Re: troubleshooting TV SMPS sequence
ds3, ds5 and check those three 16V 1000uF caps. matter effect, unhook the 24V and the 12V, take your ohm meter and measure those two against GND. Probably the 12V almost measures a short.
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Re: troubleshooting TV SMPS sequence
I would suspect a shorted diode in the 12 volt section, ds3 or ds5.
The primary circuit is working fine because the +24v is at +20v. its only a bit low because somthing in the 12 volt section is causing it to be droping a bit.
I guess you could have a shorted cap. in the +12 circuit but I doubt it.
The area in blue is the primary that drives both the +24 and the +12 and is working fine.
The area in green is working although a bit low. the area in red is where your problem is. (unless there is something connected to the +12 that is loading it down) but it does not look like it if you disconected con3 and it was still low.Attached FilesLast edited by R_J; 01-28-2016, 01:17 PM.Leave a comment:
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Re: troubleshooting TV SMPS sequence
thanks Capleaker. I did remove the cables from conn3, no load from TV set. still had lower voltages at the pin outs on conn3 of the PS for +12 and +24. I just can't get to the next logical step in the flow of troubleshooting it further.
ilikesteelLeave a comment:
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Re: troubleshooting TV SMPS sequence
Look at a different way: What could be dragging the 12V down so bad?
I would disconnect everything from the PSU and force the PSU on by itself, then check the secondary voltages again. Maybe resurrect the previous thread again.Leave a comment:
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troubleshooting TV SMPS sequence
I posted a problem with an RCA L37WD12 TV awhile ago. It's definitely has a PS problem. I've followed a logical sequence of troubleshooting and now I've run into a dilemma. I'd like to troubleshoot the problem further. here's where I'm at:
1. standby 5V good, standby LED on red.
2. PWR-ON works, PS gets AC applied to main PS, led flashes green continuously.
3. the output voltages should be +24V and +12V. the output is actually +20V and +2V respectively.
4. checked across main cap 180uf, 400V, I get 360 DC volts.
what is the next logical sequence to check voltages with DVM, I don't have access to a scope. I know there is the HOT side and COLD side with different ground references.
What would cause both DC supplies to be affected with low voltage output? that's where I need to get too.
Thanks again everyone. Budm was the last person I communicated with before the forum went off the air for about 10 days.
Thanks,
ilikesteel
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Hi all, I just need to know that, can i use SMPS type power supply to test and short circuit detection on a laptop motherboard?
I saw 95% of repair guys are using only Linear bench power supply. linear bench power supply is pricy, thats why i planned to get one SMPS supply.
i know that in linear power supply the noise will be very low comparing to SMPS supply.... -
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The switching controller is sg2525a, which I have replaced with a brand new sg3525a. The low and high mosfets are 1c27ac 6n50. The mosfet driver is IRS2301S.
Both mosfets were tested outside circuit with a component tester and seem to be fine.
With oscilloscope I see ~65khz switching signal on both low and high outputs of the controller, but on the output of the mosfet driver there is switchig signal only on the low output (flat line on the high output).
So I guess the mosfet driver is faulty?
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Hi all!
I'm trying to troubleshoot a Microsoft Surface Pro (5th gen) model 1796 that won't power on. Motherboard model is M1007506-015. My priority is retrieving data, but the SSD is integrated so it looks like if I can't repair it it'll need to go to a data recovery company. I've done a little basic board repair before, but nothing this advanced until now. So please forgive my ignorance in advance. 😅
I found the boardview for this laptop in the forums here, and am able to open it on my PC with FlexBV.
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Let me start from the beginning, the motherboard suddenly stopped working one day. There are no beep signals from the speaker, and the debug LEDs are not lighting up. After inspecting it under a microscope and using thermal imaging, I didn't find anything that could be damaged.
After that, I began voltage measurements, in which I noticed the absence of VDDQ, VDDP, VTT, and VPP lines. Later, I checked if there is an EN state on these lines,...
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