OT--Privilege SR54 NC Help please


Hi all.

Not certain if it's low batteries or malfunction but, my newly acquired calc is acting very strangely.

1--in the middle of calculations, the display will blank out, relight and lock up the keyboard.

2--If I then power cycle after a few minutes, the behaviour starts up again--the calc is fine for a few minutes but will behave awkwardly

3--when the calc comes back on from a calculation blackout the display will show a right justified 00.

I remember that the APF Mark 55 manual stated that during a low battery stage, calculation results would erroneous and since the SR54 NC is a clone, perhaps this erratic behaviour is due to the low battery symptom or is sit something else?

Your advice is greatly appreciated


Try using some fresh AA alkaline batteries in it instead.


Well, after a few hours of charging the fresh NiCd set inside, the unit will not turn on. Please help. If I install AAs, wouldn't the 4.5v supply overload the circuitry?

ADDENDUM. After switching to adding a trio of AAs, the Privileg won't turn on that way, either. Any thoughts?

Edited: 14 July 2012, 1:14 a.m. after one or more responses were posted


If you install the batteries backwards you might possibly be able to calculate square roots of negative numbers.


Are the battery compartment contacts clean ? The only other non-electronic issue that I can think of is a flaky power switch. Try moving it to intermmediate position between OFF and ON, or pressing down and jiggling it. If not, you may have some bad memory or other IC inside of it. Finally, if it is returnable to where you bought it, you may want to return it.



Yup, with a fresh set of AAs, the Privileg is back in working order. But, let me ask. The APF charger is marked as follows:

Input--AC 117V 60Hz 6W, Output--DC 3V 500mA

The diagram shows the polarity: the shell/ring marked as negative and the pin marked as positive.

Is this charger's configuration suitable for the Privileg SR54 NC I have? Or could it have been that one or all of the Tenergy cells were too drained to be charged fully?

If I go to a hardware store and pick up one of those mini screwdriver sets, what size Phillips screwdriver do I need in the set to open the battery door?

Edited: 14 July 2012, 2:13 p.m.


You must have the wrong APF charger. What model is it ? Mine is a Model 415, and it is labelled Input 117V 60 Hz 3W and D.C. Output 4.5V 150 mA. In any case, the APF Mark 55 has 3 AA NiCd cells inside it, which are a minimum 3.6V, so a 3V charger won't work. As far as pin polarity is concerned, I just checked both my APF and Privileg chargers and the Privileg is reversed from the APF, so the APF charger won't work in the Privileg anyway. So, I was incorrect in telling you that batteries can be charged in the Privileg with the APF charger. Like I said, I've been using 1.5V AA alkaline cells in my two Privileg SR54NC and also my two Omron 12SR calculators without any problems. You might want to look for a universal charger that can switch to different voltages, has different male and female pins and can swich pin polarity. The battery door screw is a #1 phillips.


The APF I have is the Mark 55. So, would the charger I previously described be suitable for my APF?




Okay. Here I go again. If I were to seek out the proper chargers for the APF Mark 55 and Privileg SR54 NC, what are the exact specs I should be looking for (especially for the Privileg since I can charge the batteries in a separate charging station)?


Edited: 19 July 2012, 10:42 p.m.


Get a charger that outputs 4.5V and has a polarity switchable plug. The APF and Privileg chargers are rated at 150mA, which works out to 0.675 VA, so as long as the charger can provide that as a minimum, it should work. I have an RCA Model AH3 Universal AC/DC Adapter that outputs 3.6 VA, and works great with both the APF Mark 55 and the Privileg SR54NC.


Hi there. Where can I get one of those chargers? Can I get it online or do I need to go to a Fry's or competitor to get one? Can you lead me to a URL of the product?



I got it on eBay a long time ago. Just do a search there or google it. There's probably a lot of other ones out there with different brand names and models. It's a pretty generic item. Or you could just try a local Radio Shack store. You need one that includes a 12mm x 2.5mm male pin.

I just found this one that looks like it should work. The 4-way connector looks just like the one on mine, and it would be the small male pin that would fit. Unfortunately, the vendor doesn't give the pin sizes, so I can't be 100% sure.

Edited: 20 July 2012, 8:05 p.m.



The APF charger is marked as follows:

Input--AC 117V 60Hz 6W, Output--DC 3V 500mA

This will not work - you obviously cannot charge a 3.6 V battery pack with a 3 V charger. ;-)

The Privileg SR54NC originally came with a small AC adapter (the German label says "Netzteil" = AC adapter, not "Ladeger├Ąt" = charger) rated 4.5 V at 150 mA. Since it was mainly sold in Germany it had a grounded ("Schuko") mains plug for 220 V~.

As usual, I strongly recommend charging the cells externally in a decent processor-controlled charger. Compared to NiCd cells of the Seventies, current NiMH-batteries offer about five times the capacity which also means 5x the charging time or more. So forget about the internal charging circuitry and use a decent external charger. And don't forget: 5x the capacity also means 5x the original operating time. ;-)



The Privileg SR54NC originally came with a small AC adapter (the German label says "Netzteil" = AC adapter, not "Ladeger├Ąt" = charger) rated 4.5 V at 150 mA. Since it was mainly sold in Germany it had a grounded ("Schuko") mains plug for 220 V~.

Yes, that is the same charger I have as well, and I have a converter so that I can use it here in the USA with a 120 vac 60 hz mains. It has the same 4.5V 150mA output as the APF AC adapter, but unfortunately the pin polarity is reversed, so they are not interchangeable.

I agree about charging the battery cells externally, which is easily done since the cells are installed individually and not in some sort of pack.

Edited: 15 July 2012, 11:14 a.m.


Michael; I agree. Absolutely. There is no reason to plug a calculator that runs off normal batteries into mains. That's risking ruining irreplaceable ICs for the small joy of playing around with them immediately.

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