I'm trying to replace C1469 and C1470, but the value for 1470 has these XX's as a value. Are these labeled that way because they are fine tuning capacitors? Should I just add one the same as the rest in the chain?
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\$\begingroup\$ are those caps near an optionally populated component? \$\endgroup\$– jsotolaCommented Sep 2, 2023 at 18:40
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2 Answers
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It could denote anything.
It could mean they are capacitors drawn just in case they are needed, and the circuit was determined not to need these caps so they can be left out from the circuit. So it might mean, "do not populate" or "do not assemble" when manufacturing.
It might mean the value is "to be determined" or "to be defined later" but was not updated to schematics.
It might also be any other error in drawing the schematics, selecting the components, or forgetting to actually replace the XXs with a correct value.
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\$\begingroup\$ Thanks for the answer. I definitely scraped a capacitor off that was populated at that point, so it's not the first scenario. Nothing in the schematic referenced them either. I read the whole thing. This is for a launch backwards compatible PS3, in case anyone was wondering. Maybe it was referencing different board revisions, as I know even on the outset they had quite a few variations. Like, if your board has a capacitor populated here, it belongs to this set. The last two scenarios you proposed could very well be the case also. Hmm... \$\endgroup\$– Derek VCommented Sep 2, 2023 at 10:04
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\$\begingroup\$ @DerekV The exact value might not actually matter too much. The schematic calls them bypass capacitors, and usually you can just use any old 100 nF capacitor for that--though if this is part of bypassing a CPU or other high-speed chip, you may need something smaller to be part of a decade bypass set. \$\endgroup\$– HearthCommented Sep 2, 2023 at 14:16
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\$\begingroup\$ I bought a little reel of 0.1u/10V capacitors from Mouser and have since mounted those values in both places, C1469 and C1470. Have not powered it up yet. I'm guessing this would allow too much voltage to leak to the CPU? (These capacitors are located right next to the Cell) May order another set of smaller value ones to replace C1470 and wait before doing a powered test. I have x4 100pF capacitors in my basket at Mouser now. Will see if anyone has more to say for a couple days before ordering. \$\endgroup\$– Derek VCommented Sep 2, 2023 at 19:21
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These are bypass capacitors (it says so at the top). usually this is not a critical choice. Find the data sheet for whatever parts are closes to the capacitors and see what value they recommend.
100nF is a popular choice.
If you look at how that diagram is arranged all the other capacitors on the bottom two lines are 100nF.
These XX were probably a 100nf capacitor that it was decided is not actually needed.
answered Sep 3, 2023 at 5:57
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\$\begingroup\$ Ordered the same as the neighboring ones listed on the schematic, hot air stationed them in and bingo!!! Back in business. Thank you all for the help!!! \$\endgroup\$– Derek VCommented Sep 5, 2023 at 1:01