Hanns G HW173A 2 seconds to Dim

[Number 47]

Hello. New here and looking to learn, I'm hoping there is someone who will have the patience to help a newcomer to electronics. I got this monitor for free after it went Dim and I'm hoping to get it fixed for my daughter so she can use it with a desktop I am building.

I'm currently re-training myself due to the economic collapse so I have no resources for repair bills or new monitors. I would certainly appreciate all advice and assistance.

When I power on this monitor it shows a good picture for 2 seconds then goes dim, I can just see the images and menu. I have read a few posts about this on this site and others and then I came across the 2 second to black troubleshooting guide. I have tried to follow it but I am past my capabilities. I learn best by doing so I hope someone will take the time to assist.

So far I have disassembled the unit as far as the ccfl tubes, everything looks ok, there was one cap that looked a bit bulgy at the side but when I removed it and cut away the plastic cover it was fine underneath. I replaced it anyway. Same result on firing it up.

I have a cheap multimeter and a few spare ccfl tubes from some old HP laptops that met the nvidia issue.


A few pics,








Hope I've done that right,

I've been trying to follow the troubleshooting guide for this issue but I'm getting results nothing like expected. I'm wondering if my multimeter is wrong? More likely I'm doing something wrong.

Humbly

Jon

[Rtech]

Re: Hanns G HW173A 2 seconds to Dim

On the right of your Power Board there is an Inverter transformer labeled T901.On the underneath side the Board it is marked with two sets of arrows, one pair at each end of the transformer.Put your meter on to the resistance Range (Ω) 2000,and with NO POWER attached measure between the top pair and then the bottom pair and advise the readings.

[Number 47]

Re: Hanns G HW173A 2 seconds to Dim

Thanks rtech.

I've done that and I'm getting 574 each pair.

I was thinking about this last night, I assumed the ccfls were ok because they were firing for a few seconds but having read a few threads I am starting to realise they could still be the problem. There is slight blacking on the end of the tubes. I will dig them out again and post up some pics.

Thanks for your help.

[Rtech]

Re: Hanns G HW173A 2 seconds to Dim

You have some Hp ccfl's no doubt with different connectors from this board, but you may well have to hard wire them in to confirm lamp fault or not, and which ones.

[Number 47]

Re: Hanns G HW173A 2 seconds to Dim

You have some Hp ccfl's no doubt with different connectors from this board, but you may well have to hard wire them in to confirm lamp fault or not, and which ones.

Yes, different connectors, I have 2 17" screens from DV8000 laptops, the plugs are much smaller, I've removed the plugs from both and will swap the plugs over. Testing one ccfl then the other.

I have 1 pink wire and 1 blue wire on the hp, 1 pink wire and one white wire on the hanns g. Both the pinks are marked with a blue dot (hanns g and HP) I'm assuming I can test using the white in place of the blue. Is polarity important on ccfl?

Many thanks.

[Rtech]

Re: Hanns G HW173A 2 seconds to Dim

Thr 'hot'one is usually the thicker one,in most cases with monitors and Tvs they are paired as pink & White......Blue and black...so it would seem you have it right.You must test with 2 sets of lamps in ie one original,be it top or bottom and one test set.Also as heat rises the top set fail more than the bottom so that is probably the one to test first.

[Number 47]

Re: Hanns G HW173A 2 seconds to Dim

An update,
I hooked everything up, both lights are lighting a third to half of the way up before cutting out. There is a fizzing noise coming from the area I marked in red when I put it in standby.

Haven't torn into my HP screen yet to get the lamp out. Sorry about the inline pics at the first post folks, didn't realise I was doing it wrong. Hopefully I have cracked it now.

[Number 47]

Re: Hanns G HW173A 2 seconds to Dim

So, tested the lamp this morning, swapped them both one by one, same result. Lighting half way. The fizzing sound I mentioned in my last post sounds like gas escaping?

[Rtech]

Re: Hanns G HW173A 2 seconds to Dim

These are older models so maybe both lamps have failed ??

[Number 47]

Re: Hanns G HW173A 2 seconds to Dim

I suppose it could be both, there's no guarantee the HP one is good either, it was working the last time I had it on.

I guess I'll have to make some kind of bulb tester. I've got some old componentry knocking around, time to build something I suppose.

Will report back.

Thanks for all the assistance Rtech, it's very much appreciated.

[Rtech]

Re: Hanns G HW173A 2 seconds to Dim

One thing you can do, which might make things clearer, is to operate the monitor WITHOUT the lamps plugged in ie join the logic board to the psu and on/off control panel,and switch on..if there is no hissing, then the lamps are the first suspects..

[ben7]

Re: Hanns G HW173A 2 seconds to Dim

Listen to transformer T901 to see if it is hissing.

I would replace all the electrolytic capacitors too, the one you put in is a crap brand too!

[budm]

Re: Hanns G HW173A 2 seconds to Dim

Light half way, that means the drive circuit is not putting out enough voltage to drive the lamps. How is that Dual MOSFET (the one with tab on top and 5 legs at the bottom (the middle leg is trimmed))? P/N?

[Number 47]

Re: Hanns G HW173A 2 seconds to Dim

One thing you can do, which might make things clearer, is to operate the monitor WITHOUT the lamps plugged in ie join the logic board to the psu and on/off control panel,and switch on..if there is no hissing, then the lamps are the first suspects..

I have tried this now, the whine/hiss is still there, except now it is there not only on standby, it is rhythmically whining when in operating mode too. I think it is coming from the coil I marked in red. When I cut power it slowly faded the noise.

[Number 47]

Re: Hanns G HW173A 2 seconds to Dim

Listen to transformer T901 to see if it is hissing.

I would replace all the electrolytic capacitors too, the one you put in is a crap brand too!

Definitely not T901 making the noise.

The crappy cap is all I could get locally, online ordering means going overseas and waiting days for delivery. It is a holiday weekend here too so not a lot I can do. Must make do with the assorted pack of (same brand) caps I have to hand I'm afraid.