Inverter failures that drive, CCFL lamps
INVERTERS: (first External, monitors then Laptops last) about 1% failure rate compared to CCFL tubes at 99% , all tubes fail at 20,000 hours or so.
Below I will show some old HP External desktop monitors. (first is the PSU the power supply inverter unit (PCB) "Printed Circuit Board"
This is a OLD HP L1711 (2009 year) Monitor PSU that uses 2 High voltage jacks at left, to run the CCFL tubes. Cold Cathode Florescent Lamp tube.
The silk screened black words there clearly show HV Caution. Giving this lil' secret away. This is a very typical External monitor main board inside. (year 2000 to year 2009)
This is no LED Screen at all.
Almost all HP external monitor of this era , have PSU's that have CCFL and the HV jacks all look mostly the same, from 4 tubes to 10 used on Huge screens.
Note how the jacks are isolated (lots of PCB space) so that HV does not ever land on that jack to the right and blow itself to kingdom come. (logic chips HATE High voltage HITS, read up on ESD?)
They (then Engineers) knew this PCB will be buried in dust too and dust conduits electrons big time with HV .; HV Shock hazards are here too, 500volts up.... wider the screen , the more volts.
LAST is the LAPTOP INVERTER cards do fail, x10 less often. (than lamps ) Lamps are 99% failure rate and Inverters are 1% .(or pure fate /luck)
SEEN before year 2010.
HP sometimes calls it CCFT (T = tube) Cold Cathode Florescent Lamp/ tube.
Many CCLF screens have an out-rigger Inverter board that converts, 5vdc? power to 500vdc. for the CCLF tube to Ionize and glow.
The tubes love to fail or go dim, yellow or flicker, or go dead, and so can the below fail. (the actual tubes may be impossible to remove, only your actual attempts to do so , finds reality here)
Some Inverters are buried deep in the screen or glued down layers or clips that break off when touched, YMMV your monitor may vary , count on that fact.
See this old HP Laptop DV-2000 inverter its really a DC to DC converter, low volts to high voltage (and can shock you playing with it)
A LAPTOP power supply inverter card, CCFL.(CCFT)
Newer laptops have the inverter so buried in the LCD sandwich that you can not find it.
But newer yet PCs with LED displays have no inverters. (it has low voltage regulator sure, but no High voltage inverters)
The below is cheap universal inverter ( aka: DC to HV DC converter) It mostly will run the CCFL full tilt full brightness, if used, and can be used to test any CCFL.
The other handy tool is CCFL tube tester. You can test each Tube 1 by one with this battery device, do touch the tip turned on. OK?
The inverter card can be this simple. (some have complex brightness control chips )
The BRT pins is brightness controls.
As you can see The chip IC1 controls the chopper Q1/Q2. The chopper creates a AC drive to the transformer primary side, The output secondary side AC feeds the CAP C1 and then the CCLF tube.
The transformer called a Ballast has a turns ratio of 50:1, (50 on the the right side is 500vac (approx) or 2 times higher on 24" displays.
This is Legacy now ,fully obsolete in 2010, when all makers of screens went to LED and vastly longer life spans (5 times more)!
version 2. 12-9-2017 ( this page can be construed as why CCLF SUX !)