Sony Trinitron KV-24FS120 four blinks

[YamahaFreak]

This is a customer repair job that has me stumped. Dirty and dusty but otherwise intact KV-24FS120 that won't come out of standby. Pressing POWER gets one relay click, steady flashing LED for about 6-8 seconds, a second relay click, and then a repeating four flashes of the standby LED. The HV never energizes and no other sounds are audible from within. Inspecting the boards revealed no burned, blown, bulged, or otherwise visibly defective components.

I used to know all the standby LED codes...Googling suggests four flashes means something wrong in the power supply, but I haven't been able to get any further. Hopefully this isn't an MCZ chip failure.