Electronics > Repair
Rohde & Schwarz UPV Audio Analyzer - teardown and repair
DaJMasta:
I'm not aware of any schematics available for any R&S equipment this recent or more recent, so I wouldn't hold my breath. That said, linear supplies are likely more straightforward, with the exception being that it will have several (3 maybe?) separate isolated grounds, so when you probe them to test various rails, make sure you're directly across the regulator or cap, if you have the wrong ground your measurements will be all wonky.
Also worth checking: the little cylindrical fuses on the vertically oriented board that distributes power to the main boards - if one of those is open, you've got a good starting point.
randymatt444:
Not sure I've seen this board. Where is it located?
randymatt444:
Dead Rohde & Schwarz UPV Audio Analyzer Update:
The R&S UPV audio analyzer uses a switch-mode power supply to run the PC and digital sections of the unit and a linear power supply to feed the analog audio generator and analyzer sections.
After finding several faults I replaced shorted diodes (3) and open fuses (3) on the linear power supply PCBA. But, seems the transformer that feeds the linear PSU has no output (open thermal link in the primary?).
Rohde & Schwarz wants $5,170 not including shipping to and from Germany for the repair and will not sell parts or schematics (as expected). This is an end-of-life unit running Windows XP imbedded,etc., not going to happen.
Anyway, dusted off some old power supplies here at home and I was able to get the analyzer section working. Here I’m feeding an amplifier input a signal from the Audio Precision 2722 generator, the output of the amp feed both the AP’s and the UPV’s channel 1 analyzer.
5, 6, 15, -15 vdc going to the analyzer section on the UPV. The rails are separated for each section, in other words 5 A and 5 G for the analyzer and generator sections.
Linear PSU not being used here, just passing AC thru to the SMPS running the PC section
Sending signal to an amplifier, this was measured on an Audio Precision 2722 analyzer
The output of the amplifier was sent to both the AP and the UPV
Pretty darn close!
randymatt444:
Did some more tweaking between the R&S and AP, looks pretty good.
AMPEXPERTS:
I found this thread while searching on cost to repair UPV. $5,170 is outrageous. Probably another $800 for freight costs as well.
My own UPV developed a problem after connecting a powered subwoofer speaker plate amp to my test setup, not realizing the output neutral speaker wiring sits at -40 VDC. That destroyed one of the relays that grounds the analyzer input and chan 1.
The relay is an AXICOM IM03. I can only find variants of this from the usual suppliers.
The other problem is access with a soldering iron. I am thinking the only option is a hot air workstation to heat up this part to remove and replace it.
There's no way I can afford 6 grand to send it off for repair, obviously. I am pretty sure that if I can source this relay, and solder it in myself, the unit will ground the input properly again. The relay on this channel is open circuit when input ground is on. The #2 channel still works, though oddly, it was connected t the same ground point on the amplifier.
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