Fix for Benq FP737s 17" (Q7T3)

[PlainBill]

Re: Fix for Benq FP737s 17" (Q7T3)

Question: I am about to resolder (touch up) the transformers, re-transistorize and re-MOSFET, and replace the fuse on my Q7T3's board. I'm going to skirt around doing the mod for improper circuit design. Am I courting disaster if I don't mod?

I wouldn't think so. The basic design was adequate. The real cause of the transistor failures was bad solder joints on the transformers. I'm not sure if the improved design would be robust enough to survive that kind of problem. Assuming it is, it would still be necessary to open up the monitor and resolder the transformers. Use of better solder when you perform the initial repair should prevent a repeat of that.

Now if you were talking about building 10,000 new monitors, I would certainly recommend going with the better design.

PlainBill

[kturnerga]

Re: Fix for Benq FP737s 17" (Q7T3)

Question: I am about to resolder (touch up) the transformers, re-transistorize and re-MOSFET, and replace the fuse on my Q7T3's board. I'm going to skirt around doing the mod for improper circuit design. Am I courting disaster if I don't mod?

[PlainBill]

Re: Fix for Benq FP737s 17" (Q7T3)

white

white
white

yes
yes orange, white

mecklan

Excellent!!! there are two possibilities.

1. Either one (or both) of the FU9024Ns are shorted. In this case, the screen may be unusually bright, and changing the brightness from the menu would have no effect.
2. The Backlight On line from the logic card to the power supply / inverter (PS/I) is not functioning, either because of a solder short, or a bad transistor. With the PS/I lying green side up, the AC power connector to the right, the cable to the logic card should be on the bottom near the left side. The two thin traces going to the left are the brightness and On/Off lines.

The easy way to troubleshoot this is to check the FU9024Ns first with power off, then if they are not shorted, trace the On/Off signal line using a DMM and watching it change level when the power button is pressed.

PlainBill

[mecklan]

Re: Fix for Benq FP737s 17" (Q7T3)

The problem is you aren't giving explicit information. I'm tired of playing guessing games with incomplete information. Walk through this scenario.

Unplug the monitor's power cord. Hook the VGA cable up to a computer that has been turned off. Plug in the monitor, leave the computer off.

Push the monitor power button until the power LED turns off. Screen white or dark?

white

Push the power button on the monitor until it turns on. Screen white or dark?

white

Wait until the power LED on the monitor goes orange. Screen white or dark?

white

Turn on the computer. Does the monitor come out of standby and display the usual POST information and eventually the desktop?

yes

Shut down the computer. Does the monitor power LED go orange? Is the monitor screen white or dark?

PlainBill

yes orange, white


mecklan

[PlainBill]

Re: Fix for Benq FP737s 17" (Q7T3)

I have replaced the transistors in pairs, the mosfet and fuse. If I turn on the Montor now I get a white screen. I turn on the PC, I have a very normal Windows screen. I turn off the monitor again, the screen is white for a sec.
Do they have a solution for white screen?

Mecklan

The problem is you aren't giving explicit information. I'm tired of playing guessing games with incomplete information. Walk through this scenario.

Unplug the monitor's power cord. Hook the VGA cable up to a computer that has been turned off. Plug in the monitor, leave the computer off.

Push the monitor power button until the power LED turns off. Screen white or dark?

Push the power button on the monitor until it turns on. Screen white or dark?

Wait until the power LED on the monitor goes orange. Screen white or dark?

Turn on the computer. Does the monitor come out of standby and display the usual POST information and eventually the desktop?

Shut down the computer. Does the monitor power LED go orange? Is the monitor screen white or dark?

PlainBill

[mecklan]

Re: Fix for Benq FP737s 17" (Q7T3)

It's teh same problem as found on any number of these monitors. Starting at the beginning of the thread may have given you this information. In your case,check the 2SC5707's. If any are shorted, replace the lot; likewise for the FU9024. Because you are getting the flash, the fuse is good. Also, resolder the transformers; that was the original cause.

NOW it may be that the transistors are fine. Then check the output voltage of the power supply; if good, see if the monitor comes on when you push the power button.

Oh, pictures help. See the FAQ on inserting pictures.

PlainBill

I have replaced the transistors in pairs, the mosfet and fuse. If I turn on the Montor now I get a white screen. I turn on the PC, I have a very normal Windows screen. I turn off the monitor again, the screen is white for a sec.
Do they have a solution for white screen?

Mecklan

[sam67]

Re: Fix for Benq FP737s 17" (Q7T3)

I know how you feel i ended up ordering some op amps from usa as over here they wanted to charge me 12 quid for £1.45 parts ,needless to say i got them from the states 3 of then inc shipping 5 bucks ..you cannot argue at that now i have 2 spare if i ever blow the other speakers lol.

[Radio Fox]

Re: Fix for Benq FP737s 17" (Q7T3)

...I have just given Farnell a ring. Guess what? "If paying by debit card/credit card... online there is a minimum order of 20.00 Pounds Sterling...

I normally order from RS, but there was a few things on my list that were not in stock, so tonight, for the first time, I wasted an hour or so compiling my first order with Farnell. It wasn't until I tried to order (after going through all the registration process), that I was told that my order needed to be over £20 before VAT (= £23.50).

Also, I couldn't find anywhere on their website that told you the p&p charges.

I didn't go through with the order.

[imalearner]

Re: Fix for Benq FP737s 17" (Q7T3)

This may help
http://cgi.ebay.co.uk/Lot-4x-C5707-2...item43979fcc08
I have never had a problem buying these from ebay dealers

OH Bollacks! I got sick of searching on ebay uk and all I kept coming up with is the exact same thing wtih free international satandard shipping from good ol USA....so now they are ordered.

Mmmmmmmmmmmmmmmmmmm, me thinks I should find practice my soldering or summat!

Cheers!
Imalearner

[Bobdee]

Re: Fix for Benq FP737s 17" (Q7T3)

Thanks Pedro for that.

I have just given Farnell a ring. Guess what? "If paying by debit card/credit card... online there is a minimum order of 20.00 Pounds Sterling.....if over the telephone it goes up........30.00 Pounds Sterling."

I said, thank you very much I'll think about it!!!

fffffffffffffffffffffffffffffff**************or goodness sake! I'm 'orf hunting for somewhere else a liitle more customer friendly.

Thanks again though.

imalearner

This may help
http://cgi.ebay.co.uk/Lot-4x-C5707-2...item43979fcc08
I have never had a problem buying these from ebay dealers

[pedro]

Re: Fix for Benq FP737s 17" (Q7T3)

Thanks Pedro for that.

I have just given Farnell a ring. Guess what? "If paying by debit card/credit card... online there is a minimum order of 20.00 Pounds Sterling.....if over the telephone it goes up........30.00 Pounds Sterling."

I said, thank you very much I'll think about it!!!

fffffffffffffffffffffffffffffff**************or goodness sake! I'm 'orf hunting for somewhere else a liitle more customer friendly.

Thanks again though.

imalearner

Shite that's obscene. Down here in Oz, Farnell's minimum for on-line CC purchase is $A10 - about six pommy quid - AND we get free shipping. Ironically I currently have some Pana FM's ordered from them en route from UK. And I had to pad the order with other stuff to make the $10.

[imalearner]

Re: Fix for Benq FP737s 17" (Q7T3)

Yep, they are fine. Farnell may not be the cheapest source, but the semis they supply are invariably from a decent manufacturer.

Thanks Pedro for that.

I have just given Farnell a ring. Guess what? "If paying by debit card/credit card... online there is a minimum order of 20.00 Pounds Sterling.....if over the telephone it goes up........30.00 Pounds Sterling."

I said, thank you very much I'll think about it!!!

fffffffffffffffffffffffffffffff**************or goodness sake! I'm 'orf hunting for somewhere else a liitle more customer friendly.

Thanks again though.

imalearner

[pedro]

Re: Fix for Benq FP737s 17" (Q7T3)

AHaaaa! Thanks for that Bobdee......I see it's coming from the states. So, my next question is (being a novice at this...) do you know if the following products, I have found based from the uk, are also suitable/safe to do the same job?

http://uk.farnell.com/international-...01?Ntt=FU9024N

http://uk.farnell.com/sanyo/2sc5707/...251/dp/1554597

Thanks for help.

Yep, they are fine. Farnell may not be the cheapest source, but the semis they supply are invariably from a decent manufacturer.

[imalearner]

Re: Fix for Benq FP737s 17" (Q7T3)

This will do it
http://cgi.ebay.com/LOT-2-FU9024N-IR...-/320492401104

AHaaaa! Thanks for that Bobdee......I see it's coming from the states. So, my next question is (being a novice at this...) do you know if the following products, I have found based from the uk, are also suitable/safe to do the same job?

http://uk.farnell.com/international-...01?Ntt=FU9024N

http://uk.farnell.com/sanyo/2sc5707/...251/dp/1554597

Thanks for help.

[Bobdee]

Re: Fix for Benq FP737s 17" (Q7T3)

Back again!

Okay, so off came the four C5707 (faulty enough for me!) and then the two unidentified others, but I am not sure how to read the markings/codes on them....any offers out there please, or suggestions about what I could use instead. Thanks.

I have used a few shots for different light to 'catch' the markings better...some might find these a useful help....these were taken about 4-6mm away from the transistors. At one point I think I fainted to stopped movement whilst breathing

imalearner.

This will do it
http://cgi.ebay.com/LOT-2-FU9024N-IR...-/320492401104

[imalearner]

Re: Fix for Benq FP737s 17" (Q7T3)

Thanks PlainBill. PLaytime starts agin early next week so I'll give it a shot.....I have noticed that the odd two transistors are not bearing the same id/specs so I may be hunting for their identity too! Will get back and thanks again.

imalearner

Back again!

Okay, so off came the four C5707 (faulty enough for me!) and then the two unidentified others, but I am not sure how to read the markings/codes on them....any offers out there please, or suggestions about what I could use instead. Thanks.

I have used a few shots for different light to 'catch' the markings better...some might find these a useful help....these were taken about 4-6mm away from the transistors. At one point I think I fainted to stopped movement whilst breathing

imalearner.

[imalearner]

Re: Fix for Benq FP737s 17" (Q7T3)

These transistors and the fuse can be tested on board. Set the meter to the lowest ohms scale (typically 200 ohms). The transistors have three pins in a row; starting at the left number them 1-3. Check the resistance between 1 and 2; 1 and 3, and 2 and 3. All readings should be > 1K Measure the resistance of the fuse; it should be less than 1 ohm.

PlainBill

Thanks PlainBill. PLaytime starts agin early next week so I'll give it a shot.....I have noticed that the odd two transistors are not bearing the same id/specs so I may be hunting for their identity too! Will get back and thanks again.

imalearner

[PlainBill]

Re: Fix for Benq FP737s 17" (Q7T3)

Hey hey! Thanks on that PlainBill. You'd be amazed at what I can achieve with your patients

Now with your continued kindness (creep creep) I wonder if you can help a little further???

Should (can) I test any/and all of these components on/off the board, and furthermore, with my digital meter in hand, what test(s) should I be puttting them thru/to?

Imalearner by name....and by nature....

Thanks again in advance.

Imalearner.

These transistors and the fuse can be tested on board. Set the meter to the lowest ohms scale (typically 200 ohms). The transistors have three pins in a row; starting at the left number them 1-3. Check the resistance between 1 and 2; 1 and 3, and 2 and 3. All readings should be > 1K Measure the resistance of the fuse; it should be less than 1 ohm.

PlainBill

[imalearner]

Re: Fix for Benq FP737s 17" (Q7T3)

Great picture. the only flaw is the board is rotated slightly counterclockwise. I'll give it a 9.6.

PlainBill

Hey hey! Thanks on that PlainBill. You'd be amazed at what I can achieve with your patients

Now with your continued kindness (creep creep) I wonder if you can help a little further???

Should (can) I test any/and all of these components on/off the board, and furthermore, with my digital meter in hand, what test(s) should I be puttting them thru/to?

Imalearner by name....and by nature....

Thanks again in advance.

Imalearner.

[PlainBill]

Re: Fix for Benq FP737s 17" (Q7T3)

Thanks PlainBIll for getting back. I'll be testing away as soon as I get back to my workshop/shed. Thinking that the upload failed last time because the images were too big....I just resized them. It may also have been just a poor wirelesss signal from my shed too! So, I'm putting this one back up just to see if that is more helpful....for future enquiries perhaps. This is max size for my camera. Hopefully part identifiers should be more legible. Fingers crossed.

Cheers,

Imalearner

Great picture. the only flaw is the board is rotated slightly counterclockwise. I'll give it a 9.6.

PlainBill