Beocord 9000: Total Recap - Replacement of all Electrolytic Capacitors

I also did a full recap for my earlier Beocord 9000 restoration. While I think it is less urgent for Beocords and Beograms due to the generally lower operational temperature (than amplifiers/receivers), a replacement of all electrolytic capacitors is always a good idea if long term stability is desired. While the Beocord 9000 contains quite a few electrolytic capacitors, the good news is that its design is pretty service friendly. They definitely learned something between the 70s and the 80s. Even in comparison to the Beomaster 8000, the Beocord offers much easier access. In my opinion it is best to simply leave the main PCBs in the unit and instead remove the front and back panels. Here is a picture with the front panels removed. Their removal is straight forward and described in the service manual. Here is an impression of the top after removing the control panels and the glass cover:

The bottom PCBs can be accessed in a similar way by removing the bottom panel:

A good 'service position' for exchanging the capacitors is to put the unit upright opened like a book:

I put it on a towel, which allowed me to turn and move the unit while in this position. Once in this position it is time for some patience and concentration. One after another the caps are removed and new ones soldered in (in the correct polarity - as I said: concentration!! listen to some calm music and you will find some BeoZen in this..;-). Here are a few pictures:

Board #11 (DAC) is one of the two boards that need to be removed for the recap since they are sandwiched on top of another board:

 Before:

After:

The other one is #13 (Oscillator Detector)

Before:

After:

The following boards can be done while installed in the frame:

#8 Microphone Amplifier:

Before (the shield needs to be removed; it simply comes off when unsoldering the two spots that hold it in place):

After (shield already installed again):

#3 Rec/Play back circuit:

Before:

After:

#6 Rectifier

Before:

After:

It is worthwhile noting that the big 5000 uF cap was very close to be out of spec. It only yielded 4000 uF. This is still good enough for stabilizing the supply, but it shows that doing the recap was probably a good idea.

#4 Power Supply:

Before:

After:

#1 Microcomputer/display circuit:

Before:

After:

There is one cap on the upper part of this board. This shows it after replacement:

#2 Dolby circuits:

Before:

After:

O.k. done!

Beocord 9000: Repair of a Broken Out Leaf Spring in the Tape Mechanism

When I opened up the Beocord 9000 that I am currently restoring I found a loose part in the enclosure. The part is shown in this picture on the left:

It turned out that it is the left leaf spring (#12035 in the exploded drawing in the service manual on p. 4-6) that holds down the head carrier. The part on the right is the right spring that I extracted to take a measurement of the ball that takes care of the friction between the carrier and the spring when the heads are pushed into the cassette. The ball of the right side was of course lost...there are many openings in the bottom of the Beocord...

The ball turned out to be a 2.5 mm diameter ball bearing ball. These are widely available. I ordered the smallest batch I could find, which was a lifetime supply of 100 on Amazon.

The black block that is attached to the spring that I found is a broken out piece of the plastic assembly that holds the spring. This assembly is pretty weak, and so it is no surprise that the spring finally cracked the plastic. It is under constant tension.

Luckily it is a straight forward repair to reattach the plastic block and the spring. All that is needed is a 2-56 3/8" screw and a nut and a washer. This picture shows the screw already inserted into the plastic part. The 2-56 screw is tight enough that it threads itself into the plastic part, which is convenient since it allows the fixing of the leaf spring in place before bolting everything together:

Before putting in the screw it was necessary to sand the bottom part of the plastic block down a bit so it would not stick out beneath the hole in the tape mechanism carrier plate into which it fits to hold it precisely in place:

After this the spring assembly can be bolted through the carrier plate. The ball is held in place during the procedure by the grease in the groove (I used a dab of silicone grease). This picture shows the underside of the carrier plate where the sanded round flange fits through the alignment hole:

The next step is to put the washer and the nut on: 

Tightening the bolt while aligning the spring completes the repair. Here are two views of the spring in its place underneath the erase head:

I tested the mechanism after I put it back into the enclosure. Seems this repair did the job.

On to the 7-segment display, which has a missing segment.

Beomaster 8000: Repair of a Broken Out Control Panel Lid Spring

The last Beomaster 8000 that I renovated came back to my bench after suffering shipping damage on the way home to its owner. There were some broken traces on the uProcessor board and a broken out button PCB in the control panel). After I fixed these issues and put it back together, I set out to write a proud email to the owner announcing the swift return of this Beomaster, this time double boxed. A few seconds after I hit the 'send' button, a loud crack happened and a piece of plastic ricocheted past my head. This is what I found. One of these pieces was located on the other side of my work shop:

First I did not quite understand what happened, but then I realized this part must have originated from the Beomaster that sat on the bench next to me! I looked around and found this situation on the back of the control panel lid:

The spring that opens the control panel had broken out of its plastic retainer and the lid hung limp on its hinges. No more springy opening after pressing the bar. This spring is surprisingly strong, and while the lid is closed it stores the energy needed to open the panel. This energy released creating a projectile.

First I asked around if anyone had a decent condition lid (3D printing still has 'finish issues; it is difficult to produce good lucking parts for exterior repairs), but I came up empty. So I further examined the situation and came up with a low impact strategy to fix it. Dillen of Beoworld.org advised me that the plastic bar that holds the spring mechanism can be slid out to the side of the lid. I opened the Beomaster up again and extracted the lid. Then, indeed, the part easily came out from its groove revealing that it is hollow. This opened up a route to a 3D printed fix. Here is a picture of the part that I had printed on a Stratasys uPrint printer in ABS:

I only had access to white filament, so I had to paint the part black on the visible areas. This part fits precisely into the gap in the plastic part and over the spring:

Fully inserted:

Then it was time to test the part under stress. I slid the bar back into the lid:

Then I put everything back together. Here is a view of the Beomaster from the back:

Not too bad...hardly visible, and if one does not know how it is supposed to look, one could almost think this is how it was designed. The Beomaster went back into my Beosystem 8000 to play with its old friends the Beogram 8000 and the Beocord 9000. I want to give it a few days of testing to make sure the shipping damage has been remedied in a stable way before I ship it out (this time double boxed...this experience demonstrated that an original B&O box is just not enough protection for today's shipping environment.