Elonex Lumina 32" SMPS Problem

[NipZ]

I have a 32" Elonex Lumina TV/PC combined media center . As soon as I plug it in to the mains it tries to power on. The screens backlights flicker on and off fast for a while and then starts calming down and eventually stays blank. While the backlights are flickering all DC voltages are doing exactly the same, but after 20-30 secs the voltages become stable around their expected values i.e. 24v=24.35v 3.3v=3.31v 6v=6.12v 12v= 12.4v and 33v=32.96v, the only one that seems a little low is standby 5v=4.45v

I am assuming the fault is on the primary side as all DC voltages are effected. I checked the caps and they appear ok apart from a high esr on one small cap which I replaced.

Could this possibly be down to the PFC(IP3002) or the PWM(Viper 12A)?

[budm]

Re: Elonex Lumina 32" SMPS Problem

What DC voltage do you have on the main DC filter cap, if the PFC is working, it should then have about 370~400VDC on that cap.
Yes, the 5V is on the low side. So did you replace all those small caps (I see 10 of them) in the primary side?

[NipZ]

Re: Elonex Lumina 32" SMPS Problem

Are the 10 I have marked the caps you mean? I only replaced the one marked with red

[NipZ]

Re: Elonex Lumina 32" SMPS Problem

Forgot the pic :p

[budm]

Re: Elonex Lumina 32" SMPS Problem

See picture.

[NipZ]

Re: Elonex Lumina 32" SMPS Problem

I've ordered 4 x 50v 47uf to replace them. What is an acceptable esr for these caps? 1 of them measures 14! but the other 3 vary from 0.72-1.2, I'm replacing them all but it would be nice to know for future reference

[budm]

Re: Elonex Lumina 32" SMPS Problem

14 Ohms is bad, try heating it with hair dryer, you should see it goes down.
Low ESR type will be <1 Ohm

[NipZ]

Re: Elonex Lumina 32" SMPS Problem

I tried a hair dryer on it and got it down to 6.4
Thanks for the help, I'll let you know my results with the new caps installed.

[NipZ]

Re: Elonex Lumina 32" SMPS Problem

wow 1 cap with a high esr and thats all it was!
Thanks for the help!

[budm]

Re: Elonex Lumina 32" SMPS Problem

Glad to hear you got it fixed.