Beocenter 1500
20th August 2008
The cassette section of this music centre worked well but the auto-stop mechanism did not operate. The mechanism and solenoid coil proved to be in order so the electronic circuit was investigated. A number of poorly soldered joints were found on the small panel at the back of the tape deck, most notably on the collector of the solenoid driver transistor 5TR5 (BD137). [Beocenter 1500]
Beomaster 3500
20th August 2008
After attending to some other faults with this receiver it was noticed that a continuous low level hum was present in the background. Voltage checks showed that the -33V supply to the output stage was low, though as nothing was getting hot an overload was not suspected. Further checks revealed that the reservoir capacitor C52 had never been soldered to the PCB at one of its terminals from new, it is surprising that the owner of the set had not complained about this before. [Beomaster 3500]
Beomaster 5000
20th August 2008
No response to either the small remote control or the Master Control Panel was the fault with this Beomaster. The voltages around the IR amplifier chip 9IC1 seemed normal and a replacement failed to provide a cure. Further checks showed that the +34V supply was low at around 12V and had a lot of ripple on it. 2C8, hidden behind the mains transformer, was open circuit. [Beomaster 5000]
Beocord 8002
15th August 2008
If there is silence during playback of one other the other channels, a good place to start looking is C102 and C103 in the first amplifier stages after the heads. These capacitors have only about 500mV across them which is not really enough to maintain the oxide layer in good condition. Replace both if either is faulty. [Beocord 8002]
Beovision 8800 (33XX chassis)
15th August 2008
The problem with this set was excessive width. The temptation to adjust the controls was resisted and instead the three electrolytic capacitors 5C13 (22uF), 5C18 (100uF) and 5C19 (4.7uF) in the EW circuit were replaced as they were all the frequently troublesome red plastic moulded types. The width then returned to normal and this very sturdy and reliable set could then be put back into service. [Beovision 8800]
Beovision 3-32
15th August 2008
This set was stuck in standby and did not respond to the remote control. The main HT line did not come up to its full voltage briefly when power was first applied as it is supposed to so a short circuit in the line output stage was suspected. Various items were checked and cleared without success until the set was tried with the tube base panel removed from the tube. The set then started up normally, without a picture of course. Loss of vacuum in the tube as then suspected but applying 6V to the heater pins resulted in the normal heater glow in all three guns so this was discounted. Meter checks showed leakage between pins 5 (G1) and 9 (GND) of the tube. Discharging a 4700 uF capacitor charged up to 50V across these two pins resulted in a bright purple flash in the tube neck, after which the short circuit was gone. On reconnecting the tube base panel a good picture was obtained. [BeoVision 3-32]
Beocord VX 5000/VX 5500
15th August 2008
Picture faults of all descriptions in these machines are normally due to defective electrolytic capacitors. The capstan motor, IF unit, modulator panel and signal routing/YC processing panel should all be carefully inspected for leaking electrolyte. A quick check can be made by re-soldering one pin of each capacitor, a hiss of boiling liquid and a strong smell indicate a defective component. Frequently large numbers need to be replaced, due no doubt to the high internal temperatures that these machines operate at. In one case however replacing many capacitors failed to cure a random line pulling effect that spoiled an otherwise excellent picture. Connecting the CVBS input of a monitor directly to the negative end of C241 (47uF) gave the same fault symptoms, clearing the signal routing circuitry from suspicion. The fault was eventually cured by replacing the luminance processing hybrid chip IC201 (HT4847F). [Beocord VX 5000, Beocord VX 5500]