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**Bobdee** · 05-10-2009, 05:52 PM

Re: Benq FP767 PS caps

Originally posted by maverick530

...so should I go ahead and replace the C5707 transistors and the pico fuse and see what happens? Or is there anything else I need to test before making my initial attempt at fixing this board?

It is advisable to resolder the 4 inverter transformers on these Benq boards as they are suspected of being the reason for the transistors demise, some members havent bothered only to find that the monitor works for sometime then a new transistor goes down again taking fuse as well, if you look at the transformers s/joints with 8 to 10 x magnifying glass you will see ring cracks in solder in most cases
Also some members have had inverter fets go down, I have never had this happen personally, it might pay to check both of yours for shorts before putting your order in as this monitor has been down long enough
Good Luck

**PCBONEZ** · 05-10-2009, 06:02 PM

Re: Benq FP767 PS caps

I agree with Bobdee.
I haven't had to deal with one of those Benq boards but the need to resolder those transformer joints comes up SO often here in the forum when Benq comes up that it should be a standard precautionary measure on the Benq boards.

**Wizard** · 05-10-2009, 07:00 PM

Re: Benq FP767 PS caps

Unfortunely, I had a one go down hard, took out a PITxxxx IC even the fet driver that IC is driving all 4 transformers are good and all I did was replace all 8 2SC965 and resolder all transformers. Still no pulses, checked everything, the IC is damaged.

Generic 19" made for Westinghouse.

Cheers, Wizard

**maverick530** · 05-27-2009, 09:14 AM

Re: Benq FP767 PS caps

I finally replaced a pair of C5707s, the 5A pico fuse, and resoldered all transformer solder joints, and now the board powers up and displays an image!

However, now the backlights stay on-- always. They're on immediately when you turn on the monitor (before you even hit the front power button), and stay on, even when the monitor goes into power saving mode (and the front LED turns from green to amber).

What would cause the back lighting to remain on and how can this be fixed?

**Bobdee** · 05-27-2009, 10:19 AM

Re: Benq FP767 PS caps

Originally posted by maverick530

What would cause the back lighting to remain on and how can this be fixed?

Probably one of the FU9024Ns, they are known problem when the B/Light stays on, or bad solder joints to them possibily

bob
Well done BTW

**EGuevarae** · 05-27-2009, 12:24 PM

Re: Benq FP767 PS caps

Originally posted by Bobdee

Probably one of the FU9024Ns, they are known problem when the B/Light stays on, or bad solder joints to them possibily

bob
Well done BTW

I agree with Bob. Check those FUs.

**maverick530** · 05-28-2009, 09:42 AM

Re: Benq FP767 PS caps

I'm not familiar with FU9024N. I don't see any on my board.

I found 2 x J598s near the inverter side of the board, as circled. Do these perform the same function as the FU9024Ns?

If not, can someone please show me where they'd be located?

Also, if so, does anyone know how to test them? The PCB labels the leads as "G D S" on these J598s.

Attached Files

**Bobdee** · 05-28-2009, 09:56 AM

Re: Benq FP767 PS caps

Originally posted by maverick530

I'm not familiar with FU9024N. I don't see any on my board.

I found 2 x J598s near the inverter side of the board, as circled. Do these perform the same function as the FU9024Ns?

If not, can someone please show me where they'd be located?

Also, if so, does anyone know how to test them? The PCB labels the leads as "G D S" on these J598s.

Yep those are the ones
G D S = gate, drain, source
you are checking for shorts, also check out the solder joints on the good one.
this link by Krankshaft will apply to your board,they are both Benq boards
https://www.badcaps.net/forum/showpo...&postcount=240
it will help you

**Bobdee** · 05-28-2009, 10:13 AM

Re: Benq FP767 PS caps

Originally posted by maverick530

I'm not familiar with FU9024N. I don't see any on my board.

I found 2 x J598s near the inverter side of the board, as circled. Do these perform the same function as the FU9024Ns?

If not, can someone please show me where they'd be located?

Also, if so, does anyone know how to test them? The PCB labels the leads as "G D S" on these J598s.

they have yours on Ebay
http://shop.ebay.co.uk/?_from=R40&_t...All-Categories

**EGuevarae** · 05-28-2009, 12:06 PM

Re: Benq FP767 PS caps

Originally posted by Bobdee

they have yours on Ebay
http://shop.ebay.co.uk/?_from=R40&_t...All-Categories

And if in USA, try this

**maverick530** · 05-28-2009, 10:44 PM

Re: Benq FP767 PS caps

Ok I measured the J598 that corresponded to the top half of the inverter circuitry where I already replaced the C5707s and I measured from source (S) to drain (D) and sure enough, it was shorted (0.0 on diode reading) in both directions. Good call, gentlemen.

I will buy new J598s and replace the bad one. The other one seemed ok and I'd rather not have to replace it if I don't have to considering how expensive these are. I'll let you know how it goes.

**EGuevarae** · 05-29-2009, 12:17 AM

Re: Benq FP767 PS caps

Originally posted by maverick530

Ok I measured the J598 that corresponded to the top half of the inverter circuitry where I already replaced the C5707s and I measured from source (S) to drain (D) and sure enough, it was shorted (0.0 on diode reading) in both directions. Good call, gentlemen.

I will buy new J598s and replace the bad one. The other one seemed ok and I'd rather not have to replace it if I don't have to considering how expensive these are. I'll let you know how it goes.

Replace them both. More than once, PCBONEZ has suggested that being mirrored components, it is better to replace them in pairs.

**maverick530** · 05-30-2009, 08:19 AM

Re: Benq FP767 PS caps

I couldn't wait and so I desoldered the remaining good J598 from one board, and soldered it onto the other (I had 2 bad boards remember), and now the LCD back lighting turns off when it's supposed to! Thanks everyone for all your help!

Anybody know where else besides eBay I might be able to order J598's for less than $6.50+ a pair? I'd still like to fix my other board that now needs 2.

**EGuevarae** · 05-30-2009, 09:21 AM

Re: Benq FP767 PS caps

Originally posted by maverick530

I couldn't wait and so I desoldered the remaining good J598 from one board, and soldered it onto the other (I had 2 bad boards remember), and now the LCD back lighting turns off when it's supposed to! Thanks everyone for all your help!

Anybody know where else besides eBay I might be able to order J598's for less than $6.50+ a pair? I'd still like to fix my other board that now needs 2.

http://www.mouser.com/Search/Refine.aspx?Keyword=2SJ598

**Grape** · 08-14-2009, 11:08 PM

Re: Benq FP767 PS caps

First off...this site rocks!!

I just fixed a free monitor with the help of all you geniuses out there.

$6 for CAPs and about 3 hours total (had to go to 2 places to find the right values) - I just did the 'leaning' and leaking ones, probably about half of them; but I think in the future I'd do them all. I'm handy with the solder and taking apart of things - I wouldn't recommend it to just anybody - you DO need SKILLS.

I'm super-impressed and I saved this monitor from the garbage..!!

**EGuevarae** · 08-15-2009, 01:46 AM

Re: Benq FP767 PS caps

Originally posted by Grape

First off...this site rocks!!

I just fixed a free monitor with the help of all you geniuses out there.

$6 for CAPs and about 3 hours total (had to go to 2 places to find the right values) - I just did the 'leaning' and leaking ones, probably about half of them; but I think in the future I'd do them all. I'm handy with the solder and taking apart of things - I wouldn't recommend it to just anybody - you DO need SKILLS.

I'm super-impressed and I saved this monitor from the garbage..!!

Congratulations. Another one that didn't bite the dust ....

**dotniet** · 09-02-2009, 05:31 AM

Re: Benq FP767 PS caps

------------------------

Hi.
My Benq 767-12 monitor has the same problem: every 10 minutes it turns off for one second then it works again. I think that when it is hot in my room, the monitor has this behavior often.

I open the monitor, removed the transistor and measured them. All show the same characteristics and seem to be ok (2.2KOhm between base and emitter/collector; and almost infinite resistance the other way).

The capacitors are also ok. None is inflated or leaking.
I have also re-soldered those 4 high-voltage transformers.

But the monitor still shows the problem.
What else to check? Maybe something that is related to heat.

-----------------------------

**Bobdee** · 09-02-2009, 11:01 AM

Re: Benq FP767 PS caps

Hello Dotniet
Not quite same problem, intermitent and last for one second could be a tough fault to find
Faulty CCFL maybe but why every 10 mins
Annoying but maybe best left till fault gets worse and shows more syptoms
You could check all solder joints carefully, or recap even

**PlainBill** · 09-02-2009, 01:58 PM

Re: Benq FP767 PS caps

Originally posted by Bobdee

Hello Dotniet
Not quite same problem, intermitent and last for one second could be a tough fault to find
Faulty CCFL maybe but why every 10 mins
Annoying but maybe best left till fault gets worse and shows more syptoms
You could check all solder joints carefully, or recap even

Resolder every transformer pin, and the leads of every component that is mounted on a heat sink.

I'd suggest recapping if the original caps are from a bad manufacturer.

PlainBill

**chotzeny** · 02-25-2010, 04:42 AM

Re: Benq FP767 PS caps

Image of trouble shhoting the Power Board
and concept of replace parts...

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