Dell W2600 lcd TV fault

[netdent]

Got given this for free, will not switch on! have read lots about these screens being dud! this one will power up sometimes and once on will stay on, but switch it off it will not come back on!

from what I can see I think it's logic board related, the psu clicks on ok with good 5volts 3,3 power on, and 9 volts all going to the main board, when it comes on the blue led lights, when it refuses to power no led light but relay clicks on.

Probably not going to get anywhere with this! but just thought I would ask to see if anyone here has experienced this

thanks Ronnie

[Th3_uN1Qu3]

Re: Dell W600 lcd TV fault

Bad caps or poor soldering.

[netdent]

Re: Dell W2600 lcd TV fault

Bad caps or poor soldering.

Should be W2600 typo on the first post! have had a good look over the psu, all caps look good, all seem to be rubicon green caps, looked for dry joints too, not removed the main logic board as yet

thanks Ronnie

[PlainBill]

Re: Dell W2600 lcd TV fault

An easy method of troubleshooting problems like this is to look at at the control input, and the voltage outputs of the power supply. Relay clicks can be misleading; heck many power supplies don't even have relays.

Normal operation is as follows:

1. The power cord is plugged in. The standby supply comes up, sending the standby voltage (usually 5 volts, but I have seen other voltages) to the standby processor on the main board.

2. In response to the remote or the power button the standby processor sends a PS_ON signal to the power supply. The power supply turns on the main supply, the processors on the main board power up.

A. If the standby voltage is not present at all times, it's a problem with the power supply, or there is a remote chance a defect on the main board is pulling it down.

B. If the PS_ON signal is not sent back to the power supply when the power button is pressed, it's a problem with the main board.

C. If the PS_ON line goes high, but the main supply does not come up, it is a problem with the power supply, or rarely a problem with the main board overloading the main supply.

D. If the main supply comes up, but there is no action (sound, picture, LEDs) from the main board, it is a problem with the main board. One thing to check is the voltage regulators on the main board. As previously mentioned, also suspect bad solder joints or bad caps.

PlainBill

[netdent]

Re: Dell W2600 lcd TV fault

Thanks PlainBill, one thing I have noticed, when it fails to power on ( most of the time) you are not able to switch of it's in limbo! no leds light set is dead, but when it powers on and works, it responds to power of, voltages I have found going to the mainboard are 3.3v, 5v, 9v, will look at these pins more closely and report back with pics.

thanks Ronnie

[netdent]

Re: Dell W2600 lcd TV fault

Ok, have looked at these pins and read the symbols

pow_off
pow_stb
3.3v ( OK)
5.1v (ok)
sgnd
+9.1v (reads 8.98)
BR1 orBRI? (this reads 4.4v when powered, wether it comes on or not)
INV_ENA

If it fails to power at switch on it will never come on even if left for hours! and any amount of tapping or poking it will not come on.

thanks Ronnie

[PlainBill]

Re: Dell W2600 lcd TV fault

Ok, have looked at these pins and read the symbols

pow_off
pow_stb
3.3v ( OK)
5.1v (ok)
sgnd
+9.1v (reads 8.98)
BR1 orBRI? (this reads 4.4v when powered, wether it comes on or not)
INV_ENA

If it fails to power at switch on it will never come on even if left for hours! and any amount of tapping or poking it will not come on.

thanks Ronnie

That is not uncommon. There are several processors on the board. They are expected to start up in a precise sequence. If one fails to start the others may hang.

I've identified several voltage regulators and possible regulators. I've circled them in red. I've also marked pin 1 with a black dot on some of them, the same pin is pin 1 on the rest. Pins are numbered 1 2 3 from left to right, the tab is usually connected to pin 2. I've also circled one mounting stud in red; use that as the ground point. There are several pieces of information I would like from you.

1. The complete part number.
2. The voltage on pin 1, pin2, and pin 3 when the set is operating.
3. The voltage on pin 1, pin2, and pin 3 when the set is not operating.

PlainBill

[netdent]

Re: Dell W2600 lcd TV fault

Thanks PlainBill your your input it is much apreciated, just to clarify which was wrong earlier! the pin marked BR1 or BRI shows almost zero volts when tv powers properly, when it hangs it shows 4.5volts, will come back shortly with those pin behaviours you asked for,

thanks Ronnie

[netdent]

Re: Dell W2600 lcd TV fault

Ok, of those 3 pins, only pin 2 changes to almost zero volts, pow_stb, I think there is about 8 regulators on the board, they read about 3 to 5 volts (most of them) on pin 3, have posted some more pics showing the board number, the psu is a liteon DA-5161-1M, hope this is enough info PlainBill, I changed one cap near the power connector as I thought 9volts was a bit low, this never changed thing! but worth a shot Ithink

thanks Ronnie

sorry forgot to state the pins

pow_off 3.285v
pow_stb 3.306v (when tv hangs 0.345)
3.3v 3.333v

[retiredcaps]

Re: Dell W2600 lcd TV fault

I think there is about 8 regulators on the board, they read about 3 to 5 volts (most of them) on pin 3,

I see a Fluke 177 with 6000 count and 0.09% DC V accuracy and all you report is "about 3 to 5 volts" ?????

Voltage regulators have specs with usually a 1% accuracy rating. That means a voltage regulator can be

3.3V x 1.01 = 3.333
3.3V x 0.99 = 3.267

If it is outside those ranges, that means a regulator measuring 3.0V is bad!

AND

you didn't report the part numbers or the operating voltages for all the pins.

[netdent]

Re: Dell W2600 lcd TV fault

I see a Fluke 177 with 6000 count and 0.09% DC V accuracy and all you report is "about 3 to 5 volts" ?????

Voltage regulators have specs with usually a 1% accuracy rating. That means a voltage regulator can be

3.3V x 1.01 = 3.333
3.3V x 0.99 = 3.267

If it is outside those ranges, that means a regulator measuring 3.0V is bad!

AND

you didn't report the part numbers or the operating voltages for all the pins.

Ok retired caps, thanks for the response, maybe I got confused with what I was being asked by PlainBill

I'm not sure what voltages I should be getting on these regulators, so I just checked to see if there was any activity on the pins.


as for the part numbers I thought it was for the main board (picture taken) if wrong please advise.

the pin voltages, PlainBill only asked for the 3 pins which I did, that plug has 13 pins, some voltages are duplicated i.e there are 3 pins that are +5v etc

thanks Ronnie

[netdent]

Re: Dell W2600 lcd TV fault

Please note also the red circled heatsink has a regulator below it, cap marked x has been replaced

thanks Ronnie

[netdent]

Re: Dell W2600 lcd TV fault

Ok I think I have grasped this, sorry for bein dumb

I measured 6 devices inc the one under heatsink, these are all LM1085

Starting just under the power plug on the left and working clockwise

location pin1 pin 2 pin 3

1247 .584v 1.838v 3.339
1244 .590 1.844 3.315
1214 2.098 3.344 5.085 (centre under heatsink)
1211 2.086 3.330 5.058
1213 .578 1.621 3.336
1212 2.092 3.339 5.095

the above were with the tv on properly

when the tv hangs I noted no big change I.E no drops in voltages maybe slight increase in all pins, there are some smaller sized regulators dotted about, I should probably check those too, but getting late for today

thanks Ronnie

[PlainBill]

Re: Dell W2600 lcd TV fault

Ok I think I have grasped this, sorry for bein dumb

I measured 6 devices inc the one under heatsink, these are all LM1085

Starting just under the power plug on the left and working clockwise

location pin1 pin 2 pin 3

1247 .584v 1.838v 3.339
1244 .590 1.844 3.315
1214 2.098 3.344 5.085 (centre under heatsink)
1211 2.086 3.330 5.058
1213 .578 1.621 3.336
1212 2.092 3.339 5.095

the above were with the tv on properly

when the tv hangs I noted no big change I.E no drops in voltages maybe slight increase in all pins, there are some smaller sized regulators dotted about, I should probably check those too, but getting late for today

thanks Ronnie

Yes, checking the smaller regulators would be helpful.

PlainBill

[netdent]

Re: Dell W2600 lcd TV fault

Ok PlainBill will do that in the morning, I thought the pins 1,2 and 3 were on the power plug! got the wrong end of the stick sorry!

thanks Ronnie

[PlainBill]

Re: Dell W2600 lcd TV fault

I missed some posts in the thread. It happens on days when I play pool boy, landscaper, robot minder, procurement officer, and cook.

The fact the pow_stb line drops to .345 volts is definitely a smoking gun. Normally I would expect to see a line with that designation be an output of the power supply. Which means I am now requesting pictures of the power supply top and bottom with that pin identified if it already isn't.

PlainBill

[netdent]

Re: Dell W2600 lcd TV fault

I missed some posts in the thread. It happens on days when I play pool boy, landscaper, robot minder, procurement officer, and cook.

The fact the pow_stb line drops to .345 volts is definitely a smoking gun. Normally I would expect to see a line with that designation be an output of the power supply. Which means I am now requesting pictures of the power supply top and bottom with that pin identified if it already isn't.

PlainBill

Yeah, sorry I was adding bits and pieces as I found, will double check that statistic and report back with pics.

thanks Ronnie

[netdent]

Re: Dell W2600 lcd TV fault

Ok Plainbill, thanks again, I hope we are getting there, be nice to get this working properly

yes pin 2 pow_stb when tv runs is 3.306v, when tv hangs .045 this time, pin marked in the pictures, also 2 caps marked that I changed

thanks Ronnie

P.S in picture 3 I put the red line on wrong pin, sorry, should be other end of socket

[PlainBill]

Re: Dell W2600 lcd TV fault

Ok Plainbill, thanks again, I hope we are getting there, be nice to get this working properly

yes pin 2 pow_stb when tv runs is 3.306v, when tv hangs .045 this time, pin marked in the pictures, also 2 caps marked that I changed

thanks Ronnie

P.S in picture 3 I put the red line on wrong pin, sorry, should be other end of socket

Thanks for that additional bit of information. I was questioning my eyesight AND sanity. This is not the standby power output; it's some sort of status or control line.

Here's what I would like from you.

1. An over-all picture of the back of the TV with all boards in place and all cables next to their connectors, if not connected. I want to see what goes where.

2. A picture of each connector on the power supply showing the legend for that connector.

3. pow_stb appears to be connected to Q706. What are the letters on that transistor?

PlainBill

[netdent]

Re: Dell W2600 lcd TV fault

Hi PlainBill no pwr_stb is not connected to that transistor, the trace goes off the other side to R422 marked in the 3rd picture . I hope these pictures are good enough for you to see

thanks Ronnie