momaka
-
I hate to say it, but I just cannot recommend either Windows 10 or 11 for old people. It's a tricky OS (yes I grouped both into singular thing, because they are) and there way too many things "going on" or try to regularly steal your focus from whatever you are doing. You can quiet it down a bit if you take the time to go through every single setting to disable everything that your mother may not have a use for (read: this may take you upwards of a few hours... which is exactly why I HATE setting up Win10/11). Alternatively, you could use something like Tiny 10 or Tiny 11 - a stripped-down...Last edited by momaka; 04-16-2025, 08:32 AM. -
Before anything else, first always try power supplies with a proper load. An old worthless Pentium 4 / Core 2 motherboard is usually good for this... though if you don't have that, a few 12V auto/car incandescent bulbs (20-40 Watt ratings) on the 12V and 5V rails are usually good enough too. The reason I suggest this is because I have seen this quite a few times where some PSUs won't start without a proper load. They simply "twitch the fans" and turn off.
So try the PSU with a proper load and let us know what happens then. If still the same symptoms, put your multimeter...Leave a comment:
-
If the PC worked fine before cleaning and not afterwards, then it is almost definitely NOT going to be a BIOS issue.
I suggest to O/P to double-check what he/she did.
As Dmill89 suggested, check if the CPU was possibly pulled out or partially puled out when changing the thermal compound. Better yet, re-seat it as suggested.
Also, what was the new thermal compound that was used? Anything conductive, like Arctic Silver 5 or anything from the category "liquid metal"?
On that note, even if non-conductive thermal compound was used, check to see if any...Leave a comment:
-
Ah, OK, sorry about the confusion on my part.
Well, given the symptoms (slight interference rolling lines) and the fact that you can make them go away when passing the signal through another device (DVD decoder) and that all of the VCRs exhibit it, perhaps might suggest that the units that show the interference might be more susceptible to line noise than the latter 2000's VCR that doesn't have this issue. Either that or perhaps the analog cables are poorly shielded, but the 2000's VCR might have some kind of extra filtering on the signal lines, clearing that interference up, whereas...Leave a comment:
-
Are you sure those "KZE" caps are not actually [b]KME[/b] series?
As far as I know, KZE wasn't around in the 90's yet... not sure if even KY series were.
KME, on the other hand, was quite popular in 90's equipment that used Japanese caps. These are the non-lead-free version of KMG... or rather, KMG is the lead-free version of KME, which are now obsolete and haven't been produced for probably over 2 decades. Same goes for SME and SMG - the latter is the lead-free series that replaced the former, which also were popular in the 90's (85C general-purpose caps.)
So if your...Leave a comment:
-
[B]Seasonic B12 BC-550 – recapped[/B]
Let's start the recap with hall-of-shame -worthy pictures of the Asia'X capacitors.
Ah, lovely!
Except for the two 50V 220 uF ones, all the other ones were completely out of spec, as seen above. Even the -12V rail cap, which is sitting [B]behind a linear regulator[/B] (LM7912) and does not see any stress or heat at all, still managed to fail on its own. I think that alone speaks volumes about the quality (or lack thereof) of Asia'X caps (particularly the TMX series.) Seasonic, if you are reading these, PLEASE drop...Last edited by momaka; 03-12-2025, 04:12 PM.Leave a comment:
-
Seasonic B12 BC-550 – barely 2 years old and with BAD CAPS already!
[FONT=Times New Roman][FONT=Arial]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.[/FONT][/FONT]
[FONT=Times New Roman][FONT=Arial]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).[/FONT][/FONT]
[ATTACH=JSON]{"data-align":"none","data-attachmentid":"3591771","data-size":"medium"}[/ATTACH]
[url]https://www.badcaps.net/filedata/fetch?id=3591771[/url]...Last edited by momaka; 03-12-2025, 03:48 PM. -
Well, there's not much math one needs to do when repairing these APFC circuits anyways.
The topology / method of operation is relatively simple and pretty much the same for every APFC circuit: the "boosting" MOSFET(s) (QP801S and QP802S in this case) turn ON, causing a certain current draw through the APFC inductor. When they turn off, the APFC inductor wants to continue "supplying" this same amount of current through it (since inductors don't like instantaneous changes in current), and it does this by pushing current through diode DP802 and into the primary bulk electrolytic...Leave a comment:
-
Jeez, why are all of the replies here so aggressive?! (Or at the very least, too direct & rude.)
[USER="617671"]smort[/USER] : I enjoyed reading your post here very much and curious to find out how you end up fixing this issue. It's not a "waste of time" if you're learning... and even more so, when you are posting your findings online so that others can learn from what you did.
FWIW, fixing TVs these days ain't worth it whichever way you look at it, and especially as a business. So like you said, if you wanted a working TV, you wouldn't have bothered...Last edited by momaka; 03-12-2025, 12:44 PM.Leave a comment:
-
In case of putting both 110V windings in parallel: yes, each primary winding will then handle about half of the total load on the output. However, with the 110V windings in parallel and connected to 220V AC line, each 110V winding will still see the full 220V AC line across it... which is not good.
Windings are meant only for AC up to their stated voltage (and at worst case, up to +15% max usually). That's because each winding has a certain impedance under 50/60 Hz - i.e. an "AC resistance", in simpler words. When you raise the AC voltage to 2x its nominal rated value, the...Leave a comment:
-
^ Flux is a must for me.
Yes, you can (and should) use fresh solder on top of the old leads to improve the heat transfer from your soldering iron to the board/joint. But once you have the cap pulled out, you might find that clearing the hole can become a bit of a "mess" if you just keep adding solder. At some point, just adding flux and heating with your iron is more helpful than adding fresh solder.
As for clearing the holes, I prefer doing it the "manual" way, with a (stainless steel) sewing needle - basically heat each hole with the soldering iron and then push...Leave a comment:
-
Yup, exactly.
5VSB goes over the Zener diode's voltage and the Zener diode shorts out, protecting everything else connected to the 5VSB output (motherboard and peripherals) at the expense of killing the 5VSB circuit (usually.)
Obviously, this is not the best way to have a protection... but at the end, if you had to choose between destroyed motherboard or destroyed PSU, I think the choice is usually the latter.
Now, you could make a better protection circuit by having the Zener diode trigger an SCR on the primary side and make the 5VSB just turn off... but that's a relatively...Leave a comment:
-
Check the fuse and NTC thermistor on the input. If these are good, you have a wiring error somewhere... or user error (multimeter not connected properly or on the wrong setting)... or?? At this point, only you can find out, unless one of us has a chance to teleport and look over your shoulder to see what's happening.
....Leave a comment:
-
It appears you are using the Zener diode incorrectly. By the looks of the voltage drop, you have the 5VSB going through the Zener diode as a regular diode and then out to 5VSB - that, unfortunately, won't do anything for voltage protection. Instead, what you're doing is you're only making the circuit less efficient (by loosing an extra 0.5-0.7V through the diode... hence why your 5VSB dropped from 5.05V to 4.55.) Also, at high output current, your Zener diode will likely overheat and short out... so it really CANNOT work the way you have it wired. and 4.55V is out of spec. Lowest allowable for...Last edited by momaka; 03-10-2025, 07:06 AM.Leave a comment:
-
You CANNOT put 230V through a winding intended for 110/115/120V AC, because it will overheat the winding (eventually) if not cause the transformer to saturate right away.
Put the two PRIMARY side windings in SERIES to get one whole primary winding for 220/230/240V.
However, careful attention must be paid to how these two are placed in series. If you don't put them in series the correct way, the two windings will cancel each other out and you get a near short-circuit on the primary, which =
. To avoid doing that, use a 100W incandescent light bulb in series with the transformer's...
Leave a comment:
-
Just fully recap the PSU - that is, replace all caps except the big 200V caps... and that's about as good as you can do in terms of making it safer and better.
More specifically about the recap, make sure to change all of the small caps. And if a rail has 2 cap spots, make sure those two cap spots are filled. Ideally, the 3.3V and 5V rails should get no less than 2x 2200 uF caps each. The 12V rail will benefit from having 2x 1200 uF caps... or if there is space for only one cap, use a 2200 or 3300 uF cap. And lastly, the 5VSB - use 2x 1000 uF caps minimum. 2x 1200 or 2x 1500 uF will be fine...Last edited by momaka; 03-06-2025, 07:21 PM.Leave a comment:
-
That's not right then.
It's OK for a resistor to read lower resistance while in-circuit than it's actual printed value.
Its NOT OK for a resistor to read higher resistance while in-circuit that it's actual printed value.
So that one needs re-checking out of circuit and/or replacing.
It's not supposed to anyways, so that's normal.
In fact, that's the whole idea of most PSUs: to isolate the primary side from the secondary side so that you don't get shocked.
Make it match... with wires, like I showed in the picture at the end of post...Leave a comment:
-
No problem, glad to hear it's up and running.
So looks like really the 3.3V rail was the main and only problem here the whole time.
BTW, 1n4148 is *not* a Zener diode. It's just a [B]regular[/B] small signal[B] diode[/B].
So that's 1 out of 3 for the count... with the FSP being almost there.
.No problem, glad to hear it's up and running.
So looks like really the 3.3V rail was the main and only problem here the whole time.
BTW, 1n4148 is *not* a Zener diode. It's just a [B]regular[/B] small signal[B] diode[/B].Leave a comment:
-
Just about every (not completely trash) power supply has working SCP and OVP/UVP.
Anything based on forward converter topology (many of those Dell and HP OEM PSUs) will have OPP on the primary.
OCP may or may not be present, and maybe only on the 12V rail... but for the most part, these are relatively modern PSUs and DO have OCP usually.
OTP is the only one that is not always included in the design. For that one, you do really need to open the PSU, look at the ICs inside, and also see how the thermistor for the temperature pickup is wired - it could only be used for speed control...Leave a comment:
-
Not yet!
I think we are just starting to hit the problem right now.
First, check that resistor R31 (47 Ohm) again. Maybe that's burned out, or starting to, with the 12V being backfed.
Correct, it's a regular 1n4148 indeed.
Have a look (again) at this simplified schematic from the KDMpower thread again (it's of a Raidmax RX-380k PSU):
[URL]https://www.badcaps.net/filedata/fetch?id=2058927[/URL]
In your case above, D19 corresponds to D25 on that Raidmax schematic, and there is no 2nd diode above it on your PSU like there is...Leave a comment:
No activity results to display
Leave a comment: