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Wise Wing F199 19'' LCD monitor - recapped

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    Wise Wing F199 19'' LCD monitor - recapped

    Looking through my repair pictures and notes, it's been a long time since I posted anything in the LCD monitors section. So here goes that.

    I'm dedicating this thread to one of the very first LCD monitors I repaired (if not the first one), which was more than 10 years ago now. The monitor is a Wise Wing, model F199. It's a 19” CFL-backlit LCD. I got it for free off of Craigslist in 2009 from a guy, who said he bought it for cheap from Wallmart and the monitor worked only for a little less than 2 years before quitting.

    When I saw the Craigslist post, I wasn't sure if the issue would be bad caps or not. Although I knew what they were and how to identify them, I was fairly new to BCN and recapping back then (started my electronics and PC repair journey around 2007-2008 or so.) But a 19” LCD back then was still considered decent for desktop use. And if nothing else, it seemed worth a shot at repairing, even if just for learning purposes.

    So I got the monitor (and it seemed no one else was interested in it anyways.) This was it:

    A classic “square” 5:4 ratio monitor. No stand was included (original owner had it on a custom mount, IIRC.)

    I tested the monitor as-is first, and it just made a terrible high-pitched squealing noise. LED on front did not light up. So I tore it open (though, it looked like the original owner might have done that too before me, because there were some marks on the case possibly from tampering.)

    LCD panel info:

    Made by Chunghwa, model CLAA190EA. As I found out later throughout the years, Chunghwa is one of the cheaper manufacturers often used in “budget” and low-tier monitors. Between them and Chi Mei, though, I can't say which one is better (or should I say worse?)

    Unfortunately, I forgot to snap pictures of the monitor boards as I found it (I didn't document repairs as thoroughly as I do now.) But the power+inverter board in this monitor is an FPS035-1Pi01ZT, which seems to be a pretty popular board for bad caps. And of course, the issue on mine did turn out to be bad caps: 3x CapXon KF, 16V, 470 uF, 10 mm dia. and 1x CapXon KF, 16, 470(?) uF, 8 mm dia. - all obviously bulged. I replaced them with 3x Panasonic FM, 16V, 470 uF 10 mm dia. and 1x 16V, 470 uF, 8 mm dia.


    Here is a bottom (solder) side picture, just for component references possibly:


    After this, I reinstalled back the PSU board, put on safety glasses, and plugged the monitor in the wall, half-expecting something to blow, as I had never done a recap before this (remember, this was me 10+ years ago .) Unsurprisingly, though, nothing blew up. Instead the monitor powered up and normally and displayed the usual message about lack of signal.

    So I closed the case back up and put the monitor through a test session… with the monitor sitting on the ground and propped against the wall (due to not having a stand for it.) The monitor worked just fine. However, I noticed that even in a mildly warm room temperature, the case of the monitor on the back felt rather warm. I stripped the plastic case and ran it again for about an hour to see how hot it would get. I didn't have my type-K thermometer back then, but the metal case was getting pretty warm. This had nothing to do with the recap, but rather the PSU was probably just being pushed quite a bit in terms of its power rating and hence why it was running hot.

    Thus, I decided to do a few modifications. First, I changed the “start-up” CapXon KM cap on the primary with a Panasonic FC (50V, 10 uF, 5x11 mm). Then, I put a bunch of holes on the metal back cover.
    https://www.badcaps.net/forum/attach...1&d=1598287764

    However, the monitor still appeared to run too warm for my tastes (and TBH, I've always been “a little” obsessed with keeping my electronic gear running cool – i.e. I always held the notion that if I couldn't put my hand on something, it's running too hot.) So for a while, I mothballed the monitor in storage while working on other projects and thinking of how to improve its cooling.

    When I came back around it (some years later, since I kept using my CRTs), I found the hottest running parts on the power board were, unsurprisingly, the heatsinks. While thinking of how to increase the surface area of the two heatsinks, the logic board also caught my eye.


    More CapXon!

    I don't remember if these were KM or KF series again, but more studying of the logic board showed that the toroidal inductor on the upper-left corner is part of a 12V to 5V buck converter. Having read how buck converters can fail sometimes if their caps went bad, I decided not to take any chances, so I recapped the input and output caps on it. IIRC, the input had a single CapXon (KM or KF), 16V, 470 uF cap, while the output had two CapXon (KM or KF) 16V caps (one 470 uF, and another 220 uF), along with a few smaller caps. I replaced the input and one of the output caps (the 220 uF one) with United Chemicon KZE, 16V, 680 uF and Nichicon HD, 10V, 470 uF, respectively.
    https://www.badcaps.net/forum/attach...1&d=1598287764
    https://www.badcaps.net/forum/attach...1&d=1598287764

    I didn't touch the smaller caps, because they were on the outputs of linear regulators (one of the linear regs is for 3.3V and the other for 1.8V, IIRC.) Instead, I soldered a few 4.7 uF SMD ceramics to the leads on the smaller caps. Figured that would be enough.
    https://www.badcaps.net/forum/attach...1&d=1598287764

    After this, I also came up with a plan for helping the PSU components to cool a little better.



    Basically, the secondary heatsink received a small extension to its surface area by bolting onto it (and coupling with thermal compound) a u-channel aluminum piece.

    Meanwhile, I noticed that the inverter MOSFETs (U2 and U2) on the solder side of the PCB had their Drain pins tied together through small copper tracks and a jumper. Since many SMD MOSFETs usually recommend large copper tracks to connect to their Drain pins for better cooling, I soldered a “heatsink” (of sorts) to the jumper that connected the Drain copper tracks.
    https://www.badcaps.net/forum/attach...1&d=1598288106
    This is probably not the most effective solution, but it does help. The copper wire running across the steel sheet spreads the heat from the copper pads connected to the Drains on the MOSFETs, and the heatsink did actually appear to get as warm as the MOSFETs. I also used hot glue for extra “bracing”, just in case the heatsink somehow broke off or got loose. This probably wasn't the smartest idea, though, because as the monitor ran for its first 10-20 hours with these mods, the room did always end up smelling like someone had just plugged in a hot glue gun.

    At this point in time, though, I had already acquired my type-K thermometer. After running the monitor again for a few hours then unplugging it, I stuck my type-K probe through the vents of the monitor and was rather shocked at how hot it ran: 55-65°C, depending on how far I slid the probe in. I think the highest I was able to measure was on a hot summer day (with room temperature close to 30°C): 69-71°C! No wonder those original CapXon caps died so quickly. This monitor is like a mini-oven inside. Heck, even the Panny FMs are bound to get a stressful workout at these temperatures (though being rated at 3000-4000 hours for the sizes of caps I used and assuming an average internal PSU temperature of 65°C, the FM caps should still last close to 6-8 years if used 24/7.)
    Attached Files

    #2
    Re: Wise Wing F199 19'' LCD monitor - recapped

    So all in all, I figured the recap and modding done on the monitor at this point felt complete enough for putting it into service. The monitor just needed a stand. I've been keeping an eye for one on Craigslist throughout the years, but never found one that was compatible and/or cheap/free or close by… so I made my own with scrap wood:


    A little basic, but it works.
    I upgraded the monitor on my parents' desktop machine (the old one was a 17” Dell) - good enough for the occasional use they put it through (mostly just when they need to print something.)

    The monitor worked nice and dandy until I came to do some SW upgrading and maintenance on their desktop one day. As I was using the PC, I noticed there were wavy diagonal lines running across the screen. Reading through posts on BCN suggested this may be a mains cap issue. After all, I didn't change the original primary cap, which was a CapXon KM. And with the PSU still running very hot (despite my attempt at improving the cooling), it didn't go past me that the main cap could be bad. So I tore up the monitor and found this:

    Ah crud!

    Desoldered to take a close look and test:


    Surprisingly, though, that primary CapXon cap still measured fine on my cap meter.


    But then I let it cool down a little. Although still in spec, the ESR did increase slightly:


    Unfortunately, I didn't have any 400V caps in stock to replace the CapXon. But there was no way I would put that cruddy CapXon cap back in there. Then it dawned on me : I live in a country with 120V AC line, so I don't technically need to use a 400V. A 200V cap would work just as well, provided I never move this monitor overseas or somewhere with 220/230/240V AC. With that in mind, I took a look through my junk bins, and found this good old Panasonic TSNH cap, rated for 200V and 150 uF.
    https://www.badcaps.net/forum/attach...1&d=1598288510
    And it's still in spec , despite coming from a dumpster-picked early 90's Panasonic TV that was smashed to pieces. I suppose it's never a bad idea to collect PCB boards from old CRT TVs - they always have a ton of useful components.

    Getting the cap soldered to the PSU board was not the hardest part.



    However, putting the metal PSU cover back on the monitor wasn't quite so possible, because the “new” Panasonic primary cap could not fit in any direction without getting in the way of the metal PSU cover. Seeing that I already had drilled ugly holes through the cover, I figured why not take it all the way.


    And while at it, I also widened the holes on the bottom part of the metal case for even more cooling.


    Then I slapped it back together and tested. However, it turned out the wavy diagonal shadow noise on the picture perhaps wasn't caused by the main cap after all, because it was present even with the new primary cap. To isolate the issue further, I tested with another monitor and saw the same wavy shadows. I know the VGA cable (yes, I'm still using analog cables ) is not a cheapo, as it came with the original Dell 17” monitor. So the noise is likely originating from somewhere else (possibly even the PC itself.) Of course, I'm still glad I changed that primary CapXon cap, as it would likely have died in the least expected time and probably ruined the PSU (caps with crud like that often fail open-circuit, as the crud is actually from the terminal lead getting eaten away by the electrolyte and loosing connection to the cap's foil layers.)

    With all that being said and done, my suggestion to everyone is to avoid buying cheap monitors. If this monitor is to serve as an example, you can see that bad caps were not the only issue here. Bad thermals/cooling will ruin any cap over time - even the good brands. Also, the picture on the Chunghwa TFT is not so great either - it exhibits mildly compressed colors (though not as bad as Chi Mei LCDs) that I couldn't quite fix through the menu options, no matter how much I turned up/down the color gains and contrast. Even more amusing is the “water colors” effect about 3-4 mm into the corners of the screen. From what I read, this is just a fault of the TFT. It tends to get more pronounced as the monitor warms up. Nothing too bothersome, though.

    In any case, this was still a fun repair with some interesting challenges, so I have no regrets about the time I spend fixing this monitor. Hope you enjoyed the read too.

    Also, a final word about the recap I did with the Panasonic FM caps: these were often the recommended caps to go to by default by many members here on BCN. However, I'd like to note that it's still a good idea to check the spec sheet of the original caps and maybe try to get replacement caps closer to their spec. In my case, the Panny FM caps had way lower ESR/impedance than the CapXon KF caps they replaced. Although not detrimental to the operation of the PSU, the Panny FM caps did cause the PSU to produce a rather audible high-pitched squealing when the monitor was turned Off or in stand-by mode. I've repeated this experiment (where I used caps with ESR much lower than the original) on many other PSUs with flyback design (as is the case with this monitor), and the results were always very similar: PSU would squeal with light or no load. Regulation is OK, but the audible noise can sometimes be bothersome in a very quiet room - at least for those who are a little more sensitive.

    So to sum it all up, I acquired the monitor in late 2009, fixed it mid-2010, put it in long-term service in 2015-2016 and didn't touch anything until noticing the wavy shadow noise around 2019, after which I swapped the primary cap in early 2019 and put the monitor in use again.
    Attached Files

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