Heidenhain tnc355 monitor black.

[Oviksnc]

Hi.

We recently bought a Mikron with tnc355 control. Everything worked fine until yesterday when i was starting up the machine.

First i saw some yellow lines flipping around on the monitor and then -- Black!

Nothing can be done with the control. CE --> power on does´nt work either.

When i came home i found the service manual and how to fault find the monitor ( remove the monitor cable and check for a yellow field on the screen ).

My question is. If the monitor is fine i guess it´s the CLP board causing this? Does anyone know what the common failure on this board is and how to repair it? I work with cnc machines all day long but only the mechanical bit, but have friends who are very good with the electrical. So if we know what to look for maybe we can fix this board.

Thanks

/Johan.

[Oviksnc]

UPDATE!

The monitor is still black without the monitorplug from the controller.

But none of the fuctions on the machine can be moved. I talked with an Heidenhain repairguy and he said it was strange that none of the commands worked. Anyone had similar problems?

Thanks.

[awemawson]

Sorry to be gloomy, but if the controller doesn't do anything, and the monitor is now u/s then I would presume some catostrophic power supply failure has not only killed the TNC355 but also the monitor. I do hope I'm wrong for your sake.

[Oviksnc]

No problem.. The NC seems to be broken. I have done some measures tonight and the powersupply card control LED´s on the NC pulses dark green as long as i have the processor board connected. When i disconnect it the LED´s are bright green and seems fine. If that´s my power supply causing it i don´t know. But i have ran my TNC 150 controlled Bridgeport Int 4 SII on the same supply for 5 years with no problem. Guess it´s bad luck and old electronics. Just hope i can find some spares or repair this board.... And monitor

Life could be better right now :/


/Johan.

[Oviksnc]

Ok. An update if any of you would trip on this in the future.

I have taken another look at my monitor and found a "test" button behind it. This was something the older versions of the monitors did´nt have and therefore i did´nt even search for it. The monitor seems to be working but the nc was´nt.

After i measured all the points on the boards i found out the either the CLP board or the processor board had a short that caused the power supply to drop.

I turned the machine off and disconnected the CLP board but not the processor board and the problem was still there. After i switched to the clp board with the processor board disconnected the power supply worked again and fed the CLP just fine.

Took the processor board to work today and made some test with a friend. It turned out that the +5v circuit did´nt seem to have any problems but the +-12v had a huge resistance. After observing the circuits we found a small blackness on one of the pins at a sn75188n component. This is the rs232 driver and when we removed it the board seemed ok.

I have ordered a bunch of sn75188n drivers and will try to have the board in the machine for tryout by the end of the week.

Surely hope this was the problem due to the fact that Heidenhain will charge me for $5800 for a new board :/

( I noticed that the previous owner had disconnected the rs232 module from the machine and connected the cable from the PC directly to the board, i assembled the factory wiring again before i transfered any programs. If that would have anything to do with it i don´t know )

/Johan.

[awemawson]

Well that sounds like positive progress - good. Boards of this age often have tantalum capacitors dotted arround across the various supply rails, and I've known quite a few to go short circuit, though they are easy to spot as they fry up and smell horrible when they go. As a temporary measure they can just be cut off as there are multiple ones usually.