Philips Wake-Up HF3520 Power supply repair

Scritto Da: Thomas Widmaier (e un altro collaboratore)

Commenti: 7
Preferiti: 0
Completamenti: 2

Philips Wake-Up HF3520 Power supply repair

Difficoltà

Moderato

Passi

Tempo Necessario

Suggerisci un tempo??

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.

Strumenti

Nessun attrezzo specificato.

Parti

New Item

Non in vendita

Visualizza

Passo 1 Disassembly

Disassemble according to this guide:
https://de.ifixit.com/Anleitung/Philips+...

Traduci

Passo 2 Replace IC

On the main PCB with the power-jack, replace the MTX2410 switchmode regulator IC (SO-8 Package).

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.