The Hall of Shame - Badcaps Photo Montage

[mariushm]

That's a classic transformer, which means the other components are just a bridge rectifier and the capacitor to smooth out the output.

7.5v and 900 mA makes it a 10-15 VA transformer, and with those low VA values, it's common to have up to 20% variation in output voltage when there's no load.
The transformer is also selected in such a way as to have higher output AC voltage, to account for losses in the bridge rectifier and to make it possible to use smaller capacitors.

This, coupled with small voltage drop on diodes at low currents (when you don't have anything connected to it) makes 10v quite reasonable. As soon as you have something connected to it, the voltage will drop.

As you're dealing with 100-120 Hz, general purpose capacitors would work fine. You're not dealing with 30-150kHz frequencies common with switching power supplies. to require low esr capacitors.

-

So basically any general purpose capacitor is fine there. It may have been damaged in factory, but doesn't matter, eventually they die... it's a closed enclosure, no ventilation, and classic transformers heat up when in use.

[kc8adu]

panasonic fm issue...again!

[momaka]

Originally Posted by wacce

I was aware that it's normal for the output voltage to climb without load, but didn't expect it to go over 10V.

It is for small transformers like that. And the smaller the transformer gets, the worse the regulation voltage between the loaded and unloaded condition.
I have a "3V" very small transformer (possibly from a phone or some other old electronics gadged). Unloaded, that thing goes past 9V - three times the stated voltage on the label! Of course, it drops pretty close to 3V with the stated current.

Originally Posted by kc8adu

panasonic fm issue...again!

Fake?
Or are even "invincible" Panasonic caps no longer invincible? I see a bulged C(r)apXon cap in the background.

[ben7]

Originally Posted by kc8adu

panasonic fm issue...again!

I don't see what the issue is :P

[lti]

The sleeve is rotated so the negative marking stripe is pointing at the positive lead. Look at the length of the leads.

[momaka]

^ You must have eagle eyes! I would have just installed them and then wondered why they bulged.

[ben7]

Originally Posted by momaka

^ You must have eagle eyes! I would have just installed them and then wondered why they bulged.

Heh, same, I didn't notice that. However, usually I go by the stripe on the capacitor, not lead length

I have a new FM (from Mouser,) 3300uF 6.3V
12.5 x 20 (mm)
Has the correct lead orientation/lengths too.
The font on mine looks to be a size or two smaller than the font on yours! wtf?
The red date-code thing on mine is "3N12QG"

[Heihachi_73]

I only saw a CapXon issue there.

[Pentium4]

Damn, lti, you're a boss. Nice eye!

Here's a new one: MOSTCON. Their name is just them bragging about how they have "THE MOST CON" of any other chinese company It read 159µF. Spotted in a dead Topower 80 Plus PSU. (Check the build quality thread later)

[wacce]

Originally Posted by mariushm

As you're dealing with 100-20 Hz, general purpose capacitors would work fine. You're not dealing with 30-150kHz frequencies common with switching power supplies. to require low esr capacitors.

-

So basically any general purpose capacitor is fine there. It may have been damaged in factory, but doesn't matter, eventually they die... it's a closed enclosure, no ventilation, and classic transformers heat up when in use.

That's good to know, thank you for the info. I might change some better quality, but general purpose caps for the warts. And yeah, they are doomed to fail at some point by design.

Originally Posted by momaka

I have a "3V" very small transformer (possibly from a phone or some other old electronics gadged). Unloaded, that thing goes past 9V - three times the stated voltage on the label! Of course, it drops pretty close to 3V with the stated current.

Surprising! It's good to be aware of this behavior, as keeping a wart both loaded and unloaded at times will make the output caps adjust to the changed voltage each time, and possibly shorten their life.

[kc8adu]

at least it doesnt ask permission "can i con?(canicon)

Originally Posted by Pentium4

Damn, lti, you're a boss. Nice eye!

Here's a new one: MOSTCON. Their name is just them bragging about how they have "THE MOST CON" of any other chinese company It read 159µF. Spotted in a dead Topower 80 Plus PSU. (Check the build quality thread later)

[kc8adu]

sometimes a careful examination of what you are working on does more than focusing on the obvious.

Originally Posted by momaka

^ You must have eagle eyes! I would have just installed them and then wondered why they bulged.

[Philly Cheese Steak]

Guys need some help(mood feel free to move this, to its own topic under motherboards).
I have an EVGA 680 motherboard, no boot no display. I was using a multi meter to check for blown mosfets as the board will do nothing when I hit the button, no sound no noise no power on. The board looks good caps look good, no smell, no nothing
So I used a jumper on the green n black wire of the power supply 24 pin harness and boom I got power on, now the 2 (7) segments displays show - - as if part of the board is not getting power.
I need a place to start testing and some direction as to what to look for or at?

Thanks!

[kasfamily]

Radio Koyo KTR-1770 a lot of bad capacitors

[kasfamily]

Power supply satellite receiver

[Heihachi_73]

Originally Posted by Heihachi_73

I only saw a CapXon issue there.

Quoting myself, it's here too.

[ReeceyBurger123]

Originally Posted by kasfamily

Power supply satellite receiver

That cap has gone mental !!!

[momaka]

Originally Posted by kasfamily

Power supply satellite receiver

Normally I hate CapXon, but in this case I don't think it's the cause of the problem. Look at how charred that PCB is next to it. Something tells me the power supply deisng is shit (either that, or its cooling).

[ReeceyBurger123]

Originally Posted by momaka

Normally I hate CapXon, but in this case I don't think it's the cause of the problem. Look at how charred that PCB is next to it. Something tells me the power supply deisng is shit (either that, or its cooling).

Probably due to cooling, most of the power supply's in these receivers aren't up to the job and over work also with poor passive cooling and no fan they burn up easy.

[mariushm]

No, that mosfet (with heatsink) really cooked the pcb under it. Slim chance it was only poor soldering, but probably the mosfet started to fail internally heating so much it cooked the pcb and the capacitor, transferring heat through leads.