Dull sound through the PH input with some pickup cartridges (e.g. B&O SP and MMC models) can be cured by changing capacitors 24 and 42 from 1nF (ceramic) to 100pF (polystyrene). These capacitors are located in the first BC109 stage, across the base-emitter junction of the transistor. [Beolab 5000]
The power amplifier of this receiver was overheating badly so the bias current was checked and found to be greatly in excess of its correct value on both channels. Disconnecting 3P22 returned the conditions in the output stage to normal and it was soon found that the output of the pre-amplifier contained a large amount of high frequency noise. This was coming in through the -12V supply, adding a 100nF 63V capacitor across the B-E junction of 2TR8 (BC557B) in the -12V regulator circuit provided a complete cure. [Beomaster 5500]
Failure to complete the loading cycle when play or record is selected is usually cured by replacing the loading belts. This is now not always effective and one often finds that the lubricant of the loading gears has hardened, jamming the mechanism. The gears are best accessed by removing the complete video head cylinder and the plate that surrounds it on the upper side of the deck, the loading arms can then be removed from their spindles (penetrating oil may be required). Cleaning and re-greasing the spindles and the other moving parts should restore normal working, it is wise to wind the mechanism through a complete cycle before applying mains power and ensuring that the guide poles are correctly located and do not touch the video head drum. [Beocord VHS 91.2]
Faults in the FM tuner section can normally be resolved by linking across each pin of 2P6 and 2P7 (the two connectors that join PCBs 1 and 2) with short lengths of stiff wire. In one case the fault, a normal display but no control over the actual tuning with stations coming and going by themselves, was not cleared by adding these links, instead 9IC5 (U264B) inside the microcomputer can was found to be defective.
The reliability of the microcomputer system of this model can be improved by adding a 100nF ceramic capacitor directly across pins 1 and 2 of 6IC4 (7805) and ensuring that the voltage on pin 3 is as close as possible to the correct figure of 5V. Replace 6IC4 if it is not. [Beomaster 8000]
This set worked normally when cold but after about half an hour the selected radio station or source would randomly change, all the touch controls could still be operated but the selection could not be held for any length of time. It was also noticed that the fault became worse when the radio aerial was connected. The 15V supply at TP16 was found to be slightly low and containing excessive amounts of ripple, not surprising as the voltage at the emitter of 2TR27 (TIP32A) was only 15.5V. Initially 2C92 (2200uF) was suspected of being open circuit but the actual faulty component was the rectifier 2D50. The current through this part of the circuit can be in excess of 1A so it pays to fit as sturdy a rectifier as can be fitted into the available space. [Beomaster 2400]
This machine is very sturdy and reliable but here are a few common faults:
Noise and intermittent operation: Check the soldering under the regulator transistors 1TR10 and 1TR13.
Weak or no recording on either or both channels: Check the balance control, if this is in order clean the contacts of the switch built into the microphone socket.
Automatic stop system malfunctions: The wires may be broken off the two leaf switches behind the head bridge.
Noise and instability after recording: Clean the contacts of the relay 1RL1. This is hidden under the mechanism and so is easily overlooked.
No playback sound on one channel: Check 1C03/1C203 (220uF) as appropriate.
Background hum when used with Beomaster 1900/2400 models: The cassette deck should be placed to the right hand side of the receiver in order to avoid pickup from the latter’s mains transformer.
This unit would not work with a Beomaster 5000 because 2D1 (1N4148) was short circuit and 2TR12 (BC548B) was leaky. Replacements restored normal operation but the reason for the failures remains unclear. Note that the table of switch positions shown on some editions of the circuit diagram is incorrect, those in the main installation manual give the right settings.
Cassettes played back OK without Dolby but when the NR system was engaged the right channel sound became muffled and distorted. Initially the Dolby relay 2RL1 was suspected but cleaning its contacts made no difference. As the DC voltage at pin 15 of 2IC201 (LM1011AN) was only around 0.7V when the same measurement at pin 15 of 2IC101 showed 1.4V 2IC201 was replaced, clearing the fault.
Another machine showed full output on the right channel PPM display all the time, even when playing a blank cassette. As the sound was unaffected 2IC2 (LF347N) was replaced and the PPM readings returned to normal.
If, when adjusting the record current, it proves impossible to reduce the level sufficiently to accomodate modern high sensitivity IEC II tapes (such as TDK SA) change the miniature presets R121 and R221 from 22k to 47k. This gives a suitably greater range of adjustment. [Beocord 8000]
When a disc was loaded, there were a few quiet clicks and then the tray opened again. As pin 1 of 7IC101 (CX20109) never went high and the clicks appeared to be coming from the focus coil a fault in the focus servo was suspected. Even after nulling the circuit using the procedure from the service manual a DC offset of over 1 volt was still present at the coil so 7IC106 and 7IC107 (both NJM4558S) were replaced and the output transistors 7TR112 (BD137) and 7TR113 (BD136) checked, all without curing the fault. As the final stage of 7IC106 is a summing amplifier the three inputs were next disconnected in turn, however the offset remained. The cause of the fault was in fact not a faulty component but the glue used to secure the wiring to the PCB, this had become slightly conductive around the feedback connections between 7IC106 and 7TR112 and 7TR113. Removing the glue restored normal operation. [Beogram CD 50]
When the TV key was pressed on the remote control the standby light of this set went green briefly and then returned to red, with no other obvious signs of life. Defeating the “power fail” system revealed that all the voltages from the power supply were present and correct, with 154V on the collector of the line output transistor 4TR33 (BU2508DF). As there was also plenty of line drive at the base of 4TR33 and no voltage at its emitter only one possibility remained, the transistor must be open circuit. This turned out to be the case, a replacement restoring normal results. This is an unusual failure, power transistors normally fail by becoming leaky or short circuit. [Beovision MX 4002]