Bestec power supply

[sam67]

Hi guys i decided to take my mother board and psu apart to have a look round..Noticed that the psu is a 300w bestec and the 2 big filter caps which are black , have NEG capxon in ,the smaller caps on the psu board are jamicon caps.The mobo has some burgundy colored type with a gray stripe and KZG on..also some black with a gold stripe but i could not make out the name as they were all facing away from me to view them right.

Must say i have heard that Bestec are not good psu but i've had this for nearly almost 5 years in a OEM compaq presario,and it's always been running well.

Was thinking whether or not to change psu ? All the caps look ok in psu and mobo no signs of bulging or leakage ..What do you guys reckon ? Worth a recap with it being 5 years old or would you leave alone.

Happy new year to all.

[370forlife]

Re: Bestec power supply

Depends. Is it a ATX-300-12E or ATX-300-12Z, 12E have the killer 5vsb circuit, 12Z don't.

Both would be fine after a recap though.

[i4004]

Re: Bestec power supply

>Was thinking whether or not to change psu ?

if it's 12E model, yes, replace.
or mod it
https://www.badcaps.net/forum/showthread.php?t=6680

[c_hegge]

Re: Bestec power supply

Also, KZG on the motherboard is never good as they can fail without bloating. They can be replaced with Rubycon MBZ/MCZ available from badcaps.net or Nichicon HM (as long as they were made after 2005) available from Mouser. You can also use Pansonic FJ/FL or Sanyo WG if you can find a source for them.

[everell]

Re: Bestec power supply

I have a Bestec ATX-300 12E and a Bestec ATX-300 12Z. Both have the A6351 pwm chip which is a good 5vsb circuit. The ONLY bad model I have found so far is the Bestec ATX-250 12E. The only sure way to know is to look at the pc board. If it has a A6351 (8 pin) integrated circuit then it is a good power supply to use. If any doubts, post some photos.

[i4004]

Re: Bestec power supply

so i should correct it

>if it's 12E 250W model, yes, replace.

<wink>

as for sourcing he can probably also
http://stores.ebay.com/PC-MotherBoard-Capacitors-Store
prices and shipping costs seem acceptable...

[sam67]

Re: Bestec power supply

Depends. Is it a ATX-300-12E or ATX-300-12Z, 12E have the killer 5vsb circuit, 12Z don't.

Both would be fine after a recap though.

Hi guys cheers it's the 12z 300.

[sam67]

Re: Bestec power supply

Got some pics i took on my samsung phone but cannot access the samsung pc studio as there is a problem with it ,everyone on samsung forum complaining about same thing NPS error so it won't let me get pics off ( probably not that clear anyway lol) Was gonna strip it all back down and see which caps i need..would i need to recap everyone on psu even the really little ones ? Also when i removed top part of the case from the bottom it is still attached to the top part ,can i just unscrew this off ( looks like a regulator or part of a trans former not sure but i guess one of you guys will know what i am on about lol total newbie here but want to have ago ,only way to learn).

Once the top is separated there is 4 screws that hold pcb to lower case ,was thinking if i undo these and then i can get to discharge the big caps from underneath the board.

If i am wrong then any help appreciated ..I did manage to test the psu with my dvm while running prime95 on torture test and all rails were at the right figures ..I am using the pc now to type on here..Theres nothing wrong with it but i would like to have a go at recapping the psu and mobo..I am confident to have a go lol and if i did mess up then i'd just get another mobo and upgrade as it's an old pc anyway..But i would like to learn and theres no other way as there is no one here to show me.

I have been playing around with an old monitor and mobo but that was just for soldering technique which is not bad for me lol

I might have to strip it all down again and try with my digital camera to get shots but the camera is not as clear as my mobile ..

[370forlife]

Re: Bestec power supply

What you were talking about is the passive PFC coil/inductor. This can just be unscrewed from the top part, or it may be detachable from the main PCB.

Yes, you can just replace the smaller caps on the secondary, typically the larger primary ones are less likely to fail. They are also much more expensive, if you can salvage some good brands from a different power supply go ahead but otherwise I wouldn't bother.

[sam67]

Re: Bestec power supply

Hi guys thanks for the response..sorry for not getting back but was a little ill a few days ago.

So for this bestec psu would it be better changing out the jamicon 1000uf 16v or leave them as i had a look round bad caps thread some say they are ok some say they are not. like i said no problems at all with my comp but curiosity got the better of me after reading the forums so i had to have a look what caps i had .

I guess that the big filter caps in the primary section which are NEG CAPXON should be ok and not need replacing like 370forlife said.

What about the KZG on mobo ,should i change them .. Also anyone have an idea what the black with a gold stride are ? I have not had chance to strip it back down yet but will do once i feel a bit better.

Thanks in advance. p.s Thanks 370forlife for clearing up the passive PFC coil/inductor that i did not know .

[ratdude747]

Re: Bestec power supply

replace em, what we mean are the 200v+ monsters that are the size of a salt shaker.

[sam67]

Re: Bestec power supply

cheers ratdude747,

From what i remember there were some really small caps on the mobo but cannot remember what make ,is it better to replace all of the caps including the small ones on the mobo and psu but leave the 2 big capxon one's alone..

Just double checking before i strip it all back down in a couple of days..I will then have a clearer view again.

[everell]

Re: Bestec power supply

I am presently working on recapping a Bestec ATX-250 12E which had all Jamicon caps except for the two large Capxon mains (470 uF/200 volts). Nearly all of the Jamicons had esr two or three times higher than the Nichicon PW series I am using as replacements. The power supply will work with the Jamicons, but I prefer to improve performance. Only one of the Jamicons on my psu was bulging, a 2200 uF/10 volts which had an esr of 2.3. It didn't make the psu stop, but I'm sure the Nichicon PW replacement helped. The esr of the replacement Nichicon was .02. Perhaps this information will help.