RYOBI-one charger

[stj]

these green things are shit, they die after less than 2 years.
u-tube is full of people trying to fix them.
(i fix them for good)

the main problem is similar to the vestel psu's - parallel diodes.
one shorts - blows the smd fet, damages the protection zener.

[stj]

Re: RYOBI-one charger

so lets fix the bastards so they wont disrespect us again!

replace the fet with IRFR5505PBF
replace the diode with BZT55C18
replace the 2 diodes with a single MBR40250G on a customised heatsink with an insulating kit.

finish it with resoldering anything cracked, removing glue, and a full recap with FR,FC,YXJ and a BXW primary (instead of capxon)

[sam_sam_sam]

Re: RYOBI-one charger

So does it work as good as new

[stj]

Re: RYOBI-one charger

it works better than new - it does not get hot over the diode(s) now.

i replace a pair of 5A diodes with a 40A diode on a heatsink - you expect it to fail?

[sam_sam_sam]

Re: RYOBI-one charger

Thanks for posting this I have 5 of them charger and recapped three of them so far
What was the problem with it

[stj]

Re: RYOBI-one charger

problem is the 2 big diodes fail and blow stuff up - if you have that model with 2 big MBR5200 diodes, replace them with a big diode on a heatsink before one fails.

i know there is another version of this charger with a single diode on a big heatsink that has other problems.

[shovenose]

Re: RYOBI-one charger

I have one of these. Build quality seemed OK externally. Good to know it isn't quite so good inside and I will keep an eye on it.

[sulc]

Re: RYOBI-one charger

I'm repairing same charger. It came to me with broken primary (diodes, mosfet, pwm ic, gate resistors) and shorted secondary diodes + mosfet. I have replaced all parts and now its pumping (secondary voltage rises to about 30V, then restart, red led blinks). For regulator mosfet i used:

http://www.farnell.com/datasheets/19...648.1413390707

Any ideas?

[stj]

Re: RYOBI-one charger

voltage is over, did you check all the resistors etc?
also did you replace the zener across the fet?

the only other thing, i think there was a 431 voltage reference that may be bad.

[sulc]

Re: RYOBI-one charger

TL431 was replaced, all zeners are ok (not shorted). I also replaced optocoupler. Can somebody check primary gate resistors? I replaced both but i want to be sure they are correct..

[sulc]

Re: RYOBI-one charger

Some pictures...

[sam_sam_sam]

Re: RYOBI-one charger

I am watching this post carefully i have a few of these changers

Please keep us informed thanks

[stj]

Re: RYOBI-one charger

Tall zeners are ok (not shorted)

they may not be operating at the marked voltage.
you either need a zener tester of some kind, or just replace them.

[stj]

Re: RYOBI-one charger

btw, you need to check every resistor around the switching controller.
when you blow that chip, some resistors get damaged.

and make sure your new heatsink isnt touching anything.
there is a reason i cut one side off mine!

[sulc]

Re: RYOBI-one charger

Anyone has values for SMD zeners?

[stj]

Re: RYOBI-one charger

the only one that gets blown afaik is across the surface-mount fet, it's 18v.
i posted the datasheet

voltage is printed on them anyway.

[CapLeaker]

Re: RYOBI-one charger

nice fix stj!

[sulc]

Re: RYOBI-one charger

That one I replaced with right one just to be sure (old one has knee at about 18V when testing so it seems it was good).

[simonmpoulton]

Re: RYOBI-one charger

Got same problem with my charger - the mosfet looks like it blew up far worse than pictured. Have replaced mosfet, zener diode and the pair of diodes with MBR40250G. IC1 also looks burned however - does anyone know the part code for this?

[R_J]

Re: RYOBI-one charger

Post a picture of it, it might be a SG6848, Is there a model number on the charger?