Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting Computer Displays
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 09-01-2018, 10:54 AM   #21
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

Oh, that's a nice spreadsheet - thanks for the pointer. It indicates the tcon board is bad, but to check the panel first before replacing the tcon board. I'll search around the forum for how to do that.
Attached Images
File Type: jpg tcon-spreadsheet.jpg (345.7 KB, 9 views)
rrflorida is offline   Reply With Quote
Old 09-02-2018, 11:56 AM   #22
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

Well, I'm not sure how to test the panel itself - I jiggled all the ribbon cables to the driver boards with no effect. Looks like there is no availability for this tcon board, so I'll need to attempt to diagnose and repair the one I have. The u102 transistor (circled in red) measures 7.3k Ohms middle to right leg, and 100 Ohms middle to left leg.
Attached Images
File Type: jpg hanns-tcon-u102.jpg (1.47 MB, 10 views)
rrflorida is offline   Reply With Quote
Old 09-04-2018, 02:54 PM   #23
momaka
Badcaps Veteran
 
momaka's Avatar
 
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 8,442
Default Re: HANNS G HZ281 White Screen

Quote:
Originally Posted by rrflorida View Post
The u102 transistor (circled in red) measures 7.3k Ohms middle to right leg, and 100 Ohms middle to left leg.
Good find.
But left leg is the input, so 100 Ohms is not necessarily a problem.
That said, see what voltage is coming to the left leg of U102 (with respect to ground) and what voltage it is outputting on its right leg (again, with respect to ground).

Also, could you please tell us what part number is written on U102?
momaka is offline   Reply With Quote
Old 09-04-2018, 04:11 PM   #24
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,046
Default Re: HANNS G HZ281 White Screen

That is Voltage regulator IC, not transistor. See what Voltage you have on Vin and Vout pin.
I suspect the GAMMA Voltages are generated by U300, 301, get the P/N on both of them.
BTW, designator for Transistor is 'Q??', IC is U??







.
__________________
Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/

TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809

Last edited by budm; 09-04-2018 at 04:16 PM..
budm is offline   Reply With Quote
Old 09-09-2018, 07:55 PM   #25
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

momaka and budm - thanks for the responses, really appreciate the help! I will gather the requested info Monday. Sorry for the delayed reply, was out of town.

randy
rrflorida is offline   Reply With Quote
Old 09-11-2018, 08:05 AM   #26
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

U102 is a 960T45. Left leg is 4.96V, right leg is 3.24V
U300 and U301 are both BUF 07704, which Mouser says is a LCD Gamma Buffer.
rrflorida is offline   Reply With Quote
Old 09-11-2018, 10:39 AM   #27
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,046
Default Re: HANNS G HZ281 White Screen

Quote:
Originally Posted by rrflorida View Post
U102 is a 960T45. Left leg is 4.96V, right leg is 3.24V
U300 and U301 are both BUF 07704, which Mouser says is a LCD Gamma Buffer.
960T45 is 3.3V regulator, it is OK. http://www.gmt.com.tw/product/datasheet/EDS-960.pdf
GAMMA chips may be bad, need to look up spec sheet.
budm is offline   Reply With Quote
Old 09-11-2018, 04:31 PM   #28
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

Data sheet for BUF 07704 attached
Attached Files
File Type: pdf buf07704.pdf (1.32 MB, 3 views)
rrflorida is offline   Reply With Quote
Old 09-11-2018, 06:08 PM   #29
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,046
Default Re: HANNS G HZ281 White Screen

So now you have the spec sheet of the IC showing what each pin is for, start checking the Voltages and report the reading for each pin, that will be a starting point.
budm is offline   Reply With Quote
Old 09-12-2018, 02:04 PM   #30
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

Below and attached (the formatting is messed up here in the post) are the voltage readings from the BUF07704 chips. The OUT side seems to correlate pretty well with the IN side.



Pin U301 U302 Name
1 13.13 0 VDD
2 12.46 6.55 OUT1
3 10 5.31 OUT2
4 9.29 4.34 OUT3
5 8.9 3.78 OUT4
6 8.11 3.07 OUT5
7 6.76 0.64 OUT6
8 0.12 0 NC
9 5.47 7.21 OUTCOM
10 0 0 GND
11 0 0 GND
12 5.45 0.63 INCOM
13 0.76 0.65 NC
14 6.75 0.64 IN6
15 8.11 3.07 IN5
16 8.89 3.78 IN4
17 9.29 4.34 IN3
18 9.99 5.31 IN2
19 12.45 6.56 IN1
20 13.13 13.14 VDD

Attached Images
File Type: jpg GammaBuffers.jpg (77.3 KB, 6 views)

Last edited by rrflorida; 09-12-2018 at 02:11 PM..
rrflorida is offline   Reply With Quote
Old 09-13-2018, 11:26 AM   #31
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,046
Default Re: HANNS G HZ281 White Screen

https://www.badcaps.net/forum/attach...3&d=1536778904
Look at INCOM and OUTCOM of U302: U301 INCOM is 5.45V, OUTCOM is 5.47CV, but U302 INCOM is 0.63V and the OUTCOM is 7.21V
Look at pin 1 of U301 and 302: 0V on U302?

Last edited by budm; 09-13-2018 at 11:31 AM..
budm is offline   Reply With Quote
Old 09-13-2018, 01:05 PM   #32
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

Oh, I messed up pin 1 on U302 (VDD) - it's actually 13.13V, so ok there.

I see what you are saying on INCOM/OUTCOM on U302. I just double checked:
12 INCOM: .64 steady
9 OUTCOM: climbs from 1-3 volts up to 6-7 volts everytime I probe it (climbs for about 30 seconds)

Are you suspecting U302?

[NOTE: I somehow started using the wrong U numbers, but will stick with the current U301/U302 for consistency]
rrflorida is offline   Reply With Quote
Old 09-13-2018, 01:51 PM   #33
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,046
Default Re: HANNS G HZ281 White Screen

Yes, I expect U302 to behave the same as U301, it is buffer after all.
budm is offline   Reply With Quote
Old 09-14-2018, 08:12 AM   #34
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

Ok, I will attempt to replace the chip and report back. Thanks.
rrflorida is offline   Reply With Quote
Old 10-04-2018, 02:25 PM   #35
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

fyi - having trouble finding the part - Mouser just cancelled the order and said it is discontinued. More later..
rrflorida is offline   Reply With Quote
Old 10-05-2018, 06:07 PM   #36
momaka
Badcaps Veteran
 
momaka's Avatar
 
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 8,442
Default Re: HANNS G HZ281 White Screen

Maybe check with eBay. Sure there's a chance the part you get may not be genuine or high quality, but it could work fine. I've bought PWM controllers for motherboards before, and they worked okay. It's really only the high-power devices (MOSFETs, BJTs, and those STK stereo modules) that you want to either stay away from or use with lots of caution.
That, and the slow wait for the part to arrive from the far factories and shops of East Asia.

Last edited by momaka; 10-05-2018 at 06:08 PM..
momaka is offline   Reply With Quote
Old 10-08-2018, 04:36 AM   #37
Capt. Cap
Member
 
Join Date: Oct 2017
City & State: SF, CA
My Country: US of A
I'm a: Knowledge Seeker
Posts: 36
Default Re: HANNS G HZ281 White Screen

Doesn't look like any reliable retailers have it available in small order quantities https://octopart.com/search?q=buf07704&start=0

but you can get a single BUF07704 chip here
Probably not the real thing, but like momaka says, it may work well enough.

Let us know how it goes, I could be in the market for one myself soon
Capt. Cap is offline   Reply With Quote
Old 10-08-2018, 09:11 AM   #38
rrflorida
New Member
 
Join Date: Aug 2018
City & State: Tampa, Florida
My Country: USA
I'm a: Knowledge Seeker
Posts: 12
Default Re: HANNS G HZ281 White Screen

I ended up using eBay seller dicikey-max. We'll know more in 12-50 days.... Thanks for the suggestions

https://www.ebay.ie/itm/332274532555...m=332274532555
rrflorida is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2018
Powered by vBulletin ®
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 09:11 PM.

Did you find this forum helpful?