Beogram 8002 From North Texas: Starting with some cabinet repairs

Before jumping right into the Beogram 8002 circuit board restoration tasks I decided to start with a couple of cabinet repairs.  There are two necessary cabinet repairs on this Beogram 8002 that require epoxy and 24 hours of epoxy curing.

The first repair is on the securing post for the main circuit board.
On the Beogram 8002 (and BG8000) the main circuit board mounts onto the underside of the cabinet lid.
There are guides that the circuit board slides onto, then a post with a rubber grommet that secures the circuit board in place.

When the circuit board is installed it should look like this.

The circuit board fits into the slot of the rubber grommet. The grommet slides over the mounting post.

On this current Beogram 8002 project the mounting post for the rubber grommet is missing.

I have never seen that before. It makes me wonder how that could break like that.
The broken post and rubber grommet were missing...until I removed the Beogram 8002 component parts from the frame.

Underneath the floating chassis was the broken post and the grommet.
Here is a photo of the broken piece along with two candidates for a replacement.

I could epoxy the original post back in place but I don't think it would be secure enough to last.  It would surely break off again.

My fix was to fashion a replacement post with a hole through the center.
I used a drill bit and an M3 tap to make a threaded hole for a mounting screw that would go through the replacement post and into the Beogram cabinet lid frame.

With the threaded holes, an M3 screw and some JBWeld epoxy the replacement post should be able to stand up to any pressure against it.

After the epoxy cured for 24 hours I fit the grommet onto the post.  Everything feels very tight and secure.

That takes care of one cabinet problem.

The second issue is the typical problem of the fixed hinge catch for the dust cover lid lowering mechanism.

The Beogram 8002 dust cover has a leaf spring with a sliding bracket on the end that fits into the fixed hinge catch on the underside of the dust cover.  That hinge catch needs to be solidly attached to the dust cover.

The original B&O factory installation used double-side foam tape for the attachment. After over 30 years the original foam tape deteriorates and the catch becomes loose. That results in the lowering mechanism for the dust cover to fail.

Here is the hinge catch with the deteriorated tape.

I soaked the old tape residue with Goo Gone then cleaned everything up.

I applied some clear epoxy for this repair and then put some weight on the hinge catch to hold it in place for 24 hours.

After curing for 24 hours this hinge catch should be ready to use.

I will put these cabinet pieces aside now and start on the circuit board restoration tasks.

Beogram 8002 From North Texas: Project Assessment

Today is the start of another Beogram 8002 (Type 5633) restoration project.  The owner doesn't live too far away so no boxing and shipping was necessary.  Just a lock down of the floating chassis screws and the Beogram was delivered.  I like when that happens.

This Beogram 8002 is the usual USA type (5633) with the rosewood trim.

Although a little dusty, this Beogram 8002 appears to be still intact with its original parts.
The main aluminum deck panel looks like it was already re-attached by somebody though.
Same for the aluminum lid over the tonearm compartment.

The dust cover and tonearm compartment lid assemblies share a hinged panel and that piece was already off.

Three of the four plastic mounting clips for the back panel (highlighted in yellow) are broken off (missing).  The fourth one is intact.

The fixed bracket where the dust cover lowering mechanism attaches to the dust cover is coming loose. It still has the original Bang & Olufsen mounting tape that is now deteriorating.

That will have to be removed, cleaned up and re-attached.

This photo shows the tonearm compartment deck cover in two pieces (outlined in red). The original B&O tape deteriorated as usual on that piece so it will have to be cleaned off and put back together.
The two green outlined areas show that the deck and tonearm compartment lid are already securely attached.

Inside the Beogram 8002 all of the components look to be original and in good shape.  A good starting point for the restoration.

The main circuit board and the transformer assembly are intact.
I do see something interesting with the circuit board though....There should be a little post on the Beogram frame and a slotted rubber grommet that keeps the main board securely in place. That post is broken on this Beogram and the grommet nowhere to be found.

I will have to see if I can make some sort of replacement that will do the job of securing PCB 1 to the frame.

The PCB 1 board itself looks all original.  That is always good.

The same is true for the control button panel.  It looks to be in really good condition.

The only notable issues I found with this Beogram 8002 are the back panel for the dust cover (missing mounting tabs) and the missing mounting post on the frame for securing the main circuit board.  I don't regard either of those issues as anything major to overcome and I expect to have this Beogram back to like new condition.

Beogram 4004 for the Workshop: Surprise addition of the Beolover Commander Remote Control !

Since the last post for this project I successfully ran some listening tests.  This Beogram 4004 plays records beautifully again so I was ready to reattach the deck panels and listen to more records.

However...I received an amazing surprise...a preliminary version of the latest Beolover 4002/4 Commander Remote Control.

On more than one Beogram 4004 restoration project in the past I was asked by people if the restoration could include the Beolover Commander Remote Control.  Unfortunately the answer was no.  The initial version only supported the Beogram 4002 type turntables. That is now changed as this latest version includes support of the Beogram 4004. There was good reason the earlier Commander didn't support the Beogram 4004 and I will talk about that when I show the installation below.

But first, here is this Beogram 4004 with the deck panels and tonearm cover back in place.

If you look at a lot of our other blog posts of Beogram 4002/4004 restoration projects you will see that installing the deck panels includes the tedious task of adjusting the floating chassis springs.  Both the height of the platter and the centering of the platter within the deck opening can require a lot of iterations.  This Beogram was no exception but I was finally satisfied with the result.

Here is a view from the top. It includes the tools I used to get everything aligned.

Now for the special surprise of the Beolover Commander Remote Control.

The Beolover 4002/4 Commander Remote Control comes with a main board component that has the IR receiver attached as well as an LED indicator for the Beogram speed control panel.  The Commander also includes the Beogram 4004 PCB 8 connector adapter and of course the remote control itself.

Here is a closer look.

The Commander came with its board jumpers set for a Beogram 4002.  I moved the three jumpers over to the Beogram 4004 position as that is the mode I will be using the Commander.

To go along with that mode the Beogram 4004 PCB 8 adapter connector is attached to the main Commander board at the connector marked "to 4004 output board".

Now for the installation.

As I mentioned above, the original Beolover 4002 Commander did not support a Beogram 4004 turntable.  The reason is because the Beogram 4004 turntables have a different wiring harness on the button control panel.  The Beogram 4004 PCB 8 output board has an early Bang & Olufsen remote control circuit that is designed to integrate with the remote control system of the Beomaster 2400.  That remote control integration between the Beogram and Beomaster is a wired connection via pins 6 and 7 of the phono DIN connector. 

While the original Beogram 4004 and Beomaster 2400 remote control functionality is nice, it is limited to Play, Stop, Cue Up and Cue Down.  It has no forward or reverse scanning.

The Beolover 4002/4 Commander Remote Control has Play, Stop, Cue Up, Cue Down, Scan Forward, Scan Reverse and Repeat play. The scanning control also supports slow and fast scanning.

The first part of the Commander installation is to insert the Beogram 4004 PCB 8 adapter connector.

The PCB 1 mounting screw shown below will be used to attach the Commander main board to the Beogram 4004 main board.

The Commander main board connector male pins fit into the Beogram 4004 PCB 1 connector for the button control panel.

The Beogram 4004 button control panel connector for PCB 8 now plugs into the Commander adapter.

The other connector of the Beogram 4004 button control panel harness plugs into the connector on the Commander main board.

The small LED board and harness is installed in the Beogram speed indicator panel.

The Commander system is now installed.

The little IR sensor peeks out from under the trim in the front of the Beogram...ready to detect commands from the remote control unit.

But does it work?

Of course.

Very nice. 
Having played around with the remote control functions of the Beomaster 2400/Beogram 4004 system I can say the added capability of the Beolover 4002/4 Commander are quite a welcome addition.  Highly recommended :-).

Beogram 4004 for the Workshop: Measurements & Adjustments

After performing the restoration work on the two boards, PCB 1 and PCB 8 I moved to checking the voltages on 1TR3 collector for the record detection circuit and on 4IC1 collector for the position sensor.
The new 1R26 5MΩ trimmer will be used to set the voltage on the 1TR3 collector to 4 VDC.  The 1R88 trimmer will be used to set the voltage on the 4IC1 collector to 5 VDC (when the sensor is getting its light stimulus through a clear part of the position scale).

Here is the position sensor adjusted.

Here is the record detection circuit adjusted.

Trimmer 1R26 can now be desoldered and soldered in place on the other side of the PCB 1 board.

I will double-check the actual record detection waveform on an oscilloscope later but first...
I need to do some work on the tangential arm assembly.

This Beogram 4004 turntable is in really great condition but I did notice during the assessment checks that the platter motor and the tangential arm servo motor make a lot more noise that normal.

The platter motor being noisy isn't too surprising given that they often are lacking oil in their sintered bearings (self-lubricating bearings). That happens after 30 years.
Whenever I have sent Beolover some Beogram 400x platter motors for restoration I often send along a couple of my own.  That worked out nicely here as I have a nice Beogram 4002/4004 DC platter all nicely restored by Beolover to swap out with this noisy one. Note that this one is marked serial number 1947049. 

Of course the restored DC platter motor is super quiet.  There is still the tangential arm servo motor though.  It was making the most noise.  Especially when the arm was returning to the stop position.

I removed the servo motor from this Beogram and tested it with a bench power supply to see if the motor was still noisy when out of the Beogram chassis.  It definitely was.  Even at slow speed.
The servo motor is sealed and isn't a motor Beolover currently offers a rebuild for so I grabbed a spare servo motor and figured that would be a quick and easy swap.

It turned out not to be the case. The next three servo motors I tried were all too noisy for my liking.
I finally found a nice quiet one from a Beogram 4002 turntable.

Here is a photo of the four noisy servo motors.

Along with the good, quiet, replacement servo motor I installed a new aluminum tangential arm pulley for the Beogram 4004 spindle assembly.

Even though I didn't photograph the spindle cleaning and lubrication I took this opportunity to perform that task as well. I used the same lubricants as I used on my other Beogram 400x restorations.

A mixture of the NUTO H32 and Rocol MTS 2000 is used for the spindle lubrication.
I use the DX Paste Grease for the front tangential arm rail.

The next set of tasks were to get the Beogram 4004 tangential arm assembly checked and adjusted.
- First thing is to set the platter height where the surface of the top platter is 23mm below the top of the fixed arm assembly.
- Second thing is to set the lowering limit of the tonearm so the phono stylus is about 1mm above the lower platter rib section.

- Third is to calibrate the phono cartridge tracking force.

Platter height

Stylus lowering limit

Tracking Force Calibrated
I calibrate the tracking force at the 1 gram position as it is the most commonly used.

I use threadlocking Loctite for the adjustment screws so they can't move during any vibrations the turntable might experience (like transporting).

Now that the tangential arm components are adjusted to their correct positions I can set the tracking sensor sensitivity.

The position sensor, tracking sensor and record detector sensor lamps on this Beogram are all still functioning good so I decided to leave them as is for now. 

Remarkably the tracking sensor was already very close to a proper adjustment. It only required a small tweak of the eccentric adjustment screw to fine tune the setting.  

I reinstalled the platter on the Beogram and adjusted the two speeds using the Beolover RPM tool.

The platter motor silently and easily adjusted for the two speeds.

Now that the platter spins properly I checked the record detection sensor signal when no platter is present.

The record detection circuit is a good solid signal at 33.333 and 45 RPM platter speeds.  The low part of the signal goes all the way to zero volts which is what I am expecting.

Last on the task list for this post is to replace the platter speed indicator lamps with the Beolover LED lamp assemblies. It is always worth mentioning that these lamps are part of the Beogram platter speed control circuit and do affect that performance.  Beolover has measured an increased stability in the platter speed control with these LED assemblies over the original incandescent lamps.  The Beolover LED assembly is designed to work with the speed control circuit the same as the incandescent lamp but without changes due to lamps heating up.

Here is the Beogram 4004 speed indicator panel.

Here is a look at one of the Beolover Beogram 4002/4004 indicator lamp assemblies. 
They come as a set of two (left sided mount and right sided mount).

The LED lamp assemblies are soldered in place and some included double-sided tape helps secure the small boards to the panel.

The speed indicator board is complete and ready to reinstall.

This Beogram 4004 is ready to start playing some records.