bk304
Member
Last Activity: 04-15-2025, 08:22 AM
Joined: 01-27-2025
Location: Silver Spring, Maryland
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I gave up. I determined that the short is in the 5V circuit. I removed the PD chip and the 5V regulator. I injected 5V and cranked up the current and nothing much happened. I found one part of a trace on the circuit board that showed up on the thermal image. I could not find any other component that stood out. Usually it's a cap, a diode, or a MOSFET. That would be easy to fix. I don't want to put anymore time into this one. I made a copy of the BIOS if someone needs it. -
I will try and replace mine too. I will let you know what happens. One odd thing; I tried to read the BIOS chip and I couldn't. My programmer acts like the BIOS chip is dead. I may have to try it off board.Leave a comment:
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I should have done this first. I measured the resistance to ground of the 20V bus on the USBC connectors. The 20V buss connection on USBC1 measured about 9 Ohms to ground. The 20V buss connection on USBC2 measured about 229k Ohms to ground. Using a bench supply, I applied 6V to the 20V buss on USBC1 and turned up the current until it reached 6V @ 0.9A. The TPS65994AD USB PD controller chip got blistering hot as shown in the thermal image. I guess that is the problem....
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Here is the photo. I don't think it says much becuase anywhere I measure +5_ALW shows similary results. This measurement was done on UI3. I am not sure what to do next. This circuit has so many protections that I can't tell what is shutting down what....
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My meter does both autoranging and manual. I am using a Keysight 34461A and nulling out the probe resistance. I can send a photo of the meter face tomorrow.Leave a comment:
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Between pins 2 (GND) and 5 the resistance is .087 Ohms. Pin 1 shows about 3.5 MOhms to gnd.Leave a comment:
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I don't want to hijack this thread, but could [B][URL="https://www.badcaps.net/member/605098-btubbs200"]BTubbs200[/URL][/B] check to see if there is a short in their board between ground and pin 5 of UI3?
Thanks for the partial schematic.I don't want to hijack this thread, but could [B][URL="https://www.badcaps.net/member/605098-btubbs200"]BTubbs200[/URL][/B] check to see if there is a short in their board between ground and pin 5 of UI3?
Thanks for the partial schematic.I don't want to hijack this thread, but could [B][URL="https://www.badcaps.net/member/605098-btubbs200"]BTubbs200[/URL][/B]Leave a comment:
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On my 5420, plugging the original charger into USBC-1 shuts down the charger. Using USBC-2, it only goes to 5V. I am using the LA-K371P schematic because the LA-K491P schematic is not available easily. SCRIBD has it but there a too many hoops to go through to get it. The LA-K371P schematic is close but not exactly the same.
After some poking around I found that the 5V rail is not not working. I disconnected the solder jumper PJP4 and USBC-1 no longer shuts down the charger but still only went to 5V on the input. Measuring resistance on both sides of the open PJP4 showed a short on...Leave a comment:
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Did you get anywhere with this? I have a similar problem with a 5420.Leave a comment:
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From the part number you give, it looks like an SOP16 package. If it is a 16 pin chip, you need the SOP16 adapter.Leave a comment:
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Thank you very much. It worked perfectly.Leave a comment:
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Just to clarify; Do you mean no problem programming a 25R256JV as a 25Q256JV?Leave a comment:
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Dell Precision 3560 BIOS programming
I am working on a Dell precision 3560 with a locked BIOS. I used AsProgrammer software with the CH341A v1.7 set at 3.3V. AsProgrammer is the only software that works with the CH341A that lists the W25R256JV. Reading the 25R256JV with this setup returned garbage results. I switched to my T48 programmer and it identified the chip as a 25Q256JV and appeared to read the chip perfectly.
I need to reprogram the chip but I am not sure if the programming the 25R256JV with the 25Q256JV setting will work. I don't want to risk bricking the computer.
Anybody have any experience or... -
Need Intel D945GTP schematic
I need the schematic for an Intel D945GTP desktop motherboard. Anybody have this? I have the manual for the board but it does not include a schematic. The one I have does not POST. If it matters, this is in an oscilloscope. -
Dumping BIOS contents
Hello All,
This is my first post. Please let me know if I am posting in the wrong place.
Is there a way of dumping BIOS contents without hooking up to the chip? I have seen an older program that does this but it would not run on Windows 11. I don't know if this is something that only works on legacy bios or can also work in Windows UEFI.... -
I just joined. I am interested in radio, test equipment, and computer repair.Leave a comment:
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