This receiver showed no signs of life, not even the red standby light. The 5V supply to the microcomputer was low at around 0.8V, even though there was the correct 13V at the emitter of the regulator transistor 2TR2. This was because 2TR5 was cut off, with little voltage showing on the cathode of 2D5 (4.7V zener) either. The diagram shows that the cathode of 2D5 is pulled up to the 13V supply by 2R7 (1k) but in this set 2R7 was replaced by two 470R resistors (2R7 and 2R37). Their mid point is decoupled by a 220uF capacitor (2C19), which is also not shown on the diagram. The capacitor was short circuit of course, a replacement restored normal working. [Beomaster 5000]

This unit showed no signs of life. Measurements around the microcomputer showed that the +5V supply was low at 0.8V because 12F1 (1A) was open circuit. A brief meter check showed no obvious reason for the failure but when a new fuse was fitted 15F5 (2.5A) failed instead. A short circuit was now measurable across the +5V supply, after disconnecting the various loads it was discovered that 12D43 (6V2) was short circuit. A replacement diode and fuse cured all the faults; the original must have been breaking down intermittently. [BeoSound Ouverture]

If it proves impossible to set up the quiescent current of the output transistors correctly (20mA into the collector of the “upper” one is a good figure) the first place to look is at the resistors in series with the control itself. For the left channel these are 559 (1.8k) and 569 (560R), for the right channel 480 and 482. They can change value in either direction, giving either too much quiescent current or not enough, distortion, hum and excessive temperature of the heat sinks at the back are the usual symptoms. [Beocenter 3500]

Poor or absent vertical lock (a rolling picture on the TV / monitor) on tape playback can have many causes, however before adjusting the deck mechanics or inspecting for defective electrolytic capacitors, both of which can cause these symptoms, first check that the guide poles which lace the tape around the video head drum engage firmly and fully into their guide blocks. Clean and carefully re-lubricate these parts with suitable grease before proceeding further as in some cases the fault will be cleared with no further action necessary. Always ensure that the guide poles engage correctly before attempting any mechanical adjustments. [Beocord VX 5000]

With no loudspeakers connected and the volume control set to minimum the DC voltage at the loudspeaker output should be zero, if it is not the set will probably switch to standby when the loudspeakers are turned on. Assuming that the output stage components (3IC200, 3IC201, 3R226, 3R227) are not defective and 3TR205 (replaceable by a BF423) is not faulty the presence of DC at the amplifier output could be due to poor matching between 3TR201 and 3TR202 (both BC547C or BC550C), even though both may at first seem satisfactory in a simple measurement. Ideally a pair of matched transistors should be fitted as a replacement but if they cannot be obtained two from the same batch (e.g. taken from the same reel) normally yield workable results. The absence of the DC balance control makes the condition of the components in this part of the circuit critical. Numbers refer to the right channel, those on the left are numbered in the 100 series (e.g. 3IC100). [Beocenter 7002]

No output from the left channel was soon traced to TR53 being open circuit. A BC550 works well in this position. [Beomaster 3000-2]

When Powerlink loudspeakers were connected to this unit they remained switched on all the time because the 12V “power up” signal on pin 1 of the Powerlink connectors was always present. The cause of this was that the standby relay 62RL1, it couldn’t open because 62D6 (1N4148) was short circuit and 60TR4 (BC337) had partially melted and split in half. A new diode and transistor restored normal working but it is odd that this fault had no other obvious symptoms. [Beocenter 9500]

If the FM radio functions normally but reception is in mono only and the stereo indicator lamp will not illuminate the first thing to do is to check 3IC1 (MC1310) by replacement as this will normally cure the problem. The Beomaster 1500 and 2200 (along with their Beocenter derivatives) use an identical circuit so the same comments apply to these models as well. [Beomaster 4400, Beomaster 1400, Beomaster 1500, Beomaster 2200, Beocenter 2600, Beocenter 2800, Beocenter 3300, Beocenter 4000, Beocenter 4600]

If the output transistors (IC200 and IC201 or their left channel equivalents) have to be replaced then the following components should be checked before switching the set on again: R228 and R229 (both 0.22R), R220 (270R fusible), TR205 (BF423) and TR206 (BC547B). Don’t connect the loudspeakers before the mid-point voltage has been checked and confirmed to be within a few mV of 0V and check (and if necessary adjust) the bias current too, while the amplifier is still cold. The Beomaster 5000, 6500 and 7000 all use a similar circuit and can be dealt with in the same manner. [Beomaster 5000, Beomaster 5500, Beomaster 6500, Beomaster 7000]

A streaky picture lacking in detail was caused by C1564 (10uF) being open circuit, although oddly there was no sign of electrolyte leakage. In some cases a further small improvement in performance can be obtained by adding a 100nF ceramic capacitor between pins 2 and 5 of IC1526. Another machine displayed poor synchronisation of the OSD graphics in E-E mode, this was cured by replacing C1545 (10uF). [Beocord VX 5000, Beocord VX 5500]