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Philips Wake-Up HF3520 Power supply repair

Введение

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.

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  1. Philips Wake-Up HF3520 Power supply repair, Start: шаг 1, изображение 1 из 3 Philips Wake-Up HF3520 Power supply repair, Start: шаг 1, изображение 2 из 3 Philips Wake-Up HF3520 Power supply repair, Start: шаг 1, изображение 3 из 3

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

    • There are two tabs holding the panel into the back of the clock/light. If the panel does not come out easily, gently wiggle a flat-blade screwdriver or spudger in the grill next to where the screw was to loosen it.

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    • Flipping the light on its back will present a small section of the bezel that can be pried out. It is a small plastic strip with hooks that have to be disengaged to be removed.

    • Push the blade of the jimmy directly into the crevice above the cover. Once it has gone a few millimeters, tilt it to lift the cover slightly.

    • Slide the jimmy to the right side and press it against the latch to release it. Do the same for the left side.

    • A "jimmy" is essentially a small putty knife with a strong, slightly flexible blade.

    • Note: Despite the images shown, a spudger is not recommended as the fit is so tight it takes quite a bit of effort to insert and slide.

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  3. Philips Wake-Up HF3520 Power supply repair, Remove the button ring: шаг 3, изображение 1 из 3 Philips Wake-Up HF3520 Power supply repair, Remove the button ring: шаг 3, изображение 2 из 3 Philips Wake-Up HF3520 Power supply repair, Remove the button ring: шаг 3, изображение 3 из 3

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

    • Tip: Lift one end of the ring, tilting it toward the back of the alarm clock. That will get the hooks out from under the rear rim so you can start removing it..

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  4. Philips Wake-Up HF3520 Power supply repair, Front screen shield: шаг 4, изображение 1 из 2 Philips Wake-Up HF3520 Power supply repair, Front screen shield: шаг 4, изображение 2 из 2

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

    • Take care not to damage the internal screen.

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  6. Philips Wake-Up HF3520 Power supply repair, Inner screen screws: шаг 5, изображение 1 из 1

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

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

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  7. Philips Wake-Up HF3520 Power supply repair, Inner screen assembly: шаг 6, изображение 1 из 3 Philips Wake-Up HF3520 Power supply repair, Inner screen assembly: шаг 6, изображение 2 из 3 Philips Wake-Up HF3520 Power supply repair, Inner screen assembly: шаг 6, изображение 3 из 3

    • There are two tabs that hold the assembly in on the bottom left and right sides.

    • Using a jimmy — or any flexible, flat, metal tool, such as a putty knife — press the back tabs inwards to release.

    • Note: Do not be surprised if you have to push hard.

    • Tip: If you pull the inner screen assembly out slightly, you can see the tabs better. However, it puts pressure on the latches making them more difficult to release.

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  8. Philips Wake-Up HF3520 Power supply repair, Remove back cover (Optional but recommended): шаг 7, изображение 1 из 2 Philips Wake-Up HF3520 Power supply repair, Remove back cover (Optional but recommended): шаг 7, изображение 2 из 2

    • Disconnect the speaker from the main circuit board.

    • The antenna (a long white wire) has a fragile solder connection to the main circuit board and care should be taken to not yank upon it.

    • Loosen the screw and washer inside the back cover by the speaker and unwrap the antenna wire that was pinned underneath. Pull the antenna all the way through so the back cover can be removed.

    • Alternately, you may simply pull only some of it through so that the wire is slack enough that the solder joint is at no risk.

    • Caution: The speaker and the buzzer connectors are the same so be careful when reassembling.

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  9. Philips Wake-Up HF3520 Power supply repair, Replace IC: шаг 8, изображение 1 из 2 Philips Wake-Up HF3520 Power supply repair, Replace IC: шаг 8, изображение 2 из 2

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

    • Currently a seller "adeleparts2010" has this chip available (might change in future). The previously recommended pin-compatible device from Quorvo (ACT4060ASH-T) is not a good choice and might cause more damage.

    • 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.

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  10. Philips Wake-Up HF3520 Power supply repair, Soldering SO-8 IC: шаг 9, изображение 1 из 3 Philips Wake-Up HF3520 Power supply repair, Soldering SO-8 IC: шаг 9, изображение 2 из 3 Philips Wake-Up HF3520 Power supply repair, Soldering SO-8 IC: шаг 9, изображение 3 из 3

    • These are the steps for replacing the IC with a soldering iron. For best result, need a good temperature-controlled station with a fine, but not too fine tip. Solder with about 0,5mm diameter, desoldering braid and flux. (Rosin) Flux is essential, as it makes the solder flow smoothly once the flux inside the solder wire is evaporated.

    • First picture show soldering wire and tip. Then, use solder to bridge all pins on both sides, alternatingly heating both sides until the IC comes loose. This may take some time (10s of seconds), but doesn´t matter as the IC is dead anyway. Do not use too high temperature. 360°C is ok.

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  11. Philips Wake-Up HF3520 Power supply repair, Soldering SO-8 IC: шаг 10, изображение 1 из 3 Philips Wake-Up HF3520 Power supply repair, Soldering SO-8 IC: шаг 10, изображение 2 из 3 Philips Wake-Up HF3520 Power supply repair, Soldering SO-8 IC: шаг 10, изображение 3 из 3

    • Remove solder with desoldering braid. Clean with isopropanol alcohol the flux residue.

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  12. Philips Wake-Up HF3520 Power supply repair, Soldering SO-8 IC: шаг 11, изображение 1 из 2 Philips Wake-Up HF3520 Power supply repair, Soldering SO-8 IC: шаг 11, изображение 2 из 2

    • Attach new IC (correct orientation, here dot to left where '220' coil is. Then use some flux and solder to attach the remaining pins.

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Заключение

Work off the steps in reverse order to reassemble your device.

23 человек успешно провели ремонт по этому руководству.

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Thomas Widmaier

Участник с: 03/05/13

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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 - Ответить

Can somebody do this for mine?

June Goto - Ответить

Can some one do this for me??

June Goto - Ответить

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 - Ответить

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