Michigan Beogram 8002 Floating Chassis Components Restoration

I began the restoration of this Beogram 8002 turntable with the floating chassis components.

The main reason for that is two broken parts I discovered during the initial assessment.
I wanted to tackle those two (key) problems first because I wanted to make sure they could be properly fixed.

For the spindle nut with a broken guide wall for the bracket that connects it to the tangential arm assembly...I decided to go with a spare (or donor) spindle nut from my box of Beogram 800x turntable parts.

In the case of the broken tab that secures the Beogram 8002 position sensor assembly...I had to design a 3D printed part that would properly secure the broken tab and still allow the tab to let the sensor assembly board be removed.

It took some modification of my initial design but I finally achieved what I was after.
The 3D part glues onto the molded plastic that comes with the Beogram floating chassis.

The broken, plastic tab is also glued to the 3D part and the area of the chassis it broke off from.

The ends of the 3D part wrap around the chassis base on all four sides to provide strength.
The end closest to the servo motor has to have a slot for the sensor assembly.
The 3D part wall on the spindle side had to be made smaller than I originally designed it to leave room for the sensor wheel and to attach/remove a rubber belt.

Here is another view.

While I had the floating chassis components where they are still easily accessible, I decided to perform a few Beogram 8002 adjustments that involve the tangential arm assembly.

To do this I removed the spindle assembly and just left the arm assembly on the two rails.

This allowed me to manually slide the tangential arm assembly wherever I wanted to without manually rotating the spindle (which gets old fast).  I also didn't want to wait until the electronics were completed and working...then take the arm assembly out again.

With this setup I adjusted the height of the fixed-arm (sensor arm) relative to the top of the platter.
The distance per the service manual is 19.5 mm (different than the Beogram 8000 and Beogram 400x turntables).

That adjustment screw is shown in blue text in the above photo.

With the fixed-arm height set per the service manual the next adjustment is to make the top of the tonearm match the top of the fixed-arm.

The adjustment screw for the tonearm height is underneath the tangential arm assembly so you can see why I want to get it out of the way first and not come back to it.

I am not showing the phono cartridge tracking force calibration here but I did do an initial calibration of the tracking force counter-weight, phono cartridge and force selection slider while I had the floating chassis components apart.  I will do a final check later when the Beogram is assembled for testing.

Next, I cleaned and applied rubber cleaner/treatment to the two damping rubber inserts on the rear tangential arm rail. 

Note that the rubber dampers are only on the rear rails of Beogram 8002 turntables used with 60 Hz line voltages.  They aren't necessary where the line voltage is 50 Hz.

The last floating chassis component tasks I worked was to replace the audio muting relay and the two capacitors on the +5 VDC regulator.

Here is the muting relay replacement.
Note that the Beogram 8000 has a different muting relay.

Here are the only two floating chassis mounted electrolytic capacitors that get replaced.

The next post for this Beogram 8002 project will focus on the main electronics restoration work.

Beogram 8002 Type 5633: Floating Chassis Restoration Tasks

I wrapped up the work on the Beogram 8002 floating chassis. It should be ready for some functional testing of the turntable operations in the next blog post.

Here is the floating chassis before starting the restoration work on it.

It has a bit of dust as you would expect but nothing major to clean up or repair.

I removed the center hub to inspect the tachodisc and speed sensor.

Next is the disassembly of the tangential arm assembly for inspection, cleaning and lubricating.
I will also check the arm raise/lower solenoid and mechanical parts. 

The arm lower/raise mechanics looked good.
While the arm assembly was turned over I took the opportunity to align the tonearm height with the sensor arm.

Interestingly this Beogram 8002 unit has a little, square rest plate for the tonearm height adjustment screw.  Usually there isn't anything there to keep the screw from contacting the metal back of the tonearm.  That can cause problems with the arm lowering operation so I often have to place a small piece of Dura-Lar plastic there.  In this case, the problem is already taken care of.

Now it is time to clean the old oil and grease from the spindle, rails and attachment pieces.
Then re-lubricate everything and reassembly the arm assembly.

Because this Beogram 8002 was configured for the North America market the rear guide rail has rubber tip ends to dampen any vibrations from the 60 Hz line voltage.

I applied some rubber restoring fluid to the rubber ends when I reassembled the arm assembly.
For re-lubrication of the spindle I still use the original B&O combination of Rocol MTS 1000/2000  with Mobil NUTO H32 mixture. However, a good modern, synthetic oil will also work fine.  Just don't over lubricate the spindle where oil flies off when the spindle spins.  
On the shiny guide rails I apply either some M-kote DX Paste Grease or some Tri Flow Dry Lube.
At the pivot points of the spindle where it attaches to the chassis I use a little bit of Tri Flow Red Grease.

Here is the tangential arm assembly put back together with the tonearm aligned with the sensor arm.

There were a couple of electrical restoration tasks left to do that I didn't complete on the previous post.

One is the replacement of the phono muting relay.
I replaced the original muting relay with one I sourced from Beoparts.

I also installed my usual test connector for adjusting the LDR sensors that are used for the forward and reverse arm scanning operation.  It is kind of a pain to connect DMM probes to make the voltage measurement while adjusting the sensor aperture so I install a three wire test connector that allows checking (and adjusting) the LDRs without opening the Beogram 8002 into its service position.

The Beogram 8002 turntable components can now be assembled and tested.

Bay Area Beogram 8002: Capacitor Replacement

On this latest Beogram 8002 turntable project I decided to tackle the capacitor replacement tasks first. I also replaced the phono muting relay while I was doing these electrical tasks...and my soldering iron was hot.

The sequence of working the tasks isn't too important here and I often vary it.

I will start showing the replacement of the two electrolytic capacitors on the floating chassis. They are part of the Beogram 8002 +5 VDC power supply regulation.

These photos go through the replacement from beginning to finish.

As I typically do, I replace capacitors that have values 4.7uF and less with WIMA MKS capacitors. On the capacitors greater than 4.7uF I use high quality Japanese 105°C electrolytic capacitors. 

Next, here is the old and the new muting relay.  The new relay is an Omron relay as was the original.  The new relay however it fully sealed.

I changed out the 4C1 capacitor, inside the transformer box next. It is a bipolar type capacitor used in the tangential drive platter motor circuit of the Beogram 8002. 

The original 4C1 capacitor is quite large which is probably why it ended up inside the transformer box.
The modern replacement capacitor is a much smaller physical size so we like using a 3D printed mounting plate for it when we do the replacement.

Here are the before and after photos.

When I start on the PCB1 and PCB2 capacitor replacement I do usually begin with the microcomputer board (PCB2) first. So that is the case here.

There is only one electrolytic capacitor to replace on PCB2.  That is 2C28 and it is quite important. It is a filter capacitor for the +5 VDC to the microcomputer IC.  

The fit is very tight inside PCB2.  My method of replacing 2C28 now is to cut the leads first to remove it.  Then I desolder the remaining leads.  It is much easier that way with 2C28 out of the way.

I also like to remove the microcomputer IC and replace its 40-pin socket at the same time.

One thing to notice regarding 2C28 is that the negative lead has to be soldered to both sides of the board.  That is important of course and is easy to overlook.

Here are the new and original 40-pin 2IC1 sockets side-by-side.  The new socket is a beefier design with tulip style pins.

Here is the new 2C28 capacitor installed followed by the new 2IC1 socket.

Here is 2IC1 reinstalled. 

It is always worth mentioning that you need to follow good electronic precautions for static electricity when handling delicate integrated circuit devices.
 

Finally, here are the before and after photos of the main board (PCB1) capacitor replacements.

Before

After

Another important note regarding the capacitor replacement tasks on PCB1 and PBC2...
A problem we have seen before on the two boards is with the solder connections where the board connectors mount to the circuit boards.  For that reason we always reflow all of the solder points for all the board connector pins.  That is true for other vintage B&O audio components as well.

The main electrical work is done.  I still need to add my test connector to the button control panel that makes the service manual adjustment for the scanning LDR devices easier.  I will do that in the next step along with cleaning the floating chassis, lubricating and adjusting the tangential arm assembly and changing the servo motor belt.

Beogram 8002 From North Texas: Replacing the electrolytic capacitors

Moving on to the electrical tasks on this Beogram 8002 project...
There are electrolytic capacitors in the Beogram 8002 in four locations: the floating chassis, PCB 1, PCB 2 and inside the transformer box.  Typically not all of them will be out of tolerance but it is a good move to replace all of them rather than wait for them to fail one at a time. 

I will start by showing the replacement of the two capacitors on the floating chassis.
These two, 0C1 and 0C2, are part of the Beogarm 8002 +5 VDC regulating circuit.

The two capacitors are easy to get to although the yellow, black and blue wires should be disconnected and moved out of the way first.

On this project the Beogram 8002's owner had already purchased a capacitor kit for it. The kit contains most of the capacitors I normally replace and they are good quality capacitors so I will use them.

Here are the new new 0C1 and 0C2 capacitors installed.

PCB 1 is the main board of the Beogram 8002 while PCB 2 piggybacks on top and inside a shielded, metal box.  

PCB 2 houses the Beogram 8002 microcomputer IC and has just one electrolytic capacitor to replace.
It is a difficult one to deal with though.  The negative lead side is soldered to both the top and bottom layers of the board. In addition, the space is a very tight fit and is right next to the microcomputer IC.

This lone electrolytic capacitor, 2C28, is for the +5 VDC supply voltage to the microcomputer IC...so pretty important :-).

  
























I like to cut the exposed leads on the 2C28 capacitor to remove it first, then desolder and remove the remaining parts of the lead once I have more room.

This photo shows the other side of PCB 2 and the other two solder points of 2C28.

A number of years ago we started replacing the 40-pin IC socket for the microcomputer device on these Beogram 8000/8002 restorations.  Removing the old IC socket provides more operating room and the new 40-pin socket with tulip style contacts is a sturdier part than the original socket. It provides some extra insurance in reliability and is easy to replace during this capacitor replacement task.

The new 2C28 capacitor is in place and so is the new 40-pin IC socket.

I re-inserted the microcomputer IC (while taking electrostatic precautions of course).
I will apply new thermal paste to the top of the microcomputer IC later when I re-install the metal lid that has the heatsink for it.

One other step I performed on PCB 2 was to use a soldering tool to reflow the solder joints on all of the board connectors.  We have found that those connector-board solder connections can become faulty over time and they are not something a visual inspection can always catch. It is safer to just reflow the solder.

In case any Beogram 8000 owners are wondering, the microcomputer IC in the Beogram 8002 and Beogram 8000 are not compatible. The PCB 2 board and housing look the same but the functionality of the microcomputer IC itself is different enough where they are not interchangeable.

Next is PCB 1
I used this photo above but I will include it again.  The photo shows all of the PCB 1 electrolytic capacitors that will get replaced except for the one hidden underneath the metal shield box.  I will show that replacement capacitor a little later on.

As I said earlier, not every electrolytic capacitor in the Beogram 8002 will be out of tolerance but there are always some that are...

Both of those capacitors are part of the Beogram 8002 power supply circuitry.

The largest capacitor, 1C27, which is for +15 VDC supply filtering was still in tolerance but it is being replaced now while all the other work is being performed.

1C27 is a little unusual in that it has a three prong base for its negative lead.  The three prongs are for mechanical support and I have never found a modern replacement for this type of packaging.
The new capacitor is the common, two-lead, through-hole style of capacitor.

The Beogram 8002 PCB 1 board expects the 1C27 capacitor base to connect two of the board ground connections via that three prong base.  That can be accomplished with a jumper wire on the trace side of the PCB 1 or I can pop off the three prong base from the original 1C27 capacitor and re-use it.
I like to opt for the second option.

The new 1C27 capacitor positive lead goes right in the center of the three-prong mounting ring.
The negative lead gets bent around the mounting ring and soldered to it.

That is it. 
The new 1C27 capacitor will fit into the original PCB 1 holes and soldered in place the way the original was.

Here is that PCB 1, C28 capacitor that is underneath the PCB 2 shield box.

On PCB 1 on the other side of the shield box is 1C4.

That accounts for all of the PCB 1 electrolytic capacitors.

Just as I did on PCB 2, all of the PCB 1 board connector solder joints were re-flowed with solder.

The last electrolytic capacitor, 4C1, is a non-polarized capacitor located inside the transformer box.
The modern replacement capacitor is much smaller in its physical size so we created a 3D printed mount for it.

While I have the soldering tools out I took the opportunity to replace the audio muting relay on the Beogram 8002 output board, the small board that the 7-pin DIN connector is mounted to.

This is another precautionary change.  We have seen enough of these relays start to fail where it is safer just to replace them rather than wait for them to fail.

Here are the before photos.

I am including a picture of the trace side as it shows all of the wire connections for the phono audio signals.  The connections look really good on this Beogram 8002 output board. The last two Beogram 8002 output boards I worked on required re-soldering of those wires because they were poorly soldered and the connections were failing.  I expect the output board to always look like this one.

Here is the new Omron relay installed.

In the next post I will lubricate and re-install the tonearm assembly.