Atari STE reversed caps ?

[Badwolf]

On this other machine they are non-polarised capacitors anyway.

These (same brand and orientation) are what my STE carries too. Although I can't see 'NP' printed on mine, there is no + or - indication either.

BW

[HigashiJun]

So, to resume: the silkscreen might be incorrectly printed on the motherboards and the correct orientation of these 2 caps should be + towards the south of the motherboard, right ?

[exxos]

So, to resume: the silkscreen might be incorrectly printed on the motherboards and the correct orientation of these 2 caps should be + towards the south of the motherboard, right ?

Yes. That is the voltage direction I measured across the caps.

[HigashiJun]

@exxos

Thank you for this confirmation.

[HigashiJun]

@exxos

Don't know if it's really worth it, but maybe it would be nice to recap all this capacitor related stuff in the Tweaks & Fixes section for all folks willing to recap their Falcons and STEs.

[exxos]

maybe it would be nice to recap all this capacitor related stuff in the Tweaks & Fixes section for all folks willing to recap their Falcons and STEs.

True of course, it should probably be documented about this particular problem. But currently I have only mentioned caps which I have changed and tested the circuit to verify its reliable and improves the circuit.

While generally changing caps should be fine, it's not been verified by anyone as a before and after results on things like that. So I am reluctant to start adding information which hasn't been tested and verified by a lot of people first.

For example, why the need for NP cap ? Was it just because of silkscreen problems or something else ? Maybe the voltage changes polarity during power up or power down , hence the need for NP cap ? Nobody has verified if NP cap is really needed or not yet. If there is no voltage swing in the reverse polarity, then a normal polarised cap should be tried and re-tested first.

On one of my STE, one capacitor is NP (the left side cap) the other is polarised. Again why ?

Also ripple etc needs to be tested before and after. There is a lot of work to do per capacitor across a motherboard.

[HigashiJun]

maybe it would be nice to recap all this capacitor related stuff in the Tweaks & Fixes section for all folks willing to recap their Falcons and STEs.

True of course, it should probably be documented about this particular problem. But currently I have only mentioned caps which I have changed and tested the circuit to verify its reliable and improves the circuit.

While generally changing caps should be fine, it's not been verified by anyone as a before and after results on things like that. So I am reluctant to start adding information which hasn't been tested and verified by a lot of people first.

For example, why the need for NP cap ? Was it just because of silkscreen problems or something else ? Maybe the voltage changes polarity during power up or power down , hence the need for NP cap ? Nobody has verified if NP cap is really needed or not yet. If there is no voltage swing in the reverse polarity, then a normal polarised cap should be tried and re-tested first.

On one of my STE, one capacitor is NP (the left side cap) the other is polarised. Again why ?

Also ripple etc needs to be tested before and after. There is a lot of work to do per capacitor across a motherboard.

Sure, it makes sense.