08-08-2025, 02:46 PM
Hi Gary,
The white connector is fixed to the board, but the brown connector should just pull off.
Assuming there's no DC voltages at all at that connector...
As you remove the PCB, be very careful because the main smoothing capacitor might still be charged - even if it's been a while since it was last powered. Discharge with a chunky wire-wound resistor (rather than a screwdriver!) if necessary. When switched on, the DC voltage across it will be around 325V.
1. Look for high value resistors on the primary side - often they go high, preventing the thing from starting up.
2. Also check the smaller electrolytic on the primary side, as that failing can cause the same results. Generalising hugely, but startup faults were almost always caused by the resistor, but today it's perhaps more likely to be the capacitor (IME, at least). Even if it was the resistor, it's still good practice to change the cap while you're in there.
3. Those 7 pin ICs can fail, so if you can find nothing else wrong, it's worth trying that. Often, the high voltage start-up resistor is contained inside them in some form, so if you couldn't find a likely suspect for #1, that'll be why. Look up the datasheet for the IC for clues. If you can't find a service manual for the unit, the PSU might be fairly close to the example circuit shown in the datasheet.
Generally, if it hasn't gone bang, it should be fixable without too much drama. If you do get it running and the player seems to behave, it might be worth looking at the caps on the output side as a preventative measure - but if it runs but seems flaky somehow, it could be because one or more of those caps is tired. An ESR meter is useful here. Replacement caps should be low-ESR types, of course.
The white connector is fixed to the board, but the brown connector should just pull off.
Assuming there's no DC voltages at all at that connector...
As you remove the PCB, be very careful because the main smoothing capacitor might still be charged - even if it's been a while since it was last powered. Discharge with a chunky wire-wound resistor (rather than a screwdriver!) if necessary. When switched on, the DC voltage across it will be around 325V.
1. Look for high value resistors on the primary side - often they go high, preventing the thing from starting up.
2. Also check the smaller electrolytic on the primary side, as that failing can cause the same results. Generalising hugely, but startup faults were almost always caused by the resistor, but today it's perhaps more likely to be the capacitor (IME, at least). Even if it was the resistor, it's still good practice to change the cap while you're in there.
3. Those 7 pin ICs can fail, so if you can find nothing else wrong, it's worth trying that. Often, the high voltage start-up resistor is contained inside them in some form, so if you couldn't find a likely suspect for #1, that'll be why. Look up the datasheet for the IC for clues. If you can't find a service manual for the unit, the PSU might be fairly close to the example circuit shown in the datasheet.
Generally, if it hasn't gone bang, it should be fixable without too much drama. If you do get it running and the player seems to behave, it might be worth looking at the caps on the output side as a preventative measure - but if it runs but seems flaky somehow, it could be because one or more of those caps is tired. An ESR meter is useful here. Replacement caps should be low-ESR types, of course.
