Mediator MD 5811 A (1973)

A well-equipped, simply built but visually stimulating amplifier from the then Philips subsidiary. -In history you also come across models marketed by Philips itself, such as the SA 5811 and 22RH 811 from 1972. The housing is made of sturdy plastic and has 2 wooden and chrome-plated decorative strips on the left and right sides. The entire structure, both outside and inside, is still very solid and there are no signs of any serious aging damage. The only thing that needs to be glued to the door of the cassette deck is a broken plastic part. However, to open the device you need a long-axis Phillips screwdriver 3.0 x 150 mm because the 4 screws are screwed very deep into the housing.

Fortunately, the original speakers, which are in good condition, still work perfectly and only the housing and the fabric cover at the front need to be cleaned. The fabric could be carefully cleaned with a vacuum cleaner and a suitable brush attachment. The wood-look casings were carefully rubbed with a neutral care product and a cloth. The speaker cables for the speakers need to be replaced because some of them are damaged.

The surfaces of the switches have a clearly yellowed patina, which is rarely addressed because otherwise the old plastic and the labels could be damaged. It is therefore left as is. Mechanically, the buttons still work perfectly, the mechanics just need to be activated and cleaned with a special contact and cleaning agent.

The potentiometers are heavily dirty on the inside and therefore have poor contact. These can be successfully repaired using cleaning and contact agents. After checking all electrolytic capacitors, it turned out that in addition to the clearly defective 6800 uF capacitor, others in the supply and LF stages also needed to be replaced.

Compared to the previous repair work on the device, repairing and cleaning the cassette deck took the most time. The residue from the almost completely decomposed belts had to be removed, which only worked well with a lot of neutral cleaning agents. After inserting the 3 new belts, cleaning and lubricating the cassette deck, playback generally works well but slowly. It turned out that the pinch roller, which was clearly visually brittle and was responsible for the slow playback, also needs to be replaced. Finding spare parts for devices like this is now somewhat more difficult. Original parts are hardly available anymore. However, a good alternative was found for the pinch roller that does the job. The playback of the cassette is now almost perfect. - After a few more hours of operation, the electronics or the weight setting (torque) could be finely adjusted to fine-tune the slight speed fluctuations that sometimes occur. At the moment, however, this is not urgently necessary, because the result of this revision phase can be rated very well for around 5 decades of survival of the device and especially the cassette mechanism.