4-14
Problem Possible Cause
No output power (continued) HVPS output too low.
• Configure system for test mode operation.
• Set the system for Pure cut at 1 watt.
• Activate and confirm RFSUP at TP8 is approximately 95Vdc.
Improper gate drive.
• Configure system for test mode operation.
• Verify that RFGATE (TP11) and BGATE (TP5) are correct.
Improper VBASE_PWM.
• Check VB_PWM for 312 Khz signal
• Check VBASE_PWM (TP9) for dc voltage corresponding to duty cycle of
VB_PWM. VBASE_PWM is approximately linear with the percentage duty cycle
between 0.6 volts and 10 volts.
Incorrect monopolar output Bad calibration – Recalibrate
Ensure the load resistor is correct when checking output power.Bad voltage or
current feedback. Check:
• C_MVSNS, monopolar voltage sense
• C_ISNS, monopolar current sense
• These signals should match the Monitor voltage and current sense, M_MVSNS
and M_ISNS, respectively.
Incorrect bipolar output Bad calibration – Recalibrate Ensure the load resistor is correct when checking
output power.
Bad voltage or current feedback. Check:
• C_BVSNS, bipolar voltage sense
• C_ISNS, bipolar current sense
• These signals should match the Monitor voltage and current sense, M_BVSNS
and M_BISNS, respectively.
4.10.1 HVPS Troubleshooting Hints
WARNING: LOSS OF POWER SUPPLY
ISOLATION CAN CAUSE ELECTRICAL
SHOCK. WHEN SERVICING THE
HIGH VOLTAGE POWER SUPPLY,
ASSUME INTERNAL ISOLATION IS
COMPROMISED UNTIL VERIFIED
OTHERWISE.
WARNING: MAKE SURE THE LED FOR
THE CIRCUIT YOU’RE WORKING ON
IS OFF WHEN MAKING CONNECTIONS
OR TOUCHING CIRCUITRY.
• The PFC LED should always be on when
power is on. It will become momentarily and
slightly brighter during POST.
• If fuse F3 is blown, Q1 is probably shorted.
Also check surrounding components for failure if
Q1 is found to be bad.
• Check the clock frequency and reference volt-
age on the PFC controller integrated circuit. The
PFC clock must have PFC enabled to function
correctly.
• At low output current, the PFC will cycle on
and off. This is normal.
• When replacing a MOSFET, check all the gate
drive components.
4.11 Parts Ordering Information
To obtain replacement parts or additional infor-
mation regarding your unit, write or telephone
according to the contact information as listed on
the inside front cover of this manual, or contact
your CONMED distributor. To ensure prompt
service, please provide the following information:
• Model Number
• Serial Number
• Reference Designator and Description of Part
• CONMED Part Number (if known)
• Quantity Desired
• Mailing or Shipping Address
• Preferred Shipping Means (if any)
• Purchase Order Number (if applicable)
• Your Name
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