Beomaster 2000 Type 2801: Replacing Some Components and First Music Listening Test

I received most of the electronic components I needed to restore this Beomaster 2000 receiver.
Compared to the last few Beomaster receivers I have restored this one will have the least amount of capacitors replaced.  As I mentioned in the previous blog post ...for this unit I will leave in all of the red tantalum capacitors if a spot check shows them to be good...and it did.

Here is a small sampling of three different tantalum capacitors from the Beomaster 2000.

I didn't remove and test every single tantalum but I tested enough where I was satisfied the plan to leave them in is sound (sorry for the unintended pun :-) ).

I did replace the electrolytic capacitors, the no-load current adjustment trimmers (two...one for the left channel and one for the right channel) and the 2D8 bridge rectifier.

Here is a before and after photo of the 470uF 2C24 capacitor and the 2D8 bridge rectifier (located on PCB 2).

Before:

After:

The output amplifier board (PCB 7) had seven electrolytic capacitors to replace and two 250Ω trimmer resistors for the left and right channel no-load current adjustment.

Before:

After:

Note: The thermal compound on the transistors mounted on the rear heat sink of the Beomaster 2000 cabinet was still soft so I left those alone.  If there ends up being a problem with the transistors and I have to replace any, I will rework all of the output transistors.
For now...they are left as they are.

PCB 5 (IF & Preamplifier) only has two electrolytic capacitors to replace.  Here are the before and after photos for that board.

Before:

After:

That sums up the PCB component replacement tasks.

PCB 3 (Pre-set Tuning board) required desoldering of the five pre-set dials.
The issue with this board was that the black, plastic adjustment knob for each preset was slipping.

I cleaned all of the preset components with some fader lube, glued on the plastic knobs and then reinstalled the five presets to PCB 3.

Next, it was time to check powering up the Beomaster and checking voltages.

I set the voltage selection switch to 130 VAC as here in the USA the line voltage is closer to 130 V than it is to 110 V (the other voltage switch selection option available to me).

On these initial power up tests I use my variac and dim bulb tester to protect any short circuits to ground in the Beomaster power supply path.

As you can see the line voltage is closer to 130 V than 110 V so 130 V is the best selection for my area.

For reference here is the Beomaster 2000 Type 2801 line voltage supply wire routing for the four voltage select options.  Top left is the wiring for my selection.

With the Beomaster turned on (Tape selected) I measured the secondaries off the transformer.
One set should be at 26 V and the other should be 46 V.

Those are good values for the power coming in.

Checking the resulting ±30 VDC rail voltages I measure -

Those measure good.

Now to check the +26 VDC adjustment called for in the Beomaster 2000 service manual.
I monitored the +26V test point and adjusted the trimmer to get as close to 26V as I could.

After that I adjusted the output amplifier no-load current for both channels per the service manual.
The adjustment calls for no speakers connected, the volume level at zero, the amplifier warmed up and a measurement of 10mVDC across emitter resistors (7R119 : LCh, 7R219 : RCh).

Here are those measurements using the new Bourns multi-turn trimmers I installed to adjust the voltages.

Left Channel

Right Channel

Those are all the initial voltage checks I wanted to do.
Now to hook up speakers and see if I have music playing from this receiver.

This picture shows my little iPod Nano providing the music source to the Beomaster 2000 Tape 2 input.
You can also see in the photo that the lamp for the tuner dial is illuminated.

Listening to music from the restored amplifier is a nice milestone to reach in the project.

Normally I would move into some performance testing but there are a few problems to address with this Beomaster first.

There are no lamps lit up on the PCB 4 Indicator circuit.  It has four 12V, 30mA lamps and they appear to be burned out.

I should have checked that earlier but now I will have to wait for those parts to arrive.

When examining the tuner dial cord I discovered another problem.  The cord has a spot that is badly frayed.  I don't want to put in all of this work only to have the cord break later.  I ordered a replacement for that and will also have to wait for that to be delivered.

I also had to repair two of the tuning cord pulley posts because there were defects in the plastic parts.

On the left side of the dial window the plastic mounting tab for the pulley was broken when I initially checked over the Beomaster 2000 inside.

I was able to glue that broken piece back together but the break across the plastic part will see a lot of stress so I don't think it will hold up over time on its own.

For that reason I fashioned a u-channel reinforcement part that I could epoxy into place across the break.

The right side of the dial cord assembly also had a problem.
There appeared to be a missing pieces (a plastic tab) that keeps the metal rod for the dial assembly from pulling out of place.

I fashioned a second 3D part to keep metal rod in place. It too was installed using some epoxy.

That was not the end of the problems for the right side dial cord pulley though.

I could easily see that the pulley assembly was loose and would not remain in place when the tension of the dial cord was pressing on it.

It turns out there were some cracks in the plastic mounting post for that pulley assembly.

So the mounting screw would expand the cracked mounting post when pressure from the dial cord is applied.

For that repair I made a ring for the post so the cracks in the post couldn't expand.

That work out really well.  Satisfied that repair would work I epoxied the ring in place.

This Beomaster should be ready for further testing once the replacement lamps and new dial cord arrive.

Beolover Commander Enables Control of Beogram 4002 or 4004 with the Beosystem4 and the Beo4 Remote

One of the great aspects of Beoloving is the amazing people one gets to interact with. Martin, a customer in Germany, recently acquired the Beolover Commander remote kit for his Beogram 4004.

After he had received and implanted it, he got in touch and asked me if it were possible to make the Commander work with any Apple remote, instead of just the paired remote I provide it with. Pairing means that the Commander only interacts with the included remote, but not with other Apple remotes that may be in use in a particular setting. This prevents unwanted crosstalk. 

The reason for this request was that Martin was up to something exciting, where the pairing feature was a hindrance!:

He wanted to integrate his Beogram 4004 with his Beosystem4 that he controls with a Beo4 remote. This is possible since the Beosystem4 can be set up to interact with 3rd party audiovisual equipment via a "PUC" table that can be loaded into the Beosystem4. PUC stands for "Peripheral Unit Controller". Long live the use of acronyms for impressing the uninitiated...;-).

Such a PUC table contains the information the Beosystem4 needs to send out codes destined for equipment manufactured by other companies. Like Apple. This means that the Beosystem4 can be setup to control Apple TVs, and since the Beolover Commander uses an Apple TV remote, the Beosystem4 can also control a Beogram 4002 or 4004, provided that the Beolover Commander remote module is installed.

But: The PUC mechanism does not provide for controlling Apple devices that are paired with a specific Apple remote, i.e. the Commander needs to be un-paired to make this work.

So Martin got in touch and I updated the firmware in a way that the pairing feature can be turned off by the user if so desired: Simply press the "Sweep right" button on the black ring 7 times until the Autorepeat LED flashes three times. Done. From this moment on the Commander will take commands from any Apple remote, not just the provided one. For re-pairing simply perform the pairing procedure by pressing the Menu and Select buttons for ~6 seconds until the 33 RPM scale light comes on briefly. If you want to do this and you bought your Commander before January 2022, you will need to send it to me for a free update of the firmware.

At this point you are probably curious how to set this up with the Beosystem4! Since the Beolover mentally mostly lives in the 1970s, I asked Martin to provide a step-by-step description of his process, which he happily provided. This is what he sent me (please, contact him directly if you have additional questions for he lives in the present and understands newer B&O equipment):

Martin's Set-up Instructions:

"The Idea was to connect my Beogram 4004 with my Beosystem4 for full remote control with the Beo4 remote. This will also work with multi-room option in your system. 

I’ve heard about the remote control commander of the beogram 4002/4 created by beolover (https://beolover.blogspot.com/2021/09/commander-remote.html) 

What I really like with B&O is 'one Remote for everything'. B&O is providing a 3rd Party control with PUC (Peripheral Unit Controller) on some Beovision and Beosystem. (i.g. Beosystem4, Beovision 11 and Beoavant, with Beosystem3, Beovision7,8 and 10. You'll need to get the PUC Table installed by your B&O dealer!) 

The only thing you need is an IR-blaster cable (can be ordered by our B&O dealer) 

After installing the remote control commander of Beolover you just need to bring the PUC IR blaster transmitter to the Commander IR receiver, and connect the audio cable of the Beogram via an RIAA pre-amplifier to your Beosystem/vision and configure the system accordingly.

Set-Up Process:

Step 1: Install the Beogram Commander Remote Control as shown in the video (https://www.youtube.com/watch?v=Pfhm93kIU1k&list=PLQ 7T0PlkOsiMEDx1rs1uoK496Ww38hqb8) 

Step 2: Connect the IR-Blaster to the Beogram. This shows a stock photo of B&O IR Blaster cables:

The Blaster transmitter end of the cable needs to be attached to the Commander IR receiver that pokes out from underneath the plinth:

This shows the 'wiring diagram' of the setup:

So it is quite simple to physically connect the Beogram with the Commander to the Beosystem4 controller!

Step 3: Setup:

1. Un-pair the Beolover Commander from its dedicated remote: 

• The Beogram needs to be plugged in and in stop position (the arms are 'home' at the far right) 

• Un-pair the Apple Remote: Press 7 times ’carriage 
to right’ (the right Function on the black ring of the Apple remote). 

• The auto repeat LED blinks 3 times and the pairing feature is disabled. 

• Now the Commander is un-paired and will take commands from any Apple TV remote

2. Configure the Input(AVIn) of the Beosystem/vision with the “Apple TV 2 and 3” PUC 

• Press ‘menu’ on the Beo4. 

• Select “SOURCE LIST” from the menu. 

• Select “AV” source, press ‘red’ button for setup. 

• Select “DEVICE”. 

• Press ‘select’ on your Beo4. 

• Select “YES” for operate the AV access with your 
BANG & OLUFSEN remote .

• Press ‘select’ on your Beo4. 

• PUC Tables will show up. 

• If you already have downloaded the “Apple TV 2 and 3” PUC Table select this and press ‘select’ on your Beo4, otherwise download the Table – select “DOWNLOAD MORE” – “FROM THE INTERNET” – “SEARCH” – “BRAND NAMES” – “Apple” – “Apple TV 2+3” –Select and press the ‘green’ Button select “Apple TV 2 and 3” and press ‘select’ on your Beo4. 

• If you connected PUC 1A IR Sender/Blaser then select PUC 1A and Press ‘select’ on your Beo4 remote, otherwise select the connected PUC and press ‘select’ on your Beo4 remote. 

• Select one “STANDBY OPTIONS” i.e. “OFF AT SOURCE CHANGE” and press ‘select’ on your Beo4 Remote.
• Select “BUTTON” in the menu and press the Joystick to the right select the “SOURCE” Button with witch you would like to start the Turntable i.g. “A.MEM” press ‘select’ on your Beo4 Remote 

• Select the “SOURCE NAME” and change the name by pressing the ‘green’ Button on your Beo4 remote. i.g. “Beogram 400x”. 

• Store everything by pressing the ‘select’ Button on your Beo4 Remote.
• Finish the configuration by holding ‘BACK’ Button
If you now press your selected Source in my example ‘A.MEM’ You should be able to operate the Beogram by the Beo4."

And that is it! Back to the Future with the Beogram 4002/4! Very Beolovely! Thank you Martin for sharing!

Beomaster 2000 Type 2801: First look inside

Continuing on with the Beomaster 2000 Type 2801 I opened up the cabinet to see what sort of restoration tasks lie ahead.

As with other Bang & Olufsen amplifier/receivers from the mid-seventies the cabinet used a lot of M3 flat head screws.

The bottom cabinet plate surprised me a bit in that it is plastic.  Other B&O receiver bottom plates I have worked on have always been metal so that is kind of interesting.  Maybe they were trying to cut the weight down some since this is a pretty large cabinet.

With the bottom plate removed I see that everything inside is clean and rust free.

The top cover of the cabinet surprised me next. 
While it is removable it also has two slotted rails to support just tilting the top of the Beomaster cabinet up for servicing.

The mechanism looks better than it operates though. I found that it is easier to work on the Beomaster with the sliding supports removed.

Note in the photo (at the bottom) a clear plastic piece.  When I opened the top of the cabinet that piece was loose.  It is one of two lens for the tuning scale.  The other one was still in place but this one was loose.

Here it is after I put it back in place.
The other side has a piece of tape plus it is glued.  I don't know if that is the way it came from the B&O factory or if someone has worked on it in the past.

For now I will just glue this end of the loose lens using some Aleene's Tacky Glue (clear type).

Another issue I discovered with the tuning dial assembly is one of the screws that attaches the assembly to the underside of the cabinet cover has a broken plastic tab.

I will glue the plastic pieces together and will fashion a U-channel piece of plastic on the 3D printer that will span the cracks. When epoxied in place the U-channel part will support the broken plastic tab so it doesn't get stressed in the direction that it broke.

The next problem area were the five preset tuning dials.
The round knobs for tuning the presets were loose. They are plastic wheels mounted to a metal shaft of the controls.

I removed all five preset controls so I can clean the controls with fader lube and then re-attach the adjustment wheels with some epoxy.

There is one other place I will need to create a 3D part for but I will cover that when I get to it in a later post.  The end of the sliding cover for the Loudness and Tape select buttons has a plastic filler piece that is missing.  That will be a simple rectangular piece of black plastic to print on the 3D printer and glue in place.

The last things to examine are the circuit boards that have electrolytic capacitors to replace.

Here is a quick look at the Beomaster 2000 circuit boards.

The first picture is of the output amplifier assembly.  It is PCB 7 and has four power transistors at the back that are attached to heatsinks.

There are eight electrolytic capacitors to replace and two 250Ω trimmers for the no-load current biasing of the output amplifier.  I will replace the single-turn trimmers with nice Bourns multi-turn trimmers.

This picture is the IF Section & Decoder board (PCB 2).

There is one 470uF, 40V electrolytic capacitor to replace.  The rest of the polarized capacitors are tantalum type capacitors.  

You will find a lot of discussion for and against tantalum capacitors in restoration projects if you search for the topic on the web.
Some people say to always replace tantalum capacitors no matter what.  I believe that is because the tantalums tend to fail badly when they do fail.  However, they actually have good properties for audio preamplifier, filtering, tone control and radio tuner circuits.  They are not particularly good for power amplifier circuits and notice that the B&O engineers do not have any in the Beomaster 2000 output amplifier.

The tantalum capacitors have good temperature stability, low ESR, low leakage and low noise (when charging and discharging).  They are an expensive capacitor as well so the B&O engineers did not "settle" for the tantalum capacitors in their design. They selected them for a reason.

There are modern electrolytic capacitors and film capacitors that can replace tantalums so that is a valid option.
My thinking here is that I will respect the wishes of the B&O design engineers and retain the tantalum capacitors.  I will check them out to make sure they are good of course but in my other restoration projects I don't think I have come across many tantalums that are out of tolerance.

...and as you will see, the Beomaster 2000 has a bunch of tantalum capacitor components.

It should be interesting to test the results when I have this receiver working again.

While I am showing PCB 2 it was brought to my attention that the little, round bridge rectifier, 2D8 (a B40C800 rectifier device) is known to cause some issues in these Beomaster 2000 receivers.  So that device will be replaced for good measure.

Another radio component in the Beomaster is the Front End (PCB 1).

It has a 10uF tantalum inside so unless the front end is bad I don't intend on touching it.

The Beomaster 2000 IF circuitry continues onto PCB 5 which also has the preamplifier circuits on it.
Sitting on top of the IF Section & Preamp board (PCB 5) is the Tone Control board (PCB 6).  The Tone Control board is shown tilted out of the way in this photo.

Again, the IF Section & Preamp board has mostly tantalum capacitors but there are a couple of electrolytic capacitors that will be replaced.

The Tone Control PCB only has tantalum capacitors but it has four slide controls that I will clean and lubricate with some fader lube.

Similar to other Beomaster components from this time period B&O engineers used a push button switch assembly for the amplifier control selection.  Pressing the button for a given audio source will also turn the Beomaster 2000 on.  Pressing another source select button makes that source the active, playing music source. The Off pushbutton then deselects the selected source button and turns the Beomaster off.  

On a Beomaster 3000, 4000 and 4400 I always kind of dread the pushbutton switch assembly because if there is a problem with it the repair is quite difficult.  There is the mechanical aspect of the assembly then there is the electrical contacts part.  Those contacts are extremely difficult to access for repair on a Beomaster 4400 so I suspect that is the case here as well.

There should be a way to access the electrical contact areas to spray in some good contact cleaner.
I will have to figure that out on this Beomaster.

I am encouraged by the condition of this Beomaster 2000 though. The push button mechanics all operate so I think that all that is required is contact cleaner.

In the next post of this receiver I will work on the repair of the broken pieces of the tuning dial assembly.