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Re: Power supply for main amp blows fuses after replacing filter caps.
I want to add, when you test transistors on the board, it is better to remove these capacitors so that their large capacitance does not interfere with the measurement.Comment
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Re: Power supply for main amp blows fuses after replacing filter caps.
I had random popping sounds on all speaker channels. I have a post about it in this forum a week ago. When I re-flowed the original capacitors I saw some corrosion on one of the solder connections. I feared that the original caps had a leak so I replaced them.Comment
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Re: Power supply for main amp blows fuses after replacing filter caps.
Quick question. Can I use thermal pads instead of thermal paste/compound with the mica insulator? I can get these sooner than the new mica insulators.Comment
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Re: Power supply for main amp blows fuses after replacing filter caps.
While the tabs on the transistor measure out OK the plastic around the hole on the back has been damaged and can cause a short with the screw attached so I am going to replace it (again as that position is where the original transistor was shorted collector to editor. Just my luck). All other transistors test out OK. I should be getting the thermal pads tomorrow so I will post an update then. Again thanks for all of your help everyone.Last edited by acedogblast; 02-28-2023, 09:05 PM.Comment
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Re: Power supply for main amp blows fuses after replacing filter caps.
Thermal pads are installed and the AV receiver powers up but a problem that I think I solved is back. Whenever a loud sound is being played on the center channel the receiver goes into ASO protection mode. I think something is still wrong with the center channel on the main power amp.
The transistor that I have replaced twice now is properly a symptom of something else going on. I am going to create a new thread discussing this issue as the original issue for this tread is solved which is caused by not isolating the heat-sink from the power transistors.Comment
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Re: Power supply for main amp blows fuses after replacing filter caps.
not looked at protection but i guess it monitors dc offset and possibly overcurrent .it may be working as intended and the source might be the problemComment
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Re: Power supply for main amp blows fuses after replacing filter caps.
Or a bad filter in speaker.....Comment
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Hello everyone. 😀
As per thread title, this unit has a serious SMPSU fault. It blows F1001, which is a 10A M205 in the phase from the mains input.
Very first thing I tried, was simply replacing the fuse, but the replacement ceramic fuse blew immediately.
Looking at the schematic for this PSU, I then removed what I thought was the next likely candidate: D1001 - the HV main bridge rectifier.
This isolated the fault(no longer blows the main fuse), but does not point me to the actual fault.
There are no devices that have exploded or otherwise show signs... -
I suppose the real question is whether the existing pinouts from ether a 17IPS71 psu are cross compatible with a 17IPS12 psu? If they are then the exchange of the main boards should have no issues providing the screen is compatible with both main boards. Obviously you can change the screen configurations easily enough (providing you have the correct files) for the main board. Why may you ask would I do this? Well a lot of the smart features are no longer working on a Hitachi 48HBT62U main board I wish to give it a new lease of life!
Obviously the same LVDS connector for the screen connection... -
Hi and thanks in advance for any input you might provide!
I have a Sceptre U550CV-UMRD8POTV83BB 4K LED (this is a dumb tv) that I bought new in August 2021, so It's just completed 3 years.
Main power board model: TP.MS3683.PC821 T-Con board: N4TP546UHDPU2L_BO
Last Sunday I was watching a dvd and fell asleep for about half hour, when I awoke the tv screen was black and couldn't get the dvd menu to show, so I changed the input to antenna and had sound but no picture, turned it off. I then got online and found this great site! ....read many troubleshooting tips and this... -
Hello,
I picked this PSU 17PW15-8 from a friend's TV with a burnt fuse, after some days of rain and lightning strikes. The TV was on standby when it happened.
With new fuses it burns them as well. I checked bridge rectifier, all the TO220 components, diodes and basic caps, replaced IC806 SMPS, and FETS driving the big transformer. I also isolated the secondary circuit by cutting the rails of the FETs to the primary coils. I don't know even know if that makes sense, but I did in hopes to isolate the problem.
Any ideas what to look for?...
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