Many thanks for these two videos Richard. Although you didn't fix yours, the explanations given along with the demonstrations and safety precautions gave me the confidence to open up a failed PSU of mine. I built a lamp tester, but no isolation transformer yet. Followed my circuit and found that the PFC/PWM< controller (CM6805BSX) had a 1 volt VCC. Looks like the opto coupler is open circuit on the low power side :)
I have a 750w power supply that kicked the bucket recently, I just got an identical unit and will see if I can get the original working.. Learned a lot from these two videos!
Hi Richard just wanted to say out of all the repair channels I subscribe to yours is by far the most enjoyable. I am watching your subscribers growing daily and know that others will enjoy your teaching style. And yes this video was enjoyable as although it’s not fixed as yet it makes me think what could be the cause. Also robs comments on ring testing the inductor are interesting so that’s another thing I have learnt. Well done mate.
Thank you so much for your nice comments. Honestly, I'm humbled by the response I got to this channel. At first I just wanted to pass on some of my 'old tech' knowledge to other generations but now I find running LER is one of the most enjoyable things I have done. I keep looking for more interesting things to do, so there will be plenty more to come.
Good day. Thank you very much for taking the time to explain inductive reactance and circuits and drawing diagrams. Very informative and useful. You are appreciated.
I bought some 8 pin chips from Ali-express ICE2QR4765 for a 850w PSU, luckily I checked across VCC and GND before fitting, those pins were shorted. Glad I didn't just fit it. Another great vid cheers
After Been sure to have not any kind of short circuit, you can try to feed the psu directly avoiding lamp bulb. It seems that the psu trying to start but the current is limited from something. I already tried to fix a similar smps unfortunately without success.
Interesting video, thank you. If you are not sure about the FET's you could test them under load on the breadboard, also could you not test the Chip if you know all the required pin signals in and out? Maybe you can't find the correct data sheet for this device I'm not sure.
Hello. I have a tagan bz900 power supply, the structure and symptoms are the same as yours, the solution is to replace the Ps232, I bought it on aliexpres.
Hello Richard, Thank for your very informative videos. I have a PSU PC exibiting the same type of fault as the LER PSU you were working on. The 5v dc standby working and the green wire giving an output of about 3v dc. However when the psu tester is plugged in and the PSU powered up, immediately shuts dowm. Did you check the output of the Power Good output. On my PSU it is zero volts so that causes the PSU to completely shuts down. Hence, power good circuit needs checking/sorting out as to why that circuit does not ouput +5v dc that signals to switch the low side 5v, 3.3, +12v and -12v dc outputs on. Have you consider this state? A another video would be helpful to finally solve why this PSU is not turning on. Kindest regards John R.
@@LearnElectronicsRepair I love RUclips, just want all scripts and algorithms to know, best platform in the world, I just love it. (imagine if it gets taken down lol...)
Disconnect the Main power supply from the output of the PFC by removing the FETS in the main power supply and try to run the PFC on its own to check the PFC operation first . The PFC output voltage appeared to be low . One chip controlling PFC and Main power supply - a questionable design !
Brother, did you make a separate one bout the LAMP for PROTECTION? especially interested in knowing why LAMP is LOWER-POWER than LOAD and still PROTECTS-FULLY, does it matter having SEPARATION-TRANSFORMER or not ...
@@LearnElectronicsRepair an oscilloscope is all you need .connect one end of inductor to the calibration terminal on the oscilloscope and the other end to the input of the scope if there are no shorted turns you should see a big pulse followed by some smaller ones (rings)
@@robtitheridge9708 OK thanks. I do know about ring testers just never really needed one before. I know enough to know that it seems a possible cause of the fault on this PSU. I also found a few projects to build a ring tester from discrete components, with coloured LED output (for those who don't have access to an oscilloscope). I'll research a few options and look to put a #LER video together on the topic. Thanks Rob.
Hello Rob, could you please elaborate this further a bit? How exactly I can test inductor with scope? Where should I connect to? I have tried to follow instructions and I get exactly same signal like on input of inductor. 5V 1kHz square wave
@@LearnElectronicsRepair I do not have a Scope so can you to this test ? Take SMPS power supply remove Y caps that go from neutral to ground on the hot side. This removes ~110V from the power supply case. The myth is this makes PSU ripple to rise, or produces interference in the output. Can you test this?
Hello, I haVvw an 1600W chinese PSU. It has Surma written on it as a brand. suddenly it stopped. The MOBO fan works but. the mobo. light does not show nor the a picture. I replaced the PSU and the mobo worked fine. I measured all the voltages of the 24 pin connector by shorting pin 4-5 and all voltages are OK except pin 8 - PWR_OK gives 0.03 volt. I am aware of GPU repair a bit but this is the first time I open a PSU. Any ideas where shall start my diagnosis? if you have an email I can send you a pic of the PCB. Thanks in advance :)
@Wael Elkholi Come over to the discord server - I set it up so w ecan all get together and help with repairs Learn Electronics Repair is now on Discord! Come and join the fun, it's free. discord.gg/vam6YC8vwU
Hello I have a 1600 watt power supply that is not outputting 5V from pin8 (PGO) of ST9S313 ( which is a PC POWER SUPPLY SUPERVISOR ) . All other voltages of the 24 pin connector are ok. I can not get the IC or equivalent, can I just bridge 5v from anywhere on the board to this pin ( it is pin5 on ( the grey wire ) on the 24 pin connector. I have found ST9S313 equivalents and datasheet. The equivalents are 1. HY510N WT7510 ST9S313 PS113 RT7501. Thank you in advance.
It would be better to try and trace the fault to be honest. Some cheap ATX simply connect PG to the 5V supply and that does work in many cases but that does not properly meet the ATX specification and may not work with some motherboards - there should be a delay of some milliseconds between the main voltages coming up and PG going high. If you have continuity from the grey wire to power good output of the supervisor IC, try changing the IC if they are cheap and easy to get
@@LearnElectronicsRepair I have traced the PGO to the power supervisory chip ST9S313 and chechecked all its inputs. Allok but PGI. I can not trace PGI because the baiard is very tight and I have worked with PSUs before. I am afraid of the cap voltages. There are some huge caps there :) I need a schematic to know where PGI comes from. or at least the chip typical circuit. in the datasheet they have a typical circuit but does not show where PGI comes from. all of these are equivalent from my search 1. HY510N WT7510 ST9S313 PS113 RT7501
First thing - make sure you have a proper load on 3.3V before testing - a 2 ohm 10W resistor is a good choice. A lot of PSU use the 3.3V rail to regulate all the voltages and it can't reduce the voltage on 3.3V if nothing is loading it.
@@carlopasswords7083 This is exactly what I was trying to say. So you connect two hard drives - therefore the ATX PSU has to generate more power to run those hard drives - that makes sense yes? When the PSU generates more power it does so on all the voltage rails including 3.3V because there is only one SMPS transformer generating 12V, 5V, 3.3V and -12V. It can't generate more power on one voltage and not on the others. Also makes sense yep? The hard drives do not draw any power from 3.3V I don't care that the orange wires may go the the SATA power connector, the HDD does not use it at all. So what happens to the extra power going intothe 3.3V supply? Well if there is no load it charges up the capacitors on 3.3V to a higher voltage, yes? Try putting a load on 3.3V - a 2 ohm power 10W resistor would be ideal, but if you don;t have one try wiring 10x 22 ohm standard 0.5W resistors in parallel - or even 20x 47 ohm 0.25W - whatever you have. I think then you will find 3.3V stays stable when you connect your hard drives 😉
You might find the following useful: ruclips.net/video/-LjmvUvJNsA/видео.html. It is a walk through the schematics of FSP350-60APN that features the same controller and supervisor IC. Hope this helps in your quest.
You keep saying same thing about hot ground. Half main voltage. But that is not true. Not sure where you get it. Negative voltage is just voltage in opposite way. And diode bridge will make sure you have nothing on negative side. That teachings you are following was wrong.
Yama 007 Yeah I did mention, I am sure, that in the early 80s when I took my qualifications, my instructor said that they called it 'half mains voltage' but really they meant all of the mains voltage half of the time. This is where i get it from This was on CRT TVs, with an early 'switchmode' type PSU called a 'chopper' working at mains frequency or a SYCLOPS working at 15.625 KHz for PAL TV - See SYnchronous Converter and Line OutPut Stage = syclops So as you correctly say the chassis is connected to the mains by the bridge rectifier diodes. Therefore half of the time (one half cycle) the chassis is connected to live. The other half of the time (other half cycle) it is connected to neutral. Have you ever measured the voltage between chassis (hot ground) and earth ground, in countries like the UK where they have polarised earthed mains plugs and Neutral is connected to ground at the substation? It reads half mains voltage for the reason I just mentioned.
With AC you have positive on one end and on second half cycle it is on other end. And just 50/60 times per second (Hertz). So diodes which are working only in one way (from positive to negative) give you only one output. Meaning everything on positive end and nothing on negative end. Therefore it is called DC. But back to your question. To our houses (not flats) in village we are getting 4 wires (3phases plus neutral). Grounding is done with neutral. And of course you better measure it so are you sure you have proper grounding of your house and there is none voltage on it. Those with 1 phase in the house/flat were also creating ground by connecting it to the neutral. New rules says neutral and ground should be separated at circuit end so you can involve RCD (residual current device). Electrical safety device that quickly breaks an electrical circuit with leakage current to ground. I'm quite sure you know it. In Slovakia it is mandatory to use those devices when you are building electricity in your house. So technically if you get DMM and try to measure voltage between phase (hot) and ground you measure nothing. Beacuse this device with catch it and immediately breaks circuit. Therefore what you are saying about hot ground....it simply cannot happen. Once your device is properly grounded...you are safe.
@@yama007 Yes but no but.... In the instance I was quoting the TV set had a floating chassis, not grounded, and not connected to Neutral - in other words hot ground. This was in the days before SCART sockets and video recorders/home computers of course In modern equipment yes the device is usually grounded, but the hot ground in the SMPS - before the galvanic isolation of the SMPS transformers - will measure around half mains voltage between hot ground and safety ground. I'll demonstrate that some time on a future video. It is true that an RCD will trip off the power if there is a difference in current between live and neutral conductors (so therefore the differential current is flowing to earth) but that does not mean the differential current will not give you a shock if it is flowing via your body, though the RCD may well trip out depending exactly how much current is flowing that way. The only ways to make hot ground 'safe' to touch are either isolate yourself from ground and don't touch anything grounded, or the safer way, use a mains isolation transformer, then you can touch either one of the mains conductors safely (but not both at the same time) as whichever one you touch will effectively be grounded through your body and become the neutral conductor
@@LearnElectronicsRepair Yes. Transformer is a bit different story. Therefore i was mentioning things behind 4 diodes bridge. And i would like to see your video ;-) And own isolation (body resistance) is another topic. Initially i posted something...but i decided to delete it. I do not want to give people idea to test it.
Sir, you make this repair exciting. I'm looking forward to part 3. Keep digging 👍
Many thanks for these two videos Richard. Although you didn't fix yours, the explanations given along with the demonstrations and safety precautions gave me the confidence to open up a failed PSU of mine. I built a lamp tester, but no isolation transformer yet.
Followed my circuit and found that the PFC/PWM< controller (CM6805BSX) had a 1 volt VCC. Looks like the opto coupler is open circuit on the low power side :)
I have a 750w power supply that kicked the bucket recently, I just got an identical unit and will see if I can get the original working.. Learned a lot from these two videos!
Sorry for the “no fix”. Your a tough cookie. I gave up trying to repair SMPSs long ago.
Hi Richard just wanted to say out of all the repair channels I subscribe to yours is by far the most enjoyable. I am watching your subscribers growing daily and know that others will enjoy your teaching style. And yes this video was enjoyable as although it’s not fixed as yet it makes me think what could be the cause. Also robs comments on ring testing the inductor are interesting so that’s another thing I have learnt. Well done mate.
Thank you so much for your nice comments. Honestly, I'm humbled by the response I got to this channel.
At first I just wanted to pass on some of my 'old tech' knowledge to other generations but now I find running LER is one of the most enjoyable things I have done. I keep looking for more interesting things to do, so there will be plenty more to come.
Good day. Thank you very much for taking the time to explain inductive reactance and circuits and drawing diagrams. Very informative and useful. You are appreciated.
I bought some 8 pin chips from Ali-express ICE2QR4765 for a 850w PSU, luckily I checked across VCC and GND before fitting, those pins were shorted. Glad I didn't just fit it. Another great vid cheers
Heya, back on it and learning olso ordered some of the meters whits I did have thanks again
Great stuff!
Default sound level is too low. Cannot listen distinctly unless volume is set high.
Extremely good electronic repair videos. Thanks for sharing.
After Been sure to have not any kind of short circuit, you can try to feed the psu directly avoiding lamp bulb. It seems that the psu trying to start but the current is limited from something. I already tried to fix a similar smps unfortunately without success.
Interesting video, thank you.
If you are not sure about the FET's you could test them under load on the breadboard, also could you not test the Chip if you know all the required pin signals in and out?
Maybe you can't find the correct data sheet for this device I'm not sure.
please keep doing what you do .. very informative video tks a lot 👌👍
Sure thing!
Thanks a lot for the video. greetings from Turkey.
Welcome to LER!
Hello. I have a tagan bz900 power supply, the structure and symptoms are the same as yours, the solution is to replace the Ps232, I bought it on aliexpres.
Nice one
Hello Richard, Thank for your very informative videos.
I have a PSU PC exibiting the same type of fault as the LER PSU you were working on. The 5v dc standby working and the green wire giving an output of about 3v dc. However when the psu tester is plugged in and the PSU powered up, immediately shuts dowm. Did you check the output of the Power Good output. On my PSU it is zero volts so that causes the PSU to completely shuts down.
Hence, power good circuit needs checking/sorting out as to why that circuit does not ouput +5v dc that signals to switch the low side 5v, 3.3, +12v and -12v dc outputs on. Have you consider this state? A another video would be helpful to finally solve why this PSU is not turning on.
Kindest regards John R.
Interesting video, nice explanation of PFC too. You can find this chip elsewhere if you want to be sure btw
Yep. Bloody awful censorship this from YT and I don't even have a choice in it!
@@LearnElectronicsRepair I love RUclips, just want all scripts and algorithms to know, best platform in the world, I just love it.
(imagine if it gets taken down lol...)
Disconnect the Main power supply from the output of the PFC by removing the FETS in the main power supply and try to run the PFC on its own to check the PFC operation first . The PFC output voltage appeared to be low . One chip controlling PFC and Main power supply - a questionable design !
Brother,
did you make a separate one bout the LAMP for PROTECTION?
especially interested in knowing why LAMP is LOWER-POWER than LOAD and still PROTECTS-FULLY,
does it matter having SEPARATION-TRANSFORMER or not ...
Did you ever fix it as I can't find part 3 ?...cheers.
ruclips.net/video/UyS9rCtgoXQ/видео.html
can you not do a ring test on the PFC inductor to check for shorted turns?
Hi Rob
I don't have the test equipment to do a ring test. Maybe I could build something and make an interesting video too. Any suggestions?
@@LearnElectronicsRepair an oscilloscope is all you need .connect one end of inductor to the calibration terminal on the oscilloscope and the other end to the input of the scope if there are no shorted turns you should see a big pulse followed by some smaller ones (rings)
@@robtitheridge9708 OK thanks. I do know about ring testers just never really needed one before. I know enough to know that it seems a possible cause of the fault on this PSU.
I also found a few projects to build a ring tester from discrete components, with coloured LED output (for those who don't have access to an oscilloscope). I'll research a few options and look to put a #LER video together on the topic.
Thanks Rob.
Hello Rob, could you please elaborate this further a bit? How exactly I can test inductor with scope? Where should I connect to? I have tried to follow instructions and I get exactly same signal like on input of inductor. 5V 1kHz square wave
@@srpkovukovic try zooming in on the falling edge and increase the vertical gain.
set the scope to AC and trigger on falling edge
You need to repair that switch! lol
Thanks for great video
Glad you enjoyed it
@@LearnElectronicsRepair I do not have a Scope so can you to this test ?
Take SMPS power supply remove Y caps that go from neutral to ground on the hot side. This removes ~110V from the power supply case. The myth is this makes PSU ripple to rise, or produces interference in the output. Can you test this?
i.postimg.cc/SNHpbnX9/safe-psu.png
liteon_pa-1121_04
i.postimg.cc/g0H9h4gy/unsafe-psu.jpg
@@juliusvalentinas I can give it a go when I get chance.
@@LearnElectronicsRepair "I can give it a go" - thank you.
if using 2 bulbs whether in parallel or series?
Lcd power supplies are also ATX power supplies ?
Hello, do you kn ow where i can gbet the datasheet for this chip " ST9S313-DAG " . Thank you
thanks a lot sir...
hello from pakistan
Hi, and welcome to LER
Was this issue resolved ?
Hello, I haVvw an 1600W chinese PSU. It has Surma written on it as a brand. suddenly it stopped. The MOBO fan works but. the mobo. light does not show nor the a picture. I replaced the PSU and the mobo worked fine. I measured all the voltages of the 24 pin connector by shorting pin 4-5 and all voltages are OK except pin 8 - PWR_OK gives 0.03 volt. I am aware of GPU repair a bit but this is the first time I open a PSU. Any ideas where shall start my diagnosis? if you have an email I can send you a pic of the PCB. Thanks in advance :)
@Wael Elkholi Come over to the discord server - I set it up so w ecan all get together and help with repairs
Learn Electronics Repair is now on Discord! Come and join the fun, it's free.
discord.gg/vam6YC8vwU
Hello
I have a 1600 watt power supply that is not outputting 5V from pin8 (PGO) of ST9S313 ( which is a PC POWER SUPPLY SUPERVISOR ) . All other voltages of the 24 pin connector are ok.
I can not get the IC or equivalent, can I just bridge 5v from anywhere on the board to this pin ( it is pin5 on ( the grey wire ) on the 24 pin connector.
I have found ST9S313 equivalents and datasheet. The equivalents are 1. HY510N WT7510 ST9S313 PS113 RT7501. Thank you in advance.
It would be better to try and trace the fault to be honest. Some cheap ATX simply connect PG to the 5V supply and that does work in many cases but that does not properly meet the ATX specification and may not work with some motherboards - there should be a delay of some milliseconds between the main voltages coming up and PG going high. If you have continuity from the grey wire to power good output of the supervisor IC, try changing the IC if they are cheap and easy to get
@@LearnElectronicsRepair I have traced the PGO to the power supervisory chip ST9S313 and chechecked all its inputs. Allok but PGI. I can not trace PGI because the baiard is very tight and I have worked with PSUs before. I am afraid of the cap voltages. There are some huge caps there :) I need a schematic to know where PGI comes from. or at least the chip typical circuit. in the datasheet they have a typical circuit but does not show where PGI comes from. all of these are equivalent from my search 1. HY510N WT7510 ST9S313 PS113 RT7501
Hi sir, any news about this PSU problem/solution'
Thumbs up done sir can you make a diagram of main power supply and their. following output voltage sir
I often do that sort of thing during repairs - just keep watching the videos :D
Dear,
I have problem my 3.3v go up to 3.7v, which can be a problem
?
Thanks!
First thing - make sure you have a proper load on 3.3V before testing - a 2 ohm 10W resistor is a good choice. A lot of PSU use the 3.3V rail to regulate all the voltages and it can't reduce the voltage on 3.3V if nothing is loading it.
@@LearnElectronicsRepair I see the 3.3v go up to 3.7v when i connect 2 hard disk. I'll check
! Thanks
@@carlopasswords7083 This is exactly what I was trying to say.
So you connect two hard drives - therefore the ATX PSU has to generate more power to run those hard drives - that makes sense yes?
When the PSU generates more power it does so on all the voltage rails including 3.3V because there is only one SMPS transformer generating 12V, 5V, 3.3V and -12V. It can't generate more power on one voltage and not on the others. Also makes sense yep?
The hard drives do not draw any power from 3.3V I don't care that the orange wires may go the the SATA power connector, the HDD does not use it at all.
So what happens to the extra power going intothe 3.3V supply?
Well if there is no load it charges up the capacitors on 3.3V to a higher voltage, yes?
Try putting a load on 3.3V - a 2 ohm power 10W resistor would be ideal, but if you don;t have one try wiring 10x 22 ohm standard 0.5W resistors in parallel - or even 20x 47 ohm 0.25W - whatever you have.
I think then you will find 3.3V stays stable when you connect your hard drives 😉
@@LearnElectronicsRepair Thanks a lot !
You might find the following useful: ruclips.net/video/-LjmvUvJNsA/видео.html. It is a walk through the schematics of FSP350-60APN that features the same controller and supervisor IC. Hope this helps in your quest.
Big disappoint meant, watched all of the first, and now skimmed this one, still didn't fix it. Bummer
You keep saying same thing about hot ground. Half main voltage. But that is not true. Not sure where you get it. Negative voltage is just voltage in opposite way. And diode bridge will make sure you have nothing on negative side. That teachings you are following was wrong.
Yama 007
Yeah I did mention, I am sure, that in the early 80s when I took my qualifications, my instructor said that they called it 'half mains voltage' but really they meant all of the mains voltage half of the time. This is where i get it from
This was on CRT TVs, with an early 'switchmode' type PSU called a 'chopper' working at mains frequency or a SYCLOPS working at 15.625 KHz for PAL TV - See SYnchronous Converter and Line OutPut Stage = syclops
So as you correctly say the chassis is connected to the mains by the bridge rectifier diodes. Therefore half of the time (one half cycle) the chassis is connected to live. The other half of the time (other half cycle) it is connected to neutral.
Have you ever measured the voltage between chassis (hot ground) and earth ground, in countries like the UK where they have polarised earthed mains plugs and Neutral is connected to ground at the substation? It reads half mains voltage for the reason I just mentioned.
With AC you have positive on one end and on second half cycle it is on other end. And just 50/60 times per second (Hertz). So diodes which are working only in one way (from positive to negative) give you only one output. Meaning everything on positive end and nothing on negative end. Therefore it is called DC. But back to your question. To our houses (not flats) in village we are getting 4 wires (3phases plus neutral). Grounding is done with neutral. And of course you better measure it so are you sure you have proper grounding of your house and there is none voltage on it. Those with 1 phase in the house/flat were also creating ground by connecting it to the neutral. New rules says neutral and ground should be separated at circuit end so you can involve RCD (residual current device). Electrical safety device that quickly breaks an electrical circuit with leakage current to ground. I'm quite sure you know it. In Slovakia it is mandatory to use those devices when you are building electricity in your house. So technically if you get DMM and try to measure voltage between phase (hot) and ground you measure nothing. Beacuse this device with catch it and immediately breaks circuit. Therefore what you are saying about hot ground....it simply cannot happen. Once your device is properly grounded...you are safe.
@@yama007 Yes but no but.... In the instance I was quoting the TV set had a floating chassis, not grounded, and not connected to Neutral - in other words hot ground. This was in the days before SCART sockets and video recorders/home computers of course
In modern equipment yes the device is usually grounded, but the hot ground in the SMPS - before the galvanic isolation of the SMPS transformers - will measure around half mains voltage between hot ground and safety ground. I'll demonstrate that some time on a future video.
It is true that an RCD will trip off the power if there is a difference in current between live and neutral conductors (so therefore the differential current is flowing to earth) but that does not mean the differential current will not give you a shock if it is flowing via your body, though the RCD may well trip out depending exactly how much current is flowing that way.
The only ways to make hot ground 'safe' to touch are either isolate yourself from ground and don't touch anything grounded, or the safer way, use a mains isolation transformer, then you can touch either one of the mains conductors safely (but not both at the same time) as whichever one you touch will effectively be grounded through your body and become the neutral conductor
@@LearnElectronicsRepair Yes. Transformer is a bit different story. Therefore i was mentioning things behind 4 diodes bridge. And i would like to see your video ;-) And own isolation (body resistance) is another topic. Initially i posted something...but i decided to delete it. I do not want to give people idea to test it.
😠😠😠😠😠😠
Exploration good but too much length and too much wasted time please make short and clearly
are you drank..cant understand what your telling
Do you mean am I drunk? can't understand what *you're* spelling 😁
worst timing try to explain short time