Hanns G 281D Power On Problem

[Badbob]

Hi,
I'm having the same problem as Rushstrike in older thread on Hanns G281D monitor problems: I'm having to press the power button many times (sometimes 50 or more) to get the monitor to start up. Switch seems fine. Once powered on it works flawlessly. Retiredcaps suggested replacement of the start-up capacitor, but I can't find identification or suggestion of which capacitor this might be in the old threads. (I do have a set of replacement capacitors sold by Amazon, but it is a partial set of the capacitors on the switching supply board, so I need to be selective in my replacement approach.) Any suggestions where to start? I can see no noticeable defects to the appearances of any of the caps on the boards.
Thanks!
Bob

[Rtech]

Re: Hanns G 281D Power On Problem

Suggest that photos of the Board would be very helpful,to anyone wishing to help you with the repair.

[selldoor]

Re: Hanns G 281D Power On Problem

Welcome to the forum-
What make/series are the caps if not a recognised good brand they may not work in this application. Start up cap is generally a 50v 47u or 68u on the primary side of the power supply.


As Rtech says we can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
https://www.badcaps.net/forum/attach...1&d=1290283049

https://www.badcaps.net/forum/attach...7&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc.

[Badbob]

Re: Hanns G 281D Power On Problem

Thanks for the photo recommendation. Attached are photos of front and back of board. The shield on the line voltage side is soldered to the board so I didn't remove it for the picture. Maybe some filtering for the transformer? -- has 2 small electrolytic caps and 1 420V 150uf electrolytic inside the shield.
The switching supply is PHIHONG model PSM217-404-H-R. Thanks for the quick response and please let me know if you need more info.

BTW, I can solder/desolder, but my electronics experience is more hobbyist level low voltage analog and digital circuits in support of scientific instrument projects.

[retiredcaps]

Re: Hanns G 281D Power On Problem

Hi,
'm having to press the power button many times (sometimes 50 or more) to get the monitor to start up. Switch seems fine. Once powered on it works flawlessly.

Your description sounds consistent with caps that are dry and have high ESR. As the caps warm up, the ESR drops allowing the lcd to work.

Since we have had so many reported issues with this monitor running temperature hot, I suggest you consider recapping all electrolytics caps on the power and logic board. This might cost you $20 in caps, but to save a 28 inch monitor, I think it is worth the investment.

The megathread for this monitor is the 10th most viewed thread in the troubleshooting lcd section which give you an idea the problems with this monitor.

[selldoor]

Re: Hanns G 281D Power On Problem

As retiredcaps above , but just in case it is something silly can you resolder most of the joints on the top right hand corner in your "back of the board" picture. One looks burnt? Examine the rest with a magnifier and see if there are any cracks.
Im not very good translating backs to fronts but I think it is the transformer?

[Badbob]

Re: Hanns G 281D Power On Problem

Thank you all very much for your quick responses and suggestions! I have replaced nearly all of the electrolytics on the power supply board and the LCD display's start up problem seems to be resolved.