nerdbombing Posted July 27, 2022 Author Report Share Posted July 27, 2022 1 hour ago, Prehistoricman said: That's a very useful video. Thank you! 1 hour ago, Prehistoricman said: Basically you have something short-circuited on the board. I agree, as I have pin 6 & 15 (5v & 3.3v) of the LPC showing continuity to ground. 1 hour ago, Prehistoricman said: The expert repair man at NorthridgeFix always diagnoses shorts by injecting voltage with a power supply and seeing what gets hot. I don't suppose you have a thermal camera? I'm familiar with the process but from Louis Rossmann. Unfortunately, I do not have a thermal cam.... They seem a little pricey for fixing for a $25 ebay purchase (I'm sure I could use it for something else too), but I'm not thinking of buying one yet. I'll see if any of my professional counterparts have one to loan, but I'm not holding my breath. I'll try to use my other 1.6 and see if I can probe around for differences to narrow it down, but that's a crap shoot. I wish I knew, maybe with a schematic, what the 5 and 3.3v traces feed to, etc. and track things down that way... Quote Link to comment Share on other sites More sharing options...
Cytraz Posted July 27, 2022 Report Share Posted July 27, 2022 I’ll try some of this stuff on my broken Xbox when I get home, but I gave up on mine for the most part. I just assume that I burnt the motherboard during the soldering process. I decided to splurge and buy a new one instead lol 1 Quote Link to comment Share on other sites More sharing options...
Prehistoricman Posted July 27, 2022 Report Share Posted July 27, 2022 4 hours ago, nerdbombing said: I agree, as I have pin 6 & 15 (5v & 3.3v) of the LPC showing continuity to ground. This is normal, depending on the multimeter. On my 1.6, measuring resistance of 5Vsb to ground shows it rising from 0 up to 150 ohms after about 6 seconds. That is the large capacitance charging up loaded down by everything on that rail. Meters have varying thresholds for what they consider continuity before bleeping. Exactly what resistance do you have to ground on those LPC pins? Quote Link to comment Share on other sites More sharing options...
nerdbombing Posted July 28, 2022 Author Report Share Posted July 28, 2022 8 hours ago, Prehistoricman said: This is normal, depending on the multimeter. On my 1.6, measuring resistance of 5Vsb to ground shows it rising from 0 up to 150 ohms after about 6 seconds. That is the large capacitance charging up loaded down by everything on that rail. Meters have varying thresholds for what they consider continuity before bleeping. Exactly what resistance do you have to ground on those LPC pins? I'll jump through more detail shortly. But I pulled my other 1.6 board out, and yes, those points at 6 & 15 LPC pins do 'cap out'. Whereas the bad board does not, it continually is grounded, i.e. bypassing a cap to charge up. Does anyone know what capacitors those 2 points go to? I'll see if I can film it again. But right quick I'm gonna take that PNP transistor back out, and see if anything changes. -Removing the transistor didn't change my grounding issue at 6 & 15. BTW, at 6 I have 4.5ohms, and at 15 I have 37ohms. For comparison, I have 4.5ohms between any given screw hole ground pad, so it's safe to say at least #5pin is fully grounded. I removed the (5) 3300uF 6.3v caps in front of the CPU just to make sure i wasn't dealing with a faulty one when I replaced them. But no change in results, with everything previously grounded remaining grounded. At this point, I lack enough knowledge and equipment to smartly proceed. But in the back of my head I'm thinking that I need to begin to remove components until the grounding in inappropriate locations ceases. Or maybe if anyone is interested in taking this board for further diagnosis, tinkering, and curiosity, PM me.... Quote Link to comment Share on other sites More sharing options...
Prehistoricman Posted July 28, 2022 Report Share Posted July 28, 2022 You can inject voltage, aiming for a decent power consumption like 5 watts, limited to 5 volts of course, and feel the board/chips with your hands. If you can't feel anything, increase current and keep going. Quote Link to comment Share on other sites More sharing options...
nerdbombing Posted July 28, 2022 Author Report Share Posted July 28, 2022 16 minutes ago, Prehistoricman said: You can inject voltage, aiming for a decent power consumption like 5 watts, limited to 5 volts of course, and feel the board/chips with your hands. If you can't feel anything, increase current and keep going. I was thinking about that the other day when we talked about thermal vision. So the PSU is turning off, overload or whatever, so the component wont get hot. I assume you're talking about using a bench power supply or something that will not 'turn off on safety'? Quote Link to comment Share on other sites More sharing options...
Prehistoricman Posted July 28, 2022 Report Share Posted July 28, 2022 20 minutes ago, nerdbombing said: I was thinking about that the other day when we talked about thermal vision. So the PSU is turning off, overload or whatever, so the component wont get hot. I assume you're talking about using a bench power supply or something that will not 'turn off on safety'? Yes 1 Quote Link to comment Share on other sites More sharing options...
Yoinx Posted July 28, 2022 Report Share Posted July 28, 2022 5 hours ago, Prehistoricman said: You can inject voltage, aiming for a decent power consumption like 5 watts, limited to 5 volts of course, and feel the board/chips with your hands. If you can't feel anything, increase current and keep going. That meter he has does temperature as well. I don't know what it's response rate to changes is, but he could take the temperature probe and touch it to various components. Time consuming, but doable. 1 Quote Link to comment Share on other sites More sharing options...
KaosEngineer Posted August 17, 2022 Report Share Posted August 17, 2022 On 7/10/2022 at 11:33 AM, KaosEngineer said: No, there's no such transistor on older revisions of the motherboard, only on v1.6s. (Edit: that may not quite be true, there are a lot of surface mount transistors in other areas on the Xbox motherboards so one of them may also be a PNP MMBT4403LT1G transistor.) I was wrong making that statement. There are in fact two such transistors on every v1.0-1.4 motherboard as well as on a v1.6 motherboard. They are the transistors used to drive the front panel EJECT ring's red and green LEDs. On v1.0/1.1 motherboards, they are found on the bottom side of the printed circuit board at the locations: Q2V1 and Q2V2 Edit: I've not looked at all the other motherboard revisions to know the exact locations of the two, 2A labeled, transistors on them. I suspect they are in the same general area next to the front panel connector. 1 Quote Link to comment Share on other sites More sharing options...
Slavik916 Posted January 28 Report Share Posted January 28 I saw this video on replacing the diode, but when you turn it on, the coolers spin and you can hear it, and if there is no reaction to the button at all... the power supply is in perfect order, the capacitors are also in order, the coils and resistors near the processor power supply are checked, everything is checked, well doesn’t want to turn on and that’s it. I even bridged the block to start it... it doesn’t want to and that’s it Quote Link to comment Share on other sites More sharing options...
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