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Philips Wake-Up HF3520 Power supply repair

Introduzione

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.

Cosa ti serve

  1. Traduci

  3. Philips Wake-Up HF3520 Power supply repair, Replace IC: passo 2, immagine 1 di 1

    • On the main PCB with the power-jack, replace the MTX2410 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.

    • 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.

    Traduci
Conclusione

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

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Thomas Widmaier

Membro da: 03/05/13

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29 Commenti

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 - Replica

Can somebody do this for mine?

June Goto - Replica

Can some one do this for me??

June Goto - Replica

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 - Replica

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