I would like someone to tell me how to use a DMM to measure vrm voltage and cap voltage. Thanks ahead of time
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Re: how measuring voltage to caps and vrms
From the positive lead of the cap (i.e. backside of mobo) to any ground
From the (usually) middle leg of a MOSFET to ground, or more properly from the coil to ground...
Be caruful, if you short anythinng out bad things will happen, you could for example send +12v into the CPU..."The one who says it cannot be done should never interrupt the one who is doing it." -
Re: how measuring voltage to caps and vrms
Yeah i think that could have happened to me at one stage... although it was momentary. How else could it have jumped to 93C from 31 in about 150ms?Originally posted by Per HanssonComment
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Re: how measuring voltage to caps and vrms
If you sent +12v into the CPU it would fry
A jumping temp is nothing too unusual, might just have been an incorrect reading from the tempsensor (which is fairly inaccurate to begin with)"The one who says it cannot be done should never interrupt the one who is doing it."Comment
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I know I've been a little scarce lately (like the last 2-3 years), but I'm still here and still doing my thing with fixing PSUs.
For today's considerations, I have a Seasonic B12 BC-550 [A551bcafh] 550 Watt ATX power supply for you (click on links for full size images).
https://www.badcaps.net/filedata/fetch?id=3591771
https://www.badcaps.net/filedata/fetch?id=3591772
It's a modern ATX unit with fixed (non-modular) cables and an 80-plus bronze certificate. Here's the label:
https://www.badcaps.net/filedata/fetch?id=359177... -
I think this has been answered but I couldn't find the thread.
Someone asked me if it would harm a capacitor (10F [not a typo], 24v) if it was operated on nothing more than 12v.
So, I ask... Does it change any of the capacitor's characteristics/parameters/? in any way if it is never operated near rated voltage?
If operated for years at 1/2 rated voltage, does it accept full rated voltage like it would if it had always been operated at the higher voltage?
Or would it require reforming? -
Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Summary for TL-DR readers:
• Backlight is intermittent, may come on with TV boot or not. No flickering, never fails during TV on.
• Have obtained Samsung schematic & service documents - Can upload if helpful.
• Have read ALL applicable threads
• C1818 and CP820 replaced as low hanging fruit
• CN802 data taken for normal and failed BL operation. SUMMARY: Pin 2 - 5vDet = 3.52 @normal, 0.0 @BL fail. Pin 6 - EPWM = 1.631 @normal, 1.058 @BL fail.
• VCC pin (18) of PFC... -
Hello,
I have a laptop that isn't turning on. When I disassemble it and plug in the power connector with the pcb by itself, I can see with a thermal camera I bought that TPS51285A is the only thing getting hot.
So of course, the first thing I do is google the laptop model and the IC, and it just happens that I stumble upon a video by Northridgefix attempting to repair the exact same problem, only for it to catch on fire.
I thought that maybe I'd be lucky so I bought a 1285A, that came in as a 1285B. The only difference I can see between them is that the 1285B... -
Hi there, I currently have similar board with same problem. A2115 - 820-01779-3 (2020). New to Soldering and board diag.. We've located many shorted Caps using voltage injection and thermal.. This board is reading open circuit on Caps C7261-C7250 along with any other components on the PP12V_G3H_CPUCORE rail.. I however get no glowing component on the front or rear of the board.. Each of these Caps reads less than a V or Resistance when measuring directly across each one, and also beeps to ground on both sides on all of them.. This should be shorted correct? Is 1V-1.5V / 2A-5A injection to locate...
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