Re: Dell 2007FPb intermittently turning off
Could be caps starting to go bad, usually on the power supply board or inverter board. But really, it could be a lot of things. Checking/replacing the caps is probably a good place to start though (if you're inclined to open it up and spend time working on it).
tommy_b
Member
Last Activity: 05-04-2015, 03:04 PM
Joined: 02-15-2015
Location: Goodyear, AZ
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Re: No 5V on inverter board of Dell 2007FPb
I've given up on this monitor (bought another working 2007FPb last night, so my dual monitor setup will soon be complete). Too many problems to debug on this one and no schematic made it too much work. However, I am thinking about converting this one to LED backlighting, since I already have an external power supply that might come in handy for that. Haven't ever disassembled a LCD panel, so that should be fun. :-)
Anyway, just wanted to say thanks to Budm for helping me try to debug this unit.Leave a comment:
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Re: No 5V on inverter board of Dell 2007FPb
Found the MOSFET part number in another post:
p/n: SP8M3 (Rohm)
[url]http://www.alldatasheet.net/datasheet-pdf/pdf/130046/ROHM/SP8M3.html?[/url]Re: No 5V on inverter board of Dell ...M3.html?[/url]Leave a comment:
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Re: No 5V on inverter board of Dell 2007FPb
Well, I found a new problem on the inverter board. One of the MOSFET chips (8-pin, dual MOSFETs) now has a short across one of the MOSFET's (gate to drain?). There may also be a short across a 4.7V zener and/or a 5.1K resistor in parallel with the zener (haven't pulled them off to check each one individually yet) that feeds the MOSFET gate pin. The zener and resistor are connected to 19V coming in on the connector, so the short was causing my external power supply to shutdown.
Anyone know what the part number is for the...Leave a comment:
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Re: No 5V on inverter board of Dell 2007FPb
Just a reminder to myself to try measuring the ohms between 19V and Ground on each board separately, to see how each board (USB or Inverter) is loading down the supply.
Yeah, that's the ticket! :-)Leave a comment:
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Re: No 5V on inverter board of Dell 2007FPb
I've got a good part of the circuit traced out, but not sure how accurate it is. However, now I've got a new problem. My external 19V power supply is shutting down, I presume due to overcurrent. I measured ohms between the 19V and Ground pins on the inverter board connector and am getting 3.5 ohms (~5.5 Amps). My external power supply can only go to about 4.25 Amps at 19/20 volts.
Don't know what changed, as I was mostly just poking around with the DMM with power off. Before this, the external 19V power supply was staying on and...Leave a comment:
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Re: No 5V on inverter board of Dell 2007FPb
The pins on the inverter connector measure:
1,2,3 = 19V
4,5,6 = Ground
7 = 0V
8 = 3.3V
9 = 0V
I started to trace pins 7,8,9 on the inverter board and you seem to be correct about the 5V being generated on the inverter board. I only have a partial schematic sketched out (and it ain't pretty yet), but its starting to look like the 5V is generated off of the 19V input, as you said. I almost have enough traced out to determine how the 5V is generated, so I will post that portion of the schematic when...Leave a comment:
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Re: No 5V on inverter board of Dell 2007FPb
budm, many thanks for the quick response. I believe the PICO fuse is OK, as it measures 0.3 ohms across. (The PICO fuse is FP801, yellow resistor-looking part near the edge of board, yes?). The primary DCV is ~19.5V (I think it's supposed to be 19V nominally, by design).
I'm beginning to suspect that the 5V is supposed to be supplied from the USB board to the inverter board, but its not making it out of the USB board for some reason. (Makes sense logically). I've identified three signals (TP716, TP714, TP713) that originate...Leave a comment:
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No 5V on inverter board of Dell 2007FPb
Hello everyone,
First time posting here, and I know I am not following protocol at the moment by not providing pics, but I was wondering if anyone is familiar with the circuits of the inverter board for a Dell 2007FPb monitor. I am not able to get the backlights to light up (although, on occasion, I have seen the Dell logo for a second or two before it fades to black). Normally the display is just black (no flashes or anything), and the two green LEDs are lit.
I've already recapped with Panasonic FM and FC series caps, to no avail. I also replaced the power supply...Last edited by tommy_b; 04-26-2015, 02:52 PM. -
Re: Dell 2007fpb no power
For posterity, the value of C601 is 0.22uF 275Vac. Looks like its from a Chinese manufacturer called "AV Capacitors" (AVX knockoff? :-).
Here are some numbers I found on it:
R.46 MKP X2 SH
0.22uF 275Vac
40/110/56 B B TN
I found this link to what is likely the same cap, but the p/n is slightly different (i.e.,
R.46 MKP X2 SH HP
0.22uF 275Vac
40/110/56 B S B1:
[url]http://www.aliexpress.com/item/Av-r46-x2-film-capacitors-mkp-0-22uf-220nf-224-275vac-22-5mm-p/1690...Leave a comment:
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Re: New Members - please post your introductions here
Hey guys!
I'm an electrical engineer here in Phoenix Arizona. I won't bore you with all the details of my background so I can get to the funner stuff :-) Suffice it to say that I've been a board-level digital design engineer for 30+ years. I've enjoyed most of it, but have always wanted to play around a little more on the analog side. Being a hi-fi aficianado from the 70's, I decided a while back to start collecting vintage audio equipment and now have a nice little collection, most of which needs recapping and...Leave a comment:
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