Beogram 8000 Type 5513: Tomball Texas Project Completed

This nice Beogram 8000 project is now complete and is ready to return to its owner.

The last few tasks were some simple tasks like re-attaching the deck panel that fits underneath the tonearm.

The dust cover was in good shape but in the right light I could see some scratches that I felt a quick buffing would clean up.

The picture on the left is before doing any polishing.  The photo on the right is after some light buffing with the mildest polish I have.

There was already an improvement.

With a little bit more polishing the Beogram 8000 was ready to move to my listening room.
I think it looks really good.

Now for the fun part...the listening tests.
I like that a lot of the new record pressings are in colorful vinyl.  They look good spinning on the platter :-)

Beogram 8000 Type 5513: Tomball Texas Project Final Adjustments and First Record Play

The Beogram 8000 restoration project from Tomball, Texas is playing records again.

To get to this point I had to perform some remaining adjustments.

First was the forward/reverse scanning LDR adjustments.  Those are for the tonearm forward and reverse buttons on the control panel.  The Beogram 8000 uses a couple of LDR devices (resistors that change value when light hits them) and a rocker spring that is an aperture for the light source to strike the LDR.
The steady state voltage level of the two LDR devices (forward and reverse) should be around 620 millivolts (DC). I like to set them at around 650 mVdc. They are dialed in by an adjustment screw that affects the amount of light to the sensor.  

The adjustment screws are a rather coarse adjustment and is why I installed the little test connector to make tweaking the setting easier (especially after the Beogram 8000 is fully reassembled in its cabinet).

Here are the forward and reverse, steady-state measurements for the LDR devices.

I also measured the +5 VDC, +15 VDC and -15 VDC power supplies again.
I measured the +5 VDC at the filter capacitor inside the PCB 2 assembly that supplies power to the microcomputer (uC).

I checked the +15 VDC voltage going into the regulator and coming out of the regulator.

I measured the -15 VDC off the 1TR19 collector where that voltage regulation output is located.

From there I moved to making some measurements on the oscilloscope of the speed sensor, the two position sensors and the record detection sensor.

For the speed sensor I measured the raw signal coming off the sensor assembly, then at uC (2UI1-40) after the signal has been filtered.

Here is the measurement point for the raw signal from the sensor assembly (P4 pin 7).

Here is the measurement point on 2IC1-40 (uC).

...and here is what the oscilloscope shows.

Next are the measurements for the two position sensor signals and the record detector signal.
I made those measurements with the tangential arm assembly moving forward and in reverse.

Here are the measurement points.

...and the oscilloscope measurements.

The supply voltages and sensors all looked good so I moved to the final two adjustments on this Beogram 8000.

The first adjustment was to check the phono cartridge tracking force and adjust it if necessary.
The second adjustment was to set the sensitivity of the tangential tracking sensor.

For both of these adjustments I need the Beogram 8000 where I can operate it but I don't want the platter to rotate.  With a belt driven turntable it is just a matter of removing the belt.
On the Beogram 8000 it means disconnecting the P4 connector on PCB 1.  

Just to be safe, disconnect and connect the cables with the Beogram unplugged from the wall.

The tracking force and tracking sensitivity are both adjusted on the tonearm assembly.

The tracking force for the phono cartridge is always available for the owner to set using the small adjustment slider under the tracking force scale (along the side of the tonearm).
What I do during the service manual checks is calibrate the tracking weight so it is as close to 1 gram as I can get it with the slider set to "1" on the scale.

To do that I use a digital scale and adjust the tracking force counter-weight position as necessary to get 1 gram on the measurement.

Note: I make the tracking force measurement with the platter turned upside-down because it is flat enough for the measurement scale to rest on.

On the tracking sensitivity adjustment the procedure is to place a test record on the platter, then advance the tonearm over a test track (usually in the middle of the record) and set the arm down.
I also set the arm down (with a phono cartridge attached) before that and make sure that the tracking sensitivity isn't too sensitive where the arm starts moving forward by itself.

The arm should lower straight down and the phono stylus sits in the record groove with no forward advancement of the servo motor (that drives the tonearm assembly).

Next, the platter is manually rotated and the servo motor is observed for movement.
The servo motor should advance the arm within one or two revolutions of the platter to begin with, then every platter revolution after.

Should the tracking sensitivity require adjustment, there is a small adjustment screw on the side of the tangential arm assembly...shown here.

That completes the Beogram 8000 adjustments.  Now it was time to actually play a record.

I will do more complete record play testing later, when the Beogram 8000 is fully assembled.
At this point however, I like testing record play with my Workshop Beomaster 8000.
Besides being anxious to listen to a record, now is a good time to check the record play functions.
If there was a problem, the Beogram 8000 is already open for trouble-shooting.

I like testing with a Beomaster 8000 because the two components are integrated with their controls.
Pressing Play on the Beogram 8000 will cause the Beomaster 8000 to turn on and switch to the phono (PH) source.  Pressing PH on the Beomaster 8000 will cause the Beogram 8000 to start playing a record.

Note: I keep my Workshop Beomaster 8000 opened up for servicing at all times so I can use it for Beomaster 8000 board testing. Just like I keep my Workshop Beogram 8000 opened up.

The first record play test performed perfectly so I just relaxed and finished the day listening to some vinyl.

Beogram 8002 Type 5633: Final Adjustments and First Record Play

In wrapping up the Beogram 8002 floating arm assembly and electronic control restoration work I took some time to measure the activity of the Beogram 8002 servo motor and its control signals.

To get to that point on this Beogram project I had to adjust the tracking force of the phono cartridge and set the sensitivity of the tracking sensor.

Those tasks are performed with the Beogram 8002 plugged in and able to operate but with the platter motor disabled.  The way that is done is to disconnect the Beogram 8002 P4 connector from PCB 1 (with the Beogram unplugged as well of course).

The arm assembly can now operate and be lowered onto the disabled platter to measure and adjust the tracking force of the tonearm.  

This is done with an MMC cartridge installed on the tonearm and a scale to measure the tracking force.
I use a digital scale as shown in the next photo.  
My method of setting the tonearm counterweight is to set the tracking force knob to 1 gram on the slider indicator, then adjust the counterweight adjustment screw so the digital scale measures 1 gram with the arm lowered.

The tracking sensitivity is performed by placing a test record on the platter, moving the arm over the record and lowering the arm on a track in the center of the vinyl record.  The platter is then manually rotated as you observe the movement of the Beogram servo motor drive belt.  The pulley and motor should move (to advance the arm) within 1 revolution of the platter.  After that you should see the arm advance in varying small increments depending on the characteristics of the track. The tracking control should be keeping the arm tangential to the record.

Here is the adjustment screw for the tracking sensitivity.

Also shown in the photo is the SO (Switch Off) switch. The SO switch turns off the servo motor when the arm assembly returns to the Standby position and the SO switch enables the arm position counter during Play.  The SO switch can be moved slightly with its adjustment screw to manipulate the actual setdown position of the stylus on a record.

This section from the Beogram 8002 schematic shows the servo motor and its control signals.

The diagram shows the signals from the Forward and Reverse scan LDR controls feeding into the servo motor drive control amplifiers (1IC2).  That is why it is important to set the steady-state voltages on the scanning LDR devices.  This is where I use my little test connector that I added to the Beogram 8002 control panel board.  Here is a photo of the forward and reverse scanning LDR devices after I adjusted their voltages.

The LDR voltages (when Play is pressed and the tonearm is paused) should be set to 620 mV according to the service manual.  A value from 620 mV to 700 mV is actually okay.  I usually aim for 620 mV to 650 mV.

The Beogram 8002 servo motor belt is important to get right. It should not be too tight or it will damage the servo motor over time and the tangential arm assembly control will not operate correctly.

Here is a photo of the servo motor belt.

I have discovered that these servo motors (DC motor) can sometimes start squealing as they age.
It is possible to add a little synthetic turntable oil to the shaft of the servo motor (not on the pulley of course). 

That turned out to be the case with this Beogram 8002.  The pulley started making quite a racket the more I ran tests on the turntable where the arm had to move.

Once I applied a drop of oil and changed the servo motor belt, the operation returned to normal.

For monitoring the operation of the servo motor during record play I selected the arm LIFT command, one of the arm position sensors, the forward servo drive command at the amplifier input and the actual servo drive signal at the motor.

Here is a photo of the measurement points.

With these four measurement points I could view the servo motor as it goes from Standby mode to record play.  

That sequence results in the Beogram 8002 driving the servo motor at fast speed when the Play button is pressed until the arm reaches the setdown point.  At that point the servo motor slows down and stops at the setdown position.  The LIFT command is energized and the arm lowers onto the record.

The setdown point should be on the record lead-in groove and that will result in the servo motor driving the arm through the lead-in groove and stopping at the first record groove with music content.
Now the tracking control will advance the servo motor as the phono stylus moves along the record groove.  That path moves the tonearm inward towards the platter spindle.
The movement of the arm will trigger the servo motor to advance the arm assembly so it remains tangent to the record.  That controlled movement is dependent on the tracking sensitivity adjustment procedure performed earlier.

Here are the oscilloscope screen captures.

Here is a measurement that captures the Press Play event through to tracking the first record groove.

Notice that at the point the record is being played that the little "humps" in the Servo Motor signal (at P1-1) are when the motor is advancing the arm a bit.  Also note that the position sensors do not register a pulse for every motor advancement. That is because the pulses on the position sensors occur when the sensor lamp hits the sensor between the openings in the sensor wheel.  As can be seen on the 2IC1-28 sensor in the photo, there are times when the motor is advancing but the sensor signal is quiet. The sensor wheel is blocking the light during that time and the motor is only slightly advancing the wheel. 

  

One more service manual adjustment to mention is the distance from the platter surface to the top of the sensor arm.  That distance should be adjusted so you get 19.5 mm from the platter surface to the top of the sensor arm.  There is a screw at the top of the sensor arm for that adjustment.

This adjustment is to set the distance of the phono cartridge stylus at a safe distance from the surface of a record. It is easiest to perform this when the floating chassis assembly is apart.  The reason for that is while setting the end of the sensor arm position is easy from the top of the arm, the corresponding adjustment of the tonearm height is made underneath the tangential arm assembly.  That means pulling up the tangential arm assembly from the guide rails and spindle again.

As I said, the result of this adjustment is so the end of the tonearm is where the stylus can safely scan over a record with good clearance.  This adjustment has nothing to do with the Vertical Tracking Angle of the phono stylus.  On a Beogram 8002, the Vertical Tracking Angle is fixed and cannot be adjusted.

All of the floating chassis and sensor adjustments are complete on this Beogram now.
The completed floating chassis assembly can play a record all the way through and I can test the record play by connecting up these Beogram 8002 components to my Workshop Beomaster 8000.

While I am testing the record play I can start in on the Beogram 8002 cabinet restoration tasks.

Bay Area Beogram 8002: Cabinet Work Completion to First Record Play

Today I finally got this Beogram 8002 turntable into a listening room to begin record play testing.

It took a little longer than I anticipated to finish up the reassembly to arrive at this point but I took a little detour to fix the chipped rosewood trim on the front panel.

A cosmetic repair of the trim was not originally in the plans for this restoration but the more I looked at it the more I didn't like leaving the front panel chipped like that.

The journey down the path of repair for something like this can end up taking extra time of course and this one certainly did. When working on repairs like this glue is involved so that means waiting time for glues to cure.

Then there are times where it takes more than one attempt to make the repair. That also happened here.

In my initial repair attempt I decided to just try and patch the areas that were chipped. In this case two...a large chip and a much smaller one.

The fit and install of the patch for the larger chip went well. I used a piece I cut out of some rosewood veneer I keep for this type of repair. The fit and pattern match was good.

After gluing the repair patch in place I cut off the excess, sanded the repair and applied some boiled linseed oil for a finish.

It should have been a nice repair but the small patch turned too dark and I realized that the small remaining chip was too small to make a good repair. Even if I just used some wood filler.

It didn't look terrible and was better than having the chips there but I decided I couldn't leave it like this.
The large patch fit good but darkened too much and my eyes kept being drawn to the small chip that still needed to be fixed.

My rework of the fix was to cut out the first repair attempt and make the cut so that there would be just one, rectangular patch piece needed to cover both of the original chips.

I selected a lighter section of rosewood from my veneer piece in the second attempt. 
Here is the result of the second (and final) attempt.

The patch piece still darkened but I think overall this patch is much better.  It is far from perfect but better than the original chips.

As a side note...I investigated using some rosewood trim from a spare Beogram 800x turntable cabinet that was beyond repair.  I also looked at some spare Beocord 800x and Beomaster 6000/8000 cabinets for possible donor trim pieces.  In all cases the cabinets I have in my spare parts collection are all darker than the rosewood trim on this project. So my veneer piece is as good a match as I could get.

Returning to the tonearm compartment, I installed the nice, clean replacement hinge piece for the lid.
I used kilopoise grease for the lid damping and temporarily held the hinge in place with the original hinge bar for this Beogram.

The Beogram 8002 cabinet is now ready to start all of the reassembling of its components.

The first steps were to put the main turntable components (circuit board, transformer, control panel and floating chassis) back into the cabinet.

I like to do that first because until those are in place I can't close up the two halves of the cabinet and I don't like having that loose when I work with the dust cover and tonearm compartment lid.

In my haste to do the reassembly I neglected to photograph the re-install steps this time but for reference, here are the install steps from the last Beogram 8002 project.

Here is this Beogram 8002 with its internal components installed and ready for the dust cover and tonearm compartment lid installation.

For the dust cover installation I prefer to secure the dust cover and tonearm compartment hinge assembly together with the Beogram 8002 bar hinge.  By removing the bar hinge at the beginning it saved me from removing the back plate of the cabinet that has the hinge bar mounts for the cabinet frame. Removing that plate can often result in a loose rear plate because it has plastic clips that easily break off.

After I had the dust cover and tonearm compartment pieces secured with the Beogram 8002 bar hinge I attached the dust cover damping spring assembly.

Here is the dust cover installed and with the damping spring set properly to allow slow lowering of the dust cover.

The dust cover has two rubber bumper pads that mount in the front part of the lid (where it rests when lowered all the way to the deck). Those rubber pieces are always deteriorated and broken off.

I cleaned out the original bumper pad residue and installed my own 3D printed bumpers.

The dust cover now becomes an alignment guide for installing the tonearm compartment lid.

I used the same 3M VHB double-sided tape on the tonearm compartment lid as I did for the Beogram 8002 metal deck.

Everything looks like it is installed and this Beogram 8002 is ready to play some records.

It is off to my office where I can listen to records on this Beogram while I work.
Tonight I was in the mood to hear some nice jazz recordings so I broke out Quincy Jones "Walking In Space" and Lonnie Liston Smith "Live!".  

Don't stay up.  These listening tests may take a while.