My friend gave me this Viewsonic VG2236WM-LED that wont turn on. It just flashes the power light on and off, and you can hear the faint whine of a leaky capacitor.
Taking the case apart was the hardest part. After removing the stand, you have to use a spudger around the outer edge, and its best to start at the bottom of screen so its less likely to show if you scratch or bend the plastic. After that the metal cage that holds the boards is taped into place, but also all the ribbon cables are glued very well and hold the cage / boards in. I had to remove all the boards to get the largest...
cashkennedy
Badcaps Veteran
Last Activity: 07-11-2022, 03:58 PM
Joined: 08-26-2011
Location: Baton Rouge, LA
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Viewsonic VG2236WM-LED wont turn on / flashing power light
Last edited by cashkennedy; 11-06-2020, 01:46 AM. -
Re: $20 "500W" PSU From MicroCenter, how bad can it be?
I don't blame them with all the idiots I hear still insisting on 750-850w power supplies for systems with midrange processors (ryzen 3600x), and upper mid video cards (gtx 1660). Those idiots (which seem to be the majority of people building computers) usually think 500w wouldn't be enough for any system with a discrete video card. -
Re: PC7071 Lenovo PSU
The power supply may be turning off because of OCP (Over Current Protection) / SCP (Short Circuit Protection) / OPP (Over Power Protection). There could be a short on the motherboard that the power supply is detecting. So have you tried using the power supply to power a different motherboard ? (may not be realistic if the power supply uses a proprietary connector).
In your pictures some of the capacitors look a little buldged on the top like the 4 tall ones with K bungs (probably rubycon capacitors). But your pictures are pretty bad so hard...Leave a comment:
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Re: grandstream ip camera gxv3611_hd poe circuit
From what I can tell they stuck pretty closely to the isolated flyback design in the poe controller's datasheet. Ive attached a picture of part of that design.
C37 on the camera appears to be C4 on the reference design.
C39 on the camera (100v 10uf capacitor ) appears to either be c1 or c2 on the reference design.
The inductor right next to C39 on the camera is marked L3 on the board, and 100 on the part. I would assume that is L1 in the reference design. Perhaps the larger inductor and larger 100v cap...Leave a comment:
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Re: grandstream ip camera gxv3611_hd poe circuit
Unrelated to diagnosis:
I think its interesting that even in the manual for some of the grandstream IP cameras they put this:
A few parts (e.g. electrolytic capacitor) of the equipment shall be replaced regularly according to their average life time. The average life time varies from the differences between operating environments and usage history. Regular maintenance checks are recommended for all users. Please contact your dealer for more details. Though I cant imagine any dealer is sending these cheap cameras...Leave a comment:
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grandstream ip camera gxv3611_hd poe circuit
I have a bunch of these grandstream ip cameras that fail after 2-3 years of use for poe. Supplying them with 12v power instead of POE works, but id like to fix the poe portion.
Im hoping the 63v 47uF capacitor (c37) is the issue. I assume that cap filters the incoming POE which is usually 48V. Since using 12v works I assume all the 16v caps are still okay (im sure yall would replace them all anyways). There is also a 100v 10uf capacitor (c39), which im not sure what it does, perhaps a startup capacitor for the chip that handles negotiating the poe power and converting the poe 48v... -
Re: Dell poweredge 2600 power supply nps-730ab
I replaced all the startup caps, but that didn't help.
I did notice the startup capacitor for the standby supply (power integrations top244y chip) goes from 5.8v to 0v when I read both pins of the cap with my multimeter, then eventually back to 5.8v after a few seconds. The manual says: A hysteretic internal supply under-voltage comparator keeps VC within a window of typically 4.8 to 5.8 V by turning the high-voltage current source on and off as shown in Figure 8.
So I don't know if that would mean there's...Leave a comment:
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Re: Dell poweredge 2600 power supply nps-730ab
The startup cap for the top244y all in one chip that does the standby is 100uF, could i put 2 47uF in parallel for this? And could i test that without the daughterboard (i'm guessing not lol) but yeah i don't want to have to remove the daughterboard again, I did it with about 2 feet of wick since i don't have a solder sucker or hot air station or tip wider then 6mm
What are you suggesting the transistor tester for? Would it allow me to test capacitors while they were still in circuit? Its only 6-7 caps I could just undo...Leave a comment:
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Re: DPS 800 ruined
Reading 12-14v on 20 vs 200 should only change the accuracy of the measurement. So on 200 setting you get 14.3, on 20 setting you get 14.32 (one more decimal place).
Did you open the case of the power supply to make any changes? Or did you use the resistor on the outside of the of the power supply?
Also in your picture are you connecting the power supply up directly to the car battery? Did you disconnect the battery first? Are you sure you have the polarity correct on the cables?Last edited by cashkennedy; 10-21-2019, 10:22 PM.Leave a comment:
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Re: Dell poweredge 2600 power supply nps-730ab
If I have to order any caps ill order correct ones for all of them obviously. I was hoping to not have to put any money into this since I just want to backup the data on the server then donate it to local electronic charity where they will throw it in the dumpster. So if there's one cap you suspect most and think I can throw in one of the other caps I have or two of my lesser ones to add up I might try that. I can always remove the suspect cap and test it right, as it would fail even a multimeter capacitor setting at this point....Leave a comment:
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Re: Dell poweredge 2600 power supply nps-730ab
Yeah I intend to replace all of them, just not sure if I can substitute with the caps I listed above that I had on hand, since I don't have any of those uF values exactly.Leave a comment:
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Re: Dell poweredge 2600 power supply nps-730ab
I tested the voltage leaving the bridge and get 160v so that seems ok. Also did diode tests on bridge and got normal readings except 3 readings were 0.478 and the other reading that should match was 0.466 , but probably close enough that I doubt that's the problem.
I decided to just remove the daughterboard that holds the chips that I assume are for the pfc and now I just gotta decide what caps I want to use to replace these. Is it safe to increase the uF on all of these to the nearest thing I have?
Updated...Leave a comment:
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Re: Dell poweredge 2600 power supply nps-730ab
I tested all the outputs and didn't get anything over a volt.
The caps I mentioned above all had ~ 60v to neutral of the AC input. (around 22v to ground, but my house has some bad wiring where ground vs line is like 56 volts. , so in other words ground isn't very reliable for voltage testing)
Shouldn't the power to the startup caps be more like 180v? that the main capacitors would see?Leave a comment:
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Re: Dell poweredge 2600 power supply nps-730ab
I didn't do a lot of traditional diagnosis on this, maybe I should go back and do that, but these have 3 led built into the power supply that equal: plugged in, turned on, and fault. None light up. This power supply also as far as I can tell only creates 12v power which the mother board converts into other voltages, and also a standby voltage that the motherboard uses to at least turn the power supply on. I don't think theres many markings anywhere about where the standby leaves the power supply and theres around 15 small pins on the...Leave a comment:
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Dell poweredge 2600 power supply nps-730ab
I haven't touched this server in like 6 years and I was getting ready to throw it out but figured id make a backup of the data on it.
It had been connected to power but not actually switched on for a few years (would have unplugged it if I had noticed). Worked last time I used it a few years ago. Im guessing the startup cap went out, and its not really worth the money or effort for me to go much further then that to fix this (why im not just buying a power supply on ebay for $40)
Anyways trying to figure out which cap is the startup cap. Its been a while since I worked...Last edited by cashkennedy; 10-18-2019, 09:19 PM. -
Re: CyberPower PR1500 rackmount UPS - no response
Most of these will charge the batteries when plugged in regardless of whether they are turned on or not. So a good place to start is reading the dc voltage going to the batteries when not plugged in and when plugged in. You could check the manual to confirm that it recommends / supports charging with the unit off. If its not even trying to up the voltage to the batteries when plugged in then your problem isn't the on off switch.
you should take the readings with the battery connected, which means you might need to take...Last edited by cashkennedy; 06-30-2017, 03:40 PM.Leave a comment:
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Re: mge / eaton evolution battery backup
with the battery connected I get 25v on both sides of C6 and get 25v at pin 7 (Vi) of the pwm controller. not sure if that means C6 is working fine or what. Not really sure why you even need a startup cap in a battery backup that uses the batteries to initially power the IC's.Leave a comment:
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Re: mge / eaton evolution battery backup
C6 appears to be connected with its positive going to pin 7 on the pwm ic (Vi). so I assume c6 is the startup cap.
(edited the initial post, because I had wrong capacitance on c6)Leave a comment:
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Re: mge / eaton evolution battery backup
nr1 (8 pin ic) is uc3842B pwm controller (might be made by st, hard to make out logo)
nr2 (8 pin ic) is 431ac precision shunt regulator?Leave a comment:
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mge / eaton evolution battery backup
Below are pictures of 1 of the 2 boards from a mge / eaton evolution 1150va battery backup. The battery backup has no signs of life with fresh batteries. It died after a power failure discharged the batteries. / shows no signs of life, will not turn on. This is a high quality battery backup with avr / full sine wave output.
I'm trying to determine if there is a startup cap / whether it is c53 on the board, please help me with the photos below.
C53, C6 is 50v 10uf
C66, C22, C19, C2 are all 50v 47uf
C5, and C8 are 250v 22uf
c13, c65, and I believe but...Last edited by cashkennedy; 06-30-2017, 03:23 PM.
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