"M545" could be a YWW date code.

"16A" is probably the part number code. It could be a 1.5SMC16AT3 TVS diode which has a working voltage of 13.6V and a breakdown voltage of 16V.

http://www.s-manuals.com/pdf/datasheet/ ... at3_on.pdf

It seems OK to me.

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A backup a day keeps DR away.

Do you think it is OK to be replacement? With more higher working and brokening voltage? Despite it is unknown what is working voltage when tvs should work under overvoltage condition.

I have read on one site that we need solder just the same BUXxxx instead broken one or left it void. Is it proper approach? Should the first statement mean that another tvs or another smd could inproperly influence ingrained circuit except as in my case it has probably brokening voltage of 16v as it has marking of 16A? Probably the best replacement should be from the same sp0812n board or exactly same bg41-00091b pcb?

If you are concerned, then purchase an SMBJ12A from a source such as Farnell, RS Components, Mouser or Digikey.

_________________
A backup a day keeps DR away.

Here I have looked through the unsoldered tvs and it has such marking in three row: st E ; bux; c543; where "st" is st microelectronics sign and "E" is first letter of marking despite it could happen to be "Ex" where "x" is another already wiped out character that is improbable, but there could be such assumption if to look at it. Meanwhile my mb was revealed non-launching before hdd after burning of psu so I have time to find the same tvs.

So maybe the reason of mb disfunctionality was also brokening of some kind of anti-overvoltage "tvs" as several years ago mb also seemed deat but after replacement of one stabilizator the electric supply was regained to processor and mb worked about five years untill this psu burst. So maybe it was enough to replace the same stabilizator or another kind of antivoltage diode if there is such kind one? This time I try to repair in the same service, they regained the electric supply to proc on the main board, after replacing several visually ruined transistors and probably "drivers" (despite I do not assume what it means on pcb). Maybe previous stabilizator was not replaced or there is another kind that work according the short circuit schema? As I know for hdd even 1v over 12v could be ruining so what kind of overvoltage pressure could withstand the mb, as if the demands are almost the same, there should be the same "tvs"?

I have such important question. If i cannot find ata-133 supported motherboard for sp0812n HD but I have several options with two different types, similar to my original, of motherboards that support ata-100 could I buy such mainboard? Would the ata-100 mb work with ata-133 hd?

Could I have answer for such rather simple question on profile forum?

Yes.

Yes. It is due that my asus mb already officially support just udma 33,66,100 but worked with hd ide 133. Meanwhile I have question relating the zero-ohm resistor that was soldered out along broken tvs diode. Should I replace it with the same one or put just piece of wire (although it should have some resistance). What is really such resistor in this case: could it be some kind of coil as I see a lot of tiny 1r0 components but not see no r000/r0 components on hd pcb. What is the role of such resistor for transil - is it necessary to correct fusing of diode if so?

It is better if you replace it with another 0 ohm resistor.

The hdd recovery master changed my previous bux 12 tvs for another one with LEM marking (f.e. - http://www.onsemi.com/pub_link/Collateral/AND8181-D.PDF). Indeed it is stock diode from the same sp0812n, but maybe pcb is different. So the replacement got proper relatively. Master told that if 12v overvoltage would not be stopped by tvs -just the spindel chip would be damaged, so 5v surge is more dangerous. Is it true? Is the true the main risk is cold and bumps for the disk? It was also happened that O-ohm resistor was in place in previous time? There are two toasted blobs of solder that was probably one solid entity after brokerage of tvs or even before and one very small pcb toasted element with tiniest not visible marking that is located paralelly to blobs. So what is exactly the 0-resistor: this element or 2 already separate blobs? Was it enough to separate this blobs to recover the 0 -ohm resistor? Should these blobs shorten the circuit if another overvoltage would happens?

I am not technician I just see just blobs. I do not know are they soldered together or desoldered to two parts to break the circuit as the result of tvs brokage. I do not know exactly did local master soldered it back together if it is enough to recover it or he pulled out it and I need some actual replacement except present blobs? Now I have repaired system with new mb. I have checked disk and it found 8 kb of bad sectors by chkdsk on system disk (2 red dots on hd tune dots). It should be physical bad sectors so I wonder how can I try to recover it. If 8 kb it should be about 16 sectors? I have its lba so i want to find its file location. Relating to bad sector recovery I want to know can hd regenerator tool recover it? Could I use HUTIL for physical sector recovery? Could it identify the reason of damage? How is the risk to damage disk more or eraze hd by using HUTIL? What other tools can I use for samsung hd bad sector repair?