ATX Power Supply Repair

Myads

This ATX power supply came in with the complaint of intermittent no power. When testing it with power on, I could see that the fan is not working. Not only that, some filter capacitors also became bulge because of the heat accumulated inside the power supply. The failure of the fan would not suck out the heat generated by the components especially the switch mode power transformer. If you switch off a working power supply and power removed, touch the power transformer, you could feel it is quite warm. Another heat source would be the heat sink where the output diodes attached to it. Diodes run a little bit hotter in filter circuit than diodes in other circuits due to the high current present at the secondary output line.

As for the malfunction fan, you actually could use a Philips oil based contact cleaner to service the fan. The grease inside the fan would run dry after serving for sometimes and eventually stop rotating. Remove the back plastic cap of the fan and spray it with the contact cleaner and you would be surprised the fan could actually regain back its glory. It will actually work just like a new fan. If it still doesn’t rotate, the best choice is to replace with a new fan. If you have the power supply that lying down at your work place then you could salvage the fan and install it.

From the photo above you also could see those decayed glue that stick besides the components. Manufacturers purposely used some kind of glue to apply on the components where they think those components will shake or comes out when there is vibration or during shipping. After the equipment work for a long time and the heat generated inside the equipment will turn the glue into conductive and sometimes would even corrode the pins of the components and eventually cause the equipment to stop working. Scrap it off with your test pen and use Thinner solution to clean the pcb board. After replacing the capacitors, removed the decayed glue and service the fan, the Atx power supply again given a new life to faithfully serve the computer.

Some ATX power supply would take you a longer time to troubleshoot because of ‘too many’ components on the board. The most frustrated part is that you could not get the spare parts especially the power ic. Even if you could locate one, the price would be sky high and if this happen, I will usually get the customer to buy a new unit since nowadays the price of a new one are quite cheap.

PRINTER REPAIR: Epson LX300 Printer Repair-No Power and Can't Print Caused By A Faulty Max232cwe Ic

Myads

Intermittent no power was the complaint of 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 of the printer problem. There was 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 problem. In this article, I would like you to know that not all power problems must be caused by major components burnt. A loose connections, dry joints, resistor open circuit, high esr ohms in electrolytic capacitor could cause intermittent no power or no power at all.

Troubleshooting with the right techniques and using a good procedure would normally solve electronic faults easily. Another thing that I want to share with you is that the power 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 type of ic. Once you locate the pinouts, you actually could test it with your analog multimeter. 



Sometimes there are more than few problems that you need to repair. 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 okay. For your information, if this type of problems happens in other brand of printer, the troubleshooting method is the same. I will first look at the communication chip or buffer chip. In this printer, the main suspect was the Maxim Max232cwe multi channel RS232 Transceivers ic.

Solder the ic out was not a problem in this smd type ic. After the replacement with a 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 and then the communication or buffer ic.

The MAXIM MAX232CWE IC

PSP solution problem power button

Myads

Here is the video on how to repair a PSP with power problem. It is from the courtesy of youtube.com.

Do it Yourself PSP fuse repair

Myads

Here you see the different fuses inside the Sony PSP1001 model, it has a clear picture to easily identified the fuses in the circuit board.

Do it Yourself PSP fuse repair