Old Techwood (Vestel) with 17PW15 PSU

[Clydeuk]

Hi.

Had this set for ages, never been reliable enough to sell on. Had loads of issues with PSU, most of the common problems associated with caps have been dealt with. Just this last one I thought I might throw here to see if anyone's had it before I delve in deeper. Problem is initial switch on standby ok, press power button blue light goes off but no display, can't put back to standby have to power off completely. Second switch on, comes on but screen is a mess of random lines. Power off again and back on, set comes on fine and works. Only problem then is on bright scenes the audio crackles and goes off, then comes back on.

I know it's a PSU problem just wondering if anyone has had this one? There is also a faint buzz on the audio at all times while the set is on.

I have a 17PW20 in another set I could swap with, but that seems to have it's own problems. It's been a long time since I worked on these sets so can't remember what I have replaced, so this is just putting some feelers out.

[ReeceyBurger123]

Re: Old Techwood (Vestel) with 17PW15 PSU

Have you a OS scope and know how to use it to test the Psu output to see if theres any noise on the output which can cause the issues you describe ?

[Clydeuk]

Re: Old Techwood (Vestel) with 17PW15 PSU

Yes I do have a scope, but not where the TV is (I've taken the set to my folks who I visit from time to time). It might be a few weeks before I get the scope to the set now, but next time I visit I will take the scope and perhaps the other power supply just to compare.

[Clydeuk]

Re: Old Techwood (Vestel) with 17PW15 PSU

I should mention this problem of audio cracking off on bright scenes only happens on HDMI it seems, and it's not a fault on the main board as this is the 3rd one it's had (I damaged the original when I first fixed the power supply and didn't screw it down fully, the arc to the frame caused silicon damage). Works fine on SCART apart from the problem with initial power up.

I always struggle with Vestel circuit diagrams. I don't think this is a capacitor problem as I seem to remember replacing the usual bad ones (Chong - Samxxon etc) and did go over them all with an ESR meter.