I happen to have those power supplies, just sitting here. The 2 pin connector on the secondary side is for voltage sensing, but not required for operation. Thank you for the video once again, very useful!
I think the schematic on the ASTEC doc is okay. The application schematic is on forward topology and the power supply is flyback. That small inductor at the output is just for some ripple rejection. If it was on forward conversion mode then it would have been a bigger inductor probably on a toroidal core or something. The feedback (error) amplifier output is probably not a push pull type. May be its open collector type with a pull up resistor. As the inverting input is connected to ground and non inv to 2.5v so it will keep the output at high level. In that case the opto coupler can easily drop it down to ground when TL431 triggers without causing any short circuir. That comparator (the error amp) is just like LM393 type output and bypassing the comparator will enhance the regulation time and transient response. I watched your video on mobile but it looks like the controller is similar to UC3842 type generic (or rebadged) controller and widely being used in the past.
Thanks for making these videos! I really need to invest in an isolation transformer or differential probe for my oscilloscope so I can make measurements on power supplies. Too many times I have just replaced the entire power supply, instead of component level repair.
Thanks for the video. I wonder how many electronic devices have been rendered imperative by bad electrolytic capacitors? I suppose even the best fail eventually? Seems we need a different component to do this work.
Looks like the winding for the switcher supply at 8:20 is drawn wrong also? The dot should be on the low side for it to work, shouldn't it? Yikes, and the transformer secondary is backwards too.
Mmm, huge Wilkinson dividers. It looks like there is an amplifier (8dB?) and a few filters on the board? It's 2-layer FR-4 board, causing the transmission lines to be somewhat thick?
Sorry, I completely neglected the RF part. If you are interested in that, have a look at this video about a similar unit by AudioTechnica: ua-cam.com/video/Ga0E2HHvPro/v-deo.html
I learn something new with every one of your videos, thanks!
Thanks, I enjoy these switchmode supply repairs, I’m not very good at repairing them so seeing more examples helps a lot.
I happen to have those power supplies, just sitting here. The 2 pin connector on the secondary side is for voltage sensing, but not required for operation. Thank you for the video once again, very useful!
This video is EXCELLENT! I enjoy all your vids so far but this one is exceptional.
I think the schematic on the ASTEC doc is okay. The application schematic is on forward topology and the power supply is flyback. That small inductor at the output is just for some ripple rejection. If it was on forward conversion mode then it would have been a bigger inductor probably on a toroidal core or something. The feedback (error) amplifier output is probably not a push pull type. May be its open collector type with a pull up resistor. As the inverting input is connected to ground and non inv to 2.5v so it will keep the output at high level. In that case the opto coupler can easily drop it down to ground when TL431 triggers without causing any short circuir. That comparator (the error amp) is just like LM393 type output and bypassing the comparator will enhance the regulation time and transient response. I watched your video on mobile but it looks like the controller is similar to UC3842 type generic (or rebadged) controller and widely being used in the past.
Thanks for making these videos! I really need to invest in an isolation transformer or differential probe for my oscilloscope so I can make measurements on power supplies. Too many times I have just replaced the entire power supply, instead of component level repair.
Thanks for the video. I wonder how many electronic devices have been rendered imperative by bad electrolytic capacitors? I suppose even the best fail eventually? Seems we need a different component to do this work.
nearly all compact cheap PSU's. Or mostly all SPMS.Nope. there is no really good alternative to electrolytic capacitors yet. But they need cooling.
Great repair video. Can you tell me where i can purchase one of those lcr meters please?
Looks like the winding for the switcher supply at 8:20 is drawn wrong also? The dot should be on the low side for it to work, shouldn't it? Yikes, and the transformer secondary is backwards too.
i don't see why would this matter.
woow. Thanks for the precious info.
Thanks for the video.
the tonghui LCR meter is good. I need LCR meter. is good choice the DEER E DE-5000?
Please help me. Thanks FeedbackLoop
Hello sir what is the problem 1 channel got static? Thanks
Mmm, huge Wilkinson dividers. It looks like there is an amplifier (8dB?) and a few filters on the board? It's 2-layer FR-4 board, causing the transmission lines to be somewhat thick?
Sorry, I completely neglected the RF part. If you are interested in that, have a look at this video about a similar unit by AudioTechnica: ua-cam.com/video/Ga0E2HHvPro/v-deo.html
@@feedback-loop Yes, was really looking forward to you going over the RF part. Thanks for the link, though.
Can you mod the frequency response of this unit as you did on the Audio Technica ATW-D70?
yes
hi, do you have the squematic for shure ur2 ?. My display not work
sorry, no skewmatic
Thanks for showing us how "easy" can be! Do you do this for a living?
What a crazy schematic. What a confusing layout.
First