Technika lcd 32-207 intermittently sticking in standby

[LesWoollam]

I have a 32" Technika lcd 32-207 TV on the bench which is has started getting stuck in standby. It normally power-up from cold fine, but if I power down after say half an hour it then refuses to come out of standby till it's been 'resting' for a while. There are no bulging caps but the voltage across the main 220uF cap is 337v. Any ideas??

[tom66]

Re: Technika lcd 32-207 intermittently sticking in standby

Vestel 17PW15, PW20?

[LesWoollam]

Re: Technika lcd 32-207 intermittently sticking in standby

Sorry, 17PW20.1

[Techstar]

Re: Technika lcd 32-207 intermittently sticking in standby

Look for a good secondhand board off e-bay (£20) ish. Do barter with board sellers , i have had as much as 30% knocked of some board prices. There is a kit for the psu board if it is a vestel like tom says .. Sounds like maybe a dried out cap in the psu , do you have an esr meter , without one it's guess work...

[LesWoollam]

Re: Technika lcd 32-207 intermittently sticking in standby

No ESR meter I'm afraid. That said, I've already replaced most of the caps but the fault's still the same.

[selldoor]

Re: Technika lcd 32-207 intermittently sticking in standby

Look for a good secondhand board off e-bay (£20) ish. Do barter with board sellers , i have had as much as 30% knocked of some board prices. There is a kit for the psu board if it is a vestel like tom says .. Sounds like maybe a dried out cap in the psu , do you have an esr meter , without one it's guess work...

Surely if you get a SH board off ebay you are not going to be in much better position? and have to change the caps on that.

I would start with replacing the 4 smallest caps on the primary side of the
PS Board

[Techstar]

Re: Technika lcd 32-207 intermittently sticking in standby

I have a feeling it might need a kit. The price of a kit would probably be not much less than a good second hand board. When i see kits at £20 or a replacement board at £25 it's easy to see which is the best option. Could be on the primary side yes i agree. Maybe a high resistance start up resistor or a cap like you say. The prices of some kits for what they have is a bit of a rip off ... .....

[tom66]

Re: Technika lcd 32-207 intermittently sticking in standby

This model, it's the two 15nF 630V~1000V capacitors at top of PSU. Swap 'em and it should sort it though I prefer board swap with this model, cheap enough.

[LesWoollam]

Re: Technika lcd 32-207 intermittently sticking in standby

Thanks, I'll change them and report back.

[LesWoollam]

Re: Technika lcd 32-207 intermittently sticking in standby

Replaced the 4 x electrolytics on the primary side and the 2 x 15nF caps. . . problem still there.

[tom66]

Re: Technika lcd 32-207 intermittently sticking in standby

Check voltage across main cap.

[LesWoollam]

Re: Technika lcd 32-207 intermittently sticking in standby

337v in both standby and run.

[tom66]

Re: Technika lcd 32-207 intermittently sticking in standby

There's your problem. It should measure 392V when running. I had this same issue with a Sanyo. I swapped the PSU, the cost of repairing the PFC voltage boost was excessive compared to the PSU price.

[LesWoollam]

Re: Technika lcd 32-207 intermittently sticking in standby

What fails in the PFC? (There doesn't seem to be that many compnents in that part of the circuitry).

[tom66]

Re: Technika lcd 32-207 intermittently sticking in standby

I never figured it out after replacing almost everything in it. The only thing I didn't replace was the PFC IC.

[Techstar]

Re: Technika lcd 32-207 intermittently sticking in standby

Power factor correction is just another annoying add on we could do without.
It's like having a tooth filled that don't need filling. It makes the tv a little less of a gas guzzler from what i understand. Yet adds complexity and is just another thing to go wrong,, I got 2 pet hates = lead free solder and the pfc in a psu.

[LesWoollam]

Re: Technika lcd 32-207 intermittently sticking in standby

Bit of a naive question but is there no way of disabling/bypassing the PFC?

[tom66]

Re: Technika lcd 32-207 intermittently sticking in standby

Not really as the PSU is designed to operate on 392V +/-10V. When at 337V it struggles to maintain the 24V output.

[LesWoollam]

Re: Technika lcd 32-207 intermittently sticking in standby

Right, I understand. Looks like it's a replacement board then.

[selldoor]

Re: Technika lcd 32-207 intermittently sticking in standby

Thats bad news then still you will now have spares on hand.