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Philips Wake-Up HF3520 Power supply repair

Introducción

The IC (chip) inside the lamp seems to die slowly resulting in flickering/flashing lamp operation when using the radio. Also, the buttons may become unresponsive.

The problem occurs specifically when the device is cold and/or humid. Heating up the IC makes it work again.

Qué necesitas

  1. Philips Wake-Up HF3520 Power supply repair, Start: paso 1, imagen 1 de 2 Philips Wake-Up HF3520 Power supply repair, Start: paso 1, imagen 2 de 2

    • There is a screw under the shiny UL sticker. Remove the sticker and screw to remove this bottom panel.

    • There are two tabs holding the panel into the clock/light, so you might have to wiggle the panel forward and out to remove it.

    Editar

  2. Philips Wake-Up HF3520 Power supply repair, Prying open: paso 2, imagen 1 de 2 Philips Wake-Up HF3520 Power supply repair, Prying open: paso 2, imagen 2 de 2

    • Flipping the light upside down will present a small section of the bezel that can be pried upward. It is a small plastic strip with hooks that have to be disengaged to be removed.

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  3. Philips Wake-Up HF3520 Power supply repair, Remove the button ring: paso 3, imagen 1 de 3 Philips Wake-Up HF3520 Power supply repair, Remove the button ring: paso 3, imagen 2 de 3 Philips Wake-Up HF3520 Power supply repair, Remove the button ring: paso 3, imagen 3 de 3

    • We can finally unscrew two more Philips head screws to remove the button ring.

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  5. Philips Wake-Up HF3520 Power supply repair, Front screen shield: paso 4, imagen 1 de 1

    • Now the screws holding the front screen shield need to be removed and the shield can be pulled away to the front.

    • Screw organization note for later: these screws have pointed ends

    • Take care not to damage the internal screen.

    • Unscrew the four screws holding the inner screen assembly in place.

    Editar

  6. Philips Wake-Up HF3520 Power supply repair, Inner screen assembly: paso 5, imagen 1 de 2 Philips Wake-Up HF3520 Power supply repair, Inner screen assembly: paso 5, imagen 2 de 2

    • The inner screen assembly can be pulled out slightly to reveal tabs on each side that hold the assembly in.

    • Pry the back tabs inwards to release.

    Editar

  7. Philips Wake-Up HF3520 Power supply repair, Remove the screen: paso 6, imagen 1 de 3 Philips Wake-Up HF3520 Power supply repair, Remove the screen: paso 6, imagen 2 de 3 Philips Wake-Up HF3520 Power supply repair, Remove the screen: paso 6, imagen 3 de 3

    • The screen is connected to the plastic domed back with holes. There are two screws at the back of the base of this domed panel. Remove screws to remove screen.

    • Set screen panel aside for safe keeping.

    • More to see and modify...

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  8. Philips Wake-Up HF3520 Power supply repair, Replace IC: paso 7, imagen 1 de 1

    • On the main PCB with the power jack, replace the MXT2410 switchmode regulator IC (SO-8 Package).

    • There is a pin-compatible device from Quorvo (ACT4060ASH-T) which has a different internal voltage reference but otherwise works fine. Only a resistor must be changed for this to work.

    • Warning: I just encountered a problem with the ACT4060. It blew up on one lamp and damaged the LEDs as well. So it seems not a perfect replacement after all.

    • The feedback Voltage for MXT2410 is 1.222V, for ACT4060 is 1.293V, so voltage divider on Pin5 must be changed accordingly.

    • One can best adjust R4+R3 (series). Remove R4, measure R3 and R4, and increase. It should measure about 10.67kOhm (R3 plus R4), and it can be slightly increased to 11.51kOhm. So basically add 1kOhm to R3+R4.

    Editar
Conclusión

Arbeite die Schritte in umgekehrter Reihenfolge ab, um dein Gerät wieder zusammenzubauen.

14 personas más completaron esta guía.

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Thomas Widmaier

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23 comentarios

Hi Thomas,

I have the same problem, but i do not understand what you are doing with the R3 and R4. If i remove R4, with what should i replace it?

Or how should i measure it?

Thanks in advance,

Arnoud

Arnoud Otten - Contestar

Can somebody do this for mine?

June Goto - Contestar

Can some one do this for me??

June Goto - Contestar

I can only do it in Germany

Thomas Widmaier -

Hallo Thomas,

ich finde das ist eine tolle Anleitung zur Reparatur des Lichtweckers. Ich hatte mich auch auf den Austausch des MXT2410 konzentriet. Es kam dann aber doch anders. Nach ca. 2-3 Wochen warten auf den ACT4060 war dieser schnell eingebaut. Das Ergebnis war enttäuschend. Keine Änderung, die 5V waren nicht messbar. Bei der weiteren Fehlersuche stellte ich fest, dass der ACT4060 und die zugehörige Drossel schnell warm wurden. Jetzt ging es an die Suche nach einem Kurzschlußkandidaten. Er war dann schnell gefunden: D3 (SK24). Eine andere Schottkydiode eingebaut (diesmal aus der Bastelkiste) und es wurde wieder Licht und Musik.

Freundliche Grüße,

Roland

rpg - Contestar

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