Discoloration on phal leaves... virus/sun damage?
 

I got this phal about a month ago from a greenhouse. I initially assumed the yellow spots were from water sitting on the leaves while it was in the sun. I'm not concerned with the purple parts as I've heard some phals can show this pigmentation if they produce rich purple/red flowers (and it's not just the leaves that are purple, root tips and spike are also the same color.) Since I thought it was sun damage I was expecting the spots to turn brown and get dry, but they haven't and I've recently found some yellow spots on the underside of one of the leaves but they do not show on the top. This phal hasn't been in direct light since I got it and none of the orchids that share a shelf with this one have any sun damage. Is this a virus, mold or possibly just old sun damage? Any thoughts or help would be greatly appreciated.

I can't really say what might be causing this ... I'd isolate it, and hopefully some others can help!

I have a phal with similar spotting I was going to start a thread on so instead i will keep my eyes on this one! I figured mine was virus or fungus but i sprayed mine with bayer and neem 4 times and it spreads. It doesnt look like sun damage to me.

I don't vote for viruses, it's not coherent, as old leaves and brand new a affected but not those in the midle.

Also, the fact spots can be seen only on one side is mort a sign of a fungus.

(It doesn't mean there's no virus, but we can't prove it this way, very little signs can hint an effective presence).

Check if there's nothing sucking you leaves, it may be one of the causes. And I'd go for a fungicide.

If you see the affected leaves turning bad, don't be afraid to cut those. (sterilize tool, dispose immediatly of the leaf and clean you hands before and after, put cinnamon powder on the cut.)

Virus.
Look up Taiwan virus, which is a nickname for this.

The purple underside is normal for many many phals.