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