Re: LCD 19" BENQ T905 problems
Hi to all,
changed transistor and with 7 dollar monitor work ok...
Thanks to all in this forum
Hi to all,
changed transistor and with 7 dollar monitor work ok...
Thanks to all in this forum
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Re: LCD 19" BENQ T905 problems
Wanted to stop in and post and say that this helped me in repairing my monitor. Thanks to all who contributed, and contribute to other threads like this.
cheersComment
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Re: LCD 19" BENQ T905 problems
Seems Im the only one who couldnt repair his TFT
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Re: LCD 19" BENQ T905 problems
Hello everyone, I too have a benq t905 which is not working. I opened it and I found a blown fuse so I thought the problem was easily solvable. However replacing the fuse was a no go. Lamps don't light up, I can see the faint "benq" logo when I turn on the monitor. I'm going to check capacitors tomorrow. Any advice would be useful, thanks.Comment
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Re: LCD 19" BENQ T905 problems
(Sigh) Standard problem. The solder joints on the transformer pins crack. This results in one of the transistors staying on; it shorts, and blows the fuse.
Replace the fuse without replacing the shorted transistors and it will blow again. Replace the transistors without resoldering the pins on the 4 inverter transformers and a transistor will short again.
This inverter design is a Royer oscillator, it is used by Benq who supplies monitors to both Dell and HP. It MIGHT not have been discussed in this thread, now it is.
However you are correct about one thing. This is an excellent opportunity to recap.
And to repeat what retiredcaps said, don't post pictures inline. Use Manage Attachments below the test entry area.
PlainBillLast edited by PlainBill; 05-03-2011, 06:34 PM.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.Comment
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Re: LCD 19" BENQ T905 problems
I don't see any crack in the solder joints, the fuse I replaced didn't blow again. I did not replace the pf801 . Btw what are the specs for this PF?Comment
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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.Comment
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Re: LCD 19" BENQ T905 problems
update. I found two "2sc5707" are faulty and also the "1200AP40 CPBY 05475".
I tried to test the lamps and i get no value, is this normal?Last edited by chriz74; 05-04-2011, 09:26 AM.Comment
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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.Comment
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Re: LCD 19" BENQ T905 problems
It was really a relative of mine so I don't know what kind of tester he used. I'll ask. What about the 1200AP40 BLOWN, how does that sound to you? Is this normal fault? As a result there was no power being spread to the lamp connectors.Comment
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Re: LCD 19" BENQ T905 problems
Because it doesnt read 12v but 300vComment
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Re: LCD 19" BENQ T905 problems
The lamps are likely not a problem.
Can't speak for the 1200AP40, as you didn't really tell us what you measured, and how you determined.
As many have tried to tell you, this monitor has a very common failure mode.
Bad solder joints on the inverter transformers cause transistors to short, and blow pico fuses. Check ALL the 5707s, and the FETs, replace any bad ones, replace the fuse, while you're in there, recap, and then fire it up.
Of the 22 or so monitors I've repaired in the last year or so (and I'm still a newbie learning) several were this model or similar, and had this common failure.36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....Comment
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Re: LCD 19" BENQ T905 problems
The only part corresponding to 1200AP40 is a SMPS controller. If you can still see the Benq logo as you mentioned in post 7 the 1200AP40 is good.
Really, this is a waste of time in my opinion. It's difficult enough assisting in troubleshooting a monitor if the person doing the real work is interacting with us. If there is an intermediate party (you), communication becomes impossible.
1. Check for 5V and 12V from the power supply. If they are present:
2. Remove as much solder as possible from the transformer pins and resolder with real solder, not this lead free junk Benq inflicted on everyone.
3. Replace both 2SC5707s in a pair if either are shorted
4. Check both FU9024N, replace any that are associated with a shorted 2sc5707
5. Replace the picofuse if it is open.
PlainBillFor 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.Comment
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Re: LCD 19" BENQ T905 problems
Thanks for the advices, I'll tell what turns out. BTW I can't see the BENQ logo anymore so I suppose the 1200AP40 is really gone. Oh I got the schematics from BENQ, I think it could be useful for future reference.
Attached FilesLast edited by chriz74; 05-05-2011, 02:08 AM.Comment
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Hi all, I am looking for some help in ID'ing some parts in an attempt to fix a power supply from a GW2780-T monitor. The power supply PN is 715G7300-P02-006-0V3R. I have been looking around for the PN and it appear the board was used by other OEMs as well (ASUS, Viewsonic). If anyone has a schematic, it would be helpful.
Quick look on the underside of the board, I can see:
-D905 is blown - ? value
-R920 is open - 1Ω ?W
-R927 is open - 20Ω ?W
On top side, I see:
-R931 open - 0.68Ω ?W
Metered short:
-P9NK65ZFP... -
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i verified the driver of the péripherals and they are ok. i verified the definition and settings of the graphic card and of the screen : definition 1600x900 and refreshment frequency :60hz. (they are the sames for the graphic card and the screen).
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And a third battery TF03XL (looks identical) with error: Logic State: OK (0), Charge state: Blown Fuse (42)
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