Question about Sharp AL 1631 Copier

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Sharp AL-1631 overheats after replacement of fuser and fans

I have a Sharp AL-1631, put in service new in June, 2007, had approximately 5500 copies when problems started and 5700 copies today. In October, it began to display the H3 code and reverted to H3 immediately after reset. On adivce of colleagues, I decided against returning it to the Sharp repair facility and took it to a local repair shop recommended by those colleagues. According to the technician and my repair ticket, the fuser and fans were replaced, and the "fingers," bearings, transport rollers, and "controller" were OK (please pardon my ignorance, I don't really know what and where those parts are located in the machine). The H3 problem occurred again after 3 days and 40 copies. We were able to reset the machine, and it would operate without problems until it was idle for more than 10 minutes. At that point it would display the H3 code and need to be reset. We used the machine in this manner until yesterday. When we powered it up at the start of business, it displayed the H4 code and will not reset (i.e., we enter the reset code and the machine resets for 1 or 2 seconds, then reverts to the H4 error state). The original repair technician indicated that he was unfamiliar with this sequence of problems on this model of Sharp machine and declined to look at it again. I could find only one other repair facility who would agree to send a technician to look at the machine. That person told me that the problem was probably the "controller" alone or, possibly, with additional problems on the main circuit board. He advised that the machine was probably not repairable for less than its cost. Although I probably will not find anyone locally to work with it, and the cost of having Sharp work with it seems prohibitive, I would be grateful to have an idea what the problem might be, in the event I eventually find someone who will work on it.

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  • fliprobison Feb 15, 2009

    Thanks, I ordered a thermistor but will not be able to install it until Thursday. Will update then!

    Floyd Robison



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  • Sharp Master
  • 990 Answers

Hello sir; that's a simple problem whayever you mention all the parts you replace are not necessary, if you can't reset H4,or H3 then you need to replace "THERMISTOR" that is the device to control the temperature, the parts #RDTCT0128FCZZ.

Posted on Feb 12, 2009


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SOURCE: AL 1631 Sharp digital copier

H4 is an indication of a fusing unit heater problem. Most of the time this is a false code caused by power fluctuations or noise.
To reset the H4 condition, press the following key's in sequence and as quickly as possible (with 4 seconds for the first 4 keys)
Press "C" then the far left key (exposure mode) then the "C" key then the far left again.
So in other words C, far left, C, far left
If done correctly the display should go blank.
Now key in 14 as if you were going to make 14 copies.
Now press the print button.
The machine should reset and the code should be gone.
9 times out of 10 this is a false code that pops up due to power surges or noise.
If the code comes back this means you have a heater lamp or thermal fuse (more common) failure in the fusing area and will need service.
Good Luck and Thank You for using Fixya.

Posted on Sep 22, 2010

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Did you replace the thermistor? check the thermofuse also for continuity

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