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 04-08-2010, 08:21 AM   #21
frankNstein
Member
 
Join Date: Feb 2010
Posts: 35
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

This should be a PNP Pre-Biased transistor. Terminal one should be the base, terminal two should be collector and terminal three should be the emitter. There should be two 10K internal resistors used to bias the transistor and it probably will be open.
frankNstein is offline   Reply With Quote
Old 04-08-2010, 08:53 AM   #22
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Label the leads - lower left '1', top center '2', lower right '3' (see enclosed pic for how i labeled leads).

Measure resistance(Red lead/Blacklead)
Red-Black: Black-Red:
1-2: open 3Megohm
1-3: 21.9Kohm 21.9kohm
2-3 : 3Megohm 30Megohm



Diode-test: Black lead goes to the first terminal, red lead to the second.
1 2:2.1V (no beep)
1 3:2.1V (no beep)
2 3:infinite (no beep)
2 1:infinite (no beep)
3 1:2.4V (no beep)
3 2:1.1V (no beep)

Also, frankNstein could you post a link to a data sheet? Or list a part number so that i could look up a data sheet.

Thanks.
Attached Images
File Type: jpg 14_pic.jpg (5.4 KB, 17 views)
Welchs101 is offline   Reply With Quote
Old 04-08-2010, 09:52 AM   #23
frankNstein
Member
 
Join Date: Feb 2010
Posts: 35
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

I think you have an older board than I do but it looks like yours is using a DTA114GUA transistor. Also check diode ZD200 for shorts. This board is using Q200,Q202 and Q207 to supply power to pin 10 1nd 6 of U200. I haven't ordered parts for my board yet but I think that replacing Q200 will get things running unless U200 is bad. Good luck and let me know how things are going.
frankNstein is offline   Reply With Quote
Old 04-08-2010, 12:25 PM   #24
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

what is the revision number of your board? Just curious.

Also, what measurments do you have for your Q200? How do you know its bad?
Welchs101 is offline   Reply With Quote
Old 04-08-2010, 12:27 PM   #25
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Bill,

How long should i leave the light bulb "on" to try and find the short? Any suggestion? Is 1min too long?
Welchs101 is offline   Reply With Quote
Old 04-08-2010, 12:36 PM   #26
PlainBill
Badcaps Veteran
 
PlainBill's Avatar
 
Join Date: Feb 2009
City & State: Phoenix, AZ
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 7,013
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Quote:
Originally Posted by Welchs101
Bill,

How long should i leave the light bulb "on" to try and find the short? Any suggestion? Is 1min too long?
You should be safe for several minutes. Note the information from frankNstein. It would be a good idea to check the additional components he indicates may be bad. Obviously, he has much more experience with this board than I do.

PlainBill
__________________
For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.
PlainBill is offline   Reply With Quote
Old 04-08-2010, 02:25 PM   #27
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

No problem.

ZD200: Ok, diode voltage is ~ 0.7V


Below are measurements for Q200:
Label the leads - lower left '1', top center '2', lower right '3'

Measure resistance:
Red-Black: Black-Red:
1-2: 0.4Megohm 0.4Megohm
1-3: 150Kohm 150kohm
2-3 : 174kohm 290kohm

Diode-test: Black lead goes to the first terminal, red lead to the second.
1 2: infinite (no beep)
1 3: infinite (no beep)
2 3: 0.57V (beep yes)
2 1: infinite (no beep)
3 1: infinite (no beep)
3 2: infinite (no beep)
Welchs101 is offline   Reply With Quote
Old 04-08-2010, 05:11 PM   #28
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Below are measurements for Q207:
Label the leads - lower left '1', top center '2', lower right '3'

Measure resistance:
------------Red-Black: -------------Black-Red:
1-2: --------3Megohm---------------26Megohm
1-3: -------5.8Megohm ------------6.1Megohm
2-3 : ------5.9Megohm -----------(-2.4Megohm)

Diode-test: Black lead goes to the first terminal, red lead to the second.
1 2: 2.3797V(no beep)
1 3: infinite (no beep)
2 3: infinite (no beep)
2 1: 0.61V (yes beep)
3 1: 0.63V (yes beep)
3 2: 2.2V (no beep)
Welchs101 is offline   Reply With Quote
Old 04-08-2010, 05:52 PM   #29
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Do any of those i measured look bad?

I think Q200 and Q202 looked bad.......is this right? Do you think they are bad enough to cause the fuse to keep blowing?

What about Q207.........is this one ok?
Welchs101 is offline   Reply With Quote
Old 04-08-2010, 06:38 PM   #30
frankNstein
Member
 
Join Date: Feb 2010
Posts: 35
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Q200 is a fet and is probably good. Q202 is probably bad. If Q207 shorted the backlight would run all the time. Q207 is a NPN transistor #MMBT4401LT1.Hope this helps. If I can do anything to help you let me know.
frankNstein is offline   Reply With Quote
Old 04-08-2010, 07:33 PM   #31
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Thanks!

Do you know a similar part number for the Q200 device?

Do you think replacing Q202 would fix my fuse shorting issue?

Thanks again for your help.
Welchs101 is offline   Reply With Quote
Old 04-08-2010, 07:50 PM   #32
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

hi,

frankNstein you mentioned that for part Q202 i should replace this with the following: DTA114GUA

This only has a single resistor of 10Kohms.

Using your initial suggestion i was able to find this part on digikey

http://mouser.com/search/ProductDeta...hH8Lz1DA%3d%3d

would this be a suitable replacement for the Q202 transistor?
Welchs101 is offline   Reply With Quote
Old 04-08-2010, 07:55 PM   #33
frankNstein
Member
 
Join Date: Feb 2010
Posts: 35
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

I haven't found a replacement for Q200 yet but chances are that it is good. I am not sure but I think that replacing Q202 and the fuse will fix the board. There is no direct short on the 15 volt line. I think the reason the fuse is going bad has something to do with Q202 being bad or U22 could be bad. I am going to replace Q202 and the fuse on my board and go from there. The inverter can never work when Q202 is open. If you would like to see if it works, I am going to order my parts sometime next weak and I will be glad to let you know if it works.
frankNstein is offline   Reply With Quote
Old 04-08-2010, 08:45 PM   #34
frankNstein
Member
 
Join Date: Feb 2010
Posts: 35
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

I just ordered the parts for my board.
frankNstein is offline   Reply With Quote
Old 04-08-2010, 09:39 PM   #35
PlainBill
Badcaps Veteran
 
PlainBill's Avatar
 
Join Date: Feb 2009
City & State: Phoenix, AZ
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 7,013
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Quote:
Originally Posted by Welchs101
Do any of those i measured look bad?

I think Q200 and Q202 looked bad.......is this right? Do you think they are bad enough to cause the fuse to keep blowing?

What about Q207.........is this one ok?
The first two transistors are definitely bad, the third tests good. As far as being responsible for blowing the fuse, I don't know how the circuit is designed. If they could cause both drivers to be on at the same time, yes, that would certainly do it.

PlainBill
PlainBill is offline   Reply With Quote
Old 04-09-2010, 07:03 AM   #36
frankNstein
Member
 
Join Date: Feb 2010
Posts: 35
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Q200 is a FET so I think it is good. The way the circuit is designed, if it shorts all it will do is make the inverter run all the time and if it is open the inverter will not turn on at all. You can measure the resistance from the 15 volt supply to ground to check for a short but I think it has something to do with Q202 being open.
frankNstein is offline   Reply With Quote
Old 04-09-2010, 11:19 AM   #37
PlainBill
Badcaps Veteran
 
PlainBill's Avatar
 
Join Date: Feb 2009
City & State: Phoenix, AZ
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist
Posts: 7,013
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

Quote:
Originally Posted by frankNstein
Q200 is a FET so I think it is good. The way the circuit is designed, if it shorts all it will do is make the inverter run all the time and if it is open the inverter will not turn on at all. You can measure the resistance from the 15 volt supply to ground to check for a short but I think it has something to do with Q202 being open.
That sounds correct if Q200 is a FET. I was thinking it was a bipolar transistor.

PlainBill
PlainBill is offline   Reply With Quote
Old 04-09-2010, 01:57 PM   #38
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

frankNstein

Yes, let me know once you put the part in how things go.

What parts did you order exactly?


I know you said you did not find a replacement for part Q200......i did a little digging and found this ....see enclosure.......do you think this would be a good replacement for Q200 if it needs replacing...see enclosed pdf file.
Attached Files
File Type: pdf K72_ds11303.pdf (99.4 KB, 37 views)
Welchs101 is offline   Reply With Quote
Old 04-09-2010, 03:19 PM   #39
frankNstein
Member
 
Join Date: Feb 2010
Posts: 35
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

As for Q200, No I do not think it has the diode across the Drain and Source so I don't think it will work, I think it is just for protection but I don't think it will work. I think you will find that it is good anyway. Please let me know the revision number of your board because it must be different than mine. Q202 on my board is a DDTA114 but on your board looks like a K14 or DTA114GUA which has only one resistor. This must have been part of the revision. I think I saw that Mosuser had it listed but on backorder. You should be able to google the part and get the data sheet but I can send it to you if you like. I am on the Linux computer now but I will see if I can scan it in and send it to you. Good luck.
frankNstein is offline   Reply With Quote
Old 04-09-2010, 05:03 PM   #40
Welchs101
Badcaps Veteran
 
Join Date: Sep 2008
City & State: Cary, NC
My Country: USA
Line Voltage: 120V 60Hz
Posts: 757
Default Re: ACER AL2017.....not working...Led comes on....with-flashlight can see image

The board revision for this ACER AL2017 is

DAC-19M005 CF
REV: 00A

I have also enclosed a pic of the top and bottom.

Can you also submit a pic of your board for comparison.

Sorry the K72 part was not applicable.

Also, why do you think my Q202 has only the single resistor? The reason i ask is that if you look at the resistance measurements i measured ~ 21Kohm between what i was calling pin1 and pin3. Because i measured ~20Kohm i was thinking i had the "two" resistors not just the one.

Also, the Q202 marking is "14".....its hard to see from the pic but if you want i can take a better one if it would help.

I wanted to ask your opinion on another device...... labeled Q204.......do you know what this device is?

Thanks again.
Attached Images
File Type: jpg Front.JPG (408.1 KB, 43 views)
File Type: jpg Back.JPG (434.3 KB, 34 views)
File Type: jpg mag_of_a_few_devices.jpg (109.7 KB, 48 views)
Welchs101 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 - 2019
Powered by vBulletin ®
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 08:28 PM.
Did you find this forum helpful?