Clear Program in the AB/PLC 5/04 CPU

Once you remove the battery, there is a fairly large (typically green) capacitor right next to the battery, this needs to be shorted.
 
Look on the back of the board near the battery connector. You will see pins labeled vcc and gnd. Short them together for a few seconds with a paper clip, piece of wire, or pair of needle nose pliers.
 
Power down the rack, remove the processor from the rack and unplug the battery and then turn the processor over.

On the back of the board near where the battery plug is you will see two solder pads labeled Vcc and GND.

Short the two together for 40 seconds with a small screwdriver.

Reattach the battery.

The processor is now reset to factory defaults.

Make sure there is No Eeprom fitted or it will reload from EEprom when powered up.

YOUR PROGRAM HAS ALSO NOW GONE !
 
you are correct, dmroeder ... actually it IS the capacitor that needs shorting ...

but ...

my understanding is that if you short directly across the capacitor pins, then you take a chance that the resulting high current might be too much for the capacitor - and might (possibly) damage its dielectric film ...

I've heard that shorting the VBB and GND pins is safer - since it makes use of a "bleeder" resistor which limits the capacitor's discharge current to a safe level ...

or at least that's the way I've heard it explained ...
 
Last edited:

Similar Topics

i have a old gould plc pc0085 with programmer pc0105... and i have a question!! How clear program and go to prog mode.. please help me!!!
Replies
2
Views
2,334
I wish to view a program inside a 224 S7-200 PLC, but it has a password on it. From quick reading on the net, you cant view the program and the...
Replies
4
Views
1,702
attempting to load code on to a PLC from a memory module (ML1100). for some reason it took the program file, but not the updated ENET config. I...
Replies
2
Views
3,866
I recently bought a CPM1A on Ebay, seller said it was removed from equipment in working condition. I'm using SYSWIN 3.4 software and can connect...
Replies
6
Views
8,222
Hi everyone, recently i worked with a cmore panel and have the question that how can clear alarm list whit remote form,right now only can with...
Replies
0
Views
77
Back
Top Bottom