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 Post subject: WD20EFRX - damaged -> No function - pcb bad
PostPosted: September 18th, 2018, 6:23 
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Joined: November 17th, 2007, 5:38
Posts: 15
Hello,

i have here a WD20EFRX - NO FUNCTION

I remove bad diodes D4 and D2 + R43 (now bridged).
PCB is only bsy. -> No spinn.

I can see near L6 D7 a chip with letters ASPAD the case has a little hole
(or may be a simple surface damaged) !?

What is the function of the chip ? (Power reg. ?)

what can I test next?

Thanks for any help (and have no donor pcb here).


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 Post subject: Re: WD20EFRX - damaged -> No function - pcb bad
PostPosted: September 18th, 2018, 15:25 
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Joined: September 8th, 2009, 18:21
Posts: 10855
Location: Australia
DIAGS4711 wrote:
I remove bad diodes D4 and D2 + R43 (now bridged).

R43 is in series with D3 and D1, not D4 and D2. :?

DIAGS4711 wrote:
I can see near L6 D7 a chip with letters ASPAD the case has a little hole
(or may be a simple surface damaged) !?

What is the function of the chip ? (Power reg. ?)

A photo of the area would help a lot, but if you are referring to Q1, then that's a MOSFET. Q1, together with L6 and D7, constitutes a switchmode regulator with PWM control provided by the motor controller.

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 Post subject: Re: WD20EFRX - damaged -> No function - pcb bad
PostPosted: September 21st, 2018, 10:41 
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Joined: November 17th, 2007, 5:38
Posts: 15
Hello fzabkar,

fact is D2 and D4 is damaged.

I get now a new pcb and all works.

Thanks


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 Post subject: Re: WD20EFRX - damaged -> No function - pcb bad
PostPosted: September 21st, 2018, 15:22 
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Joined: September 8th, 2009, 18:21
Posts: 10855
Location: Australia
DIAGS4711 wrote:
fact is D2 and D4 is damaged.

Then I would have expected R60 to be open circuit, not R43.

_________________
A backup a day keeps DR away.


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