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Replace LM1011 on Dolby Sub Unit
Replace valve first. Check for 3.3VDC drop across gate and source of Q2, IRF730 MOSFET (may also be MTP4N40E). Replace if necessary. Replace 47k, 2 Watt plate load resistors with metal oxide type. Lastly, replace Q1, J271 FET if above fails to rectify problem.
Tighten all ground screws, better yet weld grounding pads to chassis, use a solder gun, file to metal finish first
This could be caused by the 180K resistor inside the DC-DC converter can, R901 which is a 180K 1/2W. If it isn't this resistor, I have found that replacing Q901 & Q902 will usually cure the fault (You must always use the original parts i.e. 2SA1026 & 2SC1364 respectively, because equivalents do NOT work, even the ones supplied by Sony did not work for me). Also check the capacitor C909 (68pF), I have found that one leg deteriorates and eventually breaks.
1 of 2 reasons
#1 the loading belt is slipping and needs to be replaced
#2 the open close sensor (micro switch) is defective or missaligned.
It's always the drive belt on Sony Players it streches and causes all sorts of problems, including the symptoms described.
Most probably the loading belt is stretched and needs replacing. I have repaired a few of these in the past and have all had the same problem.
Hint:- I have found that a suitable sized elastic band works perfectly well as a temporary measure.
Replace transistor C1345 pre-amps on output stage board near test pins 2L and 3 on right and C16V/47uF both sides.
Replace dual output amplifier.
This can be caused by the 4.7 ohm fuseable resistor at location R834 being open circuit. Check the 5v line at pin 1 of IC900 (Front panel board, ENB-114-1), if it is about 2.7v then it is likely to be this resistor. It can be found at the bottom of the first daughter board that is mounted on the heat sink (ENB-132-6).
Check fuses on surround sound amplifier board probably opened after an abusive playing session.
Check and replace main audio output driver transistors attached to heat sink, generally you will find a BASE-EMITTER dead short.
If the power supply appears to be running correctly, check that the two display bulbs haven't blown. The display is a backlit LCD and when the bulbs are blown the unit will appear completely dead.
Check grounds on main pcb. Run new wire grounds to all ground bus lines and then secure to chassis.
Check or replace the main amplifier IC (IC501), and also check R547 & R548 (6.8 ohms), one or other of these always seem to blow when the amp dies.
Replace leaky Q38, (p/n 2SA999)
Check for shorted outputs
This can be caused by the 4.7 ohm fuseable resistor at location R834 being open circuit. Check the 5v line at pin 1 of IC900 (Front panel board, ENB-114-1), if it is about 2.7v then it is likely to be this resistor. It can be found at the bottom of the first daughter board that is mounted on the heat sink (ENB-132-6).
Return to the menu
Replace power switch (Tv-3 or Tv-4 Type switch Arcs internally)
Check that the prim. coil of the transformer (type ATS 1540). If destroyed replace it.
Check for good logic ground connection to control board and switch pcb. Follow brown wire from switch pcb thru control pcb & chassis mounted micro switch to chassis ground. Solder chassis ground connection.
Automatic record changer won't "reject" or shut off at end
Large "cast metal" unit under turntable below tone arm stuck, free up with penetrating oil.
Check 5v power supply (emitter of Q705), if present, check that pin 24 of IC801, on the front board, is high (4v), if it's low then Q703 is probably leaking, change it (2SC3311).
Replace BOTH bias potentiometers & adjust accordingly.
Clean volume control pot & Resolder all connections associated. If no cure replace pot. Also clean speaker select and all rotary switches
C488 a 220uf capacitor is bad
Replace Audio Amp IC STK401-130 on main amp board
The main thing to remember about CD's is when they age dust accumulates on the laser lens. If you feel confident enough you may like to try cleaning your own (this will apply to CD-ROMs as well, especially taking the higher speeds involved). Remove the case, if you can see the lens from above dampen a cotton bud with isopropanol\isopropyl alchohol (all chemists have this) and twist the bud on the lens pressing LIGHTLY. Turn the bud over and use the dry end to finish. Be careful lens assemblies are expensive so don't press too hard. If you can't see the lens (as in some SONY models) you'll have to take the CD clamp off. This hould sort out the following problems, Skipping when playing, sticking on particular tracks, not reading disks, etc. If you hear the disk spinning wildly in the tray then it's probable that the lens is dirty. Another very common fault on CD's is failure of the tray to close properly (even if it seems to). Nearly all front loading CD's use a loading belt, as this ages it slips and the mechanism fails to clamp the disk correctly.
The above jobs should fix most intermittent problems with CD's.
Try to find a group of variable resistors, sometimes named on the print. Mostly you will find 3 or 5 of them. These are for focus, beam tracking and stepping tracking. Be carefull to adjust the focus: Too much focus will burn out the laser. Try to adjust the beam tracking first. Check it every little twist by hitting your player gently.
Unit finds focus, but disc wont spin or spins erraticly and won't find T.O.C. -OR- Disc skips excessivly, especially when searching from first track to last track.
Spindle motor failing, possibly salvageable by spraying CAIG DeOXIT into motor and on shaft bearing. Run unit for several minutes to work into bearings.