R&S SME03 - Power Supply Weirdness - Info Request

[edpalmer42]

I recently picked up a R&S SME03.  While checking it out I noticed some distortion on the output at high levels.  At levels > +10 dBm, the positive side of the output clips long before the negative side.  Symmetric clipping would make more sense.  This just seems odd.  Yes, I realize that this is pushing the limits of the unit.  It gives a warning at levels above +13 dBm but actually tries to put out +16 dBm.

Since step 1 of troubleshooting is always to check voltages, I checked the power supply and found some weirdness.  All of the output voltages (+15V3, +7V7, +5V2, -15V3, +24V5, +12V, and -30V) are in spec. except for REF3 which is spec'ed at 2V6 - no tolerance, just 2V6.  Mine is 4V69  .  But since all the other supplies are fine, and the unit basically works, I don't know if REF3 is used for anything.

I decided to dig deeper and check the circuitry to see if that 4V69 was reasonable.  Unfortunately, my power supply is part # 1039.1510.00 and the only copy of the service manual that I can find includes power supply # 1039.1304.00 which is completely different from mine.  I checked other units that use the same power supply but came up empty.

So my first question is, does anyone have service info for the 1039.1510.00 power supply?  If not, does anyone know if the REF3 signal is used by any of the other modules in the SME03?

Thanks,
Ed

P.S.  I'm aware of the R&S group on groups.io, but there isn't much activity on this series of products so I thought I'd start here.