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sbus
04-11-2013, 11:07 PM
I have a Bizhub C450 that won't retain touch screen calibration, and sometimes won't let me calibrate at all. First, the machine pretty much loses touchscreen calibration randomly; always when power cycled, but sometimes just for fun...! Second, the calibration isn't always possible (Accessability-->Touch Panel Adjust) because it doesn't always sense all four calibration points. But... if I power cycle, sometimes it WILL let me calibrate; and when I can, the calibration is always accurate and the touchscreen works fine *until* it just goes away again. I thought it might be the NVRAM; that doesn't explain why the calibration routine doesn't sense all 4 buttons. Also, all counters appear correct, and I have NO error codes. I thought it might be the touch screen cable; I disassembled the operator panel, removed and cleaned the touchpanel flex cable (DeOxit) and made sure it was inserted correctly. No change. I thought it might be the touch screen itself; but if it's bad, why would it suddenly start working when power cycled? I am stumped... Could really use another brain looking at this...

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04-12-2013, 02:28 AM
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Hansoon
04-12-2013, 04:09 AM
The touch panel needs to be replaced. For sure....

Hans

sbus
04-12-2013, 04:21 AM
The touch panel needs to be replaced. For sure....Hans Ok, how do you know this? And can you explain why it works sometimes and calibrates perfectly, works for hours, then is suddenly 'out of calibration'? Sounds to me like the calibration offsets that are stored in NVRAM are getting corrupted. Not that I disbelieve you (obviously I asked for help because I have no experience with this) but I'd love to understand the cause and effect before I install a new touch panel...

Hansoon
04-12-2013, 05:04 AM
And can you explain why it works sometimes and calibrates perfectly, works for hours, then is suddenly 'out of calibration'?

How'bout: "Conductive compound of the flat ribbon cable / glass pane junction deteriorated by humidity and temperature influences resulting in fluctuation of the resistance of the circuit causing calibration to be off?"

With other words: Get a new Touch Panel......

You can get them locally from KonicaMinolta for USD 230.00 + or so,
or from us in Germany for USD 68.00 incl. postal charges. Payment by Paypal only.

touchpanel[at]rex-technika[dot]com

Hans

PeterG
04-12-2013, 06:54 AM
Ok, how do you know this? And can you explain why it works sometimes and calibrates perfectly, works for hours, then is suddenly 'out of calibration'? Sounds to me like the calibration offsets that are stored in NVRAM are getting corrupted. Not that I disbelieve you (obviously I asked for help because I have no experience with this) but I'd love to understand the cause and effect before I install a new touch panel...

Because we change dozens of them!

NRTech
04-12-2013, 07:05 AM
Agreed, usually the top half of the screen is ok but the bottom half becomes unresponsive, or the buttons on the lower half of the screen register 2/3 cm further down from where they actually appear. New touch panel needed.

kronical
05-21-2013, 04:07 PM
The touch panel needs to be replaced. For sure....Hans Ok, how do you know this? And can you explain why it works sometimes and calibrates perfectly, works for hours, then is suddenly 'out of calibration'? Sounds to me like the calibration offsets that are stored in NVRAM are getting corrupted. Not that I disbelieve you (obviously I asked for help because I have no experience with this) but I'd love to understand the cause and effect before I install a new touch panel...

Because it is a very common and well known issue with touchscreens.

lrockett
10-12-2013, 03:10 AM
My C450 had the same problem. This random calibration errors is the begining of the touch panel fault. Itīll get worse until it stops at all. You can change the touch panel. Here in Brazil I found some expert that could fix the problem.

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