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It does sound like a similar problem. IF it's a diode packe issue, the shorted diode pack gets very hot (be careful not to burn your fingers!), At least it did in my case. You could do some voltage measurements on the PS rails first, just to be sure. Good luck
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Correct #17 stated ESD7004 as an option, I got that and it didn't work. I used the uClamp6514P and that worked fine. System does work without anything stuffed in that location, but I wanted to restore to original factory - bad quality design ...
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ESD7004 Does not work. We need a bidirectional TVS - I tried uClamp6514P does work!
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Confirming that uClamp 6514P works fine to replace the defective IC. ESD7004 (non-bidirectional) DOES NOT work.
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I guess the 6514P is bidirectional and the one I used is unidirectional? Can't think of why else it wouldn't have worked. Can't imagine they just added clamping diodes just because. The fact they failed, tells me these are taking heavy hits, so running without them may not be very smart - I'm guessing [ATTACH=JSON]{"data-align":"none","data-size":"full","title":"ESD7004.jpg","data-attachmentid":3168547}[/ATTACH]...
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I used OnSemi part SZESD7004 and that Did not work. I guess the 6514p seems to have an additional diode on the 3,8 pins.. maybe that's the difference? Anyway I have those on order, just now sure why the OnSemi parts didn't work.Last edited by jason123; 12-26-2023, 05:09 PM.
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Re: Samsung SyncMaster T24B350
Final Update: Ok, got the regulator, put it onboard, and voila, 3.3 is present. However, board still not turning on, and SOT23 is warmer than I'd like to see. Lifted the pins as in #35, no luck, still 31.5 Ohm across 3.3 and GND. Removed all caps on the line that I could see. Still 31.5 Ohm. Removed both memory chips on board - still no change.. at this point, board is throw away, so I removed the Big BGA / Processor and there it is. Must have had shorted pins or internal chip issue ... impedance now is 684 kOhm across the LDO (3.3 and GND) and the...Last edited by jason123; 11-01-2023, 11:27 AM.
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Re: Samsung SyncMaster T24B350
Not sure if we can assume with power (3.3 V present) that 30 Ohm will result in 110 mA usage and that's 0.363 W for standby usage? (in addition to PS standby current?)
Anyway, LDOs are on order. and I don't know where the leakage is to get the 30 ohm. I see quite few ceramic caps, and one can be semi shorted, but not sure how to detect as ESR doesn't seem to catch them all.
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Re: Samsung SyncMaster T24B350
I did comnect the on-board 3.3v to this node while regulator still on. No damage or overheating
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Re: Samsung SyncMaster T24B350
Prepping the board - removed the regulator, and it looks like the 3.3 pin was barely hanging in there. But I measured the impedance between GND and 3.3 V node, and it's only ~30 Ohm.. is that right? I guess 3.3/30 is about 110 mA, but it seems very low.
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Re: Samsung SyncMaster T24B350
Sorry, I didn't understand: Yes, and you can solder some kind of 1117 33 to check on short wires.
Do you mean I use high output current device to test and see how much the 3.3 V node is drawing??...Last edited by jason123; 10-24-2023, 02:48 PM.
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Re: Samsung SyncMaster T24B350
Thanks I searched for that marking and came up with NPN.
Any idea what part number that is? it does seem that the regulator is bad, correct?...
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Re: Samsung SyncMaster T24B350
Ok.. Quick Update. All videos, though not in english, implied the little transistor gets +5.2 V from the board and generates the Mem_VCC. However, upon running continuity check the MEM_VCC comes from Standby Voltage from the PS board!!!! I was not providing that, I was simply providing +5V, +11.9V, and GND.
Now with +5, STB(+5) and 11.9V with GND, the little transistor is getting 5V, but still the bottom right (Mem_VCC) is only coming to +.9 V. I don't know how that 3.3 is supposed to be generated. Looks like one trace goes to CPU, and...Last edited by jason123; 10-24-2023, 02:11 PM.
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Re: Samsung SyncMaster T24B350
Thanks.. I can't understand Hindi, but I think my board checks out except for the Memory Chips VCC.
I found this video of a board with very similar problem to mine. But I'm not sure how he fixed it.
[url]https://www.youtube.com/watch?v=iJQIbeiXhsg[/url]
My transistor (NPN I believe is getting 0.39 V on top pin, then 0.823 V (same as VCC on memory) on bottom right, and about 0 V on bottom left. I don't know why it's not getting 5 V on top pin??Re: Samsung SyncMaster T24B350<br />...anks.. I can't...Last edited by jason123; 10-24-2023, 12:48 PM.
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Re: Samsung SyncMaster T24B350
ATMLH208
2GB 1
1H1109
Another note: This morning when I powered up the board (applying +5V and 11.8 V and GND), the voltage at the VCC pins were 0.448 V... then when the board warmed up, it went up to 0.823 V
I momentarily applied 3.3 V (from a switcher on the board) to the VCC pins of these Flash / mem.. and the voltage held (meaning, it's not really low impedance on these nodes, simply the source is not able to drive 3.3v?)...
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Re: Samsung SyncMaster T24B350
You're correct - Pin 2 of this IC is reading 0.8 V
This pin is tied to Pin 1 of the same IC. And that's connected to Pin 8 of the adjacent IC (ATMLH208) - I can't find a datasheet for that IC!
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Re: Samsung SyncMaster T24B350
Did a reflow on the processor - no luck. Touch up many solder joints, still. I noticed that the Flash chip (with sticker) is not getting power on pin 8. From datasheet, VCC is supposed to be in the ~3V range and I'm getting 0.8 V
Lifted the pin (to see if that chip is shorted) but pad was still 0.8V. Anyone with a schematic for this board? Thank you
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Re: Vizio P65-E1 No Activities - Voltages oK
TV is up and running again. Fresh thermal paste, full clean.
Hope this is helpful to someone - Thank you...
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