ATTOTECH GR020 매뉴얼 - 페이지 14

{카테고리_이름} ATTOTECH GR020에 대한 매뉴얼을 온라인으로 검색하거나 PDF를 다운로드하세요. ATTOTECH GR020 16 페이지. Piezo driven pulsed valve

Turn on the power supply and increase the voltage. There should be a kHz noise from the poppet

vibrating against the body. If no noise, there is an electrical problem. See the corresponding

paragraph.

If the pressure in the chamber starts rising around -100 V the adjustment of the poppet is correct,

go to step 6. If the valve opens before you reach -90 V you have to turn the poppet a bit inwards,

if it opens after -120 V, you should unscrew it as described in step 5. Before doing these

adjustments make sure to turn off the voltage and disconnect the high voltage cable.

6. Once the poppet is properly set, turn off the HV amplifier, disconnect the HV cable and close

the valve body, carefully check that the electrical wire does not get clamped between the back

and the front of the body.

Pay special attention to position the front and back part of the valve correctly with respect to one

another. Be very gentle and make sure that the screws have entered the threaded holes properly.

When the screws have entered properly, only very little torque is needed to turn the screw in the

threaded hole.

The screws should be tightened in a cross tightening sequence. Add a small amount of torque for

every iteration. Pay attention not to damage the threads. Thanks' to the large number of screws

they can be tightened with a moderate torque.

7. With the body closed the valve can be tested with higher backing pressures. Values of the

opening voltage for different backing pressures measured on our test bench can be found in the

specifications section.

Electrical problems

If the valve does not open, it might be due to either an electrical problem or to the poppet not

being properly set. To find out if it is an electrical problem, open the vacuum chamber where the

valve is mounted and turn on a kHz driving voltage of -50 to -100 V. If there is a kHz sound, the

piezo disc and the electronics seem to work properly, implying that the problem comes from the

poppet. In that instance follow the adjustment procedure described in the previous section.

In case of an electrical problem, first make sure that none of the cables or the electronics are

faulty, then open the valve body and inspect the Lemo feed through and the piezo disc. If the

piezo disc must be replaced we recommend you to contact us and ship your valve to us for

overhaul.