Dell 2007WFP Won't Power On

[croket]

Re: Dell 2007WFP Won't Power On

Yes that's correct, I get 0v to the tabs, only voltage is on the 2 soldered legs

[alexanna]

Re: Dell 2007WFP Won't Power On

There is a center pin it's the tab.
This picture may be easier to read the voltages.

[PlainBill]

Re: Dell 2007WFP Won't Power On

Yes I did measure all 4 the j598s, I get 19v to both the legs on all them. The row of fuses stamped with "G" have no voltage getting to them.

The tab is the third terminal of the J598s. I had assumed you checked those and found 0 volts.

PlainBill

[croket]

Re: Dell 2007WFP Won't Power On

Yes I did measure all 4 the j598s, I get 19v to both the legs on all them. The row of fuses stamped with "G" have no voltage getting to them.

[alexanna]

Re: Dell 2007WFP Won't Power On

It has to be on the USB board
There is a row of fuses that look to protect the circut going to the small usb conector,they have a 'G' stamped on them.
Have you measured the voltages on the pins of the J598s?

[croket]

Re: Dell 2007WFP Won't Power On

Ok so your logic board is getting the same voltage on the pins as mine without the big USB board attached, so its safe to say the problem is isolated to the USB board. I don't get the 5v at the 'G' row.
PlainBill, sounds like your on to something with the gates not opening.

[alexanna]

Re: Dell 2007WFP Won't Power On

It can get confusing; I will call the USBs big and small.
The small board doesn't have to be installed for the big board to generate voltages for the signal board.
However 5 volts is on the row of ‘G' fuses going to the connector for the small board.

[PlainBill]

Re: Dell 2007WFP Won't Power On

If we are interpreting things correctly, crocket's board should be providing power to the signal card whenever the power supply is plugged in. The USB jacks will not have power unless a device is plugged into them.

PlainBill

[alexanna]

Re: Dell 2007WFP Won't Power On

Without the USB hooked up I see 19v on the black and brown wires at the logic board



on pin #9 of the 12 pin conector to the USB right about .5v

[alexanna]

Re: Dell 2007WFP Won't Power On

I will re-check a little later to make sure,but i think every thing is dead without the USB pulged in.All of the tests were done without the small USB board installed.

[croket]

Re: Dell 2007WFP Won't Power On

Alexanna, if you power up just the logic board (with out the usb board) which pins have voltage & what do they read?

[alexanna]

Re: Dell 2007WFP Won't Power On

Here are some measurements I took on my board,
The inverter is not installed so there is very little load.
The row of 'g' fuses all have 5.12v
U3 and U4 have almost exactly the same pin voltages.

[PlainBill]

Re: Dell 2007WFP Won't Power On

I've uploaded another picture detailing the leg voltage on U4, U3 also has the same voltage.

OK, I'm going to have to figure out how to get a real live TL1451 to measure.

PlainBill

[croket]

Re: Dell 2007WFP Won't Power On

I've uploaded another picture detailing the leg voltage on U4, U3 also has the same voltage.

[PlainBill]

Re: Dell 2007WFP Won't Power On

On both U3 and U4, Pins 9 show 18v and pins 15 show 0v. The connector at the end of the board is for the actual USB ports (2 ports mounted on a small board with 4 small caps). That connector reads 0v on all 8 pins.

What are the voltages on every pin of U3? U3 and U4 are the controllers for the DC-DC converter. As closely as I can determine, for some reason the gates of the J598's are not being driven.

PlainBill

[croket]

Re: Dell 2007WFP Won't Power On

On both U3 and U4, Pins 9 show 18v and pins 15 show 0v. The connector at the end of the board is for the actual USB ports (2 ports mounted on a small board with 4 small caps). That connector reads 0v on all 8 pins.

[PlainBill]

Re: Dell 2007WFP Won't Power On

Retiredcaps I re-tested with the USB board disconnected but had the same results.
I've uploaded some additional pics, one shows the bottom side of the usb board indicating the pins getting voltage,(took the picture first then plugged the board in ) the other is the U2 chip. The 4 IC's with 19v are part# J598.
I'm trying to be as detailed as possible with pictures guys , but if its too much I'll tone it down. I figured pictures tell a thousand words!

Thanks for jumping in on this Plainbill and Pedro.

I for one appreciate the detailed pictures. It makes it a lot easier if I can SEE what the part number is, and it makes it a lot easier if I can say 'What are the voltages on pins 9 and 15 of U3 and U4?' rather than have to download a picture, load it into Paint, circle ICs, and ask what the part number is.

Which brings us to the next step. What are the voltages on pins 9 and 15 of U3 and U4? Does 19 volts appear on any of the pins of the white connector on the left side of the USB board? What connects to that connector?

Briefly, these boards are a step back from what I was expecting. U3 and U4 are dual pulse width controllers. The J598s are 2SJ598, a P-Channel FET.

PlainBill

[croket]

Re: Dell 2007WFP Won't Power On

Is F19 good on the USB board?

Yes F19 gets 19v in and 19v out

[croket]

Re: Dell 2007WFP Won't Power On

Next, what are the voltages on each of the 12 pins connecting the signal card to the USB card?

There are 4 regulators you have indicated have 19V on two pins. What are the part numbers of those 4 ICs?

Last, what is the part number of U2 on the USB card. What is the voltage on the three pins?

PlainBill

Retiredcaps I re-tested with the USB board disconnected but had the same results.
I've uploaded some additional pics, one shows the bottom side of the usb board indicating the pins getting voltage,(took the picture first then plugged the board in ) the other is the U2 chip. The 4 IC's with 19v are part# J598.
I'm trying to be as detailed as possible with pictures guys , but if its too much I'll tone it down. I figured pictures tell a thousand words!

Thanks for jumping in on this Plainbill and Pedro.

[retiredcaps]

Re: Dell 2007WFP Won't Power On

The USB board obviously produces a regulated +5V from the 19V supply. Is it a possibility that THAT is the supply for the logic board, and NOT the 19V? If they are going to use 3-terminal linear regs for 3.3v etc on the logic board, that would make sense.

I knew something about this design was different. Having a dead monitor work hasn't helped otherwise it would be easy for me to get the voltage readings off each pin connector.