Philips PHP-X19 2 seconds to black problems

[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

[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

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.

[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

[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 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.

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

That was me being impatient. Maplin was open on a Sunday. I should have waited until Monday for RS Components. It will not cost much to replace the rest of the caps with Panasonics and to swap out the two from Maplin. I'll do this tomorrow.

[Th3_uN1Qu3]

Re: Philips PHP-X19 2 seconds to black problems

You need both tubes connected otherwise you'll get 2 seconds to black no matter what. And i second the advice of changing the caps on the inverter again, with proper Low-ESR units.

[bbjunkie]

Re: Philips PHP-X19 2 seconds to black problems

Maplin dont sell low ESR caps <to be accurate, they sell 2, a 6800uf and 4700uf both 63v> - perhaps you should change those 470uf 25v Maplin ones to Panasonic low ESR before reassembling.

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

I have the blackened ends on the some of the tubes. When they are on they are slightly pink, but not as bad as the ones in the photo link.

Here's a question - there are 2 tubes in each assembly, and there are 2 sets of wires (a white/black pair and a pink/white pair). Can I plug one set of wires in to light up just one tube or do both tubes need connected at the same time?

[retiredcaps]

Re: Philips PHP-X19 2 seconds to black problems

Compare your lamps to pictures at

http://s807.photobucket.com/albums/y...klight%20lamp/

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

Ok. The monitor has 2 CCFL assemblies, each with 2 tubes. One assembly at the top of the screen, one at the bottom. I could get the top one out ok, but the bottom one is tricky. Anyway, each assembly has has set of White/Black and Pink/White wires, plugging into the Inverter / Power board. I sat the top CCFL assembly outside the monitor casing and plugged the various connectors back together. I used a laptop and VGA cable as an input source.

First test had both CCFL assemblies connected up. The upper unit had a slight pink tinge (hard to tell as only stayed on 2 secs or less). I ran through several combinations as follows:

Both CCFL assemblies connected to their normal power outputs: 2 secs to black
Top CCFL assembly only in normal power output: 2 secs to black
Bottom CCFL assembly only in normal power output: 2 secs to black
Top CCFL assembly only in power output connector for bottom assembly: 2 secs to black
Bottom assembly only in power output connector for top assembly: 2 secs to black
(didn't test the final combinations of the assemblies in their opposite connectors).

I also used my laptop VGA out selection, while the monitor was powered up, to cycle through various VGA out options. Each time the monitor (and the CCFL sitting outside the monitor) lit for 2 secs before the lights went out (the image didn't look too bad with just one CCFL inside, but was a bit pinkish).

Do the above results suggest that both the CCFL assemblies are failing, or could it be something else like the CAPS I didn't replace.

[PlainBill]

Re: Philips PHP-X19 2 seconds to black problems

I've got a switched / surge protected strip to use. A possible daft question, but given that the monitor is stripped down, how much do I need to reconnect in order to test the tubes? The tube assembly cables have a decent length and could be plugged into their connectors and sat outside the monitor assembly. This also means I don't have to touch anything when I switch it on! If I connect everything up it is awkward trying to get access and see what is happening.

You have to hook the CCFLs to the power supply / inverter which must be hooked to the signal card, and of course the control panel must be hooked to the signal card. The LCD panel itself is not required.

PlainBill

[sabre504]

Re: Philips PHP-X19 2 seconds to black problems

I only suggested the transistors be changed if you changed the lamps and caps and still have 2 secs to black .
Do as bill suggested and test the lamps before you go any further you will probably find all 4 have a pink tinge done several of these and all had the same problem with the lamps ,bulged caps and two instances of the trans being scorched (darkening of the board near the inverter transformers .

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

I've got a switched / surge protected strip to use. A possible daft question, but given that the monitor is stripped down, how much do I need to reconnect in order to test the tubes? The tube assembly cables have a decent length and could be plugged into their connectors and sat outside the monitor assembly. This also means I don't have to touch anything when I switch it on! If I connect everything up it is awkward trying to get access and see what is happening.

[PlainBill]

Re: Philips PHP-X19 2 seconds to black problems

PlainBill, ok I'll give it a go tonight and hopefully won't fry myself in the process!

Well, do be careful. We need as many people as possible trying to same monitors, tvs, etc from the landfill. I've worked with high voltages for many years; I still prefer to power things up by using a switched power strip.

PlainBill

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

PlainBill, ok I'll give it a go tonight and hopefully won't fry myself in the process!

[PlainBill]

Re: Philips PHP-X19 2 seconds to black problems

I suggest you follow my suggestion and test the CCFLs. It is pointless to replace caps, transistors, etc if two or more CCFLs require replacement. The pink tint is positive evidence that you have a defective CCFL.

If all CCFLs light, ignore the advice about the transistor. If you decide to replace the defective CCFL, replace all electrolytic caps (except the 450 volt one) at the same time.

PlainBill

[roobarbthedog]

Re: Philips PHP-X19 2 seconds to black problems

Tom,

I've only replaced 2x470uF caps (these were bulging slightly at the top) and the 4x680uF caps (looked ok but I don't have an ESR meter to test). I found the same monitor on a different post and the other caps should be:

4 x 680uf 25v
2 x 470uf 25v
3 x 220uf 25v
1 x 10uf 50v
1 x 22uf 50v

I suppose I could replace the others before going any further as this is a relatively cheap fix, although I'll have plenty of spare caps as RS sell in packs of 5. Maplin do sell some singles but have a limited range and the last 2 I bought from them were unbranded.

The monitor is completely stripped at the moment and I hope I can get it back together!

[tom66]

Re: Philips PHP-X19 2 seconds to black problems

Did you replace the little 220u/25V one? On my monitor (different brand, but same power supply & probably same manufacturer) that had to be replaced before it would work.