This thread is pretty old, but if anyone is having recurring trouble with their 5088 power supply, I've been dealing with the same and this insight may help you out:
The main PSU in my particular unit houses 3 SMPS units. The unit that powers the penthouse supplies DC 12V (50amps) and is just wired from the mains switch directly to a pair of bolts through the rear of the chassis. The 12V wires to a distribution/regulator located in the console that distributes the 12volts to each penthouse module. In this case, the fans in the main PSU rack (three fans) were all toast, so I replaced them. The SMPS for the penthouse was toast so that got replaced (TDK/Lambda unit) and it was still having trouble. I was advised by a service tech at Rupert Neve Designs to check the shoulder washer that insulates the metal studs from the chassis on the rear of the unit. Lo and behold, the shoulder washer had powdered and the studs were grounding out to the chassis. I insulated the studs and reconnected it and everything seems A-OK. I've seen other boards with power supplies that wire directly to the penthouse, but this model uses a distribution box - called a RigRunner. If the SMPS voltage drops below about 13 volts, the main supply lines overheat and melt the connectors.
The support was excellent and knowledgeable, so thanks to Neve Designs for that!