Beomaster 8000 & Beocord 9000: Completing the Restoration

The final step in this Beomaster 8000 and Beocord 9000 project is a system test. To do that I needed plenty of space as these units take up a lot of room. Especially when you add in a Beogram turntable to complete the system. It is also time to clean up and put parts away. My soldering bench is my largest desk so I used it to set up the system test.

Here is a picture of everything layed out for testing.  Quite lengthy! With all of the system connected together the dependent functions can be exercised. A really nice feature of this system is that turning on one component will notify and turn on any related component. For example, placing a record on the Beogram and pressing the Beogram play button will turn on the Beomaster and switch it to phono mode. Same thing for the Beocord. Conversely, selecting PH (phono) on the Beomaster will cause the Beogram to operate. Turning the Beomaster off turns all of the other components off. To make things even nicer, all of these features also operate from the wireless remote control. The well thought out design is what makes this Bang & Olufsen system my favorite. Of course B&O continued some very cool integrated systems after this one but this system was a few years before the digital age and is analog audio at its best.

I continued testing by doing some recording on the Beocord 9000 with the Beogram 8002 as the source. I used a new TDK MA90 cassette (metal type IV) and ran the Beocord tape calibration procedure. This is when you start really appreciating the complexity of the Beocord 9000. After calibration I selected Tape End so the Beocord would run through the tape once and figure out exactly how much recording time is available on the tape. The Beocord tape counter of course displays the amount of time used and remaining. Really handy if you want to fill up as much music you can on a side.

For the recording test I like to use music with some distinct instruments and some that really get up there in range. That usually means some brass. So this time I selected an old Maynard Ferguson album from 1973, "M.F. Horn 3". It has that early 70's sound and of course Maynard screams on the trumpet. Quite fun if you like that era like I do. The recording testing all worked perfectly. I also tested pausing and restarting recording. The Beocord fast forward and reverse functions all work great (remember the belts and pulleys are all new). This is the payoff for the time and effort it took to get these beautiful machines fully restored.

With all of the Beosystem 8000 functionality working beautifully it is time for their owner to enjoy them so Beomaster 8000 and Beocord 9000 are ready to be packed up and shipped home.

For me it is time to prepare for the next project.

Beomaster 8000 & Beocord 9000: Re-Installing the Lid Dampers

In the last post on the Beomaster 8000 lid damper restoration I left off with the first damper cleaned out and fitted with new damping grease. I had to experiment with the re-assembly of the dampers to get them sealed and working properly. Out of the six damper assemblies I had available I have restored four so far. Here is a lid damper completely disassembled.

Here is another picture of the damper with new damping grease ready for joining the two main pieces.

Next is the joining of the damper and Beolover replacement arm to the deck lid. It should be done with all of the components removed from the Beomaster. Snap the new arm to the deck lid first. After that the other end of the arm attaches to the damper by sliding over the keyed mounting post on the lever. 

Now it is ready for re-installation in the Beomaster 8000.

The Beomaster 8000 deck lid now opens slowly and smoothly as controlled by the damper device. This is the result I was looking for.

Also part of this lid damper restoration is the damper for the Beocord 9000 that goes with this Beomaster. Again, installation of the reworked damper is done with the lid removed from the unit.

The Beocord still has its arm intact. Note that while the damper unit is identical to the Beomaster, the arm for the lid is not the same. The Beocord arm is shorter in length.

Here is the reworked damper installed back on the Beocord deck lid. Note the position of the damper lever and arm. As was the Beomaster, attaching the arm to the damper is done by sliding the arm on from the side. To install this on the Beocord deck lid the result will be the arm on the lower side of the damper. After the arm is attached to the damper you must rotate the damper 360° so the arm is on top (as shown in the picture below). Otherwise the damper won't be able to do its job.

Now the deck lid assembly is back in place and this Beocord 9000 has a properly working deck lid again.

This concludes the lid damper rework for these two units. The new damping grease should not liquify and leak like the old grease did. At least not for another thirty plus years.

Beomaster 8000: Ready for Some Bench Testing

Ever since I restored the power supplies, output amplifiers and preamplifiers on this Beomaster I have been exercising it with an iPod through TP1 & TP2 as well as playing the FM radio. The receiver has continued to play and sound very good as I added the restored FM boards, Filter & Tone Control board and the Microcomputer board. Now it is time to start putting the Beomaster back together and do some bench testing.

As I started the reassembly I tried the remote control for the first time. No functionality. So I will have to dive back in to the power supply board where the remote control receiver lives to see what is wrong. But first I decided to continue with some initial bench testing. I have been anxious to take some measurements and I don't see any reason to let the remote control problems delay that right now.

Before using any test equipment I decided to run a functional check pairing the Beocord 9000 that I restored earlier. These two will be returning together to their owner soon and I wanted to see how they play together for the first time since their restoration.

I used an original seven pin DIN cable for TP1 to connect it to the Beomaster. Pressing the play button on the Beocord turns puts the Beomaster into TP1 play mode as expected. Pressing the standby (off) button on the Beomaster turns both units off (and into standby mode). So they are communicating well. The Beocord also sounds great. In a later bench test I will add one of my Beogram 8002 turntables to the mix so I can both check out the phono input and do some recording on the Beocord.

Next up for this testing session though is to use my QA400 spectrum analyzer to check the Beomaster 8000 from its source input (TP1) to its output amplifiers (Speaker 1).

Beolover has featured some measurements before from his QA400. It is a nice little bench analyzer that uses a PC to do all of its analysis. The connection to the computer is via a USB cable and software on the PC sets up the tests performed. Up until now I have only done low voltage level testing with this type of setup because the inputs to sound card devices and this QA400 are limited to the ±5 volt range. Connecting to the power amplifier outputs was not doable. I picked up some differential voltage probes by the QA400 manufacturer that will allow me to measure higher voltages. For this Beomaster source-to-speaker test I will use a couple of fixed 8 ohm loads to simulate speakers and connect the differential probes to the dummy speaker connectors.

The probe is powered by batteries and has a BNC connector to run a coax cable to the QA400 input terminal. For some reason I could not get my test setup working as I wanted with both differential probes connected at the same time (one for the right channel and one for the left channel). With both probes connected I see some undesirable noise at 60 Hz from my house line voltage. So far swapping cables and probes doesn't solve the problem. The only thing that works is using one of the probes on one channel at a time. Then there isn't any 60 Hz noise present. So I performed my tests one channel at a time switching the speaker connection to the Beomaster. The measurement results look pretty good. I won't post all of the frequencies I checked (400Hz, 1kHz, 5kHz, 10kHz, 15kHz) but here is the 1kHz test on the left channel. I tested with the analyzer set to unweighted and A-weighted.

Here is a 5kHz test on the right channel.

Viewing the distortion numbers and sound to noise level readings at a few select frequencies was nice to see. This Beomaster sounds really good but I like to see some sort of measurable result besides my own ears.

Now it is back inside to see what is wrong with the remote control receiver.

Beomaster 8000: Tackling the Lid Damper

On these last two Beomaster 8000 and Beocord 9000 projects the owner had to have the damper devices for the lids removed as they had begun to leak fluid. This appears to be a common problem with the grease used by B&O on these series of components (Beomaster 8000, Beomaster 6000, Beocords 8000-9000).  Of course these these devices are thirty plus years old now so that has to be taken into account.

The Beocord 9000 I worked on doesn't have its damper anymore so I will replace it with a spare from another Beocord. The Beomaster 8000 damper is still intact although removed from the unit.

Here is a picture of the dampers I have available for this project and some of my future projects. The damper in the center has the most leakage of the bunch. Also shown are an original lid lever for the Beomaster 8000 and a 3D replacement lever that Beolover can provide. While the damper devices are the same between the various Beosystem components of this series, the levers are not. The Beomaster 6000 and Beocords require a different size lever. In the picture below the lever out of this Beomaster 8000 is not original. It is a pretty good hand-made replacement carved out of plastic. However, the plastic has become quite brittle and starts to break with the slightest pressure applied. The other lever is the Beolover 3D printed replacement. That is what I will use on this Beomaster.

This next picture shows a few of these dampers opened up. The two on the far right still functioned to some extent. The others no longer did much as their grease is pretty much gone. Two of the dampers had their plastic mounting clips melted in place as an attempt to keep the device sealed. I had to cut them open and they were pretty empty so the grease leaked out anyway. When I rebuild these my plan is to use black hot glue. I think it will hold secure enough yet allow disassembly in the future.

The next to last damper device on the right is the only one that had an additional, thin, white washer installed. I don't know if that is original or something that was added later by someone.

Here is a closer up picture of the dampers that still had functioning grease. Next to them is the replacement damping grease I will use. The thing to figure out next is how much grease is required for these dampers to operate correctly. Should the entire housing be filled? I hope not. One tube of this special damping grease is about $50 USD so it is quite an expensive product. However, it is made for the purpose of damping and claims it will not break down under high temperature.

Here is a cleaned out damper with the Nyogel applied. It is ready to be sealed up.

Beomaster 8000: Updating the Displays - Completed

Today I finished replacing a set of Beomaster 8000 display LEDs with SMD LEDs. This set had numerous faulty display segments so it was badly in need of repair.

I was a little disappointed that my SMD work station method of doing this task fell short of expectations. In my earlier restoration of the Beocord 9000 displays the work station method worked quite well and I felt like I only needed to perfect the process a little before it became my new way of doing these displays. Now I think that was just beginner's luck. Since that first display repair the SMD work station technique has meant a lot more rework and waste of new SMD LEDs (that had to be tossed when the installation failed).

The problem with the SMD work station is that even with minimal air flow, the SMD LEDs can shift during soldering. Even in the case where the solder pads are small I usually run into over half the LEDs not soldering in the position they need to be. With these Beosystem LED displays it is critical that the LEDs stay within a narrow range in their positioning. The reason for that is they have to fit nicely in the slots of the plastic housing that guides the light.

So after that hopeful experiment I have reverted to the tried and true manual soldering process.

To show what I am talking about here is the preparation for the Beomaster 8000 channel balance display. This picture shows the SMD LEDs in place on their solder paste ready for the heat to be applied.

After the board heater and heat gun melted the solder, the result was quite unsatisfactory.

The LEDs circled in red were not successful. I had to toss those LEDs as I don't trust them to be reused once I remove them. These SMD LED devices are pretty delicate so I don't want to risk them failing later on.

Here is the reworked board after manually repairing it with old fashioned tweezers and soldering iron. I used my de-soldering gun to clean up the excess solder.

Now that I decided to change over to the manual soldering method I prepared the next board by cleaning with alcohol and tinning the solder pads. This is the Beomaster 8000 volume level display.

Before placing the SMD LEDs I apply some solder flux with a syringe. The SMD board heater at least provides a nice way to hold the board in place while I work on it.

Here is the completed volume level display. As I did each display I was able to refer back to my photos I posted in the previous post that show the LED orientation on the pads. That was very helpful as I could just look at my smart phone for the reference photo as I placed and soldered these LEDs in place.

Next is the Beomaster 8000 function display. Here is the prepped board.

...and the finished board.

Finally the last board, the FM frequency display board. These display restorations are probably the most difficult job of the entire restoration. The work is very trying on one's patience as it is easy to get frustrated if you can't keep a steady hand. You have to be in the right frame of mind when doing this. 

Here is the last board before tinning. The marks between the pads is where I used a razor knife to cut the tiny pad the original LED mounted to. I found that trying to leave in place is risky because it is such a narrow gap. It is easy for solder to bridge that gap and cutting it out leaves a perfect gap for these SMD LED components.

Here is the board tinned and with solder flux in place on the pads.

The last board is now complete. One other note about the manual soldering process. I often just solder one side of the SMD LED to hold it, then test fit the light guide piece to make sure the LED component is centered in the slot. That is an extra step but it actually saves rework time and risk in destroying a good SMD LED. After I verified the fit I solder the other side of the LED.

Now it is time for the display burn-in test. I reworked my test jig since the last post and I am now going to leave these displays operating for 24 hours to make sure none of them are faulty.

Just for a reference I put the channel balance display completely back together (just pressed together, not permanent yet), the volume display and function display with just the light guide attached, and the FM frequency display bare. You can see the progression that the parts play in the final look of the display.

While these display modules are testing I can start work on the Beomaster display board recapping and the Microcomputer board recapping.

Beocord 9000: Ready for Bench Testing

This weekend I completed the seven segment display rework. I didn't run into any problems with the LEDs during the twenty-four hour burn-in test. After re-assembly of the display I checked the LEDs again. My test jig has two sections for testing the Beocord display. The one shown on the left runs tests with every LED illuminated. The section on the right is when I want to check one LED channel at a time. Or I can check just one LED at a time if I move some jumpers.

During the individual display test I noticed there was a little bit of LED bleed through from the middle "dot" LEDs into the adjacent segments. This would be a noticeable thing when the Beocord is in standby mode.

I checked that all of the SMD LED components were centered in the light guide. The base of the guide was not resting on any part of the LED. Then I remembered this board has three trace repairs. The thin repair wire must be preventing a perfect mating of the light guide base to the board. To fix this I applied a thin coat of black automotive weatherstrip adhesive to the bottom (base) of the light guide. I made sure no adhesive could get into the LED slots. This was also a good thing because the three, white, plastic mounting pegs of the light guide had to be cut away to dis-assemble the display. This adhesive would now block bleed through light at the base as well as attach the light guide to the base. I apologize for not having any pictures of this step but the adhesive has too short of a working time to allow for stopping and taking photographs.

The result worked very well although the short work time of the adhesive made for some assembly stress on the repairman. To prevent any LED light bleed through anywhere else on the assembly I taped up the back as Beolover does on his display repairs. For the outer sides of the light guide though I added a coat of black 1-Shot enamel paint.

The final step was the mounting of the red display cap. I used black hot glue to secure the cap to the rest of the display.

Here is the result.

At the lower right of the picture above you can see the Beocord's lithium battery. That supplies offline power to save any cassette calibrations the user has stored in the Beocord. The battery is soldered to the board via a couple of solder tabs so it requires de-soldering and soldering to change. This battery measured okay but it is a good idea to change the battery install to use a battery holder. That makes changing the battery a much simpler job in the future and no worries about a battery explosion (when de-soldering).
Here is the reworked Beocord battery.

Now I can button up the Beocord and move it over to the test bench. I might still have some tweaks on the Beocord before I send it back to its owner but we'll see what comes up during testing.

This frees up my workbench so I can now start on the Beocord's master...as in Beomaster 8000. That will be the next step in this restoration work. I will do a quick check of the pre-restoration state of the electronics. Then I will start in on the work.

Beocord 9000: Seven Segment Display Board Reworked

It took a little longer than I expected to get my Beosystem display board rework station set up for doing repairs again but I finally got everything in place for repairing and testing the LED display. Here is my test setup for bench testing the display and running the burn-in test. I checked the setup with a working Beocord display.

Here is another look at the display board front and back. This time I have added markings for the segments and the polarities to follow.

There are thirty-one LEDs. This is what the original LED lights look like up close.

Here is the original LED compared next to the replacement SMD type LED.

To prepare the display board for the new SMD LED devices I will scrape off the old LEDs with a razor blade. I also discovered the new SMD LEDs solder in place better if the little pad the old LED rests on is removed.

That leaves the gap just right for the new LED device. Since I have quite a few Beosystem displays from this era waiting for repair I went ahead and ordered a reel of the replacement LEDs (Lumex SML-LX06031W-TR).

A little bit daunting when you first see how small those LEDs are. You must have magnifying equipment and SMD tweezers to work with these. Here is a picture of the Lumex SMD LEDs top and bottom.

I cannot see the cathode mark without the aid of a magnifying glass so I have to examine each one first as I pick it up with the tweezers. They are all oriented the same way in the reel packaging but I still double-check because I just want to make sure myself.

If you are just doing one display board then most people hold the SMD LED in place with tweezers and apply some solder with a soldering iron fitted with a small tip. I have done that before and it works well. However, I plan to do quite a few of these and with this Beocord display alone, that means sixty-two solder points.

Another option is to get an SMD rework station. I use an Aoyue SMD rework station.

The 853A is a heating system to preheat the board being soldered so you can lessen the amount of time the heat gun has to be applied to the board. I am currently using a temperature of around 180˚C.
After I let the board warm up, I use the 968A station heat gun at around 340˚C. I set the air flow on the heat gun to the minimum setting so none of the SMD components get moved out of position (by the heat gun air).

Here is the Beocord display board before and after processing with the heating station.

After that I cleaned the board with some isopropyl alcohol, examined with my magnifiers and checked continuity with a DMM. I found three bad board traces so I had to repair them with some thin magnet wire.
Finally, a successful board test.

I am going to leave the display board powered up in the test rig overnight to make sure everything is good. Tomorrow the display should be ready for full re-assembly and put back in the Beocord.
That will leave just a couple small tasks to do on this project and this Beocord will be done.

Beocord 9000: Displays and Lamps

I left this Beocord 9000 project off waiting for some Beolover displays to arrive and preparing to give the beocord a quick functional check to see if it records and plays cassette tapes. I am happy to report the replacement lamps have arrived and my record/playback tests also worked. Once I finish the displays I will go through some organized cassette functional tests and show the results.

The display work can all be done with the Microcomputer and Display board in place inside the Beocord. Here are the display components looking from the top (so you can see the PPM scale lamp clearly).

I shouldn't have to touch the PPM displays other than the PPM Scale Lamp. I will replace the scale lamp and the indicator lamps with the LED replacement modules I got from Beolover. The 7 segment display will be disassembled, the original LEDs will be removed and modern surface mount LEDs will be installed in their place. Here is another picture of the Beocord 9000 as one would normally view the Beocord.

The first lamp to get replaced is the PPM Scale Lamp. Beolover originally posted the installation of one of these in the Summer of 2015. As mentioned on that thread, the Beolover tonearm position indicator LED replacement module can be re-purposed for the Beocord 9000 PPM scale lamp. Here is the part as I received it from Beolover.

As shown on the 2015 Beolover thread, the replacement is very straight forward. I like drop in replacements. This sequence of pictures shows the replacement.

This picture shows the Beolover replacement lamp modules for the four indicator lamps. There is also a 2015 Beolover thread on this subject.

The above picture also shows the seven segment display has been removed. It is time to prepare that part for restoration. Here is what the seven segment display module looks like taken apart.

This is a better shot of the seven segment display LED board (front and back).

The smallest dots on the display are the original lamps. This picture shows that each lamp has a tiny wire strand on one end of the display lamp. That delicate wire can be broken or about to break.

I will continue this seven segement display module restoration in the next post.