Beogram 4004 (5526): Installation of A New Output Cable

After replacing the light bulb in the sensor arm with an LED assembly it was time to look into the RCA plug 'conversion' of this Beogram 4004 (5526). This shows the output cable in the condition when I received this Beogram:

Not a very inspiring sight. The blue and yellow leads are the Beolink signal lines that allow controlling the 4004 via a Beomaster 2400. We decided to return this 4004 to its original DIN7 output scheme. Originally the 4004 came with a convertible male DIN7 plug, which can be turned into a standard DIN5 by unscrewing the two pins that are extra in the DIN7 format. This shows a plug as seen on a 4004 I restored a few years ago:

The two outer pins were removed so that the plug essentially acted like a standard DIN5 phono output. Unfortunately, such DIN7 plugs are not available anymore. A solution I came up with is to install female DIN7 plug that has all the signals on it. If extended with a DIN7 cable it turns into a DIN7 male output that will properly work with a Beomaster 2400. Extend it with a DIN5 or a DIN5-to-RCA adapter and a standard non-B&O phono output is achieved.

This shows the female DIN7 plug during the installation:

Note that the leads need to be soldered in a mirrored pattern compared to that applied for a male DIN7 plug, since male-male DIN5 and DIN5-RCA jumper cables mirror the leads for symmetry reasons.

This shows the DIN7 connected to a DIN5-to-RCA jumper cable:

The system ground connection is on a separate wire (not visible on this photo) that it can be connected to the GND terminal of the RCA input amplifier.

Beogram 4000: Upgrade of Signal Path with New DIN5 Plug and a Grounding Switch

As usual the original DIN5 plug on the Beogram 4000 that I am currently restoring was badly oxidized. This shows the original plug:

I replaced it with a new all-metal plug that has gold coated terminals:

Another useful upgrade of the signal output of any Beogram is the installation of a switch that allows connecting signal and system grounds. This is a useful feature if the Beogram is ever to be used with a DIN5 to RCA adapter. Since RCA cables do not carry the system ground, connecting it to the signal ground on the Beogram often eliminates humming. This shows the output terminal assembly of the Beogram 4000 in its original condition:

This open layout makes it very convenient to add a switch:

The shown switch position connects the two ground. Flipping the switch would open the connection.

Beogram 4002 (5523): Replacement of Corroded RCA Plugs

The Beogram 4002 (5523) that I am restoring right now was outfitted with RCA plugs and a grounding wire instead of the standard DIN 5 connector. As usual the plugs and the grounding terminal were grimy and corroded:

I replaced the RCA with all-metal gold plated plugs and I installed a new grounding terminal:

For some reason these nice compact RCA plugs do not come with a color coding, so a while back when I started using them in my restorations I designed 3D printed inserts that close off the back of the plugs and give them a distinguishing mark for the left and right channels:

On to the final adjustments and a test drive of this lovely Beogram!

Beogram 4004 (5526): Replacement of Convertible DIN7 Plug with DIN7 Socket and an RCA Adapter Cable

Any restoration of a Beogram should include the replacement of the DIN connector to ensure a low impedance signal path on the way to the amplifier. In the case of a Beogram 4004, the DIN connector is a convertible male DIN 7 plug, where the two additional pins can be unscrewed from small sockets. These two pins would carry the remote control signals from a Beomaster 2400, which is designed to control the 'start' and 'stop' operations of the Beogram 4004. An early form of Beolink, so to speak. But of course, if one does not connect to a 2400, these pins are not needed, hence the convertibility. This shows the plug with the empty two sockets at the ends of the 5 pin half-circle:

This type of plug is no longer available, and so I resorted to replacing it with a DIN 7 female socket, which then connects to a jumper cable with the desired number of pins or RCA termination. In essence this approach converts the Beogram 4004 output scheme to that found in the later Beogram 800x models, who have a DIN 7 socket mounted in the back of their enclosures. That way one can connect with both DIN 5 and DIN 7 jumper cables to a non-B&O or B&O amplifier.

Even cable mount DIN 7 sockets are difficult to find these days, but Steve at soundsheavenly.com can provide them. Here are a couple impressions: This shows the socket soldered on:

and with its shield in place:

And finally with a DIN 5 to RCA adapter cable:

Beogram 4004: Replacement of Convertible DIN 7 Plug with a Female Socket and Adapter Cables

While enjoying the Beogram 4004 that I recently restored I was looking for an adequate modern replacement for its convertible DIN 7 plug. This plug is a special design that does not seem to be made anymore. Here is a picture of its business end:

The picture shows the plug in its DIN5 configuration, i.e. it can now connect with any standard DIN5 amplifier input. The two (threaded) orifices above the pins can hold two more pins, which can be bolted in if the Beogram is to be connected to a Beomaster 2400 to take advantage of its remote control, which can be used to start/stop the Beogram. In essence these two additional pins carry the remote control signals for the Beogram. But, of course, since this is a male plug, the pins have to be removable if the Beogram is to be used in a standard DIN 5 setting.

Sadly, these plugs are nowhere to be found these days, and so, if a new plug is desired, another approach needs to be found to preserve the above 'convertibility'. My solution was to replace the plug with a female DIN 7 socket. That way DIN5 (or DIN5-to-RCA) jumper cables can be used for non-B&O set-ups and DIN7 jumpers can be used to connect to B&O setups. In essence, this modification gives the Beogram 4004 the same connectivity design like the later Beogram 800x, which have a panel mount DIN7 socket in their back panel to receive a suitable jumper cable.

It was pretty difficult to find a decent female cable mount DIN7 socket, but finally Steve at soundsheavenly.com saved the day by providing me with a few DIN7 Deltron sockets for cable mounting.

Here are a few impressions: This shows the socket installed. The red and white leads are the signals and the yellow and blue leads carry the remote control.

It is important to note that the signal leads on a female sockets need to be soldered to the other side of the connectors since male and female plugs have mirrored pin assignments to properly maintain the signal chain through the connections. This shows the fully assembled socket:

This is how it looks with a DIN5 jumper cable (also provided by Steve) plugged in:

This Beogram 4004 is finally ready to be shipped back to its owner!

Beogram 4000: A New DIN 5 Plug and Installation of a Grounding Switch

The Beogram 4000 that I am restoring right now had a badly corroded and poorly installed DIN 5 plug. Obviously not the original plug. Here are a couple pictures of the sorry state of this plug:

I think the dangling black lead may have been an attempt to reduce some humming issues (no surprise, considering the way this plug was installed...;-). Besides this strange construction, one of the signal leads was also disconnected due to a sad soldering job. 

I cut off the plug and prepared the leads for the new plug:

This picture shows the advantage of DIN connections over RCA: The entire cable and connectors are double shielded. Each lead is shielded by the signal ground lead and then there is an outer shield that connects the enclosures of amplifier and turntable. That way the shielding is complete, which gives the best defense against EMI. RCA usually only have a single shield via the signal ground. That is why there is usually a separate wire that connects the amplifier and turntable system/enclosure grounds.

Then I soldered it on:

And this is how it looks with the shield on:

Beogolden I'd say!

The final step of refurbishing the signal path was to install a switch that allows connecting signal and system grounds. This is a convenient features if there is a hum when connecting to RCA inputs via an adapter.

Switch to the left (as shown) and the grounds are connected. Switch to the right and the grounds are disconnected as in the original configuration. 

Beogram 6000 (5512): Replacement of a Corroded DIN5 Plug with a New Gold Plated Unit

Practically all Beogram 4002/4 and 6000 need their DIN5 plugs replaced due to various levels of  corrosion on the contacts, which were not gold plated back in the 1970s. This Beogram 6000 (5512) is a 'beautiful' example:

and with the shield removed:

I cut the rusty plug off and installed a new gold plated all metal plug:

and with the shield on:

Beolovely! The CD-4 preamp board is next!

Beogram 4000: Replacement of Corroded DIN5 Plug and Installation of a Grounding Switch

After rebuilding the control cluster the next step of my current Beogram 4000 restoration was to replace the original corroded DIN 5 plug with a modern gold plated all-metal plug, and to install a switch that allows connecting system and signal grounds in case there is a ground loop causing a hum in connection with the amplifier. This shows the rusty original plug:

And here the replacement:

Pretty! On to the grounding switch. This shows the terminals where the DIN cable is connected to the internal cartridge wiring:

This is the perfect spot to install the switch:

This switch allows to toggle between the B&O-original setup, where signal and system grounds are kept separate, and a configuration where both grounds are connected. B&O actually adopted this configuration in later 4002 and the 4004 Beograms. My experience is that if there is a hum, this connection in most cases suppresses it.

Beogram 8002: Transplantation of Output PCB

Finally I had some time again to work on the Beogram 8002 that I recently started to restore. The last two weeks were an 'interesting experience' after Michael Fremer's video appeared on analogplanet.com featuring my CleanerVinyl ultrasonic vinyl cleaning equipment. 

The next step in this project was to transplant the DIN7 output assembly from a parts-Beogram 8002 that I acquired from a crooked audio repair shop in Chicago. This unit is now coming in handy here since the 8002 was missing its DIN7 output cluster:

I always wonder what drives people to do such things, but here we are on our interesting little self-absorbed planet...;-).

I extracted the assembly from the parts 8002:

I decided to update the relay with a modern encapsulated unit while I had everything on the bench. The original Omron G2V-2 relay can easily be replaced with its modern G5V-2 cousin, which has the same footprint:

And here is a photo of the installed new relay:

and with its shield clamped on:

This shows the restored wiring:

After verifying that the relay worked properly I installed a grounding switch that allows to connect signal and system grounds if there is a hum problem:

On to the two other issues that I was able to identify: The deck does not detect the absence of records and happily lowers the arm onto the platter. It also has a missing digit in the RPM display. One step at a time.

Beogram 8000: Installation of a Grounding Switch, Repair of a Broken Off PCB Post and, Finally!, Test Drive with Gabor Szabo!

I gave the Beogram 8000 that I am restoring right now a couple final touches:

1) As usual, I installed a switch that makes a connection between system and signal grounds. Such a connection usually extinguishes any hum that may arise from incompatible connections between turntable and amplifier. In my view there are no adverse effects resulting from connecting the two grounds, but the original B&O set-up is to keep them separately until they meet in the amplifier, so I put in a switch to make the connection easily reversible, if desired down the road.

This shows the installed switch on the output relay board:

2) I needed to reattach a broken off PCB mounting post. The post that holds the rubber bumper that presses the main PCB into its mounting brackets broke off when I removed the PCB...this old plastic can sometimes be a bit brittle. Luckily, there was enough 'meat' that allowed me to drill a small hole through the post and the underlying plastic with my Dremel tool. Then I bolted it down with a 2-56 screw and this worked very nicely:

All good now under the hood!

I closed it up and then performed a calibration of the tracking weight:

And then it was finally time for a test drive! I had just received a new vinyl from Sweden: Gabor Szabo's "Small World" from 1972. This is one of those he recorded in Sweden. I got the original Bellaphon release (Made in West Germany...;-)

What a great record (especially after ultrasonically cleaning it with my CleanerVinyl Pro..;-)! And his awesome 1970's purple outfit! Those were the days! The album contains another version of 'people', which is one of my favorite tunes ever. And Szabo brings it to life like no other. Too sad that his life was short and things did not end that well for him. Very unfortunate! I am very grateful, though, he left us a bunch of wonderful albums to enjoy! More achievement than most of us will ever be able to claim when we go meet our Maker for that final exit interview...;-)! This is Beolove!

Beogram 4002 (5501): Replacing the Original DIN5 Plug with a Modern All-Metal Gold Plated Unit

No restoration of a 4002 is complete without replacing the usually oxidized original DIN5 connector. Those precious low voltage signals deserve the best contacts possible. Gold does not oxidize, and therefore it is able to make low-resistance and long lasting contact. This shows the original plug that was on the Beogram 4002 (5501) that I am currently restoring:

I cut the plug off and prepared the cable for installation of the new gold plated all-metal plug:

Then it was time to solder the plug to the cable:

And this shows the assembled new plug in all its glory:

Beautiful! On to the final touches to get this Beogram ready for primetime!

Beogram 4002 (5513): Installation of New Gold Plated RCA Plugs

No Beogram 4002 restoration is complete without replacing the original DIN or RCA plugs. The original plugs are usually a bit corroded since they were not gold plated. It is a great idea to install modern all metal plugs with gold plated terminals. This increases protection against EMI interference and also ensured low contact resistance to let those small MMC20 signals travel to your amplifier unimpeded. This gives an impression of the original RCA plugs that were on the Beogram 4002 (5513) that I am restoring right now:

Pretty grim...I cut them off and installed nice Amphenol plugs with a full metal body and plated contacts:

And fully assembled:

Very nice! 

Unfortunately, this Beogram also had its grounding wire shortened:

What is it about cutting off cables?? A significant number of Beograms that found my bench in recent years had severed cables, either the power cord or the output cables. How about just curling them up into a neat coil and leaving them alone if they are too long?? Oh well, I replaced the cable fragment with a new pristine 16 gauge wire matching the RCA cables in length. All good again!