Beogram 4002 (5513): Installation of Upgrades - Universal Power Supply, SyncDrive and Internal RIAA Pre-Amplifier

I just sold a Beogram 4002 (Type 5513) to a customer in the UK. The restoration of this unit is discussed in this post. The new owner wanted to be able plugging it in in the UK without using a 110-to-220V transformer (Type 5513 Beogram 4002 have a supply preset for 110V). This issue can be addressed by installing a modern 'universal' power supply that can work with any grid voltage between 100V and 240V (read more in detail about this approach here). In addition to this new power supply he also wanted the Beolover SyncDrive and internal RIAA pre-amplifier installed.

I started the work by removing the hood and aluminum panels:

This unit had already received the Beolover Commander remote control before I put it up for sale.

First I focused on upgrading the power supply. This shows the original 'classic' transformer setup in place. The encapsulated transformer sits right next to the cable feedthrough and behind the fuse box. In other 4002 Types the voltage selector sits beneath the fuse box. In the 5513 type the voltage selector is replaced with a dummy plate and the transformer is directly wired for 110V only.

This shows the modern replacement, a Meanwell RS25-24 power supply which can operate on any grid voltage: 

It can supply 25W and has a tunable 24V±~4V output voltage range. 25W is more than enough since all the DC platter motor Beograms are rated 15W. This picture also shows the 3D printed adapter plate that I had to design for bolting it into its proper location, while using the original transformer mounting holes in the enclosure.

This shows the supply with bolted on adapter plate:

I removed the four screws that hold transformer and fuse box in place:

It seems best to cut the secondary wires of the transformer at about 40 mm. This results in long enough leads for connecting the new supply:

I soldered 3mm lugs to the cut off blue secondary wires and to new wires for connecting the new supply to the fuse box:

Then it was time to connect the new input wiring for the MEanwell supply to the fuse box. For this I unsoldered the wires going to the transformer (upper connections in the picture): 

and then I soldered in the new red/black wires. Here you can see them emerging from the fuse compartment:

Then I bolted the fuse box back into place:

The next step was bolting the new wiring to the screw terminals of the supply:

Note that the polarity of either connection is not important: The input wires are AC and the blue output wires connect to the rectifier on the main board that previously turned the secondary AC of the transformer into DC for the electronic circuitry.

At this point I also adjusted the output voltage of the supply to the maximum 28V that are possible with the RS25-24. This is done with the white trimmer on the right of the terminals as far clockwise as it goes. 

After adjusting the length of the input cable a bit at the cable gland in the enclosure feedthrough I was able to bolt the adapter plate to the enclosure bottom while smoothly routing the wiring through the 'channel' that I designed for this purpose into the adapter plate. This shows everything in place together with the sub-platter (there is a ~9 mm gap between supply and platter, enough for comfortable belt mounting:

Next came the installation of the Beolover SyncDrive. The SyncDrive is a synchronous motor driven by a dedicated digital control system. This gives it exceptional log-term RPM stability, similar to the later Beogram 8000/8002. This shows the original DC motor still in place:

The SyncDrive is a 'bolt-in and play' replacement for the original motor, i.e. there is no need for soldering. This shows it in place:

The red wiring harness connects to the RPM-panel jack on the main PCB. For this a small adapter breaks out the necessary connections to the red SyncDrive harness, while the original plug is also plugged into the adapter:

The final task was the installation of the internal Beolover RIAA pre-amplifier. The Beolover RIAA directly replaces the original output PCB of the Beogram, shown here still installed:

The Beolover RIAA is also a plug and play upgrade, i.e. all that needs to be done is unplugging the original board and then plugging in the RIAA board:

Then the keypad can be installed again.

This concluded my upgrade work on this Beogram 4002. I will now play it for a couple days to make sure there are no intermittent issues, and then it will be time to send it to its new owner in the UK!

Beogram 4004 Type 5526: RIAA preamp board hiccup and fix on Beogram 4004 Turntable #1 from Dallas

In the last post of the Beogram 4004 Turntable #1 from Dallas I installed Beolover's custom RIAA preamplifier board he designed for the Beogram 4002 turntable.

I left off in that post with the Beogram 4004 ready to check that the original functionality of the modified output board still worked. In other words, the normal mode where the phono cable is connected to an amplifier that provides the RIAA preamp.

That test worked perfectly so it was on to try out the new RIAA preamp mode of the Beogram 4004.
I switched the two connectors from the original module 8 connectors P8 and P9 to the two connectors on the Beolover RIAA preamp board.

Now I would be able to connect the Beogram phono cable to an amplifier's auxiliary, tape or CD source input connectors and listen to the Beogram.

I was surprised when I tried that and the Beogram 4004 would not respond to any of the control panel buttons.

Thinking about it for a few moments I realized that while the Beogram output board on the Beogram 4002 and 4004 have the same P8 and P9 connectors, the BG4004 has an extra connector and circuitry for its remote control capability with a Beomaster 2400.

Here is a diagram of the Beogram 4004 output board and its additional remote control circuit.

The part of the diagram below the dashed red line is the phono output (with muting relay) that does not involve the remote control. The Beolover RIAA preamp board uses those two connectors to perform its function. Switching the P8 and P9 connectors between the original module 8 output board and the RIAA preamp board allows switching between the original, no RIAA output and the RIAA amplified output from the Beogram.

With the additional remote control support circuitry in the Beogram 4004 some of the P8 inputs are needed in the remote control circuit and work with the Beogram control panel via the additional P10 connector on the output board.

When I move the P8 and P9 connectors from the original output board to the RIAA preamp board the original output board loses its 30V, 21V and system ground wiring. Those are not only necessary for the remote control circuit but also for the control panel switches in the Beogram 4004.

That is the reason the Beogram 4004 acts dead when the P8 and P9 are configured for RIAA preamp mode.

The fix turned out to be simple. When the P8 connector is moved from the original board to the Beolover RIAA preamp I must have jumper wires keep those key pins (30V, 21V and system ground) between the boards connected.

Here is a diagram of the output board with the RIAA preamp board after the jumpers were added.

I retested the Beogram 4004 with the Beolover RIAA preamp board again by connecting it to the Tape 1 input DIN jack on my Beomaster 6000.

It works awesome!

This is a great mod for a Beogram 4002/4004 turntable. With this modification all of the record play bases are covered. In a vintage audio system where the amplifiers were designed with specific phono inputs you can use the Beogram with the output connectors in their original position. When you need to connect to a modern amplifier that has no phono record play support you can set the Beogram to use the RIAA board.

I will definitely want to do this same mod on one of my own Beogram 4002 or 4004 turntables.
Time to put this cabinet back together and get the Beogram ready for delivery to its owner.

Beogram 4004 Type 5526: Last minute mod on the Beogram 4004 Turntable #1 from Dallas

The Beogram 4004 turntable number one (of two) from Texas was ready to return home to its owner when a special modification was requested. The owner has a modern integrated Bang & Olufsen system from the late nineties (Beocenter 2500) that is now the intended receiver for this Beogram. That presents a problem because the modern systems do not come with a built-in RIAA preamplifier which is required to prepare raw phono cartridge signals for amplification. The resurgence in the popularity of vinyl records has meant a whole bunch of amplifier systems out there without support for phonographs.

There are quite a few third party solutions of course. Those involve a small RIAA preamplifier box between the turntable and the modern amplifier. That works quite nicely but there is a better way when it comes to a Beogram 4002 or 4004 turntable.

Beolover has designed and built a custom Beogram 4002/4004 RIAA amplifier board that connects right into the Beogram (on the existing output board).

The beauty of this design is two-fold.

1. The modification is internal to the Beogram so it doesn't require an external box and additional cables. The original phono cable is used as-is.

2. The modification retains the original connections so the Beogram can still be used with amplifiers that have their own RIAA preamplifier.

The installation of the Beolover RIAA preamp is quite easy.  Here is the sequence.

In most cases the installation is just to remove the phono output muting relay and solder in the custom RIAA preamp board. For this case I also had to remove the grounding option switch I had installed earlier in the project.

The grounding option is not necessary when using the RIAA preamp connectors. If the owner wants to change the receiving amplifier for this Beogram later, to one that has an RIAA preamp, then the grounding option is still nice to have.  The switch I had installed before would be in the way so it has been replaced with a simple two-pin jumper between signal ground and system ground.

Here is the Beogram 4004 output board with the new RIAA preamp mod re-installed.
This picture shows the board connected up for use as the original Beogram....without any RIAA preamplifier.  I want to test that the original functionality works first.  Then I will switch it to use the Beolover RIAA preamp connectors and test the Beogram in that configuration.

If any other Beogram 4002/4004 owners would like to try this preamplifier for their Beogram just contact Beolover at beolover@gmail.com.