Polar 76 EM problems


New member
Hello! I'm having paper cutter problems.
To be specific, we have a Polar 76 EM that is giving us an 88 code.

For the past few months, we have been working to try to fix this. We hired a certified polar tech and he couldn't fix it. We had it working intermittently.

We have checked the safety bolt, which is more like a safety arm that moves past two proximity sensors. We have checked the wiring and functionality of the sensors, but we are still getting an 88 code.

We checked the supply voltages. 5v is fine, 24v is fine, but 42v is giving us 58v.
During testing, our HK board stopped working. Resistor got extremely hot and burned off. We got a new HK board and it's the same issue, the green led will not light up (led 1 in the manual) and consequently, neither will the KK board.

While the HK board was still working the 88 code problem persisted. We have tried a new AR board (proper software version 4.1) and still no luck. Our next step is to try a new IAR board.

At the moment, we are considering selling the machine inoperable or trading it in to somebody who refurbished these machines.

I'm wondering, does anybody have experience with this machine? We have the schematics and the manual and have traced every wire right down to the power supply. Is 58v a problem on the 42v? If so, how do we remediate this?

I know that the HK board regulates 24v for 12v supply. I must cite that I am not a technician, but we live in a fairly remote area and don't have a choice but to try what we can.

In short, our HK board has a hot resistor now and we are still on code 88. We need to get the HK board working before we can start on remediating this code. And plug and play is not feasible because our new board had the same issue and it was tested working.

I can provide pictures if necessary.

Thank you very much Printplanet for your help.
I have an update. So the HK board needs 12v supply to light up led v1, and also to light up led v1 on the KK board. I found a shorted capacitor on the KK board and am going to get a capacitor to replace it to see if it fixes the issue. I notice that if I plug in the HK board without the KK board, I get 12v to led v1 but the second I plug in the KK board I get no green lights and a hot resistor. I ended up buying a higher wattage resistor to tolerate the heat while I test it. I'm not totally sure if a new capacitor is going to fix the issue, but I can be certain that this one is dead there's 0 load and full continuity, when compared to the same identical working one (not an expert in electronics).

This machine has been modified quite a bit. I don't know exactly why but I do know there are deliberately broken traces and wires jumping things. I'll update this thread as I go along in case anybody else has a similar issue. We had no idea it was modified so much when we bought it until we started having problems that even a certified polar tech for over 40 years couldn't fix it.

Having said that, the HK and KK boards not working is only one issue. We still have a permanent 88 code. I'm feeling as I go on though, that I'm getting closer to fixing this.

We have another cutter in the meantime and I'm working at this on slow days. I'll update this thread as I go along.


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