Beocord 9000 service manual

If you are not familiar with electronics, do not attempt to repair! You could suffer a fatal electrical shock! Instead, contact your nearest service center! Translate this page:. Hiya, am seeking a Penta amplifier circuit diagram. I have found a few on the web but this request relates to the input board.

Early Penta Mark1s used an input board numbered and used 6 transistors. As its this board that is not working i'm quite keen to get hold of the right circuit diagram. In other respects the operation, facilities and dimensions of Beocord are as described for Beocord Beocord could be used as a stand-alone tape cassette recorder or as part of Beosystems such as Beosystem or Beosystem With improving specifications of cassette recorders, tape manufacturers also made progress in the formulation of tape.

Standards committees decided to classify tapes into three main categories: oxide tape, chrome tape and metal tape. The newer categories allowed improved recording performance, but also required different recording bias levels to achieve the improvements.

Manufacturers of cassette recorders incorporated switches to adapt the recording characteristics to the tape, and later a system of slots at the back of the cassette were standardised, so that the recorder was set to the correct type of tape during recording. It should be added that once recorded, replay conditions were identical for all tape types, so that once the cassettes were recorded, they could be replayed on any machine.

While the categories were standardised, manufacturers did not strictly adhere to the standards, in an effort to offer improved performance from their tapes. This meant that bias needed to be set differently for the tapes from each manufacturer, even within each tape category.

In addition, the maximum recording level was different for each tape category, and for tapes within each category. As if this were not enough, tapes from any particular manufacturer also proved to be slightly variable from time to time, and from batch to batch. This meant that for the best recording performance, not only that bias needed adjustment for every single tape that was used, but that the level meter also needed calibration to show the optimum maximum recording level.

Operation had to be as simple as possible in order to allow maximum performance even for those who were not technically-minded. Finally, a system was developed where the user needed to press a single button, when the recorder automatically performed the calibration and set itself to be ready to record. The recorder remained adjusted for the tape until it was removed from the recorder. The analysis gives the microprocessor information about the correct bias and the maximum recording level.

If there is one outstanding characteristic of the Beocord that stands out above all others, it is paradoxically its all round balance in every area of performance. There is literally no sign of the usual commercially inspired compromises that ensure that the most brilliant pieces of laboratory work come out as shadows of what they could have been.

The result may be the finest up market cassette deck made, it is certainly the most practical and nicest to use. This machine was intended to optimise record bias, equalisation and tape sensitivity adjustments on each machine down the line, and as part of this function it was to feed several frequencies at different levels simultaneously onto a tape, which would then be played back for measurements.

When the machine was tested, it was found that the readouts from measurements were different from the predicted values, sometimes by as much as 10dB, a very significant amount. It soon became apparent what was happening. The signal, especially that at high frequencies, was itself partially biasing the tape and when high levels of high frequencies were recorded, the effective bias current was high enough so that the tape was severely over biased, and high frequencies significantly suppressed.

In effect, the self-biasing effect was making a signal dependent compressor out of the mechanism of recording itself. I said above that HX Pro is the only system that keeps dynamic bias constant However, the original Dolby HX circuit had many of the same properties. But the facts are that while Dolby HX restores some of the dynamic range available on cassette tape that is otherwise lost by the automatic compression mechanism referred to above, it does so in a convoluted fashion with for example a control signal derived from a Dolby B circuit, and is simply not as effective.

Complex adjustments were required to match the electronics to the head, and the value of one particular capacitor had to be decided upon by measurement. Ferrichome was unusual in Europe, so a Sony tape was recommended for this position. Unauthorised reproduction prohibited. Despite the automation of the recording process that CCC was capable of, the adjustment of the recording level was still manual only, with no option of automatic level control.

The two sliders were placed under the cassette lid and were identical to those fitted to the other models in the series. Another new and unique feature was the Dolby C type noise reduction. This technique was capable of 20dB of noise reduction, as opposed to 10dB with Dolby B. The noise reduction circuit was very complex and used 12 integrated circuits. Mechanically there were few alterations to the excellent Japanese cassette transport that was fitted to all these models and the Beocenter range.

The differences were that of course 3 heads were fitted and that an extra reel sensor was added, monitoring the supply spool. The second function of the additional reel sensor was to allow the spools to be slowed down during winding as the end of the tape became near.