Olevia 342-B11 PSU problem, No voltage in secondary PSU

[cashkennedy]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

Well i replaced Q3 and Q4 with the FQPF13N50CF-ND from digi-key, and put in a new good fuse. And I now have a perfectly working 42" tv for 70 + 8 dollars in parts.

In retrospect, this model was probably pretty well built after seeing the trash they throw into 32" relabled stuff (funai and proview stuff). It has lots of ventilation for the PSU, connectors for all the wires going to the PSU, a fsp brand psu, and everything was very tidy and traditional.

So if anyone else has problems with a olevia 242-s11, 242-f11, 342-b11 check the main fuse and the Q3, Q4, and Q5 transistors on the power supply.

Thanks for all your help Bill and Robbie.

[Robbiebaby]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

hehe, no problem I guess :-P. Bills all the brains in here :-) I ordered a new PSU for it for 49 with free shipping. So we'll see how that goes.

[Robbiebaby]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

Alright, I got the board in today. Replaced it and all. Except now the TV still wont turn on. Im pretty sure the new PSU works fine. I dont get any kind of indication that it is on at all, no standby light, no anything. Any ideas? I guess now the main board would be at fault :-/
Sorry for being such a bother heh.

[retiredcaps]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

Except now the TV still wont turn on.

Go back to the beginning again.

1) Do you see 165V DC volts across the main capacitor?
2) Is the 5V SB rail showing a solid and steady 5V DC?
3) When you press the on/off button, does the PS_ON pin voltage change?

[Robbiebaby]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

Ok I just checked everything, On the main cap I get 152.8.

The 5v SB rail (labeled 5v s on the psu) is the only thing that gets voltage pretty much. It get 5.04v

On the same connector I also have a brown wire labeled O/F - It gets no voltage no matter if I press the button or not.
There is also a Blue wire, it is labeled B-ON. When I plug in the TV, it reads 0.0, when the power button is pressed, it goes to 3.57v. When pressed again, it goes back to 0.0.
One more is the Yellow wire. This one reads 0.0 initially when plugged in, then when power is pressed, it jumps to 2.86v, and stays at 2.86v after that, it doesn't go down after I press the power again.
HMMM.....

[coreyand]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

I just fixed this same tv, I replaced all the caps on the secondary. Im quoting this from memory but I think it was 3 1000uf 35V, 2 680uf 25v, a 1500uf 15v?, and the small ones too, either way I replaced all on the secondary and the works again. The smaller caps showed no visual sign of problems but after testing them they were bad.

[elecson]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

helo everybody, what is part number IC3 ? please

[lightwaveguy]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

The part number for IC3 is Texas Instruments UCC28051, which is a transition mode PFC controller.

[lightwaveguy]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

Can anyone shed some light on this one for me. I re-capped this whole power supply, all of them. I get the +5v SB voltage with the power applied. When I hit the power button, I get my secondary voltages for about a second and then shut down. I need to remove power to be able to attempt restart again.

The +5v makes it to +5v, the +18v makes it to about +12v and the +24v gets to about +9v. The +5sb remains on the whole time, and I did replace IC1 a L6598 Is there a schematic for this power supply anywhere? That would be a great help.

[budm]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

So are you getting the PFC Boosted Voltage of >360VDC?

[lightwaveguy]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

I can't say just what the voltage gets to, but I do have a high freq signal out of the PFC chip and the same out of the MOSFET it's driving. Everything functions for a second.

[vinceroger69]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

can you test the voltage on the large capacitor to see what the readings are be carefull as high voltage as working on the primary side of power supply. Does this voltage also drop down after a second?

[lightwaveguy]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

As far as i can tell i get about 230V to 250V

[vinceroger69]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

Is that with the set on standby? and also when you try to turn the set on? that reading is too low as budm says maybe the pfc boosted voltage maynot be working. can you upload good clear pictures or the top and the bottom of the power supply.Someone with more experience with power supplies will advise on what to test next.

[Agent24]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

If the whole PSU is shutting down, could it be possible that the PFC circuit just doesn't have enough time to boost the voltage up to 360v?

[lightwaveguy]

Re: Olevia 342-B11 PSU problem, No voltage in secondary PSU

It's been awhile since I've posted about this. But replying to the last post in this chain. I do get +360 volts on the boost side of the primary side of this power supply. Measuring the output side the +5 is right on the mark, but the +18 get to about +13 and the +24 get to about +18 until the thing shuts down. The +360 boost stays up there for quite sometime, it drifts down very slowly and i have to let it drain to around +180 or so until i can turn it back on and get it to restart. I did recap the whole thing, only difference is i did not have 680uf caps so i subbed 1000uf caps, i don't see this having to much of an effect on the total operations of this supply. I'm about lost on this now. I would say its something with IC1 the controller for the output drive, but i can't get a handle on whats making it shut off. Anyone have voltage readings for this chip in it running state? One thing of note, i'm just running this on the bench. Does it have to be loaded down to run, or will it fire up free standing? Again, thanks for any help anyone can offer.

Another thing of note. What i see is the supply voltage for IC1 is turning off when it shuts down. The supply to the boost chip stays on, but it stops outputting, but the supply for IC1 turns off. There are two transistors over by IC2 the boost controller. They control the supply voltage for IC1. When i power it on the supply voltage for IC1 goes to about +10 and then gets shut off when the supply shuts down. This is like the chicken and the egg thing, which is happening first, IC1 or IC2? I have not been able to find schematics for this supply, found lots of ones before and after this one but not this one, and there is just enough differences to make it confusing.