Forum Home
Press F1
Thread ID: 24384	2002-09-09 21:25:00	Monitor Problems	B.M. (505)	Press F1

Post ID	Timestamp	Content	User
77952	2002-09-09 21:25:00	Good Morning all . Problem to start the day . Sons Monitor has packed a sad . Upon power on little green light beside On/Off switch flashes once and then nothing, dead as a dodo! The Monitor is a Proview 15 inch but nobody seems to want to take responsibility for the mainboard . Now, using my prehistoric technical skills I have located a transistor designated Q601 (which is a C5296) attached to a very large heat-sink which surrounds the flyback transformer . Unfortunately, well I think unfortunately, the Emitter – Base resistance is 0 ohms forward and reverse . So the question is: 1: Does this sound like the problem? 2: If so, is something likely to have blown the transistor or are they known to die of natural causes? 3: Where can I purchase a new one or an equivalent? Any ideas or comment would be greatly appreciated . Cheers Bob	B.M. (505)
77953	2002-09-09 21:33:00	<waits impatiently for Billy T to reply> :D Mike.	Mike (15)
77954	2002-09-09 21:42:00	not sure about the technical problems, when one of our monitors dies we don't even bother trying to fix it (unless it was worth heaps). as far as a new one goes, use pricespy (http://www.pricespy.co.nz) to find the best deal. its an invaluable resource.	honeylaser (814)
77955	2002-09-09 22:08:00	are you sur the monitor is at fault not the video card?	tweak'e (174)
77956	2002-09-09 22:09:00	C5296 (actually 2SC5296) is (I think) NPN 1500 Volt, 60 Watts. Google may give you an equivalent, perhaps a BUX 80? Sounds like the EHT/Horizontal scan driver transistor, but you don't know if it died of old age or because of shorted turns in the transformer or similar. You would need to do a transformer test with a flyback tester or any replacement could become a 3 legged fuse (again).	godfather (25)
77957	2002-09-10 00:42:00	Thanks all. Yep fairly sure it's a monitor problem tweake. (Another Monitor works fine) Had a lot more luck searching for a 2SC5296 as opposed to a C5296 gf. However, I note that a 2SC5296 has a built in 50 ohm resistor and Diode which can trick one into thinking there is an Emitter- Base short when in fact there isn't! Hmmmm. In case anyone else is interested this isn't a bad site www.repairfaq.org	B.M. (505)
77958	2002-09-10 01:32:00	Hi BM Your measurements might also be confused by the driver transformer secondary. Did the main fuse blow? Unless it did it is quite unlikely (though not impossible) that the transistor is short circuit B-E. What is more important is whether or not there is a short from the collector to ground. If you want to be very brave, connect a 75 watt 230v light bulb from collector to ground (on flying leads) and switch on. If it lights up the power supply is OK and the transistor is not s/c. The problem could then be a loss of drive and in that case if you can locate the driver tranformer check for dry joints on the pins. Just a guess! Awaiting results :O Cheers Billy 8-{) :D	Billy T (70)
77959	2002-09-10 03:20:00	Now your talking Billy, This is a bit of me, a light bulb indeed, to go with my old Avo 8 and new fangled Dick Smith digital multi-meter . Things are pretty basic on this ark . (It's the likely "arc" that's bothering me at the moment) I think I was tricked by this type of transistor as the fuse is definitely not blown . (yet!) Will let you know if I survive the exercise . Cheers Bob	B.M. (505)
77960	2002-09-10 04:35:00	Ummmmmmmm Billy, The light came on for a brief second, then all the lights went out! Whole street in fact! Nahhhhh, just joking, light glowed but that's about all, would be scratching to read by it . (10 watt glow maybe) . However, must prove something? I only left it on for about 10 seconds for fear of creating more problems . Any point in taking a voltage reading across the bulb? Got me interested this one . Cheers Bob	B.M. (505)
77961	2002-09-10 05:05:00	Voltage across the bulb is a bit irrelevant, as its a switched wave and certainly wont read correct (what is correct anyway?) on the digital . . . That probably proves the power supply and the transistor . If its the Line Output Transformer . . . . . . new monitor? A lot of the functions derive a signal / supply from the EHT LOPT circuitry <recalls television principles from James Logie Baird's era>	godfather (25)
1 2