Beogram 4002 (5513): First Record Play Testing

Finally....time to see how this restored Beogram 4002 (5513) turntable does playing a record for listening pleasure.

First though, a couple of pictures showing some tidying up of some loose ends. In the last post I neglected to post the pictures of installing new cabinet guides and the rework of the phono cable.
So before showing the first record play photos here are a couple of pictures showing the Beolover Beogram 4002 3D cabinet guide parts.

There are five total cabinet guides. The last photo shows the lone black one that is used for the front center of the cabinet so it isn't noticeable. Note that these are not washers. The cabinet guides hold the plinth in place but allow it to slide forward and backwards for opening up the Beogram cabinet. The early Beogram 400x turntable guides were made out of a brittle plastic that almost always broke. In the later model Beogram 400x turntables B&O switched to a metal guide to fix the problem. The Type 5513 Beogram 4002 was before the metal guide came out. Even though they are just a small part they make a big difference. A lot of people will just substitute flat washers but they don't provide the function needed.

Now the phono cable. The original DIN plug cable had already been replaced and while the replacement was a nice cable I didn't like the way the wires terminated in the P9 plug to the Beogram phono output board.

I removed each P9 pin and reworked the wire connections. The wires connected to pins 2 and 4 are not used so I removed them.

Here is the reworked cable plugged into the Beogram phono output board. I reused the blue wire and its P9 connector for the left and right channel shield wires. The small switch we install allows the option to short the shield wires to the chassis ground wire or leave it open.

That is a lot cleaner looking. I can live with that.

Time for some lively Jazz from Buddy Rich.

I have used those for Beogram play tests before and keep using them for some reason :-).

Next the Beogram will go through a day of testing like this while I make sure the set down positions are good, the phono muting delay is satisfactory and there are no tracking problems. Once those things are satisfied I will install the remaining cabinet pieces and go through a week of listening tests before this Beogram's owner picks it up.

Thanks to Beolover by the way for another excellent job on parts and the platter motor restoration.

Beogram 4002 (5513): Service Manual Adjustments & Preparing for Use

I left off in the last post with the keypad cleaning, deoxidizing and the RPM panel. The keypad response is immediate but the cueing up and down button is too sensitive now. I will have to revisit that switch. There was a delay in the RPM panel re-installation because the molded, acrylic mounting fixtures were cracked. That is very common with these Beogram 4002 turntables. Often they are completely broken. Luckily the mounting fixtures on this Beogram just had one crack in each one and were still intact. I pressed the mount fixture together as I applied acrylic repair fluid in the crack. It dries very quick. That repair by itself is not strong enough if the RPM panel is removed and reinstalled very many times. To supplement the acrylic glue I cut two strips of Dura-Lar and put one strip on either side of the mounting block. I use Araldite AB rapid epoxy. It is clear.

The patched mounting blocks attach to the aluminum frame by set screws underneath.

One thing to note is the mounting screw for the keypad and RPM indicator panel is right underneath the RPM panel so whenever there is a need to get to the keypad buttons or the phono output board, the RPM panel has to be removed. That is why reinforcing the mounting blocks is important.

Here is the panel back in place.

Next I want to make sure the voltages and signals of the Beogram detectors are good.
First up is the 4D1 LED and its 4IC1 optical sensor that detect where the tangential arm is. Markings in the acrylic slide alter the LED light to the 4IC1 sensor and Beogram circuitry reacts to those changes in the signal.

The service manual check for this sensor is to measure the collector of the 4IC1 sensor when a transparent section of the slide is between the LED and the sensor. The voltage level at the 4IC1 collector should be around 5V.  If it is not, the 1R88 trimmer (on the main board) is adjusted to set the voltage needed.

These pictures show the adjustment.

This is an important adjustment because the run-out groove detection at the end of playing a record is dependent on this voltage level being set correctly.

Next though is the fixed arm sensor that detects if a record is present (and if it is okay to lower the tonearm). The fixed arm has a light source that shines down on the platter. The reflected light is read by an optical sensor. If there is a record on the platter the reflected light will be at a low level and won't vary. That steady, weak signal is interpreted by the Beogram arm lowering logic as okay to set down the stylus. If there is no record the black ribs on the platter will affect the reflected light so that it returns as pulses to the sensor. The pulses cause the arm lowering logic to not allow the stylus to be lowered.

Obviously it is important for this signal to be working and is at a proper level.

This sensor is providing pulses that are above the required 6 volt level. No danger of accidently lowering on an empty platter.

I need to check the end groove, run-out stop circuit but first I will perform some more mechanical checks and adjustments to get the Beogram ready for record play.

I caught a break on the platter to tonearm height adjustment. The distance was already at the required 23mm.

The arm lowering limit needs to be set so the tip of the stylus is about 1mm from the top of the first platter rib. This is a safety feature that prevents the cartridge from damage should the record detection circuit fail.

Another remaining mechanical adjustment is to check the tonearm for length and parallelism.
I run a string tangential to the Beogram arm assembly then check that the stylus travel path follows the string.

The check that the tonearm is 7.7mm distance from the fixed arm and that they are parallel were checks I made earlier in the restoration when I took apart the tonearm assembly (for the oil cleanup).

We are getting close to record play now. At this point the tracking sensor sensitivity needs to be fine tuned, the run-off stop needs checking and the platter speeds need to be dialed in.

The tracking sensor adjustment went fairly smooth. It still took quite a few iterations to get the sensitivity set where the tangential arm motor moves after each revolution (2±1 revolutions initially, 1 revolution after that).

The run-off stop check measured good on the oscilloscope.

I was able to easily adjust 1R14 and 1R15 trimmers (on the main board) to set the 33⅓ RPM and 45 RPM speeds using the Beolover RPM tool.

Whew! A lot of adjustments and checks on these Beograms. I still love them though. What a great turntable design.

Now for a break for some food and fireworks (not with the Beogram :-).  Then I will do a quick adjustment on the keypad cueing button. After that I should be lying down and listening to some records.

Beogram 4002 (5513): Keypad and RPM Panel

I noticed that some of the Beogram's control panel buttons were slow to respond when pressing them. That usually means oxidation on the keypad contacts so I opened up the keypad assembly.
Sure enough, you can see the dull key contacts.

I unsoldered the contact pads and removed them for inspection. They didn't look too bad but the leaf contacts that the actuators press down on are all oxidized.

I used a fiberglass brush and some Deoxit to protect from future oxidation. The contacts all look nice and shiny again.

The last part of the electrical work is to change out the lamps for the RPM indicators. We recommend this because during the platter motor stability testing the LED replacement modules resulted in further stability of the motor speed. The RPM indicator lamps are part of the circuit that controls the platter motor. Each speed indicator has a knob to adjust the pitch (speed).

Here is the RPM indicator module with the original incandescent lamps.

Here is the RPM indicator with the Beolover lamp replacement modules.

The Beolover lamp replacement module is designed to work with the pitch control circuit and the SMD LED components used have been adjusted to mix light colors to match the original incandescent lamps.

Here are the 33 and 45 RPM speeds with the new light modules. The control panel buttons operate immediately as they are pressed now.

All of the Beogram functions are operating now. The next step is to check and adjust the Beogram per the service manual. Once those adjustments are made and all the checks pass it will be time to play vinyl again.

Beogram 4002 (5513): Electrical Work and Initial Tracking Adjustment

On to the electronic board restoration tasks. There is the main control board to recap and change the RPM relay (plus RPM trimmers) on. Then there is the output board with its phono muting circuit. It should be noted that the muting relay is the only electrical component other than wiring that is involved with the phono audio signal. Most of the electronics in the turntable are for controlling the platter motor, tangential arm, indicator lamps and operator controls. Those circuits are not in the audio path.

Here is the main control board before the recap. It has a few electrolytic capacitors and quite a few tantalum capacitors. I will change the capacitors that are 4.7uF and above with new 105°C, Nichicon capacitors. On the values smaller than 4.7uF I will use WIMA MKS polyester capacitors. When there is room I usually replace the 4.7uF capacitors with WIMA MKS as well but they are too large for this application. Another thing to note is that I will change the 1C10 electrolytic capacitor from its original 0.47uF value to 10uF per Beolover's test results of the restored platter motor. That value was determined to give the best speed stability with this particular motor.

Here is the restored main board.

Now the output board before

...and after. Note that I installed our usual grounding switch so signal ground and chassis ground can be engaged or disengaged depending on the owner's needs.

I am now ready to see how this Beogram acts with its mechanical components cleaned/lubricated and the electrical components updated. For the first electrical power on test I removed the tangential arm motor belt and left the platter off. That way if something is not right I don't have to worry about a moving component going somewhere. I also removed the arm position scale from the tangential arm transport to take a look at the switches and the position sensor lamp.

With the Beogram plugged the main reservoir capacitor shows that it is at just over 30 VDC which is good. The fixed arm sensor lamp is illuminated and so is the 33 RPM speed indicator lamp. The platter motor and tangential arm motors are turning. That is expected since the position scale is off and there is nothing there to turn the SO switch off.

However, there is one fault I can see right away and that is the tangential arm position sensor lamp is not lit.

Without the arm position sensor lamp the control logic cannot determine where the tangential arm assembly really is.

I replaced that with an amber T-1, round LED.

The replacement LED I use has a wavelength of 591nm and luminous intensity value of 13000 mcd. The viewing angle is 15°.  The important thing here is that the sensor detects the light and is able to supply the control circuit with the proper voltage level. I will do a more detailed check of that sensor voltage later when I go through the service manual adjustment/checks.

Here is the new position sensor lamp installed and working.

This is a good time to prepare the initial setting for the tangential drive tracking sensor. I had to disassemble most of the tracking sensor components when cleaning up the oil so there is a good chance that the tracking alignment is off now. I visually set the tracking sensor aperture to be centered but that was just a guess.

Using the aperture position adjustment screw I set the aperture in a position where the arm pivots easily and, when the arm is lowered, the tangential arm drive motor doesn't try to drive it somewhere.
Then I play with the tracking sensitivity adjustment screw and the aperture position to find a place where the sensitivity screw can affect the arm moving forward (when it is lowered). The goal here is to set the arm tracking control where I have enough play in the tracking sensitivity screw to lock in the tracking later (during the service manual adjustments). With that set up I can tighten down the aperture position screw.

Now on to replace the speed indicator lamps from the original incandescent lamps to Beolover's replacement LED boards. Those are the final piece of obtaining optimum platter speed stability.

Beogram 4002 (5513): Floating Suspension, Reservoir Capacitor & Platter Motor

This project is heading into the home stretch now. In this post I am showing the remounting of the floating chassis in the cabinet along with changing out the reservoir capacitor and installing the rebuilt platter motor.

Here are the components for mounting the floating suspension back in the cabinet.

The longer end of the threaded pin goes on the bottom. It is important to attach the wing-nut so that it is right at the start of the thread. I attach mine so there is enough thread in place to hold the nut and the outer part of the nut is flush with the top most thread. The idea here is to provide maximum space for the floating chassis when the the lock is disengaged. Turning the threaded pin will move the two lock nuts closer together (locking the suspension) or further apart (unlocking the suspension).

Because most of the Beogram 400x turntables have deteriorated transport lock bushings Beolover created replacements using 3D printing technology. Here are a set of the Beolover transport lock bushings for the three Beogram suspension mounts. There are a total of six 3D printed parts.

Now the rest of the suspension mount pieces can be attached. Just like the first wing-nut I started out with the top of the nut flush with the first thread.

The next re-installation in the cabinet is the reservoir capacitor.  The original reservoir capacitor is actually two in one. Not all Beogram 400x turntables have this same type of reservoir capacitor so make sure you check carefully and identify what your 400x type has.

I removed the wires and installed the Beolover replacement capacitor assembly.

It looks great. Now to install the platter motor that Beolover rebuilt for this project.

One more look over the reassembly so far shows everything looking good.

The next step is to work on the main board and the output board.