Another HannsG HG281D

[momaka]

Re: Another HannsG HG281D

Well, as the old (likely bad) caps on the logic board age, they will eventually dry out more and more until they get to a point where your monitor no longer works at all. I think it would also be easier to change those caps first than assuming there is an issue with the T-con rails. There still might be one, but if there isn't, we will be looking for a problem that doesn't exist, and this can complicate the troubleshooting process. In other words, let's try to eliminate the simple (potential) issues first. (i.e. the caps on the logic board)

[Capt. Cap]

Re: Another HannsG HG281D

Since the white screen issue is intermittent (only happens from time to time), I doubt VGL, VGH, and AVDD/AVCC are bad.

Maybe not so intermittent after all... I haven't been able to get the screen to display an image at all today, even on first attempt

[momaka]

Re: Another HannsG HG281D

I was thinking this could be a VGL issue. Do you think it's logic board related?

Since the white screen issue is intermittent (only happens from time to time), I doubt VGL, VGH, and AVDD/AVCC are bad.

So yes, I suspect the logic board for that first. Definitely replace at least the two regulator caps that budm suggested. I personally suggest to replace all of the "bigger" caps on the logic board as well as everything close to the linear regulators, as those areas typically get hot and will kill cheaper caps over time.

[budm]

Re: Another HannsG HG281D

I would at least replace those two caps for the regulator circuit on that logic board.

[Capt. Cap]

Re: Another HannsG HG281D

Did you recap the entire video/logic board or just a few caps as suggested in the thread link above.

I actually skipped the logic board entirely as I didn't have any suitable caps on hand.
I'll definitely pull out the logic board and do some replacements the next time I have it open.

I was thinking this could be a VGL issue. Do you think it's logic board related?
I have a scope now so diagnosing might be a little easier - any suggestions?

[momaka]

Re: Another HannsG HG281D

Did you recap the entire video/logic board or just a few caps as suggested in the thread link above.
I personally recommend recapping as many caps on the logic board as possible. And *don't* use general purpose (GP) caps, even if the original ones were. There are a few hot linear regulators on that board, so it's probably best to go with long life entry-level low ESR electrolytics (such as Rubycon YXJ, Nichicon PW, Panasonic FC, and etc.)

[Capt. Cap]

Re: Another HannsG HG281D

I ended up replacing just C603, 606 and 707 since I already had low ESR 22μF and polypropylene 1μF 100V capacitors on hand, and it's worked since.

However, I've recently started to get a blank white screen after the monitor has been on for an hour or more, computer puts monitors to sleep after inactivity, and then attempts to wake it back up.
Works fine again if I let it cool off for an hour or so and then turn it back on.
I may be revisiting this one soon.

[Capt. Cap]

Re: Another HannsG HG281D

Looks like I missed C406 in that first annotated photo. Can that picture be replaced?
The corrected picture is attached.

[Capt. Cap]

I'm working on a recap for a HannsG HG281D monitor with a Phihong PSM-217-404-H-R rev. A1 power supply.
There are quite a few threads on this monitor at badcaps, and I've read through all of them, but have a few questions related to my particular situation.

The monitor worked fine until about a year ago. I usually would power off the monitor completely when not using it (I don't trust the plug-an-play stuff to not fry the HDMI port on my laptop), and it would not turn back on without a couple of power button presses. Once powered up into standby mode (orange LED color) it would go into normal operation (blue LED color) just fine and not have any issues during use. Getting the monitor initially powered on started to become a bit of a chore, so I started leaving it in standby mode and doing the plug-and-play thing. As long as I didn't accidentally flip the switch on the surge protector, I would be fine. Then it started to turn itself off completely while sitting in standby mode after a week or so; getting it turned back on would be quite time consuming, though sometimes it would just kick itself back on (this monitor seems to revert back to its last state after power failures). Getting the power back on became harder and harder, and now I have not been able to get this thing powered on since the last time it turned off.

From my reading about the HG281D in other threads, it appears this is likely a power supply issue, in particular, a startup capacitor problem (as mentioned here https://www.badcaps.net/forum/showpo...2&postcount=34) does that sound about right to you guys?
Which exactly are the startup caps on this board?

Sounds like the C603, 606 and 707 are also problematic, so I was planning on recapping the entire board (except for C3). I'm wondering if film capacitors would work for the 100V and 50V capacitors or would the ESR be too low? I'd like to understand which places on the power supply board are important to get low ESR, where some ESR may be necessary, and where GP caps are OK.

According to this picture linked from another thread http://www.directupload.net/file/u/4...fvxoqk_jpg.htm the primary is everything to the left of the transformers in the middle, the secondary is everything to the right. This follows a white silkscreen line printed on the back of the PCB. However there is a low ESR cap (C108) on the primary and a GP cap (C707) on the secondary - are those just bad choices? Where is the PFC on this board?

I've attached pics of my particular PSU, also an annotated pic with the cap PCB number + specs to help identify all of the caps.
Also, that picture linked above is a nice reference (it's of the rev. A2 board, all capacitor values are the same).

PCB # / brand series breakdown is as follows:
C203 C114 are Jamicon TK series (general purpose) https://cdn.badcaps-static.com/pdfs/...0a384e50a9.pdf
C205 C606 are Taicon VT series (general purpose) https://cdn.badcaps-static.com/pdfs/...6f416a420a.pdf
C601 Ltec TH series https://cdn.badcaps-static.com/pdfs/...710cf29b67.pdf
C603 C707 C111 Ltec TK series (general purpose) https://cdn.badcaps-static.com/pdfs/...eff471caef.pdf
C108 Ltec LZG series (low ESR) https://cdn.badcaps-static.com/pdfs/...3154c18b5e.pdf

C3 Nippon Chemi-Con CLA https://cdn.badcaps-static.com/pdfs/...41a221bc5e.pdf
Everything else is Nippon Chemi-Con KY (low ESR)

I also plan to replace the DC filter caps on the logic board https://www.badcaps.net/forum/showth...ghlight=HG281D