Dell 1901 Service Manual?

[Per Hansson]

Hi, does anyone have a service manual for a Dell 1901FP?
The power button PCB and cable is missing, I just want to short the correct pins to see if it turns on, all PCB's and components visually look to be in pristine condition!
I think the power button PCB is supposed to connect to the lower left header on the PCB, I have not seen one tho so I'm not sure...

[PlainBill]

Re: Dell 1901 Service Manual?

Hi, does anyone have a service manual for a Dell 1901FP?
The power button PCB and cable is missing, I just want to short the correct pins to see if it turns on, all PCB's and components visually look to be in pristine condition!
I think the power button PCB is supposed to connect to the lower left header on the PCB, I have not seen one tho so I'm not sure...

At the risk of being 'The one who says it can't be done', it may be a little more complicated than that. Some monitors (and TV sets) use a voltage divider on the push button circuit board. The voltage on the line back to the controller is important.

PlainBill

[ecking767]

Re: Dell 1901 Service Manual?

I happen to have this board on my work bench for testing. The Off/on connector is P308. That the top right header. I don't have a service manual

[Toasty]

Re: Dell 1901 Service Manual?

It's the flat ribbon cable connector at the bottom left corner in your picture.

I'd use a resistor to jump the connection, not a wire. Maybe start at 4.7kΩ and come down from there. I had my 1905FP open a few weeks back, but no pics of the control board. It's simply push buttons with a few of LED's & resistors.

See attached pic.

[Per Hansson]

Re: Dell 1901 Service Manual?

Thanks guys, I figured as much as I wrote in my original post that "I think the power button PCB is supposed to connect to the lower left header on the PCB" (meaning the location in the picture I posted obviously)

Anyway, I'd still like to know the pinout, I just don't wanna start shorting pins on gut feeling

[PlainBill]

Re: Dell 1901 Service Manual?

Thanks guys, I figured as much as I wrote in my original post that "I think the power button PCB is supposed to connect to the lower left header on the PCB" (meaning the location in the picture I posted obviously)

Anyway, I'd still like to know the pinout, I just don't wanna start shorting pins on gut feeling

You can get close with a little detective work. It is most likely that 1 of the 7 pins is 5V (perhaps with current limiting). One is certain to be ground, another is the drive for an LED.

Toasty's suggestion would eliminate the chance for any damage while allowing you to determine the correct pin empirically.

PlainBill

[Toasty]

Re: Dell 1901 Service Manual?

I think the 1901 uses a soft-touch power on/off on that board too. Momentary contact switches logic states.

The 1905FP is that way, but the 2005FP uses a mechanical latch on/off pushbutton. 2005FP is a BenQ in Dell clothing.

[Per Hansson]

Re: Dell 1901 Service Manual?

Was going to chuck the thing in the trash today but could not get myself to do it, it looks so nice
So I got the DMM out, pin 1 and 2 are common and are ground
On pins 3>6 there is 1.8v and it slowly rises when I have the DMM on it measuring
On pins 7 and 8 I get no reading

What's my safest bet here would you say to start with?

[Per Hansson]

Re: Dell 1901 Service Manual?

pic of connector;

[PlainBill]

Re: Dell 1901 Service Manual?

Was going to chuck the thing in the trash today but could not get myself to do it, it looks so nice
So I got the DMM out, pin 1 and 2 are common and are ground
On pins 3>6 there is 1.8v and it slowly rises when I have the DMM on it measuring
On pins 7 and 8 I get no reading

What's my safest bet here would you say to start with?

Look at the layout.

Possibility 1: 1 & 2 are ground. 7 & 8 are the drive lines for the power / standby LED. (Note they are connected to transistors Q307 & Q308.) Note also resistor networks RN314 and RN315. RN314 provides a 10K pullup, RN315 is for isolation. Test by pulling pins 3-6 to ground through a 4.7K resistor (1 pin at a time). If that doesn't 'wake up' the monitor, try a 2.2K, then no resistor.

Possibility 2: 1 & 2 are ground. 3-6 are the X lines while 7 & 8 are the Y lines in a 4 X 2 drive / sense array (or a 4 X 2 sense / drive array). Clip one end of a short jumper to pin 7, then touch the other end one at a time to pins 3-6, pausing a few seconds between each pin. If you don't get any response, try using pin 8.

The identity of Q307 & Q308 will help distinguish between the two possibilities. Given the difference between the current limiting resistors (R365 & R367), I would say Possibility 1 is most likely.

Also, why not look up the datasheets for the Genesis IC? Granted, locating this may be difficult, so also examine schematics for any monitor using a Genesis controller.

For additional ideas, look at the circuit in the lower right hand corner of page 42 of this manual. Note that one has the circuitry on the logic card; others place the circuitry on the button pc board.

PlainBill

[Regent]

Re: Dell 1901 Service Manual?

Would anyone have the service manual for the Dell 1901FP LCD? I have that model with a missing circuit board that goes behind the volume & display control buttons. I need the part number of that board so that I may order a new one!!
Hope someone could help me??