Dyson AM01 Fan Cannot Start

[john_doe]

Hi,

I have a Dyson AM01 fan that cannot start.

The board is covered by some kind of coating which covered the markings on the components.

I have de-soldered and checked diode D5 and D6 and they are ok. I have also de-soldered 2 small caps of 25v 100uF and they are also ok.

When the power supply of 240v is plug in, there is 336vDC at the Big Cap but no power at both small caps.

Where else should I check? I am new to electronics troubleshooting and hope to get help here.

Thank you.
John

[john_doe]

Re: Dyson AM01 Fan Cannot Start

Hi,

There is a component LNK304DN that is connected to the Big Cap.

Can some expert guide me on how to check this LNK304DN? There is no voltage across the Bypass pin to any of the source pins. Likewise there is no voltage across the Feedback pin to the source pins.

I really have no idea whether there should be voltages or not across those pins.

I have uploaded the datasheet for LNK304DN.

Thank you.

John

[stj]

Re: Dyson AM01 Fan Cannot Start

you have a lot of cracked solder joints on those foto's

[john_doe]

Re: Dyson AM01 Fan Cannot Start

Hi,

Can you point me to those cracked joints?

Are you referring to the solder joints at the 2 diodes and 2 small caps are horribly done by me?

Can you guide me on how to check on the LNK304DN component?

Thank you.

[stj]

Re: Dyson AM01 Fan Cannot Start

if you look at the datasheet first page, there is an example schematic.
if you work out where those parts are on your board, you can meter the output voltage from the cap.

as far as the cracked joints,
a crack looks like a fine shadow-ring around the joint.
once you see one, you will be able to recognise them very fast.

i marked a few on the big chip, but it may be wise to resolder all of those pins because they are all under the same stress.

[Longbow]

Re: Dyson AM01 Fan Cannot Start

As per your description, your switching power supply is not starting. The primary d.c. voltage on the large capacitor is OK. U1 is the switching controller IC. You can check for various problems by using a multimeter on U1. For example, (power off), the resistance between S and D should be large. If it is Zero, the FET is shorted. You may be able to see a diode (using diode check mode) between BP and S - there you are checking the zener. Sharpen your probe tips so they go through the protective varnish and test the secondary components. I'm betting on a faulty U1. Perhaps the whole schematic is available somewhere?

[john_doe]

Re: Dyson AM01 Fan Cannot Start

Hi,

Thank you for all your expert advise.

I will replace the U1.

Thank you.
John

[john_doe]

Re: Dyson AM01 Fan Cannot Start

Hi,

Yes, the faulty component is the U1.

Thank you for all the help given.

[edmundteosg]

Re: Dyson AM01 Fan Cannot Start

I have the same problem, the LNK304 has blown and part of the plastic housing has cracked and dropped off even.