HannsG 281 Monitor doesn't display video

[dsallard]

Hello,

I have a HannsG 28" monitor that worked great until my kids told me that it stopped working.

I checked it out and find that it powers on, and the screen lights red for a few seconds, but goes to sleep mode.

If I press the top button on the side of the monitor, I will see RED, GREEN, and BLUE screens each for about a second then it goes back to sleep. I can repeat this by pressing the top button on the side.

I don't see any intro screen (I actually can't remember if it showed any type of 'HannsG' logo on startup when it was working).

I opened up the monitor and looked at the boards inside.

I took a photo of the main board that the HDMI and other connections go to and a second board that the display itself appears to connect to.

I did not look at the power supply board since it powers on and can show each of the colors brightly. I did take a photo of the bottom side of the power supply board since it was exposed.

I don't notice anything burned or discolored. The monitor worked great for years I had it. There were no signs of degraded performance. It was working like new until it stopped working. :-(

If you have ideas of what I can check or probe, I would be most appreciative. Unfortunately, all I have is a multimeter for test equipment.

Also, please let me know if the photos have too much reflection. I can take them at an angle next time.

Thanks,
David

[jetadm123]

Re: HannsG 281 Monitor doesn't display video

With your meter set to DC volts (use 20V scale), try measuring each pin of U7 and U8 (located in the upper left of your photo). One or both of them are voltage regulators. Report your readings. And you mentioned pushing the "top button". Just exactly what is that button supposed to do?

[PlainBill]

Re: HannsG 281 Monitor doesn't display video

In addition to jetadm123's suggestions, I have a few questions.

Which input connector were you using? Did you try the other input? (If I recall correctly, at least one model of HannsG monitor is known to have the HDMI input fail._

You mentioned the monitor going into standby. Does the power LED go to amber, or is the only change the screen going blank?

PlainBill

[dsallard]

Re: HannsG 281 Monitor doesn't display video

@Jetadm123 I'll try to probe the pins and send the results. Just curious of how many of the connectors need to be connected to get the results. I had to disconnect that board to get to the 'business' side of it. Hopefully I can get to the pins with the cables connected.

The top button on the case was the 'Menu' button, as I recall.

@PlainBill: I did try using the two inputs available on the monitor (HDMI and RGB).

However, I recently discovered I may not have had good RGB input. The replacement monitor I use does not have HDMI, so the DVD player had to use a cable that supposedly converted component to RGB. I tried that on two TVs without success.

Also, the Amber light comes on when it goes into standy. From there, I can press the top button again and get the RED, GREEN, and BLUE screens before it goes back to standby with the AMBER light on the power button. I can repeat this a lot (I did it at least 10 times before I found this forum and started taking things apart).

So, my action items are:

1) Measure output values of U7 and U8
and
2) I need to find a known good source of RGB output (like my laptop) and try again.
3) Find the manual and confirm the function of the top button.

It's getting late East Coast Time, so I'll probably post results tomorrow morning.

Thanks for the advice!

David

[dsallard]

Re: HannsG 281 Monitor doesn't display video

Removed this correction content after I edited the post above... Haven't learned how to delete this (now redundant) post.

[dsallard]

Re: HannsG 281 Monitor doesn't display video

Good morning!

With a fresh pair of eyes, I reconnected the cables (except speakers), including the case switch.

Two corrections on behavior:
When I apply power to the Monitor (turn on power strip or plug in power cable):
The Power LED is OFF

1) When I press the POWER button,
a) the power LED goes to BLUE
b) the screen is black
c) after about 7 seconds, the screen lights RED briefly (less than a second, I can see the back lights come on)
d) the screen goes black and the power LED goes to AMBER

2) With the power LED AMBER (STANDBY), Pressing SW4 (the AUTO button, NOT the MENU button as I previously reported)
a) The power LED turns BLUE
b) screen lights RED, then GREEN, each for about a second, then BLUE (for maybe half that time)
c) the back lights turn on during the screen color cycle
d) the power LED goes AMBER again


Photo 1:
The switch board shows:
SW1=POWER, SW2= LEFT, SW3=RIGHT, SW4=AUTO, SW5=MENU

Photo 2:
Probing the pins of U7 and U8 from LEFT to RIGHT:

U7 - 1.81v, 0v, -3.3v
U8 - 1.48v, 0v, -1.8v

It measures the same as long as there is power applied to the monitor whether the power LED is AMBER, BLUE, or OFF.

Hope this info is helpful!

Thanks again!

David

[PlainBill]

Re: HannsG 281 Monitor doesn't display video

By your description you seem to have eliminated 'two seconds to black'. The monitor is going into standby.

It's a minor point, obviously there was an error in your technique measuring the voltages on the regulator, you should not have gotten negative voltages. However, the regulators are clearly identified and the outputs are correct.

I note that there are several eBay auctions of capacitor kits to repair the main board. There are also several main boards, however there appears to be at least three versions of the main board and I suspect they are not interchangeable.

PlainBill

[dsallard]

Re: HannsG 281 Monitor doesn't display video

Thanks, PlainBill.

Looking at the photo, I put the black lead on the large pad on the bottom of U7 and U8 respectively. I then measured the voltage on the left, middle, and right hand pads on the top of U7 and U8.

I thought the middle pad on the top is the same as the large pad underneath, so I expected there to be 0 volt difference. Is that correct? Or should I have used a different location to get 'ground' (and I would get a difference of roughly 5v and 3.5v between the left and right most pins of U7 and U8)?

With the regulator outputs correct, you suspect the boards themselves? Or the capacitors (on the power supply board or on all boards)?

Just trying to grasp the magnitude of the next steps. :-)

David

[PlainBill]

Re: HannsG 281 Monitor doesn't display video

Thanks, PlainBill.

Looking at the photo, I put the black lead on the large pad on the bottom of U7 and U8 respectively. I then measured the voltage on the left, middle, and right hand pads on the top of U7 and U8.

I thought the middle pad on the top is the same as the large pad underneath, so I expected there to be 0 volt difference. Is that correct? Or should I have used a different location to get 'ground' (and I would get a difference of roughly 5v and 3.5v between the left and right most pins of U7 and U8)?

With the regulator outputs correct, you suspect the boards themselves? Or the capacitors (on the power supply board or on all boards)?

Just trying to grasp the magnitude of the next steps. :-)

David

The tab and the middle pin (pin 2) are usually connected internally. On both the true pin 1 (which you called pin 3) is either ground or the adjust input. the true pin 3 is the input. I usually use a mounting screw as gorind.

Originally I suspected the problem is on the power supply board, the inverter, or the CCFLs. Your description of the behavior leads me to believe it is NOT a case of 'two seconds to black'. That tends to reduce the chance the problem is on the power supply board. Further, the presence of several sellers offering replacement cap kits for the main (signal, logic) board is unusual.

There are several anomalies - usually we see 'No Signal' (or equivalent) appear if the video signal is missing. That usually indicates 'two seconds to black'. But the power LED indicates the monitor is going into standby.

I'd suggest using a known good VGA source to test the VGA input. If the problem persists, it is your decision if you with to recap or replace the signal board.

PlainBill

[dsallard]

Re: HannsG 281 Monitor doesn't display video

Hi PlainBill,

I tried with a known good RGB source and got the same behavior as I did previously.

I also checked the voltage regulators again with the black lead of the DMM on the mounting screw of the power supply board. I get (roughly) 5v, 3.3v, 0v on U7 and 3.3v, 1.8v, and 0v on U8.

Since I had already taken most things apart, I also flipped the power supply board and didn't see anything out of the ordinary there. I didn't take the heat sinks off, but what I could see underneath looked pretty ordinary.

I'll probably put it all back together and weight the options of new boards / recapping / replacement monitor with an extended warranty, etc.

You mentioned several sellers offering replacement cap kits. I checked eBay, but only see recap kits for Fender amps. If that's allowed, where do you find these and/or replacement boards?

Lastly, if I decide to punt and send it off for repair, does anyone know what folks have been charged for repair?

Thanks again!
David

[PlainBill]

Re: HannsG 281 Monitor doesn't display video

On eBay, search for HannsG 281.

PlainBill

[dsallard]

Re: HannsG 281 Monitor DOES display video!! :-) For a few minutes... :-(

Hello again!

So I decided to punt (for now) and went to reassemble the monitor and store it through the holidays.

Just to be safe I checked the behavior in the middle of re-assembly to be sure I didn't make things worse and to my surprise, the HDMI input was working!

I continued to reassemble and check that things were working. All was good through the completed assembly, and after transport and connection to my PC.

I logged into the computer, logged out, and logged back in. I took a photo to attach to my 'Thank You' note to all the helpful and encouraging folks on this forum!

But... sometime, while I was looking down emailing the photo(s) from my BlackBerry, the monitor went blank and into standby.

I tried moving the mouse and pressing the non-power buttons on the monitor but it stayed in standby (AMBER).

When I power cycled the monitor, the blue light came on for about two seconds and went back to amber. I repeated this several times.

After disconnecting the power cable for a few seconds I am now back to the original problem (flash of red screen after 7 seconds or so), pressing the 'AUTO' button cycles through RED, GREEN, and BLUE.

The monitor worked for several minutes when I periodically checked on it during reassembly. This was HDMI input from the DVD player (albeit with just a screen saver) and it was laying flat. After moving and connecting to the computer, it worked for a few minutes before failing.

I am curious if the orientation of the monitor has anything to do with it... or if there is some difference in the HDMI output from my DVD player vs. the graphics card in the computer.

One thing I didn't give much thought to during re-assembly was the connector between the 'secondary' board and the LCD panel was not well seated. I figured I probably dislodged it while twisting things around to get them back together. I had not noticed it being askew previously. I just reseated it and put the tape back.

In any case, everything was working after I put it all back together, so I didn't give it more thought.

When I open the case again I will carefully inspect the seating of the connectors. There was some tension on the heavier ones and settling may be unseating some of the pins.

The glue on the original tape isn't holding very well, but I don't have any tape similar (other than duct tape), so I didn't replace it. I'll be sure to pick some up and apply new cloth tape in the locations that tied things down.

Sorry for the 'stream of consciousness' post. Hope things are clear enough to respond. Let me know if you have other suggestions.

Thanks again and Merry Christmas!

David

[PlainBill]

Re: HannsG 281 Monitor doesn't display video

Those symptoms are characteristic of a bad solder joint. The fact that the flaw manifests itself as a 'no signal' condition (rather than a complete shutdown) indicates the problem is almost certainly on the signal card.

PlainBill

[dsallard]

Re: HannsG 281 Monitor doesn't display video

Thanks, PlainBill.

I take it the 'no signal' you refer to is not an absence of a video source to the monitor itself, correct?

During my mid-assembly testing when I first noticed something was 'different', I didn't have any video source connected, but the monitor DID display a box stating there was no input.

So, something is interrupting any video output that would normally go to the LCD panel.

Can you remind me again, which one is the 'signal board'?

Thanks!
David

[tom66]

Re: HannsG 281 Monitor doesn't display video

I've encountered the red/green/blue problem (although the colour is usually fixed, not changing) when the LVDS cable is loose. The problem turned out to be the glue on the connector: it had loosened over many temperature cycles. See if pressing on the connector while it's exhibiting the problem helps fix the problem.

[dsallard]

Re: HannsG 281 Monitor doesn't display video

Thanks tom66. I'm not sure which one is the LVDS cable, but I'll inspect and press them all!

I'll post an update when I can set up my temporary workspace again.

David

[PlainBill]

Re: HannsG 281 Monitor doesn't display video

Thanks, PlainBill.

I take it the 'no signal' you refer to is not an absence of a video source to the monitor itself, correct?

During my mid-assembly testing when I first noticed something was 'different', I didn't have any video source connected, but the monitor DID display a box stating there was no input.

So, something is interrupting any video output that would normally go to the LCD panel.

Can you remind me again, which one is the 'signal board'?

Thanks!
David

Signal board AKA 'logic board' AKA 'Main Board'; the board with the inputs.

PlainBill

[Th3_uN1Qu3]

Re: HannsG 281 Monitor doesn't display video

The LVDS cable is the one going from the signal card to the panel.

[dsallard]

Re: HannsG 281 Monitor doesn't display video

Hello again!

It's been quite a while since i last added to the post. Finally had time recently to pull everything out again and tried re-seating all of the cables. But to no avail.

Very strange. Nothing appears to be seated poorly. I plugged all the ribbon cables in and checked the behavior. it's the same as the original post.

At this point, I think I'll have to punt and get a replacement (with an extended warranty).

Thanks for the assistance in helping me debug what I could!

David