Re: Nvidia MATS help please - 33 errors on two cards?
33 errors on MATS is a known MATS bug. It misdiagnoses the blinking cursor as an artifact and throws errors. The fact that it goes black with full fans on stress test indicates that maybe some connections under the GPU are broken and it needs a reball. Run a MODS test for that.
MHTSOS
Member
Last Activity: 04-24-2025, 12:42 PM
Joined: 06-03-2014
Location: Athens
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Re: Xigmatek 500W ATX PSU went POP and stopped working
Those 18N50 on Aliexpress are 100% fake. If you measure their RDSon you'll see its much higher than normal. It's better to salvage the mosfets from another PSU or buy from a legit supplier
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Re: Toshiba Satalite C850 lack screen after LCD replacement
Is the LCD Led backlight or ccfl?Leave a comment:
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Re: FSP250-50MSP PSU from MSI Hetis G31 Barebone 250W
Does anybody know if it's safe to replace the 2 caps that help drive the bases of the transistors with mlc caps? They are located in a very hot area with no cooling from airflow and I guess mlc caps would last much longer. I have done it as an experiment on 2 psus and they seem to work fine under load but I don't have an oscilloscope to compare the waveforms between electrolytic and mlc caps.Leave a comment:
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Re: Vizio M50-D1 power supply dual voltage?
This board has APFC with 450V primary capacitors so most probably its boosting the voltage to 380V. Very strange its not labeled as universal input.Leave a comment:
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Re: Please help identify unmark glass diode
I don't know. In the darasheet of UC3854 is doesn't say anything about it. In other ICs (i.e. Cm6800) I have seen zener diodes reverse biased to Isense pin in order to protect the IC in case the primary mosfet shorts and you get a huge current through the current sense resistor and a very big voltage drop across it. I have a psu with CM6800, the mosfets were shorted, there was no zener in parallel with the sense resistor even though the darasheet shows it, the sense resistor was open/blown and the Isense pin of CM6800 got 380V and as a...Leave a comment:
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Re: Please help identify unmark glass diode
Why would it have a reverse biased diode in the ISENSE pin of UC3854?Leave a comment:
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Re: HP LP3065 black screen, LED lighted, USB works
Remove the diode and check if its full name is 1N5005.Leave a comment:
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Re: An old runner - Tagan EasyCon 480W (TG480-U15)
The only reason I can think of that they use 400V caps instead of 450V is planned obsolescence. I mean they know damn well that APFC is going to kill them eventually but it is a good way to keep the money rolling....Leave a comment:
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Re: An old runner - Tagan EasyCon 480W (TG480-U15)
I have repaired 2 of these PSUs both with blown primary drivers. On both of them the pramary caps were dead so I would start there. You will need at least an ESR meter for this kind of repair. Also check the 2 caps that are connected to the bases of the primary drivers. They should be 50V and 1uf to 10uf I don't remember atm. Judging by the age of the PSU if they are not dead by now they are definitely dying. If the dry up the PSU will work with no load but will shut down as sosn as you try to draw a few wattsLeave a comment:
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Re: Samsung SMPS
I had a unit with the same problem repaired. Check to see if it outputs 3.3V. If not replace the LDO regulator. It's the one next to C17 if I remember correctly.Leave a comment:
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Re: Cooler Master RS-500-ACAB-M3
This design looks very familiar. Check the primary capacitor. If it is 180uF 400V remove it and check its capacitance and ESR. I have had several PSU that look exactly like this one but with different brand where the primary cap failed and it had exploded the 5VSB IC. If the capacitor is faulty check all the mosfets in the primary side because they are most probably shorted.
Edit: I just zoomed at the photo and the primary cap is 270uF so this built is better that the one I have come around. You should still check for shorts in the primary...Last edited by MHTSOS; 03-11-2018, 01:38 AM.Leave a comment:
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Re: Sony mbx-252 don't power up. Help identify component
This is a reverse polarity protection diode. It is there to protect the board in case you connect a charger with reverse polarity. The board can work without it but it is better to have one. It is not a critical part. Any fast switching diode that can handle double the amps that the charger can provide will do just fine.Leave a comment:
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Re: Asistance required on troubleshooting Corsair CX500
Remove the heatsinks with the mosfets on the primary side and check them. Most probably some of them, if not all, are shorted.Leave a comment:
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Re: Worn ATX PSU still works but with reduced power peak
These capacitors are in the circuit that drives the bases of the switchers. They dry from prolonged use because they are next to the hot heatsink and when the switchers have to be driven hard to provide more power then there is not enough current to drive the base. I have seen this a few times in some very old and used PSUs and they would power on fine with light load but the output voltage would collapse when you tried to pull more power. Replace them and check. It would be wise to replace all electrolytic capacitors since...Last edited by MHTSOS; 02-25-2018, 12:50 PM.Leave a comment:
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Re: Worn ATX PSU still works but with reduced power peak
This PSU looks like it has BJTs as primary switchers. Very close to the 2 BJTs you will find 2 caps. They must be 50V 1uF to 10uF. It depends on the design. If you have an ESR meter measure these 2 caps. If not, replace them and test it again.Leave a comment:
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Re: New Members - please post your introductions here
Hello there,
I'm Dimitris and I'm a mobile phone technician for the last 13 years and I have been repairing PCs and anything electronic for as long as I can remember. Lately I've set up a small electronics lab in my home to have as a side job and I hope to discuss here weird repairs that I come around.Leave a comment:
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