[Wilhelm Tell]

On D11 I measure this voltage over it. It has this weird notch.
D12 has it a smaller notch. D13 and D14 don’t show it.

[Wilhelm Tell]

Dillen wrote:

Schottky diodes would make no difference to speak of.
And they have no place in power supply rectifying anyways, that’s not what they are meant for – or good for.

Well, Schottky diodes would have 200mV less voltage drop, resulting in much less energy burned off in the diodes. However, this then obviously shifts to the power regulators, but these are on a heatsink and are currently not as hot as the diodes.

I’m still a puzzled though, because my estimate for the forward current is only about 0.3A. An explanation could be that the reverse current is very high, maybe because of aging. However, I’d not expect this to happen to all of them, or at least not in the same rate, but my finger says they are all about the same temperature.

[Wilhelm Tell]

Mark-sf wrote:

Are the diodes mounted above the the board?

No, they are touching the PCB. Is there a copper layer acting as a heat sink?

[Wilhelm Tell]

I’ve done a full high quality recap now, except for the servo PCB.

Diodes are still getting hot. The ripple remains about 1.4V on the big C13 4700uF cap. Doing some basic calculations indicate that the current consumption of the CD player powered from this cap should be about 0.6A, which I think is not a lot, given that the MCUs, the SAA7210, SAA7220 and TDA1541 are all running from this cap.
This 0.6A would mean an average current of 0.3A per diode, which should probably only heat them up very little.

• This reply was modified 6 days, 23 hours ago by Wilhelm Tell.

[Wilhelm Tell]

No one any hints or experiences?

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