SM 74 IR Dryer problem

Has anyone run into a problem with their IR dryer, where it shuts down by itself and then sometimes starts up again? I have an SM 74 dryer, when you first turn it on, it does its initial check but then shuts down, no visible screen available on the control panel. If you turn the run stop switch on and off several times it will then start working, but after awhile it stops.

 

Hello Griznaf,

What kind of dryer is it? I assume its a drystar. If you can give me your machine number I might be able to look into it in detail. Secondly is there any error on the display? I have seen problems similar to this, normally the issue is related to short circuit in the DC line or bad contacts which makes the PLC behave this way, turning off and on randomly.

 

Yes it is a drystar. Drystar 2000 SM 74 NL/LGK for an sM 74 624905

 

Hello Griznarf,
I believe some of the hoses are damaged or broken. There should be air leakage in the circuit. Does it have control panel on electrical cabin or on CP2000?

 

The hoses are fine as the press was just installed. The control panel is on the electrical cabin. When you first turn it on, the screen lights up with writing and then it goes blank. Also when it is working and you press F4 to see the errors,, the dryer shuts down and the screen goes blank.

 

WNile the screen goes blank, does it have back light or it's turned off and black? Can you send photo or a short film?

 

So it has one of those comcons/PLC with an LCD, have you ever been able to see the errors or the PLC doesn't stay stable for that long? Plus does the screen come back again by itself without turning the switch on and off again sometimes? If it does, does the dryer again do the initial checkup? And like Mathew asked does the backlight stay lit? I would also ask you to do a 24VDC power supply check on the PLC and and keep track of any dips in the voltage level once it turns off randomly.

 

[video]https://youtu.be/N2X79rv-Eug[/video]

I have uploaded a video so you can see what is happening.

 

Hello Griznarf,

I cant overlook the fact, how dim the LED's for the outputs look as compared to LED's for the inputs, I would recommend you to disconnect one dryer cassette at a time and try running/resetting the dryer to see if the system becomes stable. If the situation doesn't improve put that cassette back in and remove the other one followed by a reset. We have to be certain that the problem isnt originating from any of the cassettes, secondly I hear a strange sound when the dryer does the initial checkup after you have reset it using the run/stop switch, sounds like a contactor, there are interface cards through which the signals from the PLC are interfaced with the rest of the components in the panel, sometimes these interface cards can result in a bad contact as the soldering at the back cracks, this can give you all sorts of problems and weekly energized contractors is one of them which can result in a similar sound that I can hear in the video.

 

Just noticed the leds flicker first and then become stable, which of course isnt normal for an output. Please follow the instructions in my previous post and see if that helps.

 

In addition to above instruction, personally believes the issue of your unit is hardware problem. I don't see any voltage drop or miss connection since you made a Hard reset by turning RUN?OFF button.
Did any technician check the unit?

 

Very true Mathew, the symptoms are pointing towards a hardware failure in the plc, if the problem cant be isolated by following the steps as described then this probably signals a possible faulty plc. Hope we can get a feedback soon.

 

I took another look at the PLC controller. I did have it apart before and looked at the solder joints but saw nothing. This time I separated all the boards and resoldered any connection that wasn't too small. I payed close attention to any pin connections, that joined boards together and where the connectors plugged in. I put it back together and put it into the dryer. Reconnected all the plugs and fired it up. It came on right away and stayed on. There was a red error light before it is now gone. So far so good. It appears to be working properly, will know when a job is run thru the press. Only issue now is it says the battery needs replacing. It was brand new so not sure what is going on.

 

Is this unit equipped to CD74? I heard about a similar issue when I was in Toronto last September.