What replacement for this timekeeper chip

[cs.dk]

I've got an Atlas Copco GA7 compressor in my workshop. The old "Elektronikon" controller suffers a problem, which renders the compressor useless 
From what i have read, the battery inside the "timekeeper" IC dies with age, and the compressor then shows "Error 200", and won't do anything at all.

Since a new controller is really expensive, i want to be prepared. (1000£ for a damaged unit! http://www.ebay.co.uk/itm/ELEKTRONIKON-Compressor-Unit-1900-0701-25-Atlas-Copco-1900070125-New-See-desc-/282200720798?hash=item41b479459e:g:eYAAAOSwpLNX7lu0 )

The timekeeper, or what it's doing is a ST M48T02-200PC1 - Datasheet; http://www.st.com/content/ccc/resource/technical/document/datasheet/cf/6a/69/ff/7a/6e/4b/bd/CD00000520.pdf/files/CD00000520.pdf/jcr:content/translations/en.CD00000520.pdf

I have seen some pics about opening the thing, and add a buttoncell externally. Seems risky though.

Is there some sort of replacement, and would I need to get some data out of it, while it is still alive? If yes, what sort of reader would grab a dumb?

[amyk]

First question: what does an air compressor need an RTC for!?

These RTCs with integrated battery are found in various other things like PCs, test equipment, and the like. I think Dallas/Maxim were the first to come up with this utterly stupid design.

http://www.mcamafia.de/mcapage0/dsrework.htm

http://www.classic-computers.org.nz/blog/2009-10-10-renovating-a-dallas-battery-chip.htm

You will need to read the contents of the IC and write it to the new one. Any multi-programmer should be able to do it.

The thought just occurred to me, this might be planned obolescence if they kept the firmware for the controller in there.

[cs.dk]

@evb149 - Thought those were obsolete. I prefer a never design with an external battery though, but maybe the chances are small.

@amyk - I don't know? But you can program the compressor to run on ie. weekdays from 6-15, weekends from 7-12 or what ever you like.
I actually don't know if the firmware is in there, but it would not surprise me if it was. The compressor is from 1998, but it is still going strong. It has only ~30K hours on it, so there should be at least 30K more, if the stupid designed EEPROM doesn't die for me.
There is a forum post about it here, but most are in russian, maybe some one can translate? http://comprforum.ru/viewtopic.php?f=8&t=954

[helius]

Of course even if you buy a new part from distributor stock I'd want to make sure the "manufacturing date" of the part is actually new enough that the built in cell is likely still going to be OK for several more years since the battery's clock starts ticking when the battery cell is manufactured.

No, this is not the case. The device is in the inactive state until it is installed and instructed to begin oscillating, and the power draw while on the shelf is insignificant (nanowatts). Of course there will be some self-discharge, but it is very low in these types of cells.

[NiHaoMike]

Does it use a direct to mains motor? If so, it should be trivial to reverse engineer how to read the pressure sensor and make a replacement controller.

[Jeff_Birt]

Theses devices are not used for firmware. Typically they are just used to store configuration or calibration parameters and the RTC functionality. I seem to recall that the guy from The Signal Path fixed a piece of test gear that had one of these and would display an error code related to it not being able to read or write to the device.

[calexanian]

Those appear to be like the famous, or infamous Dallas clock modules. we used them in some of our designs many years ago. RTC modules with ram like those were volatile ram. Once the battery dies it loses memory. I would however find it hard to believe critical information needed for startup would be stored on them, because after all they are traditionally static ram and that is a big no no from an engineering point of view. even if it has a battery backup. If there a way to hotwire this thing to just run when you need it with a pressure switch or something?

[timb]

I believe later ST versions of these did away with the integrated battery approach; instead the IC itself had four pin sockets on the top (one on each corner), essentially the RTC IC had a socket on the top. The battery was the shape of the IC and would snap on, allowing you to replace it when it ran down. They used a small capacitor to retain the information on the RTC/SRAM in the few seconds it took to replace the battery.

They called this system "SnapHat" or something like that. Ultimately they didn't take up any more space than the Dallas equivalents, but had the benefit of being user replaceable. You can still buy the batteries on Digital-Key!

[cs.dk]

Thanks for the replys, i have something to think on now.

The Elektronikon controls the following, if i am not mistaken;
The Y-D motorstarter relays, and the time in Y before switching over, how long time to run before opening the loading/unloading valve, how long time to run unloaded before a shutdown, load and unload "windows", etc. All values are programmable.
It monitors air element output temperature, dew point at the cooler, air pressure, oil temp, emergency stop, motorload/overload, automatic restart after power failure (if selected), and probably something i've forgotten.
It also count the running hours loaded and unloaded. And of course a service counter where you can reset for oil change, seperator change, filter change, etc..

[Pjotr]

Looking at the picture it is just an overmoulded standard DIL package on a IC socket. Probably a standard RTC+Battery brick. Since the battery is dead anyway I would try to replace the battery at first.

Take care to work clean. Impedances are very high to keep leakage current low. It is one of the reasons to embed the battery: To keep leakage current as low as possible. Especially in an environment where cleanliness cannot be guaranteed.

B.t.w. the data sheet states "The M48T02/12 TIMEKEEPER® RAM is a 2 Kb x 8 non-volatile static RAM and real-time clock which is pin and functional compatible with the DS1642. " The Dallas/Maxim DS1642 is widely available.

[amyk]

Theses devices are not used for firmware. Typically they are just used to store configuration or calibration parameters and the RTC functionality. I seem to recall that the guy from The Signal Path fixed a piece of test gear that had one of these and would display an error code related to it not being able to read or write to the device.

2 kilobytes is a LOT of space for calibration data, especially calibration data for an air compressor.

It's not unknown for companies to do this, storing firmware in a volatile memory: http://www.arcadecollecting.com/dead/dead.html

[Knuckx]

I have replaced the battery in some of these chips like the photo in your post shows (quite a lot of old, non-standard computers used them, as well as at least one games console).

The battery is in an overmold on top of the DIL package. The overmold is softer than the IC package itself, so it's unlikely you will damage the device unless you are careless; if you cut into the correct side of the device, you don't even have to remove the original battery, just disconnect it (if you don't want to - I would remove it though). A sharp stanley knife or scalpel, along with patience works well - heating the knife seems to help things along too.

I normally use a CR2032 holder instead of a tagged cell, and epoxy it onto the top of the IC, or another convienient surface, so next time the battery dies, I don't have to break out a soldering iron...

[Ian.M]

I'd go for the minimally invasive approach of just isolating the old battery and connecting a supplementary one.  All the resources I have seen on the web for that chip say the crystal is up at the pin 1 end and the battery contacts are in the center of the other end., so that's where you should start digging, with the chip clamped in a vice with its pins protected by a piece of wood with two saw-cuts in anf the top protected with thin card. With luck there will be enough residual voltage to determine the battery polarity without having to fully expose it.   

[Doctorandus_P]

Your best bet is probably to keep the mains power to the compressor on.
The RTC only draws current from it's battery if it has no other power.

shelf life for Lithium batteries is probably longer than your compressor wil last.

[picdev]

I am trying to fix a elektronikon controller, does anyone know where to connect a ref voltage to simulate the sensor ?

[cs.dk]

There is a schematic in the compressor instruction book - I think the pressure sensor is a 4-20 mA type, it has 3 wires.

EDIT: Can't attach more then 1 MB here - The manual is here; Atlas Copco GA7 Compressor Manual

[picdev]

  I was looking for this manual for one day! thank you very much.
I made some test with inputs and I found the analog input, it takes an analog voltage between 1-5volts, you set the pressure limits and one relay open and close.
The start and stop button doesnt work
 I will read the manual
  thanks

[cs.dk]

No problem - I have the spare part catalogue as well; Atlas Copco GA7 Spare Parts Catalogue

[picdev]

the electric diagram  isnt clear 

[cs.dk]

the electric diagram  isnt clear 

I've scanned the diagram i found inside the compressor, it should be better then the first in the manual.