Crua CR270C shorted input.

[redbaron1007]

I've got a Crua CR270C that had a short to ground on the input jack. The input was rated at 12v 4A center pin positive. When I took the board out and powered it with my bench power supply it jumped to 3v and 4A CC and a chip labeled either TM3db2 or TV3db2. I'm not able to find anything online typing in those strings of letters and numbers and searching websites like s-manuals hasn't yielded anything. It is an sot23-6 package type according to my digikey ruler and I was able to work out some of the pinout from voltages on the board and following the traces around. I'm not really sure what a suitable replacement would be for it if I cannot find the 1 to 1 replacement since I haven't had a ton of time to sift through datasheets on digikey or mouser and don't really know from looking at the board what the output should be. I'm assuming it is supposed to be outputing 5v to the rest of the board, and that the 5v would be stepped down somewhere else for the logic chip that's under the heatsink on the board.

[lotas]

TM3xxx - TMI3253

The output voltage of the microcircuit (Vout) depends only on the ratio of the values of resistors R2 and R3 and is determined by the formula: Vout = Vfb • (1 + R2/R3), where Vfb = 0.8 V.

[lotas]

What's wrong, it doesn't fit?

[redbaron1007]

I had some confusion at first because the first datasheet I found was for the TMI3253SH which has a different pinout, but I managed to find one for the TMI3253/S/T and that one has the same pinout as your attached image. I think it's the right one for the job, but I won't know for certain until I get the ones I ordered from aliexpress in and can install them.

What really sucks is I swear I have a spare board for this monitor somewhere in all my parts boards that has the part I need on it I just can't locate it.

I do appreciate the help and I'll try to remember to report back if it's the right part or if there's any other problems when the parts come in.

[redbaron1007]

I got the TMI3253 I ordered from LCSC today and popped one into the main board and it fired right up without any issues. Thanks for all the help finding the correct chip.

I would love to know what actually killed it in the first place, but I'm just going to have to assume low quality display circuitry failing prematurely or bad luck of the draw for that part in general.