OBH Nordica DC adapter

[nguberinic]

OBH NORDICA model: YJS05-2402500D.

Input: 100-240V, 47-63 Hz
Output: 24V DC 2500mA


Just out of nowhere it stopped working. What my knowledge could handle is dismantle of plastic box and measuring the input voltage which is correct 230+- V, fuse is OK, but on the output there is no voltage !
If any of you guru guys could help me to diagnose the DC adapter I would be very grateful.
By the way I have no way of measuring capacitance, have just a regular multi meter! And they all look fine ! visual appearance!

[stj]

Re: OBH Nordica DC adapter

in the center is a huge cap, at the edge of it is a small one.
replace the small one - use something decent like panasonic FR or rubycon starting with ZL

infact get it out and tell us what's printed on it,
i will try to locate a very high temperature replacement such as 125 or 130' capable.
those bricks cook regular caps!

[PeteS in CA]

Re: OBH Nordica DC adapter

That looks like a flyback topology design, controlled by a 384x type pulse width modulator IC, U1 on the bottom of the PCB. That little capacitor stj suggested you replace is essential both for the circuit to start up and to stay running. Some manufacturers use low quality parts in that function, so it fails frequently.

It's a fine point, but if that area gets really hot I'd recommend Panasonic FC, Nichicon PW, or Nippon Chemicon LXZ for that spot. ZL and FR use an electrolyte technology that does less well in hot spots. I've had good experience with Rubycon ZL and with the older Panasonic FM series (same electrolyte technology as FR), but I think FC and the other parts I recommended would be better 105C parts (which FC, FR, ZL, PW, and LXZ all are) for a hot spot.

[999999999]

Re: OBH Nordica DC adapter

After repairing something like this I cheat and drill an array of small vent holes on a drill press, with the PCB out of course.

I slap some masking tape on for contrast then a ruler and marker for a nice even grid for hole placement, then barely touch each hole with a larger bit to chamfer the edge, remove fuzzy plastic remnants.

Not recommended for wet areas or if you have small children that like to electrocute themselves.

[nguberinic]

Re: OBH Nordica DC adapter

Thank you guys will try suggestions and will post back, sry for late response !

[nguberinic]

Re: OBH Nordica DC adapter

YIHCON 10uF50V
105 degrees C

[nguberinic]

Re: OBH Nordica DC adapter

Waiting for ESR meter, till then am out of luck testing the capacitor, so will just replace it.
I did however remove before reading the posts, SCHOTTKY RECTIFIER MBR10200CT <red arrow with in the picture>.
By testing it out of the box, result were not good /reason I removed it cause readings with in the board were weird.
I did by the new cause the price is just fine.
By measuring the new one and the old one, I did find it not the same ! so I assume faulty rectifier.
What I notice now is that there is a buzzing sound coming out of the box.
Will replace the cap tomorrow and will let you know...

Thanks for the replays !
With respect !

[nguberinic]

Re: OBH Nordica DC adapter

News !
Had a spare 10uF50v, 105 Celsius, signal lamp worked, which was good enough for me, (bad me did not check dc output). I had assembled the adapter and yat bad news, it's not working again !.
I have dismantle the adapter once again and am not getting signal lamp now. !

Maybe my capacitor was bad though it was new !

[Per Hansson]

Re: OBH Nordica DC adapter

Actually in some designs the ratings for that capacitor can be very critical.
It's basically used as a timing circuit so the unit will turn on at the right time.
But if no model designations are on the old cap that's going to be difficult...

[nguberinic]

Re: OBH Nordica DC adapter

Please guys, after changing diode 1N 4751, 30v which seems to be shorted, and capacitor 10uF50V,and SCHOTTKY RECTIFIER MBR10200CT.

Board seem to be working and I have tested it, but as I switch it off, i get the same problems once again !!!. (just diode 1N 4751, 30v shorted)

Please I don't know what seems to be causing it. But there has to be a problem somewhere in between. Either transformer, but as far as my knowledge goes, if transformer is bad it's bad and it's not working at all.

Could u please inguide me what could be wrong!.
Thanks
P.S
Sending some photos of what I have changed with the help from forum guys !

[goodpsusearch]

Re: OBH Nordica DC adapter

https://www.badcaps.net/forum/attach...1&d=1502706982
Does this thing work like a thermal pad?

I believe it can get conductive (or capacitive) with time and sort something.

[jazzie366]

Re: OBH Nordica DC adapter

Please guys, after changing diode 1N 4751, 30v which seems to be shorted, and capacitor 10uF50V,and SCHOTTKY RECTIFIER MBR10200CT.

Board seem to be working and I have tested it, but as I switch it off, i get the same problems once again !!!. (just diode 1N 4751, 30v shorted)

Please I don't know what seems to be causing it. But there has to be a problem somewhere in between. Either transformer, but as far as my knowledge goes, if transformer is bad it's bad and it's not working at all.

Could u please inguide me what could be wrong!.
Thanks
P.S
Sending some photos of what I have changed with the help from forum guys !

By what you're telling us, the adapter works, then you power it down and it stops working completely again.

I'm not sure what you mean by,

Board seem to be working and I have tested it, but as I switch it off, i get the same problems once again !!!. (just diode 1N 4751, 30v shorted)

However, I think you mean the zener diode there is shorted? If it is, that's guaranteed to be the issue.

https://www.ebay.com/itm/1W-Zener-Di...0LnVBRmLqS299A

You can get them directly from there, just select the 30V version. Those diodes there *should* work, someone correct me if I'm wrong.

Also, car amplifiers that are cheap have these caps in them commonly. I can tell by the coloring of the sleeving that is in fact low ESR. Yihcon also advertises their low ESR caps as having that golden sleeving on them. The standard ones are normally a clear orange or black/white, not black/gold.

[Relayer]

Re: OBH Nordica DC adapter

Hello nguberinic,
Please refer to your modified picture below:



Would it be possible for you to take a photo of the section shown by the indicated box?
Also, what is that component encapsulated in heat-shrink, as shown by the red arrow?
No need to remove the heat-shrink, as you might be able to see what it is via circuit component designations on the bottom and/or the top of the PCB.
Thank you.
Regards,
Relayer

[budm]

Re: OBH Nordica DC adapter

That 30V Zener is the crowbar protection diode, it is connected in parallel with the output so if the Voltage try to go higher than 30VDC, it will conduct heavily until it is shorted out, so you need to monitor the output Voltage, you may bad Voltage regulation problem that lets the out put goes way beyond 24V as specified.