Hanns-G HG281D 28" TFT - Multiple Problems

[Bartman]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

It could be a number of problems causing this - as you say caps could be one and it could be the power supply the main board or both. It could also be the voltage regulators.
First thing perhaps would be to remove and reseat any connectors especially if their is a flat one to the panel which might need a clean.
Have you tried a different hdmi cable..
Have you tried it with a different pc.
As it says these run on the hot side so even if caps have no visible damage they could
still be dried out. As it is a 28 inch screen has to be worth investing in good new
caps. Start with the power supply and if no improvement test the voltage regulators
then re cap the main board. If you didnt want to do all the caps on the main board I would start with the ones near to the voltage regulator.

I checked with a different 'PC' (Pandaboard) and cable and this all seemed to go well allbeit with low resolution (640x480). I had to arrange a few things to be able to check my own computer (Macbook Pro) with a different cable. Mini Displayport to HDMI adapters are not very common and therefore pricy, so I did not want to buy a new one without knowing what the problem was. I finally arranged one and all looks fine. So it appeared to be the cable that was causing the problem! I reported to the seller and got a refund.
I checked on different forums and reviews and it appears that many MDP to HDMI adapters and cables are faulty. Not at first, but after a few weeks or months. The symptoms (screen blanking, garbled images, etc.) are identical to bad caps.
So I want to advise all of you who have a Mac to check your cable first before opening your screen or replace the capacitors!

And of course thanks to selldoor for his advice. This has really helped me.

Regards, Bart.

[Staubach]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

Just read this and the other thread about the Hanns G issues, and I wanted to say thanks to everyone for the information.

I will give an update once I get the new caps!!

[deguello2003]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

Gentlemen Thnkyou for all your help on repairing my monitor. I am having a major problem locating a replacement mother board for this computer. I have found several on line but all are sold if anyone has a spare or know where I can find one. I need it right away. If you do not know which board it is, it is the board next to power supple under the metal box with the ribbon cable to the monitor control board. Thanks Bill R Also a good source for caps with no minimum is Allied Electrical in Fort Worth Texas and they ship everywhere. Thanks again.

[retiredcaps]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

I think Retiredcaps said something about these Chemicons drying up because these monitors run hot, but I'm not sure.

Somewhere either in the megathread or its various forks (I lost track)

https://www.badcaps.net/forum/showthread.php?t=11329

I came to the conclusion after helping others with this monitor (also manufactured under other brands) from day 1 that this monitor runs temperature hot and drys out caps on BOTH the power and main board.

This is the only monitor where I recommend a COMPLETE recap of every electrolytic capacitor on ALL boards. The caps might cost $20 to $25, but you are saving a 28 inch monitor.

This model alone is the 10th most viewed thread in the troubleshooting computer lcd forum so you know there are a lot of problems with it.

[Vizor]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

i will never again buy a Hanns-g have this monitor to and it Main Board went out last night smoking came back on with a red screen.

[NeilH]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

Ok, thank you for that offer, it's really good of you. I'll have a look online first to see if I can find somewhere else in Cardiff, surely Maplin can't be the only company here. especially if they're dodgy.
I've just put the monitor back together till after the weekend and it's working again at the moment so I didn't manage to break anything.
I'll be sure to let you know how I get on but there doesn't seem to be any components near those caps so I think I should be OK with a small soldering iron so a trip to Maplin might be on the cards regardless.

Right, I'm off to bed.
Goodnight Tom and take care.

[tom66]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

For the small caps I wouldn't worry about manufacturer, just match the capacitance and size. Voltage rating should be the same or higher. I would still recommend replacing the small caps with some good quality ones. Let me know which ones you need I'll send them to you free, to save you the cost of shipping from Farnell, if you find those caps appear to be the problem.

[NeilH]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

Looks like I might have to go to Maplin then, at least I wont have it going out on me, I can't use this 15" much longer. Don't get me started on PC world either. the prices are ridiculous like you say.
I built myself a computer two years ago (surprising how easy it was) and saved an absolute fortune going online. Same with Dixons mind, they wanted over £10 for a usb lead which I got online for less than £2, no wonder they're on the rocks.

I just noticed your rank "Badcaps veteran" you certainly are that.
Anyway, I'm off to bed shortly, I've got a busy day tomorrow so thank you again for all the help, you guys here are a treasure.

Neil.

[tom66]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

I would like to get the best quality caps I can as I don't plan on doing this again soon, would that Farnell you mentioned send out such a small order if I can't find any decent supplier in Cardiff. Also is there any specific make or type I should look out for?

Farnell have no minimum order anymore (as far as I know), but there's a £5 shipping charge. RS Online is another source. eBay is okay, IF you buy from UK sellers and trust they are genuine - there are too many fakes on there so be careful.

Maplin have the advantage of 200 retail stores but they're just another PC World with disco lights and car stereos on top. And don't get me started on PC World... went in there to get 512 MB of RAM... they wanted £50... forget that! Bought some later for £18 from Crucial directly. (This was quite a few years ago...)

[NeilH]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

I remember a friend at school used to build loads of gadgets he was always looking through the component book you mentioned and he got all his stuff mail order from them. They were really fast too, next day delivery at no extra cost for small items so you're right about being short sighted, with their old reputation they could probably have cornered the market.
I would like to get the best quality caps I can as I don't plan on doing this again soon, would that Farnell you mentioned send out such a small order if I can't find any decent supplier in Cardiff. Also is there any specific make or type I should look out for?

[tom66]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

I'm surprised about Maplin, I thought they were pretty good so I'll see if there's any better suppliers here in Cardiff.
Thank you so much for all tour help Tom, I really didn't think I would be able to do this but you have talked me through it wonderfully.
I'll get on replacing them after the weekend as I have a lot on but I'll be sure to let you know how I get on.

Maybe 20 years ago, when they still published a book of electronics projects, and half the store was dedicated to componentry, but nowdays they are useless.

There a Maplin book in my local library, it's kinda sad to see what they left behind. I think they've missed out big time because the internet and "Maker" revolution means that hobbyist/small time tech electronic component sales are going up, not down. If they just stocked a small amount of decent low ESR high quality caps I'd go there almost weekly to buy them, even if it cost a few quid more in total - I'd save on shipping, and get a TV working quicker, but they are too short sighted to see this.

[NeilH]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

I'm surprised about Maplin, I thought they were pretty good so I'll see if there's any better suppliers here in Cardiff.
Thank you so much for all tour help Tom, I really didn't think I would be able to do this but you have talked me through it wonderfully.
I'll get on replacing them after the weekend as I have a lot on but I'll be sure to let you know how I get on.

[tom66]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

Is it the one on it's own, the resin around the pins has discoloured, looks like it might have overheated.

Yeah, it's the discolouring that has me worried - the cap may have simply been cooked (I've just had an LG TV which had a burnt area near a cap, the cap looks like it was cooked by whatever was very hot nearby.) Capacitors really hate high temperatures, especially the smaller ones, the electrolyte dries up.

For those as a temporary fix you can use caps from Maplin as they are less crucial. I would recommend using decent ones for greater longevity though.

Probably the one on its own is the startup cap, but replace all four to be sure if you can.

[NeilH]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

"t is the startup cap"
Is it the one on it's own, the resin around the pins has discoloured, looks like it might have overheated.
Would they be different values, I think the one on it's own says 50v 2.2 uF I can't see the other values until I get them out.

[tom66]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

No failed caps there - and they look like pretty high quality Chemicon KY. Red circle indicates the secondary caps. I think Retiredcaps said something about these Chemicons drying up because these monitors run hot, but I'm not sure.

One thing you can try to locate the faulty cap: Get your monitor into the non working condition. Use a hair dryer or hot air gun to heat up some of the capacitors. If it is able to turn on when you heat a particular cap, that cap needs replacing. In particular, I suspect the capacitors I've highlighted in blue as more likely candidates - and these ones *never* bulge when the fail. It is the startup cap, crucial to the monitor getting started, but less important when it's running. Thankfully, these caps are pretty cheap, like about 10p each...

[NeilH]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

OK Here they are


Sorry for the delay, had to find some batteries for my camers.

[tom66]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

There are some small bee capacitors one end and some larger brown tubular ones the other, which ones need changing?

I'm not sure which ones you are referring to - a picture would be great - in general you want to replace the ones on the side closest to the connector going to the main board - there will be a black or white dividing line between the sides to indicate which side is mains/primary and which is secondary. Do not touch anything on the primary side with the monitor plugged in or shortly after turn off.

[NeilH]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

There are some small bee capacitors one end and some larger brown tubular ones the other, which ones need changing?

[tom66]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

OK, got that off, there's two plates that look like heat sinks, one near where the power goes in and a smaller one the other end.

Take some pictures of the board. I'll highlight the suspected devices.

[NeilH]

Re: Hanns-G HG281D 28" TFT - Multiple Problems

OK, got that off, there's two plates that look like heat sinks, one near where the power goes in and a smaller one the other end.