FSP 19V 180W power supply repair

[lucky13]

Re: FSP 19V 180W power supply repair

Toasty,

Sorry I did not mean to ignore your question.

It was for a Viewsonic 27" N2700W.

I've already got the s/m of the TV but it does not show anyting useful about the external power adaptor. It does not even show the main board power input area so I can see if I can modify it touse 24v supply (which I have).

Strangely the back of the TV says Input: 19Vdc 4A.

So, maybe one of those el-cheapo ac adptor from eBay will work.

Yes, I have freeze spary but the voltage fluctuates as soon as I connect just the ac side so I never sprayed anything. Also, when it stopped working after a minute, the aluminium heatsink is barely warm to the touch.

Mmm, time to check if Digikey has this chip....

[Toasty]

Re: FSP 19V 180W power supply repair

Thanks for the info. I don't mean to be grumpy, it comes naturally. With all the info in front of us, it's easier to help.

I'd like you to try chilling the IC's one at a time. If you get a change, it's likely the faulty one. You have 3 on the back of the board. The L5991 appears to have 3 SMD transistors right next to it, hit them too.

I'd like you to take it slow and not blast the whole board. One at a time plz. Also, be careful of causing condensation when you do this.

(FYI- They are ~$40 on eBay)

Toast

[lucky13]

Re: FSP 19V 180W power supply repair

Darn, all the cans are empty... need to pick some up next week.

Yes, I seen those on ebay. They are not the exact original as this one has a small fan to blow in cool air. Those on eBay don't.

[lucky13]

Re: FSP 19V 180W power supply repair

Correction to what I said earlier. I have NOT freeze spray anything on this board.

I am looking at the data sheet for L6561 and see that pin8 Vcc has a 20v zener diode built in.

I checked the voltage (pin8 to pin6), it is jumping between 7 and 9v. That is too low! There is no way the zener can clamp the internal to 20v when the input is so far below.

So, perhaps the problem is near the input?

[Toasty]

Re: FSP 19V 180W power supply repair

>>Correction to what I said earlier. I have NOT freeze spray anything on this board.<<
??? When did you say that...?

Zener is for protection/limit, not regulation. Internally regulated 7v.

L5991A: http://search.digikey.com/scripts/Dk...=497-3996-1-ND

L6561: http://search.digikey.com/scripts/Dk...=497-4582-1-ND

Did you get the voltages on the other pins I asked in #34?

There are 3 IC's. We know 2, what is the third?

Toast

[lucky13]

Re: FSP 19V 180W power supply repair

>>Correction to what I said earlier. I have NOT freeze spray anything on this board.<<
??? When did you say that...?


Toast

Post#42, 2nd last paragraph....

I will answer the other questions next week as I left that thing at work.

[lucky13]

Re: FSP 19V 180W power supply repair

Min order 2500 pcs for that L6561.

And I don't understand how 1 pc of the L5991 comes out at Cdn $11.18 ?

[Toasty]

Re: FSP 19V 180W power supply repair

?? 1 = $1.44 US // $3.18 CAN

Top of page... You're looking at alternate packaging, a reel of them.

>>And I don't understand how 1 pc of the L5991 comes out at Cdn $11.18 ?<<
L5991 is $2.70 US // $1.69 CAN

Post 42 is mine. Just drop it. You never said you freeze sprayed anything. That's why I was curious as to why you said you didn't freeze anything when in fact you never said you froze anything.

Are we confused yet? I am! wheeeeeee!!!

Have a good weekend.

Toast

[lucky13]

Re: FSP 19V 180W power supply repair

Post 42 is mine. Just drop it. You never said you freeze sprayed anything. That's why I was curious as to why you said you didn't freeze anything when in fact you never said you froze anything.

Sorry was POST #41 (I couldn't count)

Yes, I have freeze spary but the voltage fluctuates as soon as I connect just the ac side so I never sprayed anything. Also, when it stopped working after a minute, the aluminium heatsink is barely warm to the touch.

Mmm, time to check if Digikey has this chip....

Toasty,

The third IC looks to be M101AC. Now, it could be 107AC. The picture I took previously cannot definitively show a 1 or 7. I will get a better magnifier glass on Monday to look again.

[Toasty]

Re: FSP 19V 180W power supply repair

101AC. Nothing found under 107AC

http://search.digikey.com/scripts/Dk...=497-5442-5-ND
http://www.mouser.com/ProductDetail/...bJYleECsqInS5i



Digikey says "non-stocked" (2,000 min qty) but has 102 on hand. LOL
Mouser is 1 at a time.

If you call or write them, you might just get a few tossed in with your other chips. I think you can get freebies from ST directly also. Enough BS and you'll get piles of stuff. Just don't tell them your fixing something...

Toast

[Gianni]

Re: FSP 19V 180W power supply repair

I checked the voltage (pin8 to pin6), it is jumping between 7 and 9v. That is too low! There is no way the zener can clamp the internal to 20v when the input is so far below.

I think they are jumping between Vcc on and Vcc off because is missing the voltage coming from auxiliary winding.
Can you feed with an external PS the L5991A?
If the PSU remains ON with an external feeding you know the controller is ok and you should check why there is no internal feeding.
Another reason could be a bad electrolytic on Vcc pin/ auxiliary winding but you have already replaced them so I have no more suggestion.
If you can keep on the L5991A (Vout must be 19.5V) check if the PFC works, you have to find around 350 - 400Vcc on the big black cap, if the voltage is only Vac x 1.41 then the PFC doesn't work.

It will be useful if you can draw the schematic following the tracks on PCB.

Ciao
Gianni