Look for Datasheet

[dabone]

I'm working on a VR-4085DF Tv, and I'm looking for the datasheet for the inverter chip.

It's a SEM2107, on a Samsung branded inverter board labeled

SSI_400_14A01.

It's got the 2 seconds to black, and I'm thinking I might have bad lamps.


Later,
dabone

[paulstef]

Re: Look for Datasheet

please post a picture of the chip, one where we can see what's printed on it. What package is it?

[tom66]

Re: Look for Datasheet

SEM2107 = Samsung ElectroMechanics part. You would be lucky to find a datasheet, it is a custom Samsung part. However, you can possibly find the schematic of the power board - is there a BN44 number printed on the power board somewhere?

[topng]

Re: Look for Datasheet

hi
SEM2006=sem2107=sem217

kim o

[paulstef]

Re: Look for Datasheet

hi
SEM2006=sem2107=sem217

kim o

Nice.

[braxton]

Re: Look for Datasheet

I noticed the SEM2107 is a 28 pin IC and SEM2006 is a 24 pin IC so how are they the same?? Does that mean the two pins at the end on either side of SEM2107 are not used or needed??

[braxton]

Re: Look for Datasheet

I've found a wiring diagram of SEM2107 but I don't know how to interpret it. Can someone tell me which pin is SDT (shutdown timing capacitor) and which pin is OVP (over voltage protection) based on the attached diagram?

[tom66]

Re: Look for Datasheet

Not possible to tell from that diagram. Possibly 4, 21, or 25 are the timer pins, but if you short the wrong one you may damage the IC.

[budm]

Re: Look for Datasheet

It is not compatible, as you can see pin 14 and pin 15 are used.
http://www.shopjimmy.com/samsung-lj9...-inverter.htm#
Picture provided by shopjimmy.

[braxton]

Re: Look for Datasheet

Not possible to tell from that diagram. Possibly 4, 21, or 25 are the timer pins, but if you short the wrong one you may damage the IC.

It is not compatible, as you can see pin 14 and pin 15 are used.
http://www.shopjimmy.com/samsung-lj9...-inverter.htm#
Picture provided by shopjimmy.

That's what I thought but many internet sites (and a post earlier in this thread) indicate that SEM2107 and SEM 2206 are the same when clearly they are not.

I'm hoping I can track down a SEM2107 datasheet or pinout...

[braxton]

Re: Look for Datasheet

Does this attachment help??

[braxton]

Re: Look for Datasheet

Ok, so not being 100% sure on the inverter IC pinout, I decided to disassemble the panel down to the CCFL bulbs. As soon as I did I found the problem. One lamp was black and actually broken at one end. When I power up the set, all other lamps come on for a second, although they do not glow all the way across before they turn out again. There are 14 lamps and the 10th one down is bad.

My next question is - can I remove the bad bulb and then trick the Inverter IC to think that the bulb is good? I don't think I will come across any spare bulbs for a 40" TV any time soon...

Thanks for the help!!

[michael dranfield]

Re: Look for Datasheet

Does this attachment help??

Could you possibly send this diagram to my e mail so I can print it out ?
md@digifixltd.co.UK
Many thanks in advance.

[braxton]

Re: Look for Datasheet

Could you possibly send this diagram to my e mail so I can print it out ?
md@digifixltd.co.UK
Many thanks in advance.

Done.


Anyways, back to my question of a "bypass", I'm thinking a resistor method might work (I'm not clear on where it goes though) or maybe removing the check circuit for the bad bulb and tying into check circuit for a good adjacent bulb???

[tom66]

Re: Look for Datasheet

No, I don't recommend you bypass bulbs as doing so can cause the transformers to fail and burn up, posing a fire risk.

[michael dranfield]

Re: Look for Datasheet

If you look at the output from each transformer there is a capacitive potential divider usually consists of a high voltage capacitor about 5pf on the hv side and a 10nf cap to ground.this is where the voltage is sampled from the middle of the two caps will have a small voltage of a couple of volts which is proportional to the high voltage .if a lamp goes open circuit the hv rises due to no load and the voltage at the tap point in turn rises and triggers the open lamp shutdown circuit in the sem chip.to disable the open lamp protection for an individual tube you need to short the middle of the potential divider to ground connected to the tube which is not lit.however on this board I think the hv capacitor is formed by two copper plates on the top and bottom of the board rather than a blue disk type cap .

[michael dranfield]

Re: Look for Datasheet

So for example looking at the bottom transformer T104 if you were to short the junction of c418 and r438 to ground which is the middle of the HV potential divider this will disable the open lamp protection circuit of the lamp connected to T104. Top end if this makes sense.

[braxton]

Re: Look for Datasheet

So for example looking at the bottom transformer T104 if you were to short the junction of c418 and r438 to ground which is the middle of the HV potential divider this will disable the open lamp protection circuit of the lamp connected to T104. Top end if this makes sense.

Thanks for the info. I am trying to understand what I can try. Bear with me as this is new for me. The board has 14 bulbs. From top to bottom, Transformers T101, T102 and T103 each handle 4 bulbs while T104 at the bottom handles the last 2 bulbs (and is a smaller transformer). I'm not sure I'm reading the schematic correctly, but for non-working bulb 10 would I short the junction of R426 and C411 to ground to remove the check?

Thanks again.

[braxton]

Re: Look for Datasheet

Also, based on my assumption, would I short the region indicated by the red circle (which can be traced to a pin on the transformer T103 low side) or the yellow circles in the attachment below?

Or am I completely off base?

[budm]

Re: Look for Datasheet

You can fool the protection circuit to make it think that is there is good lamp in place but you must also disable the high voltage from the transformer.