Pye 37K7225

What's a "pulsating power noise"?

Hmm? 79/80 sounds a bit early for a SMPSU - if there's an overload the PSU trips then tries to restart, this makes a pulsating or sometimes a breathing noise.

Yes does sound as though it is trying to restart. Any idea's?

Horizontal scan transistor maybe S/C?

Horizontal scan transformer maybe shorted turns or insulation breakdown?

Horizontal scan flyback tuning capacitor S/C

The tuning caps often crack or split when they fail, and you should have done a thorough visual inspection by now anyway! Try disconnecting the collector of the scan transistor - first test it for S/C then try powering up with it disconnected. Note that the PSU may not take to being run with no load so try connecting a 40W or 60W bulb from the feed to the collector to chassis (GND) See if the PSU fires up and lights the bulb and it wasn't a S/C transistor, this points to either shorted turns in the transformer or a load on one of the scan derived supplies S/C - such as audio or vertical sections. If the PSU still won't fire up its likely the scan transformer primary winding is shorted to GND or the PSU itself is faulty!

The set probably contains a Philips chassis - do a search on the model number to try and find the chassis type, I might just have the schematic!