Re: When it's turned on, the light on my Princeton...
I just did this capacitor replacement today after reading these posts. It worked great! I used 470uF
35volt caps from radio shack. There are three 470uF caps two right next to each other and one off by itself on the printed circuit board. The values are easily seen on the side of the capacitors. Open the monitor by removing the screws and prying the halves apart using a large straight edge screwdriver. There is a metal cover over the printed circuit board that will come loose after removing screws around its edge. There are several wire sockets that must be unplugged to allow the circuit board to be flipped over to reveal the capacitors. The board itself is held down with three screws
Once you identify the capacitors, use a fine tipped soldering pencil to melt the solder holding the capacitors in place and remove them. Position the new caps with the dark stripe matching up to the lined marks on the board, carefully apply just enough solder to each terminal to hold the caps in place. Reassemble and you're done.
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I couldn't find any fix on this monitor so I had to go it alone.......
My VG500b monitor would power on then the power light would blink off. there was no display at all but I could see the LCD panel change in brightness just a small bit during the power on and then power off. I found that there was a bad capacitor on the inverter board. I replaced the 47uF 25v capacitor with a 47uF 35v capacitor. (The 25v would be okay but I always replace a failed capcitor with a higher voltage rating) This capacitor is the shorter form in order to fit under the shield. You can use a taller capaitor but you will have to lay it down, as in bend the leads down and lay it on it's side in order to fit under the sheld when you put it back together. VG500b fired right up and is going strong once again. Hope this helps someone.
look for capacitors with the tops bulging .. these are high failure rate chinese made capacitors .. they made zillions of them and they fail frequently .. replace any that have buldging tops (should be flat with over pressure vent lines impressed)
You need to replace 6 capacitors on the power supply board. Princeton uses CapXon brand capacitors which last about 1 to 2 years before going bad. CapXon are extremely poor quality capacitors, saving Princeton 10 to 20 cents per monitor. This is the list of capacitors you need to replace. If they aren't bad now, they will be. qty 2: 1000uF, 10V (DigiKey 565-1646-ND) qty 3: 470uF, 25V (DigiKey 565-1677-ND) qty 1: 470uF, 10V (DigiKey 565-1643-ND)
You can get United Chemi-Con replacements at DigiKey. The DigiKey stock number is listed on the above list. Since DigiKey didn't have stock on the 470uF, 10V at the time I ordered, I substituted a 680uF, 10V (DigiKey 565-1644-ND) which is a larger diameter, but will fit in the area provided.
My VL1919 has been having this issue off and on for a month or so now. It happened three times in one day today, so I decided to do something about it. I opened up the monitor and poked around a bit.
I found three electrolytic capacitors on the backlight inverter board were bulging, two of which had just started to leak:
The capacitors were placed directly above and next to a large, flat metal heat sink. I say above with respect to the flow of air due to convection, and next to because the heat sink also wraps around, enclosing the group of capacitors on one side. The heat sink sits flush with the circuit board, turning the board into a front enclosing face. When reassembled, the metal housing sits a fraction of an inch above the sink, forming a back face. This assembly is at the top edge of the circuit board, so the housing then takes a 90° bend to form a top face. These capacitors seem to get almost no air flow... Together with the heat coming off the sink, it appears the engineers have created their own little capacitor oven.
Capacitors immediately adjacent to the affected components, but without blocked air flow looked completely normal. Looking at the traces on the circuit board and location of other components, the capacitors could have easily been moved out of the hot spot. This is either an act of gross negligence, or an intentionally created post-warranty failure point, designed to avoid market saturation. But that might be too pessimistic... "Never attribute to malice what can be adequately explained by incompetence."
Anyway, I scavenged a few capacitors off an old computer power supply to replace the damaged parts (one 470uF 25V two 1000uF 10V capacitor, both rated to 105°C). To avoid a repeat performance, I soldered some short extension wires to the replacement caps and moved them out to an open area of the board, being careful to give the high voltage components plenty of breathing room.
After reassembly, the monitor powered right up and came online. I guess the real question is how long it will stay this way.