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Old 01-11-2011, 08:52 AM   #1
Welchs101
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Default Hannspree HSG1064 5 seconds on then blank screen

I am trying to repair a Hannspree HSG1064 computer monitor for a friend. Its a nice one!

Problem: When you power up the monitor it comes on for 5seconds then shuts off. I opened up the case and looked for the usual "bad caps" but did not see any that were "obviously bad".

I have taken pictures of the powersupply and inverter board both front and back.

Any thoughts?

Is this also like a 2seconds to black issue like PlainBill has mentioned?
Attached Images
File Type: jpg Overall.JPG (377.8 KB, 164 views)
File Type: jpg PowerSupply_inverter1.JPG (404.3 KB, 196 views)
File Type: jpg Bck_PSU_Inverter.JPG (414.9 KB, 105 views)
File Type: jpg Bck_Mag1.JPG (416.9 KB, 85 views)
File Type: jpg Bck_Mag2.JPG (418.4 KB, 58 views)
File Type: jpg Bck_Mag3.JPG (429.4 KB, 54 views)
File Type: jpg Bck_Mag4.JPG (409.2 KB, 37 views)
File Type: jpg Bck_Mag5.JPG (417.9 KB, 38 views)
File Type: jpg Bck_Mag6.JPG (412.8 KB, 45 views)
File Type: jpg Mag__of_chip1.JPG (383.2 KB, 75 views)
File Type: jpg Mag_of_chip2.JPG (362.8 KB, 54 views)
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Old 01-11-2011, 10:18 AM   #2
retiredcaps
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Quote:
Originally Posted by Welchs101 View Post
Is this also like a 2seconds to black issue like PlainBill has mentioned?
1) I circled the secondary inverter transformer pins. Measure the resistance between the yellow pins. Do the same for the red pins. They should be within 3% of each other.

2) If the above is good, then the problem might be the ccfl lamps or the ccfl wiring. If you have a spare lcd monitor, it would be easy to narrow down the problem.
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Old 01-11-2011, 11:27 AM   #3
Welchs101
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

I measured the resistances between the two red circles and two yellow circles you showed in the pictures.

One measured: 0.994kohm
One measured: 0.984kohm

I guess i need to check the lamps......let me see if i can do this now. i will get back to you.
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Old 01-11-2011, 12:03 PM   #4
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Quote:
Originally Posted by Welchs101 View Post
One measured: 0.994kohm
One measured: 0.984kohm

I guess i need to check the lamps......let me see if i can do this now.
The inverter measurements look fine.

Since this is a 25 inch lcd, try to get a spare monitor that is at least 20 inches. A smaller ccfl tube like 17 inch may not be a valid test? However, if all you have is a 17 inch lcd, it still may work?
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Old 01-11-2011, 02:22 PM   #5
Welchs101
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

hi,

I tried testing the bulbs using another computer monitor. I have a 19" samsung 191TPlus monitor that i use to test bulbs. I wired lines from the inverter of this monitor into a homemade jig which plugs into the connector of the "test monitor". I could not really test any of the bulbs on the 25" monitor.

Normally, a "bad" bulb shuts of my 19" tester-monitor. Well, all 4 bulbs of the 25" monitor shut down my 19" tester-monitor. Now all 4 bulbs of the 25" monitor could be bad but i doubt it. I think my test setup is suspect.

Any suggestions?
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Old 01-11-2011, 02:29 PM   #6
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Do you think 19" is too small to use as a tester?

What size do you think i would need to use as a tester to test a 25" computer monitor?
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Old 01-11-2011, 02:36 PM   #7
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Quote:
Originally Posted by Welchs101 View Post
Do you think 19" is too small to use as a tester?

What size do you think i would need to use as a tester to test a 25" computer monitor?
I am a little confused to what you tried.
Did you plug the ccfls from the 25 monitor into the 19 monitor?
Al
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Old 01-11-2011, 02:39 PM   #8
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

I do it this way.

1) Disconnect Hannspree ccfl connector #1. Plug this connector into the Samsung ccfl. Watch for 2 seconds to black.

2) Wait 1 minute for things to discharge.

3) Replug Hannspree ccfl connector #1 into Hannspree. Unplug Hannspree ccfl connector #2. Plug #2 into the Samsung ccfl. Watch for 2 seconds to black.

4) Wait 1 minute for things to discharge.

5) Repeat for #3 and #4.

The above is #5 at

http://www.badcaps.net/forum/showpos...1&postcount=14
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Old 01-11-2011, 03:57 PM   #9
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Thats basically how i do it as well. The only difference is this. Since some connectors are "different" between different monitors I did the following.
1) I removed one of the connectors going to the CCFLs on a monitor with a cracked screen.
2) I then soldered wires in place of the connector so that i could attach a homemade "jig" which i then plug into a monitor i want to test.


For some reason when i used my homemade tester ...... my tester could not power up the ccfl's ........at least for very long. I wondering if ineed a biger tester-monitor.
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Old 01-11-2011, 04:10 PM   #10
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Quote:
Originally Posted by Welchs101 View Post
I wondering if ineed a biger tester-monitor.
Some have commented that there are U or M shaped ccfls like shown below

http://ccflwarehouse.com/spshccla2.html

You could have one of these in this monitor and using a "simple" straight 19 inch tube might be insufficient for testing?
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Old 01-11-2011, 05:28 PM   #11
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

hummmmmm.........i had not thought of that. Why couldnt i use a 19"? Its still just two leads to the lamp right?

i was thinking of what you said........that i might need a larger monitor in order to test the 25"

(thanks for your help)
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Old 01-11-2011, 05:37 PM   #12
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

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i was thinking of what you said........that i might need a larger monitor in order to test the 25"
In a very recent thread, the OP had a 19 inch monitor and tried to use a 15 inch ccfl tube for testing 2 seconds to black. It didn't work properly. He then took apart the 19 inch lcd and found one of the ccfl tubes had a hole in the middle.

So for that particular case and that particular circuitry, the 4 inch difference in tube length was too much.

It could be the same in your case?
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Old 01-12-2011, 02:43 PM   #13
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Well, i talked to a friend who had a 20" monitor. I asked if i could take it apart and use it to try and test the 25" monitor. He said yes. Unfortunately, it did not work.

Question: Does it matter how the lamps are wired........ie....which wire i plug the "hot" into?

Question: Any ideas on how to test this 25" bulb?
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Old 01-12-2011, 03:45 PM   #14
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Anyone know the answer to this question:

I am assuming that this 25" monitor requires a larger operating voltage than either my 19" or 20" can provide.........is this correct?

What would happen if i took the output from the 25" and fed it into one of the 20" bulbs? Would it destroy the bulb?

Just trying to figure out how to determine which bulb (if any) in the 25" are bad so i can rule the bulbs out or not.
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Old 01-12-2011, 04:28 PM   #15
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Quote:
Originally Posted by Welchs101 View Post
Anyone know the answer to this question:

I am assuming that this 25" monitor requires a larger operating voltage than either my 19" or 20" can provide.........is this correct?

What would happen if i took the output from the 25" and fed it into one of the 20" bulbs? Would it destroy the bulb?

Just trying to figure out how to determine which bulb (if any) in the 25" are bad so i can rule the bulbs out or not.
I would imagine that the 'strike voltage' of the 25" is larger than that required by anything smaller,However the 25" Inverter should Power a 19",20" CCFL.
As far as current is concerned,as all CCFL's are the main load on the inverter, then they will only take what current they require, so that should not be a problem.
You also may be correct in that the 'test jig' did not work, because the wiring was wrong between the Test CCFL' and the Hannspree, so that would be the next thing I would check.
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Old 01-12-2011, 05:11 PM   #16
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Quote:
Originally Posted by Rtech View Post
I would imagine that the 'strike voltage' of the 25" is larger than that required by anything smaller,However the 25" Inverter should Power a 19",20" CCFL.
As far as current is concerned,as all CCFL's are the main load on the inverter, then they will only take what current they require, so that should not be a problem.
You also may be correct in that the 'test jig' did not work, because the wiring was wrong between the Test CCFL' and the Hannspree, so that would be the next thing I would check.
A minor correction. A CCFL shows a negative resistance curve - the more current it draws, the lower it's resistance. The inverter puts out a constant current, adjusting the voltage to maintain the desired current. The overall effect is the test may not work if there is a mix of tubes of different lengths.

The inverter design assumes all CCFLS are identical. What CAN happen is the inverter raises the output voltage until the total current through all the CCFLs is correct. However, the shorter CCFL may be carrying too much current, and trip the Over Current Protection. If all CCFLS were the same length, even if shorter than the originals, that would not be a problem. I've noticed the current ratings of most CCFLs are the same, obviously the longer ones require a higher voltage.

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Old 01-13-2011, 01:46 AM   #17
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Thanks Plain Bill, must have had a 'blonde moment...with a slight touch of Grey now', constant current being the case.On a practical basis however, I have certaily used test CCFls, for example 19" on a 22" screen,with no problem,so in this case, perhaps as in a lot of things in life...size is important,and the 5" difference between his test screen and the Hannspree inverter is the reason for the testing failure.
At the moment I have not got a similar working inverter, to pop some 20" tubes on and see what happens knowing the inverter and lamps are both good...perhaps someone has ??
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Old 01-13-2011, 04:43 AM   #18
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

I am sure you guys answered this but not following all that your talking about. If i connect from the inverter of the 25" monitor to the lamp of the 20" monitor........do you think this will "destroy" the lamp of the 20" monitor?

Why do i want to do this?
First i am assuming the followingare these good assumptions?)
Note: Connecting the 25" inerter to the 20" bulb cant destroy 20" bulb.
Note: Connecting the 25" inverter to the 20" bulb must light the 20" bulb not causing the 25" monitor to shut down.

Since i know that connecting the 20" inverter to the 25" bulb does not seem to work maybe i can learn something going the other way. Connecting the 25" inverter to the 20" bulb. In my experience you usually have "one" bulb go out......not 2 or 3 or 4. Here is what i was thinking of doing.

25"-inverter-connection1 =====> 20"-bulb1
CHeck to see if 25" monitor stays on? Yes, then 25"-bulb1 is bad.
25"-inverter-connection2 =====> 20"-bulb1
CHeck to see if 25" monitor stays on? Yes, then 25"-bulb2 is bad.
25"-inverter-connection3 =====> 20"-bulb1
CHeck to see if 25" monitor stays on? Yes, then 25"-bulb3 is bad.
25"-inverter-connection4 =====> 20"-bulb1
CHeck to see if 25" monitor stays on? Yes, then 25"-bulb4 is bad.

If 25" monitor does not stay on for any of the tests above then May i assume that the bulbs in the 25" are ok? If not then this test might be pointless.


Of course if someone knows of a way to test the 25" bulbs let me know.

Also, if i assume the bulbs are ok.....cause it looks like a new monitor......what else should i be looking at to determine why this 25" monitor turns on for a few secs (showing a nice image) and then shuts off.

If i have not explained things well......let me know and i will try again.
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Old 01-13-2011, 06:30 AM   #19
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

Welches101, one problem I'm having is what you mean by 'doesn't work'.

You have an inverter for a 25" monitor that is exhibiting 'two seconds to black'. If you hook a CCFL from a 20" monitor to the inverter for the 25" monitor and the CCFLs come on and stay on, I'm sure we would both say it works. If NONE of the CCFLs come on, we would both say it doesn't work. If the 20" CCFL doesn't come on, we would say it doesn't work. If the 20" CCFL does come on, but you still have 'two seconds to black' is it working or not?

If you do hook up one 20" CCFL to the 25" inverter, all CCFLs should come on. It may still show 'two seconds to black' because of the mismatch in tube length.

If you (temporarily) replace ALL the 25" CCFLs with 20" CCFLs they should come on and work, and stay working.

None of these test scenarios should damage the 20" CCFL. As a general rule of thumb, I don't recommend tests that may result in death or destruction. Unless I'm in a REALLY bad mood.

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Old 01-13-2011, 07:16 AM   #20
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Default Re: Hannspree HSG1064 5 seconds on then blank screen

What i ment by "connecting the 20" inverter output to the 25" ccfl is that when i do this the 20" monitor shuts down after 2 seconds. The same thing happens to the 20" monitor when i just disconnect one of the ccfl tubes from the inverter and dont connect it to anything. So connecting one of the 20" inverter outputs (there are 4 since i have 4 bulbs) to one of the 25" ccfl tubes seems to be equivalent to just disconnecting one of the 20" ccfl bulbs.........thus i am not able to "test" the 25" ccfl bulbs.........this is what i ment by does not work..........

in the past i was able to use such a setup to "test" the bulbs of a monitor that did not work. If my test-monitor shut down after 2 secs then i knew that the bulb of the monitor-under-repair was bad. But in this case i am unable to test the bulbs of the 25" monitor.

So in a little while i will try and connect the 20" ccfl to the inverter output of the 25" monitor and see what happens. see if i learn anything useful or not.

Again, if we assume the bulbs of the 25" monitor are ok......what else should i look at to determine what is causing the 25" monitor to shut down. Just wondering if i can do a few things in parallel as far as trouble shooting.
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