Beogram 5500 Type 5943: As Received

 I recently opened up and examined a Beogram 5500 turntable audio component that goes with this Beomaster 5500 restoration I did earlier.

This Beogram 5500 does not function and appears to be dead.

Opening it into the service position I immediately saw a problem with the tangential arm assembly drive...the drive string was not connected.

Both ends of the drive string are disconnected and a bit tangled.

After sorting the drive string out and began to re-install it, I discovered a problem with the common mounting post for the two ends (Point H in the service manual diagram).

Mounting post "H" is missing.

It might be possible to make some sort of replacement but I do happen to have a parts unit Beogram 3000 Type 5903. It is in really bad shape and beyond restoration consideration. However, its internal parts are in good shape.

Bang & Olufsen used this same internal Beogram assembly on quite a number of their tangential turntables (including the Beogram 3000 and 5500).  I should be able take the white, plastic tangential arm assembly chassis (1106) from the Beogram 3000 and use it in the Beogram 5500.

Here is a photo of the Beogram 3000 arm drive mount on its 1106 chassis.
It clearly shows the missing mounting post "H".

On a positive note, I discovered this Beogram 5500 has a blown main fuse.
Replacing it got the turntable to turn on again and its motors run.

Beogram 4002: From Oil Cleanup to First Operational Test

My restoration plan for this Beogram 4002 project encountered a detour. After restoring the main board I intended to do the reservoir capacitor replacement and the output board. However, the rust and corrosion I found when starting the project got me thinking that I need to address that first. Applying rust neutralizer and painting takes time because you have to let the parts dry between applications.

Here are a couple of pictures of the worst rust spots again.

This Beogram is interesting in that it has some really nasty looking rust damage but the overall condition of the turntable is actually really good.

I decided to apply three coats of the rust neutralizer.

After 24 hours I painted the parts with black, oil based paint.

Now I can proceed with the normal restoration. Since I had to disassembly the chassis to get to all of the rusty areas I discovered there were a few puddles of oil in the Beogram. People often make the mistake of applying thin oil to the Beogram turntables...and too much of it.

Thin oil applied to the moving turntable parts end up being slung against other turntable parts. My next step was an oil clean up job.

I had removed the floating chassis to get to the first oil spill.

The tangential arm assembly needs going over anyway so I moved those steps up in my project schedule.

There is a lot of wet oil around the spindle bearing nut. That means thin oil instead of grease was used on the tangential arm drive spindle.

The tangential arm drive spins as it moves the tonearm and you can imagine how that would really throw loose oil like this around.

There was quite a bit of oil on the surface of the floating chassis but I found the most gathering of oil in the tangential drive sensor housing.

The oil could interfere with the sensor preventing it from working properly.
I cleaned all of this area up and put the tangential drive sensor assembly back together.

The tangential arm sensor should be in good shape now when I get to the record tracking adjustment procedure.

I moved on to the arm lowering damper. It was in good shape but I cleaned it and applied some light grease to its piston.

I discovered the tangential drive pulley had small, hairline cracks as most do by now. That makes the pulley deform when the set screw tightens to the spindle shaft. The result is a wobbly running spindle.

I am still amazed that the transport bushings on this Beogram are still really good. That is a rare sight.
Here is the new pulley. It is one of Nick's aluminum pulleys and it works as great as it looks.

I also performed and initial tonearm tracking force calibration. It is easy to work on the tonearm assembly when it is removed like this.

Note that I installed the usual Beolover mod where a small locking nut is added to insure the tonearm counter weight stays where the calibration put it.

That takes care of the initial tangential arm mechanical restoration tasks. Now I can get back to the electrical step of replacing the reservoir capacitor.  Here is the original one as pictured before I started the rust and oil clean up.

Here is one of my favorite Beolover replacement parts. The 3D printed housing with the new reservoir capacitors.

Before this nice assembly I use to glue the new reservoir capacitors to the cabinet floor. This is so much nicer and it uses the original Beomaster clamp.

I am getting close to running an operational test on this Beomaster. First I went ahead and changed the capacitor and muting relay on the output board. I still need to add the grounding switch but I will come back to that.

Here is the before picture of the output board.

...and here is the after.

Now for some reassembly. I have to re-install the rust repaired chassis components so the floating chassis can be put back. I also have to re-install the DC platter motor that Beolover restored for me.

Here are some pictures of various components as they are fitted back into the Beogram chassis.

Whew. It is looking like a Beogram again. I should be able to install the sub-platter, belt and top platter then give this Beogram a test run.

I love it when things work the first time.

Even though this Beogram thinks it is ready I don't trust it enough to try a record yet. I will run through the service manual checks first to make sure it is ready to play a record.

Beogram 4004 Type 5526: Tangential Arm Position Detector

Just a quick and short update...
I didn't get as much bench time as I wanted the last couple of days but I did sneak on long enough to connect power and adjust the Beogram's tangential arm position detector voltage.

Just like I did on the previous Beogram 4002 (Type 5513) project, I needed to verify that the base voltage of 1TR17 is at a nice 0.7 VDC when the light source 4D1 is illuminating the tangential arm position sensor, 4IC1.

It was a little off so adjusting trimmer resistor 1R88 was necessary to bring the voltage down. This picture shows the initial adjustment.

Once I re-attached the position scale I re-checked the voltage at 1TR17 base with the 4D1 LED at a transparent part of the scale.

I then ran the Beogram tangential arm through some of its operations. Everything worked great.

Later tonight I will measure and adjust the new 2M ohm trimmer for the fixed arm record detector.

Beogram 8000: Replacing the Platter Tach Disc and Cleaning the Tangential Arm Assembly

Tonight I completed the tangential arm assembly cleaning and lubrication as well as changing the platter tach disc to a new, metal replacement.

The Beogram 8000 turntables started out with a plastic tach disc containing transparent and black markings that a photo-sensor uses to send pulses to the Beogram microcomputer. The microcomputer dials in the 33 1/3 RPM and 45 RPM speeds with these pulse signals.

Unfortunately, over time these plastic discs did not hold up so Bang & Olufsen replaced them with metal discs. As I mentioned at the beginning of this project, it is quite surprising that this Beogram 8000 actually has an original, functioning tach disc. Feeling that it is on borrowed time we decided to go ahead and give it a more permanent tach disc that Martin Olsen supplies. 

Here is the Beogram 8000 center hub with the tach disc next to the replacement disc I got from Martin Olsen.

...and here is the replacement installed.

Before testing the new tach disc I took the opportunity to clean the floating chassis and take care of some maintenance on the tangential arm assembly. I always clean off old oil and grease from the tangential arm drive so I can inspect the parts and apply fresh lubricants.

I was surprised to discover this Beogram's tangential arm drive screw bushing has a badly worn edge. It appears to come from the stress of the arm return travel.

This picture shows the worn bushing and the floating chassis before cleaning.

Here is a better look at the worn bushing after cleaning the parts.

For now I decided to turn the bushing around. That gives two solid edges pressing against the black, plastic transport bracket during the return travel of the tonearm. The stop travel puts the most stress on the bushing. During play the forward travel is in very small increments so there is very little stress on the bushing.

I reassembled the tangential arm assembly to give the new tach disc a test run. 

The Beogram speed testing with the new tach disc went great. The two speeds immediately lock in. I did some quick tests of the tonearm navigation and so far it runs very smoothly. Later, when I get to the record tracking tests I will re-evaluate how solid the tangential arm drive is working.

Next up I will re-install these components back in the main Beogram chassis and start on the mechanical service manual checks. It is getting close to actually playing some vinyl on this baby.