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Thread ID: 140454	2015-10-14 08:53:00	Toshiba Tecra display issues	Billy T (70)	Press F1

Post ID	Timestamp	Content	User
1409867	2015-10-14 08:53:00	Hi Team I have acquired an old Toshiba Tecra laptop for occasional use and most of the time it is running off the mains. Battery power is ok when off the mains, but the screen defaults to a very low backlight level as soon as the power plug is pulled. I am assuming that since the computer is OK on mains, there is nothing electrically or electronically wrong with the back-light itself, so I've been looking for any set-up facility that might increase the back-light level a little when on battery power. Other laptops I have used did drop their back-light level a little when on battery (for power saving reasons) but this one does a good impression of a coal-mine by candlelight. I've searched the various options provided but found no means to increase brightness, so I've come to the conclusion that when not running on mains, the inverter voltage source is operating well below par, probably through capacitor failures. If so, is this a feasible repair? I have been in electronics since Adam was a boy but tracking down the location of the inverter might be a mission. I have an ESR meter that will tell me if any caps are bad but I don't really want to dismantle the thing as it might prove difficult to put back together. Any ideas? Cheers Billy 8-{)	Billy T (70)
1409868	2015-10-14 09:26:00	I have a Toshiba Tecra laptop, model M3 I believe, sitting in cupboard at moment. Toshiba laptops come with a lot of custom software to enhance your experience. Try searching for: "Toshiba Power Saver Utility" within the laptop. Try looking in "Start/Programs/Toshiba etc I'm fairly sure that you will be able to adjust the screen brightness on battery power within this utility. Also, see here: aps2.toshiba-tro.de	zqwerty (97)
1409869	2015-10-14 20:13:00	I custom software to enhance your experience. I would have described their bloatware in a less flattering way than enhance :badpc: Go into power save options (in control panel) , the setting will be very obvious in there , or as above Tosh may have their own software that bypasses win power save : mainly on older laptops	1101 (13337)
1409870	2015-10-18 04:31:00	Thanks zqwerty/1101 I will get it out again tomorrow and follow your advice. Cheers Billy 8-{) :thumbs:	Billy T (70)
1409871	2015-10-18 06:11:00	Does FN key plus F3 help?	Greg (193)
1409872	2015-10-18 23:11:00	Well, nothing turns up in Power Saver Options, FN +F3 doesn't help, 'Power Options' similarly draws a blank, and I downloaded a TECRA M5 manual that talks the talk about monitor brightness control on batteries, but provides no assistance whatsoever . To the best of my knowledge I have full administrator access, and the only hope I have now is to find a manual specific to this model: PTM51-A-0RM05P [note that the 0's are zeros] . The display is absolutely perfect on mains power but you'd have to turn the lights out to use it on batteries (which are also OK by the way) . Cheers Billy 8-{) :waughh:	Billy T (70)
1409873	2015-10-19 10:53:00	Most likely a software setting, but could be a hardware fault. The inverter will likely be part of the screen assembly, you'd have to measure the supply voltage to it to check your theory. Of course, it could be something more complicated like a faulty current\voltage sense circuit which thinks the machine has very low power on battery and goes into maximum power saving mode. Does the overall performance of the computer drop significantly on battery too? If it does then such a fault is plausible.	Agent_24 (57)
1409874	2015-10-22 08:21:00	[QUOTE=Agent_24;1233311Does the overall performance of the computer drop significantly on battery too? If it does then such a fault is plausible.[/QUOTE] I'm not really stressing it, so performance seems OK and there is no measurable performance difference between battery and mains supply apart from the backlight. It is mainly used to acess external disks and to run instrumentation programs. Am I right to assume that the screen backlight is run via an inverter both when on battery and when on mains? It would seem pointless and unnecessarily complex to have two entirely different supplies when one inverter could run the screen with a simple switch between mains derived LV and Battery LV. I'm not up to speed with which specific technology is used, but I'm well experienced with inverters in general and their faults. You don't seem to find circuit diagrams for the the non-computing parts of laptops [like, frinstance, inverters :( ], which does make life a little more difficult than it needs to be! Cheers Billy 8-{)	Billy T (70)
1409875	2015-10-22 21:11:00	Yes, the backlight will always be driven by an inverter (or LED driver if a modern LCD with LED backlight) regardless of the laptop's current power source, since both CCFLs and LEDs need very specific supply requirements (as I'm sure you know!) Just looking at the schematic of my own Toshiba P35, the inverter is powered from the main and archaically named B+ rail (which comes from either the AC adapter or the battery). Since the B+ will be a few volts lower when running from battery than on AC, a faulty inverter might have trouble with the lower voltage when running on battery. Or there could be a bad connection somewhere between the B+ and the inverter, dropping enough voltage that when on battery the inverter just doesn't have enough power to run properly. The LCD\inverter cable is a good candidate since those usually get a fair bit of movement from the screen being opened and closed all the time... Good place to start anyway. If you're looking for an inverter schematic, you might get lucky if you look up the LCD panel model number and find its datasheet (the inverter and panel are often from the same manufacturer)	Agent_24 (57)
1409876	2015-10-27 22:34:00	If you're looking for an inverter schematic, you might get lucky if you look up the LCD panel model number and find its datasheet (the inverter and panel are often from the same manufacturer) Hmmmm . . . . . . . . . . I'm not too keen on the idea of dismantling the top cover/screen! No doubt it is easy if you know how, but I usually get a 'sproing' noise and a face full of tiny bits when I venture into unknown territory . Probably best that I live with the inconvenience, I very rarely use it on battery anyway . Thanks for the advice . Cheers Billy 8-{)	Billy T (70)
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