I have a new Sony 19" flat screen monitor model: SDM-M81 It was given to me by a friend that is owns an electronics and computer store, he gave it to me because it was used as a display model & it is missing the power supply. I found that a new power supply is available from eBay for around $60.00 & Sony sells it thru the parts & accessories department for $138.00 That makes for a pretty expensive power supply compared to current prices of new monitors similar to this one. I don't know if it will power on and I need to test the unit before I spend any money on the power supply. I'll buy a new monitor before I pay Sony $140.00 The power connector plug socket has 4 terminals and is shaped similar to a trapezoid, it looks like a pyramid with the top cut off, see picture. Needless to say it's kind of and odd connection when comparing to the barrel type of connectors normally used on most monitors. I need to know which terminals are positive and ground. I know the voltage is 18volt dc @ 4-5amps & wattage is around 50-60 watts. What I need help with, I don't know if 2 of the 4 terminals are positive +18volt dc and the other 2 (negative) -18volt dc or does it have 2 different voltage circuits which means it may have a 5volt dc circuit & a 18volt dc circuit. If it has the dual voltage type circuitry, what terminals are positive +18volt dc & (negative) -18volt dc for the 18 volt circuit and what terminals are positive +5volt dc & (negative) -5volt dc for the 5 volt circuit. I'm not sure if it has the dual voltage circuitry, and if it does have I'm not sure that it is 5volts dc on that circuit, it could be more or less, I thought I saw this shown somewhere awhile back but I failed to make a note of it. This information is not available from Sony since they will not provide that information or a copy of the wiring schematic unless I am a authorized Sony monitor repair center. The only authorized repair center for Sony monitors is located in San Diego, CA. I called the repair center and they would not give out the info unless I am a authorized Sony monitor repair facility. This is were I think Sony's customer service & technical departments SUCK. They wont provide anyone, not just me, with this type of information unless you are a authorized Sony repair center as I stated before. Sony doesn't have but 1 repair center in the USA and if you don't work there I guess you are out of luck if you need technical data on an older Sony product. From now on I will advise all of my customers, friends, and family not to buy Sony products since they won't help an outside repair shop with technical data to repair or diagnose the products they make. It's not like I'm asking for secret business related materials. I hate to do the negative publicity for Sony because I really like allot of the products they manufacture and I have quit a few. Can someone help me please. Thanks,hi-tekk_redneck@sbcglobal.net