Re: Select-able wall wart power supply - dead
But if they were shorted they should read 0 in both direction,right?
Also 4 shorted diodes at once is unsual..
You don't have to check ESR on that cap.That kind of power supply doesn't stress much caps and it would show you some reading on voltmeter even without any cap at all..
My bet is that transformer primary is open..You can put multimeter on Ohms and check if its resistance is below 500 ohms or ssomething similar.
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Re: Select-able wall wart power supply - dead
Minor nit. Those readings are millivolts or 0.460V.
All those readings suggest all 4 diodes are shorted. A good diode should read between 0.3 and 0.7V one way and 0L (out of range) the other way.
Desolder all 4 and remeasure out of circuit to verify.Leave a comment:
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Select-able wall wart power supply - dead
hello, this is probably simple, but I searched and didn't find a thread with this specific repair, so I thought if nothing else, I'll document mine.
This is a variable voltage output wall wart power supply, with reversible polarity. It was mainly used for a power supply for audio pedal boards. It has died. This could go under audio, I suppose, but because it is a universal power supply, I thought this section to be better.
This was my friends, and the cord looks like a candy cane its so twisted... Maybe there's a short there somewhere.
When I plug it in, there is no voltage to any of the optional tips.
I opened it up (after fabricating a split flat screw driver tip with a dremel tool and an old flat screw driver bit) and it looks pretty simple. A transformer, 4 diodes, 1 capacitor 25v 1000uF , and 2 resistors. A switch for dc voltage output and a switch for +- polarity reversal.
I have no idea whats wrong with it. Diodes in circuit read 460v 459v 464 and 464v respectively. reverse reads 598 598 602 and 602v respectively.
Caps not bulged. ESR meter won't be here until next week.
Any thoughts on where to begin on this would be appreciated. I don't know how to test the transformer...Attached Files -
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Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
Assuming... -
Hello!
i got a damaged Manson NTP-5561 (60V, 1,6A DC output) and and the main issue is that the controler IC for the LCD display has a short. The controler IC PIC18F87K90 is mounted on the back of the back of the LCD. Vss-Vdd = 3 Ohm. The 5V and 3,3V power line was killed as well, but that is not a problem. A new LDO 3,3V and 5V 7805 is already ordered.
Replacing the PIC18F87K90 is necessary but that makes no sense without having the HEX dump of the new controler.
Does anybody have such a power supply and could do a HEX dump of the Flash and EEPROM memory?
...04-12-2025, 10:38 AM -
I have wanting to do this project for quite sometime now and I finally found a switching power supply that will work on this desoldering gun station ZD-915 that the original switching power supply took a shit and just was not worth trying to fix it because this switching power is not quite big enough to handle the heater element and the vacuum pump
One note when I tested the switching power supply and the voltage control board I noticed that this desoldering gun heat up much faster than the original switching power supply which I was really surprised by to the point that I might buy... -
Hi, have this Samsung QE 75 Q 7 FGMTZG TV with no function. First analysis shows the power supply board is dead and fuse blown. Power Supply has the number BN94-11439A. I did short circuit test transistor and diodes and those do not appear to have shorts. I must admit I did not look at every single data sheet.
In the TV was some black dust residue, so probably one of the electrolytic caps blew, but they do not show short either.
Does anyone have schematics for that board ?
Any good tip, what could be the issue ?
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I have a floodlight-security camera that recently died on me.
its hardwired to 115v po115v outlet. One evening it simply died. After some troubleshooting (ensuring it had power and ensuring the electronics were actually functional by supplying 5v via usb port) i realized the power supply must be the issue. The supply was noticably warm to the touch even though it was not powering anything.
Trying to understand what i was up against i went looking for others with similar issues and anyone who might have attempted a repair. While a few ppl have had the...
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