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I'm looking for assistance identifying this SOT-353 surface mount component with "AC" marked on top. This is on a Powersoft DSP board out of a Digimod audio amplifier. My understanding is that someone plugged the wrong thing into the output of this amp and let out the magic smoke. I'm attempting to repair the board and I want to be certain that I replace this component with the correct part.

Close-up of SOT-353 package with "AC" marking on top

There are several of them on the board and I've asked ChatGPT to try identifying it. GPT is convinced that it's "a single low-power rail-to-rail operational amplifier, LMV321 or equivalent" but I can't find any pictures or datasheets showing this package with this marking. But I'm not going to just take GPT's word for it.

Image showing multiple SOT-353 packages with "AC" marking on the same board

I actually have two of these boards, One is a good working board and the other had a couple larger blown OP-Amps that I replaced. After replacing the damaged parts I used a thermal camera to look at both boards when powered on and I noticed that the component in question gets much hotter on the damaged board compared to the good board. So that's why I'm trying to ID and replace it.

Two thermal images of two boards powered on. The top board is the good board with a green arrow pointing to the component in question, which does not show excessive heat. The bottom image is the bard being repaired. It has a red arrow pointing to the component in question which shows excessive heat compared to the good board.

I really appreciate any and all thoughts!

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  • \$\begingroup\$ dunderMethods - Hi, (a) I think the question just stayed the right side of the line this time, because we can ignore the ChatGPT part and it's still an allowed identification question. But in future, please make sure to stay well away from any question format which seems to be in the style of "{ChatGPT / Google Gemini / other genAI tool} says X, is that right?" for the reasons explained in this meta discussion. (b) Please see the tour & help center as site rules here differ from typical forums. Thanks and welcome. \$\endgroup\$ Commented Oct 25 at 0:10
  • \$\begingroup\$ dunderMethods - Hi again, (a) We don't put "solved" into Q&A. (b) It's too late to extend this question & add a follow-up here. We don't expect answer-writers to chase a moving target, and it's unfair to make existing answer(s) look wrong or incomplete by changing the question after they were written. These are some of the points of etiquette which come with the Q&A format on Stack Exchange: ask a specific question & get answers to that specific question. The question shouldn't change after answer(s) have been given to the original question, so I reversed that last edit. \$\endgroup\$ Commented Oct 25 at 23:39
  • \$\begingroup\$ (continued) Your new question needs to be asked as a separate, self-contained, standalone question - so include all necessary info there, but do also include a single link back to this question so readers who want to, can see the context. It is a more "risky" question, as it asks for speculation. I won't prejudge what response the question could get. I think the lack of knowing what happened and the lack of a schematic, won't help that repair-type question to be well-received :( \$\endgroup\$ Commented Oct 25 at 23:40
  • \$\begingroup\$ Understood. Sorry. And thanks. \$\endgroup\$ Commented Oct 26 at 1:10

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My guess is a 74AHC1G04GW inverter. (Or similar, but this NXP part number is associated with the AC code.)

  • Based on the package dimensions, that looks more like SOT-353 (SC-70-5).

  • ChatGPT's suggestion does not make sense; the LMV321 (like most opamps in this package) has its negative supply on pin 2, but there are clearly signal traces connected to pin 2 on all of the chips.

  • There are thick traces with multiple vias connected to pins 3 and 5, so these are likely the power pins.

  • There are also no traces connected to pin 1.

This all matches the 74AHC1G04GW (image from section 6 in the Nexperia 74AHC1G04; 74AHCT1G04 datasheet):

74AHC1G04GW pinout

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  • \$\begingroup\$ You're right! This is definitely not big enough to be a SOT-23, and I should have caught that but I just rolled with what chat GPT guessed. SMH. I'll update the post accordingly. For the record, I'm an ME, and a shade-tree EE ;) \$\endgroup\$ Commented Oct 24 at 23:53
  • \$\begingroup\$ The LCSC Nexperia 74AHC1G04GW,125 page has a picture of a device which matches the marking style in the question, so agree with this answer. \$\endgroup\$ Commented Oct 25 at 7:09
  • \$\begingroup\$ Well it looks like you nailed it and answered my question beautifully! Thank you so much!! \$\endgroup\$ Commented Oct 25 at 18:04

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