anhui9435
06-13-2011, 09:27 PM
This section is for business purchasers. D.I.Y. individuals can naturally also put into action significantly less, precisely the same, far more, or variants. But individuals purchasing a conversion value a description of what is typically furnished. I also goal to provide exactly what the consumer needs or requirements, not a prepackaged answer,Office Professional 2007 DJ Equipment Turntables - Electronics - Guitar Wholesal (http://www.chemsns.com/bbs/viewthread.php?tid=1030171&extra=), so will not be afraid to request for that which you need. Description subject to vary with out discover (usually bug fixes & enhancements etc).
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Here is a final update (I hope) regarding the malfunctioning power supply. A short recap:
My scanjet resets during scanning. After some searching I found out that the -12 v supply collapses during scanning causing a reset of the mother board via the orange power_good signal. Connecting power_good to a constant +5V signal reduced the problem to the display. My first assumption was that the capacitors involved in the -12v circuit were bad. Replacing them however did not solve the problem.
A closer look at the -12 v supply reveals that the voltage is stabilised using a KA 78R12 voltage regulator. This IC has a voltage disable pin (pin 4) which disables the output voltage. Pin4 is connected using an opto- couple to another circuit. After connecting pin 4 with a stable voltage the reset problem disappeared. Bingo! Conclusion the -12v supply was not the cause of the problem but was merely resetting as a consequence of another problem.
Following the opto coupler I found out that it was connected to pin 11 of KA3501. Pin 11 is the power good output signal of the +12 +5 v regulator.
This signal triggered the reset of both the -12 v circuit as the mainboard.
Measuring VCC at pin 7,Buy Office Home And Business 2010 (http://www.windows7prokey.net/office-home-and-business-2010-64-bit-x64-product-key.html), I measured around 18 V. Then I saw a small trimmer (potmeter as we say in Holland) close to the KA 3501. Turning this trimmer clockwise I was able to increase the VCC to 20 V. After that the problem was over.
So my recommendation with similar powersupply issues is to measure the voltage at pin 7 of the KA 3501. If it is below 20 v. Try increasing it using the trimmer and check whether symptoms disappear.
Top Of Page
Here is a final update (I hope) regarding the malfunctioning power supply. A short recap:
My scanjet resets during scanning. After some searching I found out that the -12 v supply collapses during scanning causing a reset of the mother board via the orange power_good signal. Connecting power_good to a constant +5V signal reduced the problem to the display. My first assumption was that the capacitors involved in the -12v circuit were bad. Replacing them however did not solve the problem.
A closer look at the -12 v supply reveals that the voltage is stabilised using a KA 78R12 voltage regulator. This IC has a voltage disable pin (pin 4) which disables the output voltage. Pin4 is connected using an opto- couple to another circuit. After connecting pin 4 with a stable voltage the reset problem disappeared. Bingo! Conclusion the -12v supply was not the cause of the problem but was merely resetting as a consequence of another problem.
Following the opto coupler I found out that it was connected to pin 11 of KA3501. Pin 11 is the power good output signal of the +12 +5 v regulator.
This signal triggered the reset of both the -12 v circuit as the mainboard.
Measuring VCC at pin 7,Buy Office Home And Business 2010 (http://www.windows7prokey.net/office-home-and-business-2010-64-bit-x64-product-key.html), I measured around 18 V. Then I saw a small trimmer (potmeter as we say in Holland) close to the KA 3501. Turning this trimmer clockwise I was able to increase the VCC to 20 V. After that the problem was over.
So my recommendation with similar powersupply issues is to measure the voltage at pin 7 of the KA 3501. If it is below 20 v. Try increasing it using the trimmer and check whether symptoms disappear.