EPSON LX 300 Printer FONT Selection Not Working Repaired
Customer visited my workshop with LX 300 Printer complaining that he is not able to change the FONT through control panel.
I have powered on the printer and tried to change the font with the switch but it is not working.
In this printer process is like these – first power ON the printer then you have to press paper out /pause button for 3 second then you will get the beep sound from the printer then you have to press the FONT button to get the required FONT.
(Caution: This type of printers having multiple internal setting option by using these combination Keys you can customize paper size, width, height adjustment and so on. So please refer the user Manual before the process. Remember each printer model having different combination Keys so this setting is not applicable to any other Printer manufacturer and printer Model.)
Now for this problem my first suspect is FONT Switch itself. So I have removed top cover as follows…
I have desoldered this micro switch for testing, while testing with multimeter I found this switch is not working properly hence I have washed this switch by isopropyl alcohol and tested again this time it gives me positive result . 
Hence by giving power to the printer I have followed the process as said above for testing the FONT switch it works perfectly and now I am able to change the FONTS as per my requirement.
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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Note: You can check out his previous repair article in the below link:
https://www.jestineyong.com/pronet-8-port-network-switch-repaired/
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vikrant
July 20, 2015 at 1:54 pm
Nice job sir,many technicians even refuses to open dot matrix printers.Keep sharing...
Albert
July 20, 2015 at 3:14 pm
Hi Yogesh, good to know that it is possible to clean a not working switch with Isopropyl Alcohol. But I myself would probably have just replaced the bad switch by another good working switch. Maybe I can safe the trouble next time by using your method? But it still requires me to desolder the switch and place it in alcohol. By-the-way: I've tried cleaning Xbox360 GPU/CPU processor's from their cooling Thermal Paste with Alcohol. And that is just not working! In such cases Terpentine works fantastic to get rid of the old Paste very easily!
RobertyBob
July 20, 2015 at 8:39 pm
This article makes me appreciate the skill and patience for small simple things. And that there is no substitute for time spent.
Anwar Shiekh
July 20, 2015 at 10:19 pm
I have a habit of letting some silicone oil into the switch, without even desoldering it; have had some good results so far.
Humberto
July 21, 2015 at 12:40 am
Good job Yogesh, but I think like Albert, changing the switch would have been much better. Thanks for sharing.
Corriete
July 28, 2015 at 11:13 am
nice job. many of those switches are the causes of no functions. one may say that was an easy fix but may not understand the technicality of it. so great job sir.very good and interesting article.