HP w2007 PTB-1773 - Where to start?

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

Krankshaft, I think you're right. I'd like to replace both the Q103 and Q105 transistors, in addition to the caps as suggested. Does anybody know where I can find some of these transistors? I think I found a data sheet for AP9962GH (see attachment). Is this what I need?

[PlainBill]

Re: HP w2007 PTB-1773 - Where to start?

PlainBill, I'll take a stab in the dark: does BRI stand for BRIghtness?

I took another power board (just to learn) that I knew was working, and sure enough, you can see the voltages even though it's not connected to the logic board. It makes sense now--how can the logic board give the feedback if it's not being constantly powered?

Got it in one!!!

One of the things to remember is the major power hog on an LCD monitor is the backlight and the inverter. CCFLs run 3-5 watts each, the inverter soaks up a fair amount of power, and flipping those little pixels on and off takes up something too. One recent monitor I worked on had a 5V power supply rated at 5.1V, 1.6 A. That's 8 whole watts!! The rest of the power was sucked up by the inverter and CCFLs.

On your power supply, the problem MIGHT be a shorted transistor in the inverter, especially if one looks fried. I didn't see a fuse in the inverter supply, so apparently they just let it overload and shut down the power supply - unusual. It looks like J008 caries power to the inverter, lift one end of that and if the power light comes back on you're on the right track.

PlainBill

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

PlainBill,

I will try lifting one end and seeing if the board outputs 5.1 v at that point as soon as I can get to a lab.

All,

I know I furnished a data sheet, but that's all I can find after scouring through google, eBay, bluestar, and digi-key. I am still having a hard time finding where I can even purchase these transistors. If I can't get these anywhere, does anybody know of a compatible part? Thanks so much in advance.

[PlainBill]

Re: HP w2007 PTB-1773 - Where to start?

PlainBill,

I will try lifting one end and seeing if the board outputs 5.1 v at that point as soon as I can get to a lab.

All,

I know I furnished a data sheet, but that's all I can find after scouring through google, eBay, bluestar, and digi-key. I am still having a hard time finding where I can even purchase these transistors. If I can't get these anywhere, does anybody know of a compatible part? Thanks so much in advance.

I can't find any cross-reference to an equivalent part. Searching for AP9962GH does generate a lot of hits from component locater sites. HKin.com indicates Chip E-Go Trading Ltd has 50 of them available. Indications are they will ship to the US,and you may not have to buy all 50. HKin.com does have a mechanism for requesting a quote. Give it a shot.

PlainBill

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

I lifted one end of J008 that delivers power to the suspected transistor that is bad, and I still don't get any voltages out of the power board. They are all zeroes. Should I try lifting one side of J015 which looks like it leads to the other transistor?

[PlainBill]

Re: HP w2007 PTB-1773 - Where to start?

I lifted one end of J008 that delivers power to the suspected transistor that is bad, and I still don't get any voltages out of the power board. They are all zeroes. Should I try lifting one side of J015 which looks like it leads to the other transistor?

J008 appears to bring power to the inverter; J015 is ground. Better not lift that one.

PlainBill

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

What does this tell us then, that Q103/Q105 aren't bad?

Should I order the cap replacement and then re-test?

Should I Chip-Quik desolder Q103 and Q105 and test them and/or replace them anyway?

What else can I test?

[Bobdee]

Re: HP w2007 PTB-1773 - Where to start?

What does this tell us then, that Q103/Q105 aren't bad?

Should I order the cap replacement and then re-test?

Should I Chip-Quik desolder Q103 and Q105 and test them and/or replace them anyway?

What else can I test?

I would go back to power supply and check mosfet q803 on lower heatsink looking for short with the diode test on m/meter, power off
Also check all the three components that are on Heatsinks for bad solder joints and resolder if necessary,
BTW I hope your meter is as Bill advised you, red in first socket to left and black in centre, if so keep it that way it measures diode check + OHMs + AC and DC thats all you need, no need to move probes from there
bob

[Bobdee]

Re: HP w2007 PTB-1773 - Where to start?

It looks like the two transistors are connected together the only way to get a true reading would be to remove one.

If you replace one be sure to replace them both.

Also be sure to check for cracked solder joints all over the board it may just be the pics R811 for example looks cracked to me.

Krankshaft or anyone, can you please enlighten me
Can I take it by your post that these transistors will give the same readings when on the board and diffrent when one is removed (as a pair of the 2SC5707s do on the Benq boards) ???

Also can I take it that the reason being is that this board has only one transformer ???

Also does this apply to all single transformer boards ???

Thanks in advance
bob

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

mosfet q803 on lower heatsink reads a value from G to S in both directions (1.33 and .721). G to D reads for a sec then goes to 1 (infinity?), and doesn't read in the other direction. I don't see a short (0.0). What does this mean?

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

I'm trying my hand at hkin.com to get these 2 transistors and have had the hardest time getting a decent quote from anybody. Most sellers want $20-$50 more in shipping costs! Are they serious? Cheapest I've seen is $16 for qty. 2 (after shipping). Is this fair? Should I pull the trigger?

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

Ok, after a long while, I finally got some replacement transistors for Q103 and Q105 (AP9962GH) and replaced them both, but still nothing.

I tried testing the old Q103 & Q105 off-board and from G to S my DMM measures (on diode test) 1 (infinity) in both directions, and from G to D it measures 1 as well in both directions. This is consistent with the new parts (I got loads of them).

The only reading I get is when I probe from S to D:

New parts: 0 (sometimes, and .55 at other times) and 1 in the other direction
Old Q103 & Q105: .55 and 1 in the other direction)

At any rate, I check the new ones on the board, and they still read out pretty much the same way as the old ones, and the board still does not power up.

So I conclude that unfortunately, it was not the 9962's that are at fault. Does anybody know where I should look next?

[Bobdee]

Re: HP w2007 PTB-1773 - Where to start?

Ok, after a long while, I finally got some replacement transistors for Q103 and Q105 (AP9962GH) and replaced them both, but still nothing.

I tried testing the old Q103 & Q105 off-board and from G to S my DMM measures (on diode test) 1 (infinity) in both directions, and from G to D it measures 1 as well in both directions. This is consistent with the new parts (I got loads of them).

The only reading I get is when I probe from S to D:

New parts: 0 (sometimes, and .55 at other times) and 1 in the other direction
Old Q103 & Q105: .55 and 1 in the other direction)

At any rate, I check the new ones on the board, and they still read out pretty much the same way as the old ones, and the board still does not power up.

So I conclude that unfortunately, it was not the 9962's that are at fault. Does anybody know where I should look next?

I assumed rightly or wrongly that you had no voltage at J008, by your postings
That is why I suggested you go back to the power supply mosfet
??? Is there voltage at J008???
If answer is no then power supply needs checking out

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

I get no voltage across J008 when powered. This is the main bridge between the power supply and the inverter functionality of the board?

What else can I probe while it's powered? I need help knowing the flow so I can better diagnose where it's stopping. Thanks in advance,

[lucky13]

Re: HP w2007 PTB-1773 - Where to start?

I took another power board (just to learn) that I knew was working, and sure enough, you can see the voltages even though it's not connected to the logic board. It makes sense now--how can the logic board give the feedback if it's not being constantly powered?

Are you saying you have another identical board like this that is working?

As a last stab, you can try disconnecting that wire assembly to the main/logic board where the VGA/DVI connectors are located. Then check if you have 5v at the terminals marked on the power supply. Sometimes there is something wrong on the main board and pulls down the 5v rail.

[Bobdee]

Re: HP w2007 PTB-1773 - Where to start?

I get no voltage across J008 when powered. This is the main bridge between the power supply and the inverter functionality of the board?

What else can I probe while it's powered? I need help knowing the flow so I can better diagnose where it's stopping. Thanks in advance,

Can you check the dual diode on heatsink, board number D809
check Solder first if ok then remove and check pins 1 + 2 with diode function both ways, you should have a reading only one way and infinity the other
Repeat the procedure on pins 2 + 3
I will get back to you on the P/Supply flow info, as soon as I can find it

[Bobdee]

Re: HP w2007 PTB-1773 - Where to start?

Maverick
This is not your board obviously but it will give you a good understanding of how the P/S works (thanks to Plainbill)
https://www.badcaps.net/forum/showpo...9&postcount=18
I cant give advice on taking powered up voltage readings as I am not quallified to do so, safer leaving that to others

Only just realised that this P/S posting above was sent to you by Bill

[PlainBill]

Re: HP w2007 PTB-1773 - Where to start?

I get no voltage across J008 when powered. This is the main bridge between the power supply and the inverter functionality of the board?

What else can I probe while it's powered? I need help knowing the flow so I can better diagnose where it's stopping. Thanks in advance,

You won't get any voltage across J008, it's just a jumper wire. Unsolder one end of J008; this will isolate the inverter from the power supply. Then plug in the power supply and measure the output voltages. Do this without the logic board connected. If you get 5.1 volts, then you have to figure out what is overloading the supply.

Do that by unplugging the AC power cord, waiting a few minutes, hooking the logic board up again, then hooking up the power cord again. If you now have a working power LED you know the problem is in the inverter section.

PlainBill

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

Are you saying you have another identical board like this that is working?

The other power board I have is for a HP 1955 LCD that I fixed up (thanks to everyone's help). Unfortunately, I do not have another identical to this one I can probe against. Unlike the HP 1955, it sounds like this HP w2007 board has a problem with the power side of the board, not the inverter, so this will be fun to figure out.

As a last stab, you can try disconnecting that wire assembly to the main/logic board where the VGA/DVI connectors are located. Then check if you have 5v at the terminals marked on the power supply. Sometimes there is something wrong on the main board and pulls down the 5v rail.

All of my power supply voltage readings have been without the main logic board connected. Good suggestion to check for though, thanks.

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

You won't get any voltage across J008, it's just a jumper wire. Unsolder one end of J008; this will isolate the inverter from the power supply. Then plug in the power supply and measure the output voltages. Do this without the logic board connected. If you get 5.1 volts, then you have to figure out what is overloading the supply.

Do that by unplugging the AC power cord, waiting a few minutes, hooking the logic board up again, then hooking up the power cord again. If you now have a working power LED you know the problem is in the inverter section.

PlainBill

I desoldered one end of J008 and still got no output voltages when power is applied. This proves that it is a power side problem. Now to test D809...