HP S2031 20" - 2 seconds to black
eBay purchase as "parts or not working". Unit in good condition and only 8 months old. Manufactured 11/2011 per the label. Not the greatest of units, but a worthy repair IMO for a good client on a limited budget, still running on a 17" CRT. 
Separated case and discovered the board section/shield is attached to the rear case from the inside. The panel can remain in its' surrounding plastic, but is easily separated also. The front panel key board is easily removed from the bezel.
Care must be taken to not damage the wiring from the panel (TCon and HV lines), whilst balancing the rear case and stand mount, to disconnect the wiring.
Upon inspection, indeed it does 2 seconds to black. Investigation showed no bulging or otherwise (Su'scon) caps. All within spec per Blue ESR meter. ~10mΩ
Removed both the PSU/inverter and graphics cards from the rear case/shield. With unit on bench face down with boards on cardboard to test voltages etc. Display now remains on but -very- dimly. Tipped unit up to view directly and illumination flickered. Checked all connections and re-soldered HV transformers and other connections. (Was a common issue a while back cold joints at transformers.)
No improvement. Found if I moved the upper lamp wiring, it would flicker to brighter and then shut off. I'm on to something, but I don't know what as of yet.
Removed the wiring from the HV plug and re-crimped a bit to be sure it was not that... it wasn't. Still, wiggling the wire seemed to have more of an effect at the end nearest the board at the connector. There is a piece of foam backed tape that it runs under before it goes another 3" into panel. Removed that and separated the wires (Heat-shrinked for about 2") to see if that made a difference. It did, but it was nicely lit, but 2 seconds to black returned.
Checked voltages and transformer (only 1). All seemed normal, but it's tough to get a good read when it keeps shutting down. I could no longer get it stay on, even dimly. Also listened closely and could now hear a slight HV hiss before it shut down. Could smell ozone also. Turned out lights to see if I could locate the arcing, but I could not.
Brought out my computer case CCFL setup and hooked it to each lamp separately. Lower one looked fine. Upper one was very dim. Ahh, the culprit is found! Just to be sure, I connected the inverter upper connection to one of the CCFL case lamps and left the other on the panel connected. The LCD inverter unit now illuminated both the the panel lower lamp and the case lamp, and it remained running.
Dissembled the panel. This is an top and bottom edge lit unit, with a solid polycarbonate 1/4" plastic light panel behind the LCD, diffusers, and lenticular.
Began to remove the upper CCFL and found it was broken about 2" inside the panel. The only thing I can conclude is that this was a factory defect as there is no physical abuse evident to the unit, and the tube is wrapped with 8 small silicone rings for shock absorption. A slight amount of torque applied when installing the tube may have been the underlying cause.
490mm x 2.4mm tube with shipping was $15 from CCFL warehouse.
http://www.ccflwarehouse.com/24x49fuspcc.html
Prior order from them was well received and -extremely- well packed. (2407WFP Dell acquisition with the same issue 2 years ago. Broken U tube CCFL.)
Repair parts and purchase: $40
Time: roughly 1.5 hours
Education: priceless
I'll sell it for $100 and stand behind it for 2 years.
Separated case and discovered the board section/shield is attached to the rear case from the inside. The panel can remain in its' surrounding plastic, but is easily separated also. The front panel key board is easily removed from the bezel.
Care must be taken to not damage the wiring from the panel (TCon and HV lines), whilst balancing the rear case and stand mount, to disconnect the wiring.
Upon inspection, indeed it does 2 seconds to black. Investigation showed no bulging or otherwise (Su'scon) caps. All within spec per Blue ESR meter. ~10mΩ
Removed both the PSU/inverter and graphics cards from the rear case/shield. With unit on bench face down with boards on cardboard to test voltages etc. Display now remains on but -very- dimly. Tipped unit up to view directly and illumination flickered. Checked all connections and re-soldered HV transformers and other connections. (Was a common issue a while back cold joints at transformers.)
No improvement. Found if I moved the upper lamp wiring, it would flicker to brighter and then shut off. I'm on to something, but I don't know what as of yet.
Removed the wiring from the HV plug and re-crimped a bit to be sure it was not that... it wasn't. Still, wiggling the wire seemed to have more of an effect at the end nearest the board at the connector. There is a piece of foam backed tape that it runs under before it goes another 3" into panel. Removed that and separated the wires (Heat-shrinked for about 2") to see if that made a difference. It did, but it was nicely lit, but 2 seconds to black returned.
Checked voltages and transformer (only 1). All seemed normal, but it's tough to get a good read when it keeps shutting down. I could no longer get it stay on, even dimly. Also listened closely and could now hear a slight HV hiss before it shut down. Could smell ozone also. Turned out lights to see if I could locate the arcing, but I could not.
Brought out my computer case CCFL setup and hooked it to each lamp separately. Lower one looked fine. Upper one was very dim. Ahh, the culprit is found! Just to be sure, I connected the inverter upper connection to one of the CCFL case lamps and left the other on the panel connected. The LCD inverter unit now illuminated both the the panel lower lamp and the case lamp, and it remained running.
Dissembled the panel. This is an top and bottom edge lit unit, with a solid polycarbonate 1/4" plastic light panel behind the LCD, diffusers, and lenticular.
Began to remove the upper CCFL and found it was broken about 2" inside the panel. The only thing I can conclude is that this was a factory defect as there is no physical abuse evident to the unit, and the tube is wrapped with 8 small silicone rings for shock absorption. A slight amount of torque applied when installing the tube may have been the underlying cause.
490mm x 2.4mm tube with shipping was $15 from CCFL warehouse.
http://www.ccflwarehouse.com/24x49fuspcc.html
Prior order from them was well received and -extremely- well packed. (2407WFP Dell acquisition with the same issue 2 years ago. Broken U tube CCFL.)
Repair parts and purchase: $40
Time: roughly 1.5 hours
Education: priceless
I'll sell it for $100 and stand behind it for 2 years.
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