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HannStar Hanns-G HC194d LCD monitor repair

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    HannStar Hanns-G HC194d LCD monitor repair

    Normally, I never post repairs this quick after I do them, because… I am usually very slow. But today, I’m making an exception here. Why? No idea. Perhaps only because the repair details are still “fresh” in my head… which is ironic, given this is a 16 year old monitor that hardly anyone will care about today. It is new to me, though. I picked it up last November from someone on my local Craigslist. It wasn’t very close to where I live, but was close to a family friend that I had to go visit anyways. So after watching the posting on Craigslist for a few weeks and seeing it getting reposted over and over, I sent a message to the person and he told me I was the only one that inquired about it. As such, I went to pick it up after visiting my friend that day.

    Anyways, according to the original owner, the monitor has progressively been taking longer and longer to turn On. Also, it would never turn On right away when it’s been sitting Off for a while and would usually require unplugging and plugging multiple times. I told the owner the issue is likely bad caps (in case he wanted to put that with the post before we had agreed for me to pick it up.) But he said I should just have it, since no one else was interested for the whole 2-3 weeks the post was there.

    So here it goes, first a look at the Hanns-G HC194d monitor outside:




    And a shot of the label, showing its true “vintage” (made in 2006).


    After a quick clean up (it was a bit dusty), I connected power to the monitor to see what it does. And indeed, it didn’t power On at all. It just kept ticking / clicking. Time to open it up! Removing the back cover reveals this:


    Some info on the TFT panel itself:


    OK, let’s look under the metal covers to see if we can see anything.

    Yeah… CapXon and Teapo caps everywhere… and they are all done for.

    Here’s another view from the side:

    Wow! I’m surprised this thing worked for so long with so many bad caps.

    Time to fire up the soldering iron! But before that, here are some hi-res pictures of the power supply and video boards (I always take a few, just in case there is a good up… even though this is as simple of a monitor recap as it gets.)





    While taking these, I realized something – the FPS043-2Pi01 power board looked very familiar. Going through my pictures collection, I’m not surprised – this PSU board is very similar to what was in a Wise Wing 19” LCD monitor that I recapped way back in 2010. In fact, that was my very first LCD monitor recap/repair.

    I find it interesting how that one only lasted about a year or two with the original caps (IIRC, the Wise Wing LCD was manufactured in 2007 or 2008), while this one made it almost all the way to the end of 2022. Goes to show how inconsistent lower tier cap manufacturers can be. Of course, other factors like running temperature and frequency of use, could have affected this as well.

    Anyways, let’s mark the voltage rails on the caps (I do this to get a better idea of what caps I can use, based on my current stock… and for anyone trying to recap one of these boards too, I suppose. )


    There! Red dot = 5V rail and double blue dot = 12V rail. Simple as that. As for the small cap by the transformer – that’d be the “startup” cap… 50V, 22 uF.

    The logic board wasn’t that much more complicated.


    Here, red dot = 5V rail, double blue dots = 12V rail, black dash = 3.3V or 2.5V or 1.8V (didn’t measure what the linear regulator is outputting), blue dot + red dash = output coupling caps for the TDA7496LK amplifier IC. And the one cap by the blue headphone jack is the ripple rejection filter for the TDA7496LK (yes, can you believe it? That one failed/bulged too! Teapo SC quality right there. ) What I find odd about the logic board caps is how all of the Teapo SC that were connected to the 12V rail were rated for 16V only, yet the PSU board exclusively used only 25V-rated caps on the 12V rail. The 12V rail did go up as far as 13-14V with a higher 5V load and no load on the 12V rail… so cutting it a bit close there, though nothing too crazy.

    Normally I post a shot or two of how these failed caps read on my transistor tester meter. But here I just decided not to bother. Almost every one of the caps on the output of the power board read open-circuit. Miraculously, the 22 uF startup cap was OK. On the video board, most of those green Teapo caps were the SC series. Pretty much all of these read either too low or too high in capacitance, and often with really high V_loss, suggesting high internal leakage.

    I suppose all of these caps have already more than done their jobs. 16 years of life is not bad for non-Japanese brands. Given the vintage of the display, though, I didn’t feel like wasting too many high-quality caps. So I did the repair partially with good caps and partially with re-used caps that read good. Here is the PSU board with this “hybrid” recap:


    The PSU board originally had 3x 25V, 470 uF CapXon KF caps on the 12V rail and 2x 10V, 1000 uF CapXon KF caps + 1x 10V, 470 uF CapXon KF on the 5V rail.
    I used 2x 25V, 470 uF UCC KZE and 1x 25V, 470 uF Ltec LZG for the 25V caps.
    Meanwhile, the 5V rail was replaced with 1x 10V, 1000 uF Rubycon ZLH, 1x 16V, 1000 uF “CS-logo”, and 1x 16V, 470 uF, CapXon KM. The “startup” cap was replaced with a reliable Nichicon PW of the same voltage and capacitance as the original (50V, 22 uF). And the primary cap was left as-is. I didn’t feel like pulling it out to measure it. Let’s hope it doesn’t go bad anytime soon like the CapXon in that Wise Wing monitor mentioned above.

    And here’s the recapped video/logic board:


    Originally, it had 6x Teapo SC 16V, 330 uF caps in 8x11 mm size, among other small caps.
    The one of the 12V rail by the power connector was replaced with a Samxon GF 25V, 470 uF (and as you can see, it’s a wee bit taller. ) The cap next to it is a filter for the 5V rail (also was a Teapo SC 16V, 330 uF) that I now replaced with a somewhat questionable OST RLP 10V, 1000 uF. But no worries! The brown cap close to the SOT-223 regulator is a UCC KY 10V, 220 uF, 6.3x11 mm size. It also filters the 5V rail, so no big deal if the OST RLP above it fails. The output of the regulator had a 16V, 10 uF cap, IIRC. I upped that to 100 uF with a Rubycon YXA.
    The 12V rail filter cap close to the TDA7496LK amp IC was also a Teapo SC @ 16V, 330 uF. I replaced that with an OST RLX 16V, 470 uF. I mean, everyone knows that low ESR caps tremendously improve audio quality, right. Never mind that the “speakers” in this monitor are just glorified headphone drivers… heck, their driver “cone” diameter is so small, I’ve seen headphones with bigger drivers. But whatever, I continued with this “more is better” trend and replaced the 16V 330 uF output coupling caps on the TDA7496LK amp IC with 2x 16V, 470 uF. One’s a Teapo SK 85C GP cap, and the other is a CapXon KM that I salvaged from… I don’t even remember anymore. I’m sure the extra 140 uF worth of capacitance will go above and beyond to improve the audio quality too. And lastly, the ripple rejection filter cap for the TDA7496LK amp IC: again, I went with a 470 uF cap. This time a Tocon –branded cap out of a Netgear mr814v2 router that was recapped preemptively over a decade ago. Actually, 470 uF is what was suggested in the TDA7496 datasheet sample circuit. So all of this 330 uF everywhere nonsense needed to go. :gfto: I think I also replaced one or two more 16V 10 uF caps with 100 uF Rubycon YXA, too. That’s about it, though.

    Yeah I know… I really went hard at work cleaning my scrap cap bin for this monitor recap. It worked, though… and right on the first try, so whatever.

    But if y’all think I’m done here, then clearly you haven’t read/seen any of my previous repairs. In particular, I have a bad OCD when it comes to fixing a design with poor cooling. Knowing how hot the FPS035-1Pi01ZT PSU board ran in the Wise Wing monitor, I certainly wasn’t going to leave the FPS043-2Pi01 in this monitor in its stock form – no sir/madam! (insert the opposite of the “nod” smilely here, which we don’t have. Hint, hint? )

    First, let’s check how much height we have between the PSU board and its top metal cover. Answer: not much.


    So I figured I’ll just do something similar to what I did with the PSU board from the Wise Wing – attach an aluminum extension to the existing secondary heatsink and maybe something to the jumpers connected to the MOSFETs’ Drain pins on the inverter board.

    The result was not the same as the one on the Wise Wing PSU board, but very similar.






    All it took was a scrap aluminum U-channel piece from my workbench, 1x M3 screw (from a recently scrapped plasma TV, if that matters to anyone ), a tiny bit of silicone/caulk, and… LOTS of fiddling to get a hole in the secondary heatsink drilled without removing it from the board. (Don’t even dare ask – that’d be a full 15k char. post by itself. )

    You can also see I replaced some of the jumpers in the inverter area with “tall” jumpers made of 14 AWG copper wire. Why? - Extra cooling for the inverter MOSFETs. I know this silly monitor worked fine for… what is it now? 16 years?... and the MOSFETs were OK without heatsinks. But nevertheless, I just dislike how hot these FSP PSU boards run. My OCD just won’t leave me at peace.

    In case you’re wondering what the 14 AWG copper wire jumpers attach to…

    … MOSFETs U2 and U3 Drain/Source pins. It might not seem like much, but each jumper is roughly 5 cm (50 mm) in length. At 14 AWG (1.63 mm dia.), this adds up to about 260 mm^ of extra surface area (or 2.6 cm^2 if you like). And that’s per single jumper.

    Likewise, I did a rough estimate for the surface area of that small aluminum U-channel, and I came up with about 10 cm^2 of extra surface area – that’s without counting the common contact area between the two heatsinks (which I coupled with thermal compound, of course.)

    But I didn’t stop even here. Actually, the main problem with the cooling, IMO, is the metal housing in which the PSU and logic board sit in. Let me show you why.
    First, this is how the monitor looked like on its back bottom side in stock form:

    ^ Not many ventilation holes there and certainly not very big. :\

    Here’s the metal cover without the monitor’s plastic back cover:

    ^ Yes, the metal cover does have ventilation holes on the back… but get this – they are all covered by the plastic back almost completely. There’s maybe 1 mm or so of distance between the plastic back cover and the metal case. Whoever though this would provide good ventilation clearly does not understand how airflow works.

    Now here’s the top side of the metal cover:

    Again, the ventilation holes are tiny for whatever reason. To add insult to the injury, notice the sticky residue on the metal cover. This is leftover from where the aluminum shielding tape was put. It essentially covered most of the ventilation holes.

    The good news is: crap like this is what I save for when I have a s#!ty day and need to do some stuff with my hands. In the case of this monitor’s back cover: drill, baby, drill!

    Let’s add some marks. This is the metal cover’s top side, BTW.


    Drilled out.


    While at it, why not do the side too, right?


    And finally, the bottom side:


    Yeah, that’s A LOT OF HOLES.
    Drilling them was actually the easy part (well, easy only once I got to my bigger Craftsman and Dewalt quality drill bits.) De-burring was what took the longer part of this exercise, because… you know why.

    Anyways, this is how it looks with the monitor all closed up:


    Aside from the 3 extra holes I drilled in the back plastic cover, probably no one can tell anything was done to the monitor.

    And to think all of that work for saving a mid-2000’s 19” LCD monitor that I can’t even give away (locally) for free.
    But here it is anyways


    If things go right with my future plans, though, maybe one day you’ll see the idea I had behind saving all of this junky stuff.
    Attached Files
    Last edited by momaka; 03-15-2023, 10:24 PM.

    #2
    Re: HannStar Hanns-G HC194d LCD monitor repair

    I have a Hanns-G 19 inch LCD too, but it's a wide-screen 1600x900. Three bad caps was all it took. It did make it all the way to last year from 2007. Found it on the curb.

    And yes, no one wants it even for free. Not even here in Romania.
    Originally posted by PeteS in CA
    Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
    A working TV? How boring!

    Comment


      #3
      Re: HannStar Hanns-G HC194d LCD monitor repair

      Originally posted by Th3_uN1Qu3 View Post
      I have a Hanns-G 19 inch LCD too, but it's a wide-screen 1600x900.
      Cool.
      Yeah, that's what I thought mine would be, as there was no picture posted and I didn't look up the model number prior to getting it. 5:4 LCDs, while not rare, are definitely not seen very often anymore. At first, I was a bit disappointed it wasn't a widescreen. But then looking at my hoard of old "retro" PCs, I think having more 5:4 and 4:3 screens is better. A lot of early 2000's and older games don't have wide screen resolution support (not unless modded anyways.) So if I do get to build out a "mini" personal LAN party, the 5:4 LCDs will likely see more use.

      Originally posted by Th3_uN1Qu3 View Post
      And yes, no one wants it even for free. Not even here in Romania.
      LOL!
      The gypsies don't break them for the metal inside? In your southern neighboring country, they still do.
      That said, I got lucky last summer and managed to pick up a 19" Samsung monitor (forgot the model) that wasn't smashed yet. 1 bad cap is all it had and took for it to not work. I also saw a microwave... but by the time I went down to pick it up 5 minutes later, it was a mess of wires, bits, and pieces all over the place. I don't think even a grenade would have done as much damage as (likely) the gypsy that took/beat it apart.

      Comment


        #4
        Re: HannStar Hanns-G HC194d LCD monitor repair

        Originally posted by momaka View Post
        LOL!
        The gypsies don't break them for the metal inside? In your southern neighboring country, they still do.
        No. Since 2019 a plentiful, ubiquitous and much richer resource for that has been introduced - rental electric scooters.
        Originally posted by PeteS in CA
        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
        A working TV? How boring!

        Comment

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