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08-02-2019, 02:21 PM
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#1 |
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New Member
Join Date: Jun 2019
City & State: Watertown
My Country: United States
I'm a: Knowledge Seeker
Posts: 17
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Lexmark 654dn power supply dead fans on part # 40x4355
Hey all,
Working on another failed Lexmark LVPS power supply. The printer gradually had more and more trouble making it to the post screen until finally no power on at all. I'm replacing the two large caps, and the one small 100uf 35V cap that shows a small bulge. That is the only visible cap issue, but I hear a faint fast clicking that tells me caps are probably the issue. Have a look at this board and let's make predictions about what's wrong with it, I'll post my repair results and we can see what the issue was. Thanks! |
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08-02-2019, 05:11 PM
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#2 |
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Badcaps Veteran
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,054
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
Bad caps may show no sign of bulging but they can have high ESR. It sounds like you have bad startup/running caps (typical small value 47 ~ 56 uF 50V) in the HOT side, they are for filtering the Voltage for the VCC pin of the SMPS IC's.
__________________
Never stop learning Basic LCD TV and Monitor troubleshooting guides. http://www.badcaps.net/forum/showthr...956#post305956 Voltage Regulator (LDO) testing: http://www.badcaps.net/forum/showthr...999#post300999 Inverter testing using old CFL: http://www.badcaps.net/forum/showthr...er+testing+cfl Tear down pictures : Hit the ">" Show Albums and stories" on the left side http://s807.photobucket.com/user/budm/library/ TV Factory reset codes listing: http://www.badcaps.net/forum/showthread.php?t=24809 |
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08-02-2019, 07:03 PM
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#3 |
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New Member
Join Date: Jun 2019
City & State: Watertown
My Country: United States
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
Hmmm, OK, this board has a ton of 35V and 50V caps on it. Perhaps one of them is the culprit.
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08-02-2019, 08:24 PM
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#4 |
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Badcaps Veteran
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,054
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
ton of Lytics cap?
https://www.badcaps.net/forum/attach...2&d=1564777195 I see C501, C801, but the third one I cannot see in that picture. |
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08-02-2019, 08:50 PM
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#5 |
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Badcaps Veteran
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 6,612
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
I see that one bulged cap and would bet C106 is also bad
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08-03-2019, 04:26 PM
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#6 | |
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Badcaps Veteran
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,054
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
Quote:
https://www.badcaps.net/forum/attach...0&d=1564777195 Time to recap as a set. |
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08-03-2019, 07:08 PM
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#7 |
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Leaking Member
Join Date: Dec 2014
City & State: Atlantic Canada
My Country: Canada
Line Voltage: Ground, 0Hz
I'm a: Hobbyist Tech
Posts: 4,638
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
replace all caps that are near a heat source. big or small, doesn't matter much.
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08-04-2019, 12:29 PM
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#8 |
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New Member
Join Date: Jun 2019
City & State: Watertown
My Country: United States
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
Well, last night I replaced the bulged cap and the two large caps, and the unit now functions with no problems. Startup and post.
Good prediction in naming the small cap as the likely culprit. |
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08-04-2019, 12:31 PM
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#9 |
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New Member
Join Date: Jun 2019
City & State: Watertown
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
Here are the images after repair.
Thanks for all the posts. |
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08-10-2019, 06:40 PM
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#10 |
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Leaking Member
Join Date: Dec 2014
City & State: Atlantic Canada
My Country: Canada
Line Voltage: Ground, 0Hz
I'm a: Hobbyist Tech
Posts: 4,638
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Re: Lexmark 654dn power supply dead fans on part # 40x4355
glad to hear that you got it going again!
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