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Old 06-03-2019, 09:31 PM   #1
Jluxster
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Red face Lexmark 544dn power supply clicking sound model 40x5409

Lexmark Laser printer 544dn , loud fast clicking sound from the power supply, no power, but the 24V fan on the case was twitching and chirping, no power shown on LED indicators.

I have replaced the large 450V capacitor, as it appeared to be the source of the clicking. Old capacitor was visually fine, no bulging that I could see.TaDa!

Good news: now the unit powers on and works properly.
Bad News: the power supply now makes an ominous cyclic buzz about every second or so.... Which makes me think that I didn't really solve the problem after all. Which is why I'm posting. If it wasn't the big CAP what was it? Am I just going to have to do this again in a month?

On a more philosophical note: what is the name for that feeling which makes me want to spend 2 hours repairing this old laser printer.

Photos of both sides of the board and the serial no of the power supply.
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Old 06-03-2019, 09:40 PM   #2
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

It sounds like the power supply is in startup/shutdown cycle. Are the 5V and 25V steady if there is no loads connected?
What are the resistance between GND and 5V, GND and 25V when the loads are connected and not connected?
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Last edited by budm; 06-03-2019 at 09:43 PM..
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Old 06-04-2019, 11:51 AM   #3
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

Alright. I am repairing a second lexmark printer with the same issue tonight. I'll check the Voltage before and after changing the capacitor.

Gotta warn you, this multi meter is the $5 ebay kind, but it should give us an idea. Any help in identifying the 5V and the 24V output? There are two cable bundles coming out, I'm guessing one is each...
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Old 06-04-2019, 05:54 PM   #4
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

I have repaired a few similar power supplies that had the main cap bad, basically open, and little to no bulging. I suspect the sound you here "ominous cyclic buzz " is because it is in standby, the power supply is in burst mode. it gives a small burst of drive just to keep the low current demand standby voltage working.
I doubt you will have +5 and +24v untill the power supply sees the power on command from the main printer board,

Last edited by R_J; 06-04-2019 at 06:09 PM..
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Old 06-04-2019, 07:08 PM   #5
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

May be I miss understand, so the fan is no longer pulsing when when printer is running?
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Old 06-04-2019, 08:04 PM   #6
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

I may have miss read part of the post, It souds like the printer is working ok now but...
"the power supply now makes an ominous cyclic buzz about every second or so"
Does this sound happen when the printer is on and working or when it is turned off and is in standby?
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Old 06-05-2019, 06:53 AM   #7
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

Hi guys. To clarify:
1) BEFORE replacing the big cap it made a loud clicking sound and the 24V fan was sort of twitching. Otherwise the printer was completely dead.
2) AFTER replacement the printer powers on and works great. BUT I hear a low buzz from the power supply about once a second.

My worry was that there may be another bad component on the board somewhere which caused the large cap to fail. Not sure if there is a good way to know for sure.
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Old 06-05-2019, 06:55 AM   #8
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

And to answer the second question. Fan is working properly after replacing the cap.
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Old 06-05-2019, 06:57 AM   #9
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

Also, only hearing the cyclic buzz when the PS is powered on.
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Old 06-05-2019, 06:56 PM   #10
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Unhappy Re: Lexmark 544dn power supply clicking sound model 40x5409

OK, tonight I opened the second power supply on the second unit which I will name Wanda to keep it from getting confused with the other identical power supply from the first post. Wanda is the, same model. Symptoms: dead no power on no lights, fan twitching and making a faint chirping sound.

Finding the voltages:
I went to find the line voltage for 5V out and accidentally picked the 120V in instead, and somehow shorted it to ground. Oh well, glad it was only $5 since now the leads are both melted on my multi-meter which I am obviously better off not using!

Anyway, this power supply does have bulging capacitors, but not the large one. Two smaller 2200uF 10V are both bulging on a nearby part of the board.

I said why not and replaced the big 450V cap anyway thinking it might allow the unit to power on. No dice. Unit is still dead while I order a set of these busted capacitors.
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Old 06-05-2019, 10:37 PM   #11
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

I rechecked the picture of the first power supply and there is a small cap that looks like it could be bad, hard to tell by the picture, but I circled it. It might be causing the odd sound.
As for the second power supply, are you getting any voltage across the large primary capacitor?
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Last edited by R_J; 06-05-2019 at 10:39 PM..
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Old 06-11-2019, 07:43 AM   #12
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

So. I replaced the two busted 2200uF caps. And the PS was still not powering the unit on. In the end I gave up and recycled the unit. So, one repaired, and one failed repair.
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Old 06-12-2019, 06:15 AM   #13
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Default Re: Lexmark 544dn power supply clicking sound model 40x5409

Hello Jluxster

I would review the small capacitors with an ESR meter.

If they are out of value it is possible that they cause those oscillation problems and sounds that you hear.

On the internet there are several easy designs to build as the "ESR RAPTOR" helps detect capacitors with high resistance.

Greetings.
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