Philips PHP-X19 2 seconds to black problems

[PlainBill]

Re: Philips PHP-X19 2 seconds to black problems

I've now changed all the capacitors to the same rating Panasonics (FM series, except for one FC). I managed to get a picture for 10 seconds before the usual "2 seconds to black" problems started again. The tubes do look blackened at the ends and have a slight pink glow. It's now getting to the point where I need to decide if it is cost effective to continue.

One thing I did notice is that when I did a multi meter continuity test on some of the connections on the board, mosts points highlighted in the attached photo appears connected to each other. This is where the inverters are soldered in. Is this correct? I can't see any obvious shorts, but there are some jumpers on the front of the board connecting some PCB tracks.

The behavior of the CCFLs matches my experience. If CCFLs at 'end of life' are unused for a time they will take longer to trip the protection circuit.

The area highlighted is the primary side of the inverter transformers and the drive mosfets. It is normal for thos points to have a very low resistance.

PlainBill

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

I've found some replacement dual tube assemblies on ebay and will hopefully get these delivered in a couple of days. I'll post an update later in the week.

Cheers
Roobarb

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

2 nice shiny new dual CCFL assemblies arrived today (bought on Monday on eBay so that was quick). Hopefully I'll get to fit these tonight.

updates later.

[retiredcaps]

Re: Philips PHP-X19 2 seconds to black problems

2 nice shiny new dual CCFL assemblies arrived today

Take it slow and easy. Replacing the ccfl is a delicate job. I estimate that about 50% of members have broken the new ccfls trying to force them in by rushing things.

There is a tutorial below (generic), but if you got instructions with your ccfls, I would follow the ones you got.

http://www.ccflwarehouse.com/lasotu.html

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

Woo Hoo! New CCFLs installed and I've had a bright stable image for over an hour now! Luckily the CCFLs came installed in a metal strip enclosure (2 tubes in each strip), already wired up ready to be plugged in.

Before installing I checked them out by plugging them into the inverter board. Nice bright light on both set of dual tube assemblies. Getting them attached to the diffuser was a bit of a pain, but I eventually got there. Reassembled the panel and ran a quick image test ok before rebuilding the rest of the monitor. I replaced any old metal tape that I had taken off with fresh tape.

One odd thing though, at the moment I've connected my laptop up as a video source, and it is plugged in to the same power strip as the monitor. Getting some interference / ripple on the monitor image. This disappears when I pull the power from the laptop and run off batteries. Maybe I've missed a bit of tape shielding? There was some exposed shielding braid on the cable from the processor board to the front panel controls. Maybe I need to tape this down (this means prising open the case again!).

All in all this has been an interesting project. 3 weeks ago I didn't really have a clue how a LCD monitor worked and hadn't heard about bad capacitors. I've changed all the electrolytic caps on the power/inverter board for Panasonic FMs and 1 FC (2 of the originals were domed), completely stripped the monitor and replaced the CCFLs.

Thanks for all the advice and keep up the good work.

Roobarb