Beogram 6000 (5512): Replacement of the Sensor Arm Bulb with a FlexPCB Based LED Assembly

The final light bulb to replace with an LED in the Beogram 6000 that I am restoring right now was the bulb in the sensor arm. It is arguably the most difficult bulb to replace due to the space constraints, as well as the design of the control system, which demands that a current comparable to a light bulb flows though the light source in the sensor arm. More detail about the specifics can be found in this recent post where I implanted it into a Beogram 4002.  Here are a few impressions of the process for this particular Beogram 6000:

This shows the original light bulb:

This is the replacement assembly based on a Kapton flex PCB that folds into the bulb compartment and places the LED in the right spot:

And this shows the LED in action:

Like all Beolover parts featured in this blog, this assembly is available to other enthusiasts. Just send me an email or use the contact form on the right.

Beogram 8002: Recapping Complete

For the replacement of the electrolytic capacitors I will pick up where I left off...with the Beogram 8002 transformer box that I opened up. The 27uF capacitor for the motor circuit will be replaced using Beolover's nice 3D printed assembly. I like to measure the old capacitors to see how many are bad, out of tolerance or on the verge of being out of tolerance.

The original 4C1 27uF capacitor of this Beogram is out of tolerance by almost 20%. 

The replacement part just drops into the transformer box and the two leads soldered to the new 4C1 27uF capacitor. This is a bipolar capacitor so it doesn't matter which wires to connect to the capacitor module leads.

That is way better than soldering a new capacitor and letting it dangle loose inside the transformer box.

The next capacitor is the 2C28 47uF capacitor in the microcomputer case. I cleaned off the old thermal paste (that was starting to dry out) from the microcomputer integrated circuit and the heat sink. The 2C28 capacitor was replaced and new thermal paste was added to the heat sink. The replacement of the 2C28 capacitor is a little tricky as the negative side of the capacitor must be soldered to the board on both the trace side and the component side as noted by Beolover a while back.

For the Beogram 8002 main board I replaced all of the electrolytic capacitors 2.2uF and less with WIMA MKS capacitors (the rectangular, red capacitors in the picture). The rest were replaced with new 105°C, long lasting electrolytic capacitors. For the large 1C27 2200uF, 50V capacitor I like to use the three prong base off an original Beogram 1C27. I had a spare base so I used it here.

The center hole is for the capacitor positive lead. I take the capacitor negative lead and solder it to the metal base. After that I use black hot glue to secure the rest of the capacitor to the base and place it on the board. This makes for a solid installation of this capacitor like the original.

The last two capacitors are on the Beogram 8002 chassis - 0C1 and 0C2. These are easy to get to. Just remove three wires (the yellow, black and blue).

The next picture shows how close together traces are on the Beogram 8002 main board. When re-flowing the solder joints of the board connectors it is best to use a smaller tip on the soldering gun. If the tip is too wide it is really easy to accidentally create solder bridges between traces. I have to use a magnified lamp when soldering on this board to tell if the result is good.

That completes the electrical restoration of the Beogram. A quick check of the work with the Beogram turntable assembly verifies that everything is good.

Now it is on to the service manual adjustments which will make sure this Beogram is ready for full use again.

Beogram 4004 (5526): A New Arrival from California

A customer in California who already bought some Beolover parts for his Beogram 4004 (5526) recently decided to send me the entire unit for a restoration. Unfortunately, it arrived with a bit of damage due to sparse packaging. I can only recommend watching our Beogram 400x packaging videos on the 4002 and 4000 pages listed on the right. So far, we never had shipping damages with the packing technique outlined in the videos.

Here are a few first impressions of this 4004:

This is how it looked after I took it out of the box:

The RPM panel was not taped down and therefore it liberated itself and unfortunately caused a few minor scratches on the keypad:

I think one could still recover from this damage and restore this pad to a fairly pristine state. Another area with issues is the tonearm:

It is missing its mounting screws. This Beogram was also shipped with a fairly new looking Soundsmith SMMC 20EN cartridge on the arm without much protection except a plastic tube and some bubble wrap:

Miraculously, this cartridge may have survived the dangling RPM panel and the loose arm:

The cantilever seems still straight, but I would need to do a few measurements to see if it is indeed undamaged. There are a few more cosmetic issues around the unit. One is the broken off aluminum trim on the left side of the hood:

Another is a crack in the veneer of the plinth on that side:

The platter also has a few marks:

There is nothing one can do except finding a better platter. On the positive side, this Beogram has very nice plinth corners at the front:

Under the hood I found a mostly original set-up

except that the Beolover tracking sensor light source has been already installed:

Due to the condition of the carriage/arm I did not turn the unit on yet, but it was immediately clear that the platter motor has issues. It can only be turned with some force, indicating that the bearings need attention at a minimum. 

So in summary, this unit is in a bit of trouble, but could still be returned to a pristine state if a better looking platter and hood with intact trim could be procured and the keypad would be restored.

Beogram 8002: Preparing the Restoration

The decision has been made to do the full restoration on this beautiful Beogram 8002. The first step is to open it up for service and prepare the parts for restoration.

These early eighties Bang & Olufsen audio components were designed to open up for servicing similar to an automobile hood. The modular design makes it nice to work on. There are still some tricks to learn in properly opening the units up and some out of the ordinary tools are a big help.

I already removed the dust cover and tonearm compartment lid assembly. I need to check why the alignment is off on that later so by removing it the lids won't accidently flip open and get damaged when the deck is tilted up.

To get the Beogram deck open there are only two screws underneath the left side that have to be removed. However, to open the deck up you must carefully detach the three suspension springs and when the deck lid is tilted up you have to maneuver the platter assembly to the right slightly. The reason for that is there is the deck cannot clear the tonearm assembly unless the platter assembly that holds it is shifted.

Here is the Beogram with the deck lid up (dust cover and tonearm compartment lid assembly already removed).

As noted in the photo, with the Beogram open I discovered another missing trim piece. There should be a black plastic cover for the exposed wiring board on the tangential arm assembly. I will look for a spare or fashion one out of a sheet of Dura-Lar.

Turntable adjustments and tests can be made with the Beogram opened up in this service position. For restoration work though I fully remove the Beogram assemblies so they can be worked on individually or connected together and tested.

This picture show the Beogram 8002 assemblies removed from the case and operating.

When I had first examined this Beogram I noticed the horizontal parallelism of the reference arm and tone arm was off. The tops of the two arms should be the same. In the picture below you can see the tone arm is slightly higher. The service manual has a procedure for adjusting that and it requires taking the tangential arm assembly out to get at the underside. That isn't a big deal as I was going to lift out the arm anyway to check the lubrication of the tangential arm drive.

Besides the service manual mechanical adjustment procedures this restoration will rework the Beogram 8002 main board. The electrolytic capacitors will be replaced and solder joints re-flowed on all of the board connectors. Here is the Beogram 8002 main board opened up.

...and inside the metal box with the microcomputer.

There is also a capacitor Bang & Olufsen engineers mounting in the transformer box. This capacitor is a coupling capacitor for the platter drive motor. It is obviously too big to have fit on the main board or on the platter chassis so it was put in the transformer box.

That is it for preparing everything for this restoration. It is time to start the work.

Beogram 6000 (5512): Replacement of Transport Lock Bushings and Cabinet Guidance Washers with 3D Printed Parts

The Beogram 6000 (5512) that I am restoring right now is slowly coming together and it was time to replace the deteriorated transport lock bushings and the cabinet guidance washers. Replacement parts are available via the Beolover Shapeways store. Six of the bushings parts (two per bushing) and five of the guidance washers (there is one underneath the keypad) are needed to replace all original parts.

It is a good idea to get these items into proper condition before doing all the adjustments to line up the arms with the platter and the rest of the chassis. There are two types of transport lock bushings that were used in this type of Beogram, grey and orange plastic. The grey plastic seems to survive much longer, while the orange type usually is about to break up into pieces. So if you find telltale orange plastic fragments in your Beogram enclosure like this one found next to the motor 

then it is time to have a look at the bushings. This is what I found in this Beogram:

and with he lock components removed:

Before replacing the bushings it is a good idea to take the entire floating chassis out to remove plastic fragments that may possibly be underneath the chassis. If there are, it is possible that they impede the free movement of the chassis negating its isolating properties against vibrations. DC motor Beograms like this unit definitely have an advantage here, since the chassis can be fully removed once the transport locks have been removed and the PCB connectors are unplugged:

After cleaning out the enclosure and removal of the bushings remnants with needle nose pliers, the new bushings could be installed:

This is how they look once the locks are reassembled:

On to the cabinet guidance washers. This is what I found:

They usually crack into two halves. They can be replaced with my identical shape replicas:

It is a good idea to order one of them in black since the one at the front can be seen a bit between the wood plinth and the aluminum plate on top of the unit, and if it is black it is more or less invisible, similar to the translucent originals. Here you see one of them (under the keyboard with the CD-4 board in the background) installed:

Perfect fit! Having these renewed makes sure that the plinth seats properly and symmetrically around the top aluminum plates. Beolovely!

Beogram 6000 (5512): Dead IR Diode in Carriage Position Sensor

After restoring the PCBs and the platter motor of Beogram 6000 (5512) that I am restoring right now it was not working properly. The platter rotated, so I was able to do the RPM stability measurement, but  the carriage did not go to the 30 cm set down point, but rather traveled across the entire platter without intervention. It also immediately switched to 45 RPM after start. This suggested that the culprit was not the record detection system, but rather an issue with the carriage position sensor. This sensor uses an IR diode as emitter and a photo diode as detector. The plastic 'ruler' that is attached to the carriage has black markings on it, which allow the control system to detect what action is needed depending on the carriage position and speed of travel.

That it switched immediately to 45 RPM after traveling for about 1 cm after pressing start suggested that either the IR diode or the photodiode were dead. A strong light beam from a LED flashlight elicited a response from the photodiode. That left the IR diode. I measured the voltage across it and the result was 0.95V instead of the prescribed 1.1V. This was remarkable, since these diodes usually die by going open circuit, i.e. one usually measures a much higher voltage across it. First I tried adjusting R88, which controls the brightness of the diode, but it was maxed out already...so someone tried to adjust it previously...I took the carriage PCB out, which is an easy task in DC motor Beograms since it is just plugged in (one does have to unsolder the two leads to the carriage motor) and exchanged the IR diode with a low intensity amber LED and put the board back in. This is how it looks in action:

One can pretty much use any standard LED to fix a broken IR diode on this board. The photodiode is responsive to visible light. The issue is that modern IR diodes are designed for high output and high current, and so it is better to use an easy to find low output standard LED. The sensor does not need much light intensity. A crucial point of this fix is to adjust the working point of TR17 properly via the LED brightness trimmer R88. This shows my multimeter hooked up to the base of TR17 where 0.7V are specced in the circuit diagram. Just adjust R88 until 0.7V appear while the sensor is under illumination (i.e. none of the black markings can be between the LED and the sensor for this adjustment).

After this procedure the deck operated normally.

Beogram 8002: New Arrival

Today I started looking at a Beogram 8002. The original owner had the original B&O shipping box and was able to hand deliver it to me. That is always a bonus when shipping can be avoided.

This Beogram 8002 is reported to have some issues with the initial tonearm set down position and play time (especially when cued forward on a record). There might also be some cosmetic work needed and possibly the usual restoration updates on these turntables at this point of their life.

Time to inspect this unit and see what state it is in.
The Beogram was properly packed and the suspension was locked down.

Lifting the cover I found the top platter to be in exceptional condition. It has been well taken care of.

Removing the platter and its packing material I found the first odd thing with this unit. The front suspension spring has an additional washer and some glue. I am not sure why that was put there. Obviously this unit has been worked on before.

The inside and back reveal the dust cover and tonearm compartment lid have also had work. The lids are in good shape overall but they don't fit quite right. Looking at the back I can kind of see why. There are attachment screws added (red arrows in the photo) to keep the Beogram cover on. I am not too surprised by this. As much as I personally like this model of Beogram it does have a design weakness when it comes to the lid. While it looks great the lid originally attaches to the Beogram chassis using plastic tabs (yellow arrows in the photo). These often break off over time resulting in a dilemma of how to attach the dust cover. The choice of screws makes sense but there is some problem here with the final alignment of the lids.

Another problem with the dust cover is the black plastic cover (blue arrow in the photo) for the dust cover's spring hinge is missing. There are glue remnants so tabs probably broke off the original.

The original black plastic cover on the dust cover lid hinge looks like this.

I might have a spare in my parts bin or maybe this is a new candidate for a Beolover 3D part.

For some reason the control panel was loose already so I took a peak inside.
Inside I can see that the three larger power supply capacitors were already replaced by someone. That makes sense as that is a typical problem. When the repair was done it was probably much earlier than the present so a full recapping of the electrolytic capacitors was not performed. The top part of the following picture shows this Beogram power supply section of the main board. The lower part of the picture shows what an original state main board looks like.

Now that I had a chance to look over the Beogram I decided to give it a spin. This Beogram came with an MMC2 cartridge mounting on the tonearm and a SoundSmith SMMC3 spare cartridge. I will check out both cartridges while it is on the bench.

First though I had to set the tracking force as the slider had slid up to the maximum 2 grams of tracking force. The MMC2 should be able to track at 1 gram so I adjusted it.

Using a test record I check the Beogram with the already installed MMC2 cartridge. My QA400 audio analyzer showed activity on both the left and right channels but as the owner reported, the Beogram would suddenly stop playing. I pulled out the black panel in the tonearm compartment so I could observe the tangential arm assembly tracking sensor module. The tracking sensor lamp was illuminated so that check is okay. Next I removed the top platter again so the tonearm would lower into blank space as if a record was present. By gently nudging the tonearm towards the center of the turntable I simulated the tonearm moving inward as if playing a record. I could see the tangential arm motor turn to keep up with the movement.

So the usual quickie tests looked good but the turntable had exhibited faulty tracking. I put the platter and test record back on and tried a track half way in on the record. Quickly I noticed the stylus and cantilever of the MMC2 bend inwards with the tonearm not moving so I raised the arm and stopped play. That looks suspiciously like a cartridge problem.

I switched to the SMMC3 cartridge which is obviously a much younger cartridge. I pressed the play button and observed the Beogram play the test record from start to end where it lifted up and returned to standby position as expected.

Here is a picture of the SMMC3 cartridge test. You can see the tracking sensor lamp illuminated underneath.

It is possible then that this project will be a quick clean, lubricate and service manual check. I will need to test the suspect MMC2 cartridge in one of my own Beogram 8002 units to double check. The service manual checks should expose any other hidden problems. It does appear that the tonearm height may need checking. I also need to find out what is wanted regarding the cosmetic problems with the lid alignment.