Rexroth Bosch Group VT2000 Proportional Amplifier

5.4 Adjustable components on the front panel

Gw potentiometer: maximum command value attenuation (i.e. maximum current/pressure limit). Increase clockwise.

R130 (Zw): bias current regulation, located on the PCB (not the front panel). Used to set the zero point (minimum pressure). The adjustment range is 0~300mA.

5.5 Measuring sockets

w: Internal command value voltage, 0~+6V corresponds to 0~100%.

I: The actual electromagnetic current corresponds to 800mA at 800mV.

Summary of Technical Parameters (Engineering Key Values)

Parameter values

Working voltage 24 VDC (allows 22-35V, including+40%/-5%)

Power consumption<25 VA

Current consumption<1 A

Fuse 2.5 A slow melting (T-shaped)

Command value input 1 0~+9V (refer to MO)

Command value input 2 (differential) 0~+10V, Ri=100k Ω

Slope time adjustable range 30ms~1s or 5s

Maximum electromagnetic current 800mA (+10%/-5%)

Electromagnetic coil resistance 19.5 Ω (rated), actual cold state about 20-30 Ω

Bias current range 0~300mA

Clock frequency 100Hz or 200Hz (± 10%)

Internal voltage regulation output ± 9V ± 1%, ± 25mA

Measure socket w 0~+6V (100% command value)

Measure socket I 800mV corresponding to 800mA

Connector 32 pin DIN 41612, D-type

Card size Euro card 100 × 160mm

Front panel height 3 HE (128.4mm)

Front panel width component side: 3TE; welding side: 1TE

Working temperature 0~50 ° C

Storage temperature -25~+85 ° C

Weight approximately 0.1kg

On site troubleshooting steps

When the proportional pressure valve does not work or responds abnormally, the VT2000 amplifier should be checked in logical order. The following steps refer to the 8 checks in the manual and are expanded based on practical experience.

Step 1: Check the working voltage

The voltage between terminals 24ac and 18ac should be between 22-35V DC. If there is no voltage, check the external power supply, card slot connection, and fuse.

Step 2: Check the amplifier fuse

The VT2000 onboard fuse is a 2.5A slow melting fuse. Remove the card and measure the continuity with a multimeter. If the circuit is blown, the cause needs to be investigated: short circuit of the electromagnet, cable damage, or output stage failure. Attention: After replacing the fuse, the same specification (2.5A T-type) must be used, and fast melting cannot be used as a substitute.

Step 3: Check the internal ± 9V voltage

Measure whether there is ± 9V at the measuring socket or corresponding testing point. If not, it may be a fault in the power circuit on the board (such as damaged voltage regulator or capacitor). This step requires the use of test points on the PCB, which can typically measure+9V output (terminal 10ac for MO).

Step 4: Check command value input

If using an external potentiometer: check if there are jumper wires between 10ac~12ac? Is the wiring of the potentiometer correct (10ac and MO at both ends, 12ac on the sliding arm)? Is the Gw potentiometer set to zero?

If differential input is used: check if the voltage on 28c and 30ac is 0~+10V? Are both wires connected or disconnected at the same time? Is the reference potential correct?

Step 5: Check the electromagnet circuit

Unplug the amplifier (power off) and measure the resistance between terminals 22ac and 20ac. Normally, it should be 20~30 Ω (temperature of the line of sight coil). If it is infinite (open circuit) or close to 0 Ω (short circuit), the valve coil or cable is faulty. If the resistance is normal, check if the cable is short circuited to ground.

Step 6: Monitor and measure the socket

Given an instruction value (e.g. 5V), the voltage of the "w" socket should rise with the ramp up to the corresponding value (e.g. 5V input corresponds to about 3V? Note the conversion relationship between input and w: 100% instruction value corresponds to 6V, and 100% instruction value may be obtained by attenuating and ramping the 9V or 10V input. During actual debugging, given the maximum command value, adjust Gw to reach 6V, and the output current should be 800mA.

Measure the voltage of the "I" socket, which should be equal to one thousandth of the actual output current (mA) value. For example, when outputting 400mA, the I socket should be 400mV.

Step 7: Check the over temperature shutdown

If the output stage temperature is too high (such as working at full current for a long time and poor ventilation), the internal thermal protection will turn off the output, but the "I" socket may still display a command value? In fact, the thermal protection cuts off the output stage, and the current detection may return to zero. At this point, it will automatically recover after cooling. There is no separate alarm, so it is easy to be ignored.

Step 8: Check the external contacts of the slope

If the external quick ramp function is used, check if the contact accidentally closes, causing the ramp time to be forcibly shortened and causing the valve to respond too quickly.

Replacement and engineering precautions

8.1 Replacement of discontinued models

The VT2000 4X series has been discontinued, with 5X serving as a replacement. Attention should be paid when replacing:

Ensure that the jumper settings (ramp time range, clock frequency) are the same as the old card.