Rohde & Schwarz SMG lowbattery error 6

[Alexander51]

Dear All,
My R&S SMG meets error 6. It's a low battery message.
My question:

What kind of battery is it?
Where can I find it in my SMG?
Is it easy to replace?
Will I lose important data when I replace it?

Thank you very much for a positive reply

Alex

[wn1fju]

I have neither an SMG nor the service manual, but since nobody who does has yet responded to you, I can at least offer some general advice:

1.  The battery most likely backs up some RAM which usually just stores things like user front-panel settings.  If that's the case, it is not a big issue if it dies.  However, there are cases (fortunately only a few) where a manufacturer will also store calibration constants in the RAM.  In that case, a recalibration is necessary after battery replacement (but see item #4 below).

2.  The battery is usually on the board with the RAM and that is usually the main processor board.  The board may be under a cover, so you may need to do some disassembly to get to it.

3.  The battery can be NiCd, NiMH, Li, etc.  The main issue is whether or not it is the rechargeable type.  Normally one would use the same battery, but it is possible, for instance, to use a non-rechargeable battery (two AA alkalines for instance) to replace a rechargeable type.  Just throw a Schottky diode in series with the battery to prevent it from seeing voltage when the unit is turned on.

4.  When you finally locate the battery, measure the voltage.  If it is below about 2 to 2.5 volts, your RAM has probably lost its contents.  If it is above 2.5 volts, the RAM may still be alive (even though the SMG is throwing a low battery error message).  In that case, you can parallel a 3V external power supply (through a 1K resistor) across the battery circuit while you replace the battery.  If you are careful, this will preserve the RAM contents while you make the battery change.

5.  You asked, "is it easy to replace?"  Usually, it is not a big deal.   What you really have to fear is when the battery has leaked.  Not only can this make a mess, but it can easily corrode or destroy components, leads, traces, etc.  If you find any leakage, you need to scrub the board several times (alcohol) and do a very careful visual inspection.  Check any suspicious areas with an ohmmeter to make sure connections haven't been eaten through. 

[Alexander51]

Dear reader of my question,

Thank you very much for your information regarding a backup battery in my SMG.
I will respect your proposals and will try to repair it soon,
The advise to use a Schottky diode and the idea of a parallel mounted 3 Volt battery parallel to the original backup batt.while replacing it seems me a very good idea.

Thank you very much!!

Alex