Identifying blown caps

[Caiuse]

Hi Guys,

I'm new to the world of caps and would appreciate a little first time advice.

I'm attempted to fix my LCD monitor. I've been having problems with it powering on, flickering and hissing then turning off 30 seconds later. After some reading around I've concluded its probably the caps on the power supply board. I've pulling it open and had a look at the PSB however they are not showing the obvious signs of being blown.

I was wondering if I could firstly get an expert eye to conclude if they are blown and secondly if indeed they are blown it would be great to some advice on the replacement cap I will need.

Thanks, C.

[selldoor]

Re: Identifying blown caps

Pictures? They may still be bad without showing any sign. What make/series are they

[Caiuse]

Re: Identifying blown caps

Pictures? They may still be bad without showing any sign. What make/series are they

Thanks for the quick reply.

I've included pictures do they not show?

"HEC 24V 470uF" is all I can make out.

[selldoor]

Re: Identifying blown caps

Pictures need to be smaller than 2mb and in jpg format.
Add them using manage attachments use Post reply and scroll down
do not use quick reply.

I doubt if it says 24v 20v or 25v perhaps?

[Caiuse]

Re: Identifying blown caps

Okay hopefully these will work...

[selldoor]

Re: Identifying blown caps

Ok - they look alright - I would consider changing them but hissing and flickering is more likely to be a bulb issue or inverter issue. What is the make and model of the set? can you post a straight on picture of the power supply front and back.

If you get round to replacing the caps just get panasonic FR FM or FC
in the values to match the old ones and just check the physical size to make sure they fit. CPC.com have a post free offer at the moment.

[mariushm]

Re: Identifying blown caps

Hissing and all that sounds more like one (or several) wire came loose from the fluorescent lamp end and it's now arcing against the metal shield of the lcd panel.
The fluorescent lamps have 700-1000 volts running through them (at low currents) so these arcs are sometimes enough to trick the inverter controller to think the lamp runs properly.

Carefully, pull the silicone boots from the end of the lamps and see if everything is soldered properly to the lamp ends.

Capacitors in one picture are HEC 470uF 25v ZT series, they're not very special... you can find the datasheet here if you really want to see it.
Like selldoor said, the Panasonic capacitors will work. Just match the uF value and the voltage rating and you'll be good to go.

[Caiuse]

Re: Identifying blown caps

Okay thanks for the information selldoor and mariushm, I'm really hoping its not a bulb issue read it was a difficult fix. I'll study those lamp ends to check.

I'll give the cap replacement a shot too, out of curiosity more than anything.

Here are the front and back close ups of the power supply...

[selldoor]

Re: Identifying blown caps

ok looks like it may be one of these Proview PL926WBI,or Xerox XR6-19DW.?
There are a few threads on the proview. Some have backlight fails.
You need to look at the bulb ends also maybe a wire just needs taken off and resoldered.
Bulbs become very brittle with age - care and patience is the key.

[Caiuse]

Re: Identifying blown caps

Yes thats right, Its a Proview PV190WLCM.

I've got as far as the bulb ends, I'm not sure what I'm looking for at this point ( attached pictures ). Do I need to some how remove those silicone covers, seems like its going to be a real pain, was pulling at it for a bit but its glued in place.

[selldoor]

Re: Identifying blown caps

Ok I think you need to remove the lamp assembly from the panel first. This will enable you to see the bulbs and then you only need to go further if they are black or broken. The end caps tend to weld to the glass tubes.
There are a few tutorials about try youtube. and here
http://www.ccflwarehouse.com/lasotu.html.

Also have you tried plugging it in with the panel as it is to see if you can further
locate where the noise is from. Any signs of arcing on the frame?

[Caiuse]

Re: Identifying blown caps

Quick update :

Put it all back together to identify where the sound was coming from ( like selldoor suggested ), it was silent, plugged a HDMI in and it worked perfectly. Taking the whole screen apart and fiddling around has somehow fixed the issue.

Massive thanks for all helpful advice. As I went and brought a soldering iron kit just to do this I've decided I'm going to source a cheap broken LCD off ebay as a little project.

Cheers, C.

[selldoor]

Re: Identifying blown caps

Well I hope it continues to work for you, unfortunately when sets just fix them selves it is often shortlived. If you have to come back open a thread in the troubleshooting computer monitors and put the model number in the title and a brief resume of this thread.