| Intermittent no power was the complaint of this Epson | | | | book, you could find out the internal diagram of this |
| lx 300 printer. As usual, the main suspect was the | | | | type of ic. Once you locate the pinouts, you actually |
| power on/off switch. After removing the power board | | | | could test it with your analog multimeter. About how to |
| from the printer, I could clearly see a dry joint at the pin | | | | test optoisolator, you could refer back to my website. |
| of the switch mode power transformer. This was the | | | | Sometimes there are more than few problems that |
| caused of the printer problem. There was no other | | | | you need to repair. In the above case, after power up |
| loose connection or dry joints on the other part. | | | | the printer, it can’t print at all. It looks like there was |
| Cleaning with the thinner solution and applied fresh | | | | no signal entering the CPU IC. The printer self test |
| solder solved the intermittent no power problem. In this | | | | works perfectly okay. For your information, if this type |
| article, I would like you to know that not all power | | | | of problems happens in other brand of printer, the |
| problems must be caused by major components burnt. | | | | troubleshooting method is the same. I will first look at |
| A loose connections, dry joints, resistor open circuit, | | | | the communication chip or buffer chip. In this printer, the |
| high esr ohms in electrolytic capacitor could cause | | | | main suspect was the Maxim Max232cwe multi |
| intermittent no power or no power at all. | | | | channel RS232 Transceivers ic. |
| Troubleshooting with the right techniques and using a | | | | Solder the ic out was not a problem in this smd type ic. |
| good procedure would normally solve electronic faults | | | | After the replacement with a new ic the printer works |
| easily. Another thing that I want to share with you is | | | | beautifully. Remember, whether you are |
| that the power board is using a dual photo coupler | | | | troubleshooting the Epson lx 300 printer or any other |
| (optoisolator) NEC PS2561-2 ic. There are two | | | | model, first check the printer cable and then the |
| separate optoisolator ic built into one single package. If | | | | communication or buffer ic. |
| you have the ECG Philips master replacement guide | | | | |