Download HVPS Hardware Failure Notes

Hardware failures appear in red.
PART 1: HVPS SIGNAL GENERATION
PROBLEM:
Due to wear over time and slight damage during movement, each of the 610C and 615-3 HVPSs do not
conform to the original behavioral specifications stated in the user manual. Specifically, each HVPS does
not amplify the analog input signal by the exact factor stated in the user manual to generate the desired
voltage or current when the HVPS is placed in AMPLIFIER mode.
SOLUTION:
Since these devices lack adjustment controls on the front and back panel it is necessary to make slight
adjustments to the -10/+10V analog control signal through the Measurement & Automation Explorer
(MAX) tasks used by Labview, specifically by applying finely-tuned scales.
AMP CABLE TYPES & SAFETY CONSIDERATIONS:
The coronode HVPS only needs to generate positive current, the grid HVPS only needs to generate
negative voltage, and the toner HVPS only needs to generate negative voltage for the purposes of
discharged area development (DAD).
The analog voltage control signals sent to the Grid and Toner HVPSs can either be sent as negative
voltages through a NON-INVERTING AMP cable or positive voltages through an INVERTING AMP cable. In
order to avoid potential safety problems caused by accidently using the wrong cable type, adjustments
have been made to the AMP cables in the system so that they are all NON-INVERTING.
Each of the MAX tasks and scales have been configured to only allow current and voltage control signals
within acceptable ranges for each of the HVPSs. An error message will appear in MAX or Labview if a
user attempts to send a signal outside of the acceptable range and the signal will not be sent.
Note: If charged area development (CAD) is desired, the MAX tasks and scales will need to be modified
to account for the new signal ranges.
* Refer to page 11-3 of the Trek Operator’s Manual Model 610D High-Voltage Supply/ Amplifier/
Controller for more information on cable types. If the incorrect type of cable is used then the Labview
software will not be able to control the HVPS settings correctly.
CORONODE HVPS TRANSCONDUCTANCE AMPLIFIER
The coronode Trek 610C HVPS is designed to take a -10/+10V analog input signal and generate a
-2000/+2000uA current. Thus, uA = 200 * Vo. A scale can be created in MAX and applied to the
“Set Coronode Current Limit” task as seen below:
“Basic Trek 610C HVPS Clim Table” scale
However, the actual scaling capabilities of the HVPS are not perfect and thus the following scale was
used instead. Note how the acceptable range of values for HVPS output is limited to [0, 2000uA].
“Coronode Trek 610C HVPS Clim” scale
GRID HVPS VOLTAGE AMPLIFIER
The grid Trek 610C HVPS is designed to take a -10/+10V analog input signal and generate a
-1000/+1000V voltage. Thus, V = 100 * Vo. A scale can be created in MAX and applied to the
“Set Grid Bias Voltage” task as seen below:
“Basic Trek 610C HVPS Vamp Table” scale
However, the actual scaling capabilities of the HVPS are not perfect and thus the following scale was
used instead. Note how the acceptable range of values for HVPS output is limited to [-999, 0V].
Although a lower limit of -1000V would be desirable, an analog signal < -10V cannot be generated by the
DAQ equipment. According to the scaling equation below, an analog signal of -10.01V would be required
to generate -1000V, which is not possible.
“Grid Trek 610C HVPS Vamp” scale
TONER HVPS VOLTAGE AMPLIFIER
The toner Trek 610C HVPS is designed to take a -10/+10V analog input signal and generate a
-1000/+1000V voltage. Thus, V = 100 * Vo. In a perfect would the “Basic Trek 610C HVPS Vamp Table”
scale previously shown should work.
However, the actual scaling capabilities of the HVPS are not perfect and thus the following scale was
used instead. Note how the acceptable range of values for HVPS output is limited to [-590, 0V].
Although a lower limit of -1000V would be desirable, the toner HVPS cannot generate a signal < -590V.
This can be determined by placing the HVPS in SUPPLY mode and attempting to set a voltage less than
that amount. This behavior is observed even when the high voltage output connection to the developer
is unplugged.
It is assumed that after extended use generating voltages in the [-600, -500V] range that the toner HVPS
has either been “worn in” to work at that range or damaged.
Note: The toner HVPS fails to generate current in SUPPLY mode. This can be determined by placing the
HVPS in SUPPLY mode and attempting to set a current. The front panel will always read zero.
“Toner Trek 610C HVPS Vamp” scale
TRANSFER HVPS VOLTAGE AMPLIFIER
The transfer Trek 615-3 HVPS is designed to take a -10/+10V analog input signal and generate a
-10000/+10000V voltage. Thus, V = 1000 * Vo. A scale can be created in MAX and applied to the
“Set Transfer Bias Voltage” task as seen below:
“Basic Trek 615-3 HVPS Vamp Table” scale
However, the actual scaling capabilities of the HVPS are not perfect and thus the following scale was
used instead. Note how the acceptable range of values for HVPS output is limited to [-3000, 3000V] for
safety purposes.
“Transfer Trek 615-3 HVPS Vamp” scale
PART 2: HVPS SIGNAL MEASUREMENT
PROBLEM:
The reference voltage (Vo) and reference current (Io) analog output signals from the back panel of a
610C or 615-3 HVPS do not match the exact measurements shown on the front panel of the HVPS. The
measurement signals appear to be more erratic when the HVPS is off.
SOLUTION:
Since these devices lack adjustment controls on the front and back panel it is necessary to make slight
adjustments to the -10/+10V analog reference signal through the Measurement & Automation Explorer
(MAX) tasks used by Labview, specifically by applying finely-tuned scales.
Please refer to the MAX software to inspect and configure each of the scales for the MAX tasks that start
with “Read …”, such as “Read Coronode Bias Voltage” and “Read Coronode Current”.
PROBLEM:
The reference voltage analog output signal from the back panel of a 610C or 615-3 HVPS appears to be
erratic when the HVPS is off.
The voltage measurement behavior that occurs when a 610C HVPS is off is exemplified below. Notice
that the full phase of a noisy sine wave is recorded.
Note that the 610C operates on a 63 Hz frequency. The sine wave below is the result of recording 1000
Vo samples at a frequency of 63,000 Hz, which equates to 1000 samples over the entire phase of the
610C operating frequency.
One would assume that the measurement voltage would be consistently near zero when the HVPS is off,
but that is not the case.
“Read Coronode Bias Voltage” HVPS on measurement
SOLUTION:
The voltage measurement behavior that occurs when a 610C HVPS is on, and voltage set to zero, is
exemplified below. Notice that there is no longer a sine wave pattern. The signal is noisy but averages
around zero, which is desirable.
1. HVPSs should be left on in order to obtain reasonable voltage measurements. Specifically, the
HVPS should be in the “HV ON” state and the red indicator light should be lit up.
The Labview software will set the voltage of each HVPS to zero when it is not in use; however,
the device will still remain in the “HV ON” state, which some people may think is a safety
concern.
2. Take 170 measurement samples at a rate of 10kHz to capture the entire phase of the waveform.
Average these samples together to calculate a single value representing the voltage of the
device for that time period. The HVPS can be on or off when the samples are taken.
“Read Coronode Bias Voltage” HVPS off measurement
PROBLEM:
The reference current analog output signal from the back panel of a 610C or 615-3 HVPS appears to be
erratic when the HVPS is off.
The current measurement behavior that occurs when a 610C HVPS is off is exemplified below. Notice
that the full phase of a noisy wave is recorded. The shape of the wave shown continues to repeat itself.
Note that the 610C operates on a 63 Hz frequency. The wave below is the result of recording 1000 Vo
samples at a frequency of 63,000 Hz, which equates to 1000 samples over the entire phase of the 610C
operating frequency.
One would assume that the measurement current would be consistently near zero when the HVPS is off,
but that is not the case.
“Read Coronode Current” HVPS off measurement
SOLUTION:
The current measurement behavior that occurs when a 610C HVPS is on, and current set to zero, is
exemplified below. Notice that there is no longer a repeating wave pattern. The signal is noisy but
averages around zero, which is desirable.
1. HVPSs should be left on in order to obtain reasonable current measurements. Specifically, the
HVPS should be in the “HV ON” state and the red indicator light should be lit up.
The Labview software will set the current of each HVPS to zero when it is not in use; however,
the device will still remain in the “HV ON” state, which some people may think is a safety
concern.
2. Take 170 measurement samples at a rate of 10kHz to capture the entire phase of the waveform.
Average these samples together to calculate a single value representing the current of the
device for that time period. The HVPS can be on or off when the samples are taken.
“Read Coronode Current” HVPS on measurement
TONER HVPS CURRENT MEASUREMENT
The toner HVPS reference current analog output signal from the back panel of a HVPS appears to be
erratic whether the HVPS is on or off. This is probably related to how the toner HVPS is incapable of
generating current when it is set to SUPPLY mode. This does not seem to impact the toner HVPS’s ability
to measure voltage.
The current measurement behavior that occurs when the toner 610C HVPS is off is shown below. Note
that the pattern is different from the “Read Coronode Current” HVPS off measurement shown above.
“Read Toner Current” HVPS on measurement
The current measurement behavior that occurs when the toner 610C HVPS is on, and current set to
zero, is shown below. Note that the pattern is different from the “Read Coronode Current” HVPS on
measurement shown above. Also note that the signal has a definite shape which cannot be attributed to
noise alone.
Also note that when the toner HVPS is attached to the charging station grid it fails to properly read
current when the coronode HVPS is supplying 1800uA.
Overall, the current generation and measurement abilities of the toner HVPS appear to be damaged.
“Read Toner Current” HVPS off measurement