Re: samsung t200hd won't power up
Happy new year,
Here's an update of the last week.
Finally got to an electronics store in the neighbourhood to get the zenerdiode replacement. I printed out the specifications-sheet from fairchild and gave it to him. He told me he had it in store and gave me a 15W zenerdiode.
Measurements after soldering it in:
Secondary (output) Voltages --> all 0
Voltage over the start-up cap --> 0
Resistance over the start-up cap -->36.2 Ohms
Resistance over the SMPS-controller...
jananas
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Last Activity: 06-08-2012, 01:43 PM
Joined: 12-17-2011
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Re: samsung t200hd won't power up
Ok, I desoldered ZD101.
New measurements:
SMPS-controller: pin 4-pin 6: 36.2 Ohms
ZD101: 0,001V - 0,002V
Looks like the problem is located than. I'll try to get an replacement and update.
Do diodes die from non-specific causes or should I look for an ultimate cause of the diode becoming shorted?Leave a comment:
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Re: samsung t200hd won't power up
I'll keep that one in mind.
Just tested the smps-controller.
1.2 ohms--> I would say not shorted, correct?...Leave a comment:
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Re: samsung t200hd won't power up
@selldoor:
Thanks for the warning
Already did so and after I unplugged the board I wait some time and then short all the caps with a screwdriver to make sure I don't get a jolt. This wouldn't damage the capacitors would it?
Leave a comment:
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Re: samsung t200hd won't power up
The replacement cap is an axial cap. Got it from a television repare store in the village where I live in. Do you imply there's a fundamental difference in composition between axial and radial capacitors other than the position of the poles?
The original cap gave 0.0 Vdc, so does the new one.Leave a comment:
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Re: samsung t200hd won't power up
Merry Christmas everybody,
Here are the results of the measurements.
[B]The diodes that were circled:
[/B]
D201C is the one near the heatsink
D201C: 0.178V out of range
D201B: 0.178V out of range
D201A: 0.178V out of range
D201: Strange, there's is a slot for it in the pcb but it is not there. Pretty sure it didn't fell off when I took the powerboard out of it's case. Soldering joints also dont look like something broke off.
[B]The diode mounted on the heatsink:[/B]...Leave a comment:
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Re: samsung t200hd won't power up
The soldering of the start-up cap is solid. There are however a few scratches on the pcb. Could this create shorts?
Results of the measurements:
D101: 0.55 Ohms - Out of range
D103: 0.72 Ohms - Out of range
ZD101: 0,002 Ohms - 0,002 Ohms
Q101 with pins numbered like this, multimeter on 200 ohms:
1
2 3
1-2: out of range
1-3: out of range
2-3: 160 Ohms
I did some reading on the zenerdiodes and...Leave a comment:
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Re: samsung t200hd won't power up
Update:
I connected it, voltage over the start-up cap is still 0.0 V.
Are there other components which I can check? I don't see other fuses that might be blown.Leave a comment:
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Re: samsung t200hd won't power up
Ok, so I finally got some time again to continue this project.
Here's the update:
I replaced the fuse and measured the secondary DC voltages (I interpreted this being the output voltages of 5.1 and 15 V). They were 0.0 V.
I continued with measuring the main filter cap. It gave a value of 317 VDC, a bit lower than the 325 VDC it should give. Would this be a problem?
I also measured the start-up capacitor (C103, just above ZD101). It gave 0.0 VDC. I replaced it and before I connected the whole thing...Last edited by jananas; 12-23-2011, 10:49 AM.Leave a comment:
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Re: samsung t200hd won't power up
Thanks for the quick reaction.
Understood.
all out of range, so I guess that's good.
I have another one that goes up to 600V. I'll use that one.
It is out of range, don't know if it was before or if it burned due to the short I created.
The replacement capacitors are from KSC, I can't see the series. All the other information on it are the specifications (1000 uF, 16 V, -40 - 105 degrees Celsius)....Leave a comment:
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Re: samsung t200hd won't power up
Ok so I decided to check the voltage again just to be sure and set it to DC, the output was zero now. I also thought I might try to measure it on AC just out of interest and it gave a negative value around -300.
Then I accidentally made a shortcut which created a bang and appeared to be a very convenient way to shut down all my electric appliances:P
Flipped over the switch and the power is back again.
Think the capacitor is broken now and I'm not sure if I can plug the board in again. Would this be a...Leave a comment:
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samsung t200hd won't power up
Hi,
I have a problem with my samsung syncmaster T200hd lcd monitor. It won't power up anymore.
I opened it to look at the capacitors, two were bulged and i replaced those. After putting it back together it still wont power up. I checked the output signals (the 5.1 V and 15 V) of the board and they give no output at all.
I also checked the voltage of the main filter capacitor (the big one 450 V 100 uF) and it gave a voltage of 600-700V. I have no idea if this is good or not but it seemed to high.
Can anyone give me some diagnostic advice on this?...
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