I have an a2141 missing pp5v_g3s. 5v on ammeter and 1.6 amps. one port occasionally will negotiate 20v but still no power. I am stuck
-
-
Re: 820-01700 No Power, 5v rail missing
What is the history of this unit ? Liquid damage ?
pp5v_g3s is generated by U7650.
Remove all power (no adapter / no battery).
Meter in resistance mode (2k scale is ok).
Check the resistance to ground of pp5v_g3s (L7600 pin #1 or #2 - red meter lead; black to shield ground).
What is the resistance reading ? If it is low, then you may have a bad cap on this leg of the power rail. If not a low resistance, need to check if U7650 is being enabled.
Check the voltage of U7650, pin # 4 (P5VG3S_EN_R) -
Re: 820-01700 No Power, 5v rail missing
history:
cx came in with a no power device. claimed it was left in subzero temps overnight in a motorhome. When he retrieved it in the morning, He dropped it in the snow. device presented with minimal corrosion, only visible corrosion was on C6455, PPBUS_G3h_SPKRAMPL. I tested the resistance to ground after cleaning and it was in the milliohms.Comment
-
Re: 820-01700 No Power, 5v rail missing
checking voltages now as resistance is in the milliohms. thanks for the tips, Ill post back if lost. I'm also going to pull that one corroded cap as my g3h voltage is 12.3 not 12.6. not sure it is enough but im ruling out a parital shortComment
-
Re: 820-01700 No Power, 5v rail missing
enable voltage is missing.Comment
-
Re: 820-01700 No Power, 5v rail missing
Am i looking at a U7800 issue here?Comment
-
Re: 820-01700 No Power, 5v rail missing
Check for the voltage @ R7691, pin #1.
See attached.Attached FilesComment
-
-
Re: 820-01700 No Power, 5v rail missing
Well something has changed, my ammeter is now looping at im getting pulses of 3.3v at pin 1Comment
-
Re: 820-01700 No Power, 5v rail missing
But you do not see this pulsing @ R7691, pin #2 ?
If not, remove R7691 and apply a solder blob to short pin #1 & #2 pads for this device. It is only a 0 ohm resistor - acting much like a fuse.
Perhaps corrosion ate away on this part.Comment
-
Re: 820-01700 No Power, 5v rail missing
UB000 and I assume the cd3217 on the underside are now heating up.Comment
-
Re: 820-01700 No Power, 5v rail missing
I see the same pulsing on both sides of r7691Comment
-
Re: 820-01700 No Power, 5v rail missing
Too hot to touch or just warm ? The ACE controller(s) may be defective. Need to check the voltage of each LDO rail on each such controller.Comment
-
Re: 820-01700 No Power, 5v rail missing
hot to the touch. I will look into it. So check im getting the 3v3 and 1v5 LDO rails on each CD3217?Comment
-
Re: 820-01700 No Power, 5v rail missing
There are a number of power rails including 1v1 for the BMC communication interface (CCx).
Check each.
Louis also suggests to check each rail with no voltage but meter in diode mode. Red meter lead to ground; black meter lead to the pin to test.
Post the readings. His forum has known good diode values for the CD3215 devices.
Hot to touch often means a defective CD3215 / CD3217.Comment
-
Hi, I'm Daniel, and I'm new to the world of repairing motherboards.
I would like to create a table, or more likely a guideline about the voltage rails and their possible resistance rail.
I know that the motherboard design has a very big depend on the rail's resistance, but I would like to know what is the smallest value for a rail that can be acceptable. For example, I heard that some new gaming motherboards can have 0,5 Ohm resistance on the GPU rail, but on an older type, it could be a sign of a shorted GPU rail.
So, I generated a table with AI so I can... -
Sub: Missing enable on +5v sec pwr rail AMD Firepro D500-B/Mac Pro late 2013
Ref: 1/ MacPro6,1 Late 2013/A1481 MD878LL/A (3.5 GHz 6 Core Xeon E5-1650v2)
Gfx-B: APN: 661-7548 PPN: 820-3533-A AMD FirePro D500-B 3GB Vmem
2/ Figure 1 Gfx-D500-B Front Facing
3/ Figure 2 +5v supply (zoom-in)
Intro:
While troubleshooting a Mac Pro(6,1) referenced above I discovered the +5v secondary supply did not stand up on the D500-B graphics card as a result of a missing enable signal. The +3.3v secondary rail was the only rail that did standup. I tried to perform...12-07-2023, 09:55 PM -
I am trying to repair my Samsung Chromebook Pro. There is no boot. Upon turning on, the screen is blank and there is no backlight. Power LED is blue. I tried refresh with power and esc refresh with power with no avail.
When I measure the 1.2V rail, it is pulsing. It will jump from 0 to 1.2V then 0 again. I replaced the 2 MOSFET and even power management IC and it is the same. Resistance from midpoint between mosfet to ground is 0.5 kOhm but it will show 250 Ohm first before jumping to 0.5 kOhm. So it feels like it was charging up some capacitor. Since MOSFET and IC was replaced, I... -
Hello everyone, i have zotac gtx 1060 3gb, and it has missing one rail. I think its 1v but I'm not sure. This rail has 34 Ohms, but after test on on my testbench, it drops to 2ohm, after some time it back to 34 Ohms. Next to this coil is up1727q. And there are 3,3 on vin pin and 5v on vdd pin. I changed this chip with another one but it didnt help. When i tried Short circuit test, core didnt heat up so maybe its still alive. I dont have thermal camera :/. I dont have boardview and schemstic for this GPU too. What should i check next? Or maybe its just dead core? -
Hello All
Have a Surface pro 5. Main board model; M1007506-015. Main 15v power rail is present.
1st image;
Missing 8v rail at inductor (circled in blue). Suspect main cause is power is being drawn at dead short on C4517.
2nd image;
3.3v rail was measured at 0.17v (at top most capacitor with red cross in 1st image).
Capactors crossed out in red are shorted.
Are the 5v and 3.3V rails tied in somehow e.g. generated at a single IC?
2nd and 3rd image;
C4517 circled in red is shorted at pin...
Comment