the plug that connects the heads (make sure that the deck is unplugged when the plug is pulled to prevent magnetization of the heads - not sure why, but that is what it says on the half-obscured small print warning label in the operating panel - obscured and small print: that is how warning labels should be..;-):

After this I unsoldered the solenoid connections:

The drive is held at the front by two screws that go in from the bottom of the enclosure into the solenoid bracket. Here is a picture from below the enclosure:

These screws needed to be removed or just loosened that the drive can slide forward.

In the back there is no screw that holds the mechanism, only a bracket that fits into a slit in the mechanism. By sliding it forward the drive can be lifted out.

Almost done. The last step was to remove the large wire to board connector from the back of the drive:

This connector sat fairly snugly, and I had to carefully pry it loose with a small screwdriver from the side, and then pull it downwards. At that point I wished I had taken out the plexiglass cover for better access, but finally it came loose, and the drive was liberated.

Here is a pic of the drive after I took it out:

And the 'cavity' left behind in the enclosure:

That is it for today...next step is to partly dismantle the drive mechanism to get at the belts.