Need help DCLCD 19" LCD Monitor - I already replaced caps

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I believe the small one in the red circle is a startup cap.

Sorry, I meant which brand and make of capacitor did you order?

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Sorry, I meant which brand and make of capacitor did you order?

I ordered couple Panasonics from DigiKey.

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I received my startup cap today. Soldered it in and....nothing. Clicking sound from the area of big capacitor and blinking power LED.

Monitor still does not work

Can you guys point me what and how I should check?

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I received my startup cap today. Soldered it in and....nothing. Clicking sound from the area of big capacitor and blinking power LED.

Check for secondary voltages to the logic card.

Connect all your boards together including grounding screws.

Set your multimeter to read DC voltage 20V range. Black probe in COM, red probe in voltage.

Plug in your monitor. You do not have to power up, just have it plugged in.

1) on the logic card, put your black probe on a ground screw on the logic board. This is your ground.

2) Put your red probe on the connectors. Some should read 5V, some maybe 12V 19V DC depending on the design, and some are 0V (ground).

If you don't see any of these voltages, we will have to do different tests.

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Check for secondary voltages to the logic card.

Connect all your boards together including grounding screws.

Set your multimeter to read DC voltage 20V range. Black probe in COM, red probe in voltage.

Plug in your monitor. You do not have to power up, just have it plugged in.

1) on the logic card, put your black probe on a ground screw on the logic board. This is your ground.

2) Put your red probe on the connectors. Some should read 5V, some maybe 12V 19V DC depending on the design, and some are 0V (ground).

If you don't see any of these voltages, we will have to do different tests.

On 2 of them was 5v, on 3 or 4 was 4.94.
There was no 12v neither 19v.

I also tested resistance on two transistors in the top right corner connected to the L shaped heatsink. I numbered pins 1-2-3 when looking at the back of transistors from power connector.

Transistor #1 (on the left)
1-3 0.32
1-2 0
2-3 85.8

Transistor #2
1-3 0.32
1-2 0
2-3 112.1

[PlainBill]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I've just looked through this thread. What we REALLY need are good quality pictures of the top and back sides of the power supply / inverter card. The fact that 5 volts are present at the logic card makes me wonder about the rest of the voltages.

PlainBill

[alexanna]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I received my startup cap today. Soldered it in and....nothing. Clicking sound from the area of big capacitor and blinking power LED.

Monitor still does not work

Can you guys point me what and how I should check?

Thanks for the photo,Sorry my suggestion did not work for you.
Follow Plainbills and retiredcaps suggestions on diagnosing your problem as they are much better than that I am at this.
Something I am wondering about the clicking noise you are hearing, Can you identify where its coming from, It has been suggested to use a cardboard paper towel tube like one of those ste???ascope things {have no idea on spelling} to try to isolate it. Something very simple you could do would be to reflow solder on the thru hole stuff in that area. I have found in some cases solder joints that look good to the eye can still give a problem.

Al.

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I also tested resistance on two transistors in the top right corner connected to the L shaped heatsink.

Transistor #1 (on the left)
1-3 0.32
1-2 0
2-3 85.8

Transistor #2
1-3 0.32
1-2 0
2-3 112.1

What is the part number for these 2 transistors? A reading of 0.32ohms suggests that are shorted, but an in circuit test may not be 100% reliable because other components may be affecting this reading.

To be 100% sure, you will have to measure them out of circuit.

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

What is the part number for these 2 transistors? A reading of 0.32ohms suggests that are shorted, but an in circuit test may not be 100% reliable because other components may be affecting this reading.

To be 100% sure, you will have to measure them out of circuit.

I pulled the transistors out and measured their resistance

Feet # 1 2 3 Feet # 1 2 3
1-2 116.6 1-2 92.2
1-3 0 1-3 0
2-3 0 2-3 0

In diod testing mode

1+ 2- 233 1+ 2- 174
1+ 3- 0 1+ 3- 0
3+ 1- 0 3+ 1- 0
3+ 2- 235 3+ 2- 174
2+ 1- 0 2+ 1- 0
2+ 3- 0 2+ 3- 0

Part # are visible on the attached picture but just to make sure
FCH10410 and SRF1060C

[alexanna]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Those are schotty diodes, google testing of those.
can you get pitcures of your boards?
Al.

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Those are schotty diodes, google testing of those.
can you get pitcures of your boards?
Al.

I already posted pictures earlier, but here is another set

[alexanna]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

sory did not see them.
srf1060
should get you a data sheet on one of those.
Al

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I pulled the transistors out and measured their resistance

Feet # 1 2 3 Feet # 1 2 3
1-2 116.6 1-2 92.2
1-3 0 1-3 0
2-3 0 2-3 0

In diod testing mode

1+ 2- 233 1+ 2- 174
1+ 3- 0 1+ 3- 0
3+ 1- 0 3+ 1- 0
3+ 2- 235 3+ 2- 174
2+ 1- 0 2+ 1- 0
2+ 3- 0 2+ 3- 0

When you list 0, do you mean 0L?

0 = zero. 0L means infinity. Different multimeters may have different ways of displaying infinity or out of range.

Also for the diode measurements, do you mean 0.233 or 233?

116.6 and 92.2 ohms look bad to me.

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

When you list 0, do you mean 0L?

0 = zero. 0L means infinity. Different multimeters may have different ways of displaying infinity or out of range.

Also for the diode measurements, do you mean 0.233 or 233?

116.6 and 92.2 ohms look bad to me.

I have a digital multimeter and for normal # it shows the value on the right side of display. When there is no value it shows 1 on the left side. (maybe it's considered I for infinity )

On diod measurement it was 233 and 174.

Do you think I need to replace those diods? What is the good source of them?

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I have a digital multimeter and for normal # it shows the value on the right side of display

What is the brand make and model number of your multimeter?

If you put your multimeter on the lowest ohms setting and touch your two probes together, what reading do you get?

[alexanna]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Well I have some questions.
My neck is on the chopping block, so at any time chop if need be.
The reading posted for both diodes are very similar.
116.6 almost has to be 116.600 ohms and 92.2 would be 92.200 ohms
On the diode tests 233 has to be 233mv or .233v and 174 most likely is .174v
Measuring a good diode here. I am measuring pos on #1 and neg on #2, I read .220v
With pos lead on # 3 and neg lead on#2 again right at .220v.And when measuring pos to #2 neg#3 the reading is ol and #2 to#1 is ol.And #1 to #3 are open both ways.
Is the .174v to low of a reading on the one diode?And is that a valid test?
At least the diode for the 5v rail is good,. From what I have read when these diodes fail you can usually see damage is that correct.
In a earlier post good quliaty photo were requested are the photos attached of good enough quilaty to be able to trace circuts?
Well is my neck still attached?
Al

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

What is the brand make and model number of your multimeter?

If you put your multimeter on the lowest ohms setting and touch your two probes together, what reading do you get?

The multimeter I have is Craftsman from Sears.
While on lowest ohms I have 11.4 displayed.

[retiredcaps]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

The multimeter I have is Craftsman from Sears.
While on lowest ohms I have 11.4 displayed.

What model?

If you are touching just the red and black probe together and getting 11.4 ohm, there is something seriously wrong with your multimeter.

You should get about 0.3 ohms.

[wenter]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

Here is another set of pictures: bigger size

[hoadle]

Re: Need help DCLCD 19" LCD Monitor - I already replaced caps

I had Sceptre X9G Komodo IV same problem, when monitor had power the powerlight blinking about 5min & monitor turn on ok long the had 110 VAC hook up the monitor, if I'm disconnect power had go same steps above again
I open can't find any caps bad but replace all but still same problem (maybe some transitor bad?)
any one know how to fix this problem?
Thanks