Question about Samsung SCX 4521F All-In-One Laser Printer

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I have the same printer, it says that its havin an Open heat error and it's not operating showing the same error every time I start it.

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Needs fuser, non user replacable but it is the hot bit at back whare paper turns around and exits.

Part required (U.S.) link below, fit at own risk, best taking to agent.

also see link below for more info different model same problem.

Posted on Nov 14, 2007

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Re: OPEN HEAT ERROR - Samsung SCX 4521F All-In-One Laser Printer Printers & Copiers

Open heat error

Posted on Sep 21, 2010

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wanted to thank "guest" above for the excellent 16 steps! I had the same issue, followed the steps just to find out that my heat sensor (the "probably silicon rubber" part in #7) melted actually on the drum (henec the burnt smell I had together with the "heat" message). So, new parts for me entirely, but at least I did not have to pay anyone to discover the melt and do not need to pay anyone to fix it back, so thank you very much "guest", it was very helpful to me! thanks for spending the time to write all that, it is hard ot see this dedication these days on the internet!

Posted on Nov 12, 2008


Fix for open heat error - worked on Samsung scx 4500 printer
The problem may be caused by dirt getting in between the fuser cylinder and heat sensor. Before ordering a new fuser -which can be expensive - and if you have some experience with electronics, you may try the following:
1)Disconnect the power supply from the mains and the printer cable and wait for the printer to cool. Do not just turn the printer off; unplug it.
2) Open the printer. Remove the printing cartridge.
3) Locate the two Phillips screws that hold the fuser cover (the one that has high temperature and/or high voltage warnings printed on it) and remove them with a suitable tool.
4) In the middle of the fuser unit on the interior side there is a heat sensor. It has two wires, that go to a connector on the left of the interior side (with the printer open towards you). The connector sits in a holder. Pull it out of the holder, then disconnect the male from the female. Untangle the sensor's wires from the plastic wings that hold them onto the unit.
5) Now you are ready to remove the heat sensor. It is held in place by one Phillips screw similar to the two you removed from the fuser cover.
6) Having removed the screw, pull the sensor first slightly away from the fuser (to clear the plastic margin on the fuser unit) and then straight up. DO NOT apply force! it should come out very easily.
7) Now you are holding the heat sensor. You are looking at a black square piece of plastic with a hole in the middle (for the screw) out of which on one side come out the two wires ending with a connector, and on the other side, two thin plates laminated together in a soft transparent plastic material (probably silicone rubber). If you look carefully, inbetween the two metal plates sits a very tiny component - the actual semiconductor sensor.
8) On the side of the sensor that when in operation faces the hot fuser cylinder, you will find a layer of solid black residue. Now comes the tricky part: removing the residue. Careless manipulation of the sensor may result in a permanently damaged sensor. You have been warned.
9) Hold the sensor (or place it on an adequate surface, eg rubber) so that no excessive mechanical tension is applied to its active parts (the laminated plates and semiconductor). Scrape the residue off the sensor gently with an object that will not harm the transparent plastic lamination. Do not use anything sharp. The residue should come off very easily. If it doesn't, do not apply excessive force.
10) You are ready to mount the sensor back on the fuser unit. Insert it exactly as you removed it, with the active part down. The wires that go to the connector should come out the side opposite to the connector (if you took notice when you disassembled, they make a u-turn when assembled). You will not be able to mount the sensor if you insert it the other way around.
11) Secure the sensor with its Phillips screw. Do not apply excessive torque.
12) Thread the sensor's wiring through the plastic wings on the fuser body and assemble the connector.
13) Put the cover back on the fuser unit and secure it with its 2 screws.
14) Put the printing cartridge back in place.
15) Close the printer. Connect it to the mains and to the computer. Turn power on.
16) Happy printing.

Posted on Oct 21, 2008

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