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Posted: 29 Mar 2019, 00:41 

yaffle2345

Ic311 which supplies 5v and Ic411 which supplies 3.3v each have a CT pin which require a 2v switching signal to switch from STANDBY to ON.

That signal is controlled from the remote and is only operational when the power supply board is installed in the laser disc player.

The darkening, on the pc board, around R105,R106 & R109 is not uncommon.These resistors,all 68k,form a voltage divider across the rectified

mains DC.They,along with C116, provide the KICK START for the SMPS.Please check C116,1mfd/400v, for both ESR and capacitance.

The ESR reading should be a low value, approximately 7-8, and the capacitance should be approximately 1mfd.If in doubt change it.

I recommend that you also check the filtering capacitors,C211,C611,C311,C312,C511&C512 on the power supply secondary.If any are faulty

they can affect the supply's operation.Q101,Q150&Q151 are all N channel mosfets,ShinDengen 2SK2333.

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Posted: 10 Apr 2019, 02:26 

I notice that a number of contributors to this forum have raised the question of running 100/110 & 120 volt laserdisc players from 240 volt/50 hertz source
using step-down transformers.Whether the source voltage is 50 or 60 hertz does not matter as the player switch mode power supply rectifies the mains
voltage to DC.The resulting high voltage DC is then switched at high frequency and regulated using pulse width modulation.
I would also recommend that any step-down transformer be a toroidal type.They are more efficient, more compact and their external magnetic field is limited.

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Posted: 13 Apr 2019, 23:45 

Yesterday,following my query on this forum,I viewed a video showing the servicing of one of these players and discovered that I had mistakenly confused the
CLD & DVD Laser assys and got them reversed.Repositioning them has solved the problem and the two switches in the turn mechanism now activate as they
should do.Very sorry for the confusion.Very much a continuing learning experience.
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