toshiba AC adapter

[vince59]

Hey all, I have a falulty toshiba AC adapter and would likke to fix it.
The adapter connected to main power giveas a reading of 19,05 volts DC but if connected to pc does not work. Adpater light on PC stay on for a while then tunros off and then ciclying this wai. I tested also with a lamp and the lamp is flashing continously. I can hear a very low " tick ...tick.." every flashes.
I have no experience with AC adapter and do not know what to check.
Any help from you would be appreciated.
Pictures enclosed

[stj]

Re: toshiba AC adapter

the tick sound is the psu resetting, it could be detecting an overload or short-circuit.
(or it could be faulty)

[petehall347]

Re: toshiba AC adapter

replace those bulged capacitors

[vince59]

Re: toshiba AC adapter

replace those bulged capacitors

Thank You, I will give it a try.

[vince59]

Re: toshiba AC adapter

the tick sound is the psu resetting, it could be detecting an overload or short-circuit.
(or it could be faulty)

I will have a look at the capacitors. Any suggestion what to check from your expertise?

[sam_sam_sam]

Re: toshiba AC adapter

Please post a picture of the back of the board

[vince59]

Re: toshiba AC adapter

Hey, there are two pics in the opening post of tboth sides of the board.
By the way I think it is dead...I visually inspected the capcitors and they are not bulged. I removed the two small close to DC exit, they are 560mF 25V and the multimeter gives a reading of 650mF each one.
I put them back but now tha adapter blows the fuse.
I think it is on the way to the garbage bin...but I would like to fix it to learn and better understand about AC adapters!

[petehall347]

Re: toshiba AC adapter

you caused a short or put the caps in backwards .

[budm]

Re: toshiba AC adapter

BTW, you need to also check ESR of the cap, not just capacitance, also make sure the caps are put in with correct polarity as suggest and make sure there is no solder bridge.
One of the filter caps in the cold side does have bulging top.

[vince59]

Re: toshiba AC adapter

you caused a short or put the caps in backwards .

I guess so but I just cleaned the board nothing else. Caps are mounted correctly. I am aware about polarity.

BTW, you need to also check ESR of the cap, not just capacitance, also make sure the caps are put in with correct polarity as suggest and make sure there is no solder bridge.
One of the filter caps in the cold side does have bulging top.

Ok do not know how to measure ESR...multimeter is ok?. I will double check for bridges.
Maybe it is an effect by the pictures but I can assure caps are not bilged at all.
Can I test with one single cap of 1000mF instead of those two?

[budm]

Re: toshiba AC adapter

Try heating the small lytics startup/running cap in the hot side with hair dryer then power up the unit to see if it becomes stable.

[vince59]

Re: toshiba AC adapter

Try heating the small lytics startup/running cap in the hot side with hair dryer then power up the unit to see if it becomes stable.

Thnak you I will try and report...but I think it will not because as soon as I connect the AC the fuse blows.

[budm]

Re: toshiba AC adapter

Of course you have to fix the shorted problem after your initial repair attempt before trying heating the cap. Recheck you works in details to see what was done wrong to cause the fuse to blow now.