Samsung 940N 2 Seconds fade to black

[jack-pwc]

Re: Samsung 940N 2 Seconds fade to black

Hi,
You can see in the pics it is a combi transformer with both wound on one ferite.
Just desoldered and tested again, same results as before - 1 secondry is 1.25kOhm, the other is still all over the place.
I will buy one on EB and try that first.
Thanks for the help!

[retiredcaps]

Re: Samsung 940N 2 Seconds fade to black

This ebay ad says the secondary should be around 1.1K ohm

http://cgi.ebay.co.uk/TMS91429CT-Fau...item3cb30bf053

If the transformer is indeed bad, I found 2x inverter transformers for a total of $5 USD with free shipping to Canada. It was just listed 6 hours ago.

http://shop.ebay.com/i.html?_kw=TMS91429CT

That is an excellent price for 2 transformers. Normally, 1 is around $12 to $20 each.

[retiredcaps]

Re: Samsung 940N 2 Seconds fade to black

T2
Primary - starts at 100 kOhm and rises to 300 kOhm after 5 seconds
Secondary - jumps around from 0.7 - 0.8 MOhm

Desolder T2 and retest to make sure it is not affected by surrounding components.

[jack-pwc]

Re: Samsung 940N 2 Seconds fade to black

Transformer measures as follows:

T1
Primary 0.1 Ohm
Secondary 1.249 kOhm - and is rock solid

T2
Primary - starts at 100 kOhm and rises to 300 kOhm after 5 seconds
Secondary - jumps around from 0.7 - 0.8 MOhm

[retiredcaps]

Re: Samsung 940N 2 Seconds fade to black

2.
Can I measure the transformers without desoldering? I would think so.

3.
The CCFL's work on start up. Do you mean they could still work and also be faulty? Like they are out of spec? Unfortunately I do not have any spares.

2) Yes.

3) See explanation post #10, #11 at (but you can get ideas from entire thread)

https://www.badcaps.net/forum/showthread.php?t=12407

[jack-pwc]

Re: Samsung 940N 2 Seconds fade to black

Some Pics attached

[jack-pwc]

Re: Samsung 940N 2 Seconds fade to black

Hi,
Thanks for the reply.

1.
All of the Caps are JH (maybe Jaing Haius) rated 105 degrees and look great.
I will replace them with some Lelon 105 low ERS's I have.
Ratings are:
100uF 450V - Power supply
68uF 25V - Power Supply
330uF 16V - Supply to Video Card & CCFL Transformers
1000uF 16V - Supply to Video Card & CCFL Transformers
1000uF 25V - Supply to CCFL Transformers
1000uF 25V - Supply to CCFL Transformers

BTW it seems very difficult to get the 68uF. I maight have to leave that one for now.

2.
Can I measure the transformers without desoldering? I would think so.

3.
The CCFL's work on start up. Do you mean they could still work and also be faulty? Like they are out of spec? Unfortunately I do not have any spares.

[PlainBill]

Re: Samsung 940N 2 Seconds fade to black

So my 2007 died last night after much trouble free service.
I use it as a second screen, so it was easy to check that the graphics card was working fine, and that it was something with the screen. It stays on for maybe 2 seconds and then goes to black.
Few months ago I actually tried to fix a friends 17" by changing all Caps, and that was way before I discoved this excellent forum. Unfortunately than did not work so I chucked it out.
Now after reading this forum, I see it may not have been the caps, but maybe the transformer or something else.
So here's the spec:
PS is a Suntronix BN-44000123E, with 1 big cap, 4 mids and 1 small. I can get replacements for maybe $10.
Transformer is a TMS91429CT, which I see is about $9 on EB. -
Question - do I replace the Caps, the Transformer, or get my multimeter out?

Thanks!

Quick sequence for solving 'two seconds to black' problems.

1. Replace any suspect caps (Elite, Suscon, Capxonand other caps on the bad caps list are automatically suspect).

2. Compare the resistance of the transformer secondaries. If they don't match to within 3% replace the one with the lower resistance.

3. Substitute known good CCFLs

PlainBill

[jack-pwc]

So my 2007 died last night after much trouble free service.
I use it as a second screen, so it was easy to check that the graphics card was working fine, and that it was something with the screen. It stays on for maybe 2 seconds and then goes to black.
Few months ago I actually tried to fix a friends 17" by changing all Caps, and that was way before I discoved this excellent forum. Unfortunately than did not work so I chucked it out.
Now after reading this forum, I see it may not have been the caps, but maybe the transformer or something else.
So here's the spec:
PS is a Suntronix BN-44000123E, with 1 big cap, 4 mids and 1 small. I can get replacements for maybe $10.
Transformer is a TMS91429CT, which I see is about $9 on EB. -
Question - do I replace the Caps, the Transformer, or get my multimeter out?

Thanks!