Zebra GK420 - The label prints, but many empty labels come out afterwards. Zebra GK420 - label prints but produces many blank labels afterwards Warning lighting models

The safety (bursting) membrane works in tension: operating pressure affects its convex surface.

In case of increased pressure working environment to a given value (operating pressure) at t = 0 ... 1 0 0 ° C, the safety membrane loses stability and turns out with a sharp bang reverse side. At the same time, it is cut by intersecting knives of the output ring and frees up the required cross-sectional area.

Following the safety membrane, the sensor is triggered. In this case, the electrical circuit of the built-in rupture sensor DRP-1 opens.

The system for monitoring the current state of the protected object receives a signal about the activation of the membrane through the connecting wires.

After activation of the MPU, replacement is required safety membrane and a response sensor.

MPU consists of:

Membrane fastening unit installed between two flanges;

Trigger sensor;

Rupture disc.

Attachment point consists of a safety membrane installed between the inlet ring and the outlet ring, which are fastened together with two strips and screws.

Trigger sensor located behind the safety membrane in the direction of movement of the working medium and consists of an auxiliary membrane and a DRP-1 rupture sensor.

Environmental parameters

Air temperature:

• normal version from minus 40 to plus 50 °C
• northern version "C" from minus 50 to plus 50 °C

Relative air humidity at 35 °C or more low temperatures

• normal execution 95 %
• northern version "C" 80 %

Work Environment Settings

Temperature, no more 290 °C

Installation

The installation location of the MPU is determined according to project documentation. In this case, the direction of the flow direction sign must coincide with the direction of flow of the working medium. LPA in assembled form welded into the pipeline. Welds must be checked for leaks.

The ends of the connecting wires of the trigger sensor are connected to the cable of the system for monitoring the current state of the protected object using terminal blocks or soldering.

Signal sensors are installed in production or at oil and gas production sites as a means of quickly visually determining the condition of protective equipment.

Methods for installing signal sensors

An alarm sensor on a tank or pipeline can be installed behind a rupture or release disc, protecting the equipment from increasing pressure beyond the permissible limit. In addition, sensors can serve as a means of optimizing protection systems and increasing the ease of maintenance and operation of equipment.

When purchasing equipment, you should pay attention - signal sensors may be part of the safety membrane kit. If they are not supplied with safety equipment, such devices must be purchased separately.

Principle of operation

The most common is the diaphragm rupture sensor. The principle of their operation is based on the fact that a solid membrane is an element that closes an electrical circuit. When the pressure increases beyond the critical value, the signal membranes are destroyed, thereby breaking the electrical circuit.

Features of use

In order to ensure the possibility of installing alarm sensors on explosive equipment or in explosive areas, low current sources are chosen to power them. In order to increase the efficiency of the equipment, a noticeable light or sound alarm is required, for which an amplifying relay is required.

IN automatic systems control and management, electrical signal sensors are used with the ability to transmit a control signal to executive bodies(valves, valves with drives, automatically opening valves, etc.).

Models for warning lighting

In some cases, so-called “beacons”, signal sensors indicating the dimensions of the structure, are installed on large tanks and other equipment installed outdoors. The power supply for such models can be electric, but in some cases models with solar panels are used.

The advantages of the latter are safety, efficiency, possibility battery life even during a power outage. The main disadvantage can be considered the inability to control and manage the charging of signaling equipment.

Zebra Label Printer GK420d

Introduction. There is this type of “on-the-fly” repair; on the one hand, the ease of repair gives high rates of repair speed, on the other hand, such repairs are only possible with in-depth knowledge of the device being repaired. The lack of diagrams and fundamental knowledge, but the simplicity of the unit being repaired, can also provide minimal repair time. Behind the daily routine of repairs, it is difficult to determine what is a complex repair and what is completely simple, since behind the simplicity for a specialist, there is an insurmountable mountain of problems for a beginner. Let's look at one such repair using the example of a label printer, or rather the repair of a label break sensor.
Malfunction according to the customer. Zebra GK420 label printer, the label prints, but after it a lot of empty labels come out, I have to turn off the printer and turn it on again.

Primary diagnosis. Manual media calibration produced a sensor profile as if the sensor was missing.

Profile of the label break sensor before repair.

As you can understand, the label break sensor does not see the label break at all. We check the printer settings to see if the label tear sensor is enabled. We check the operation of the emitter using the phone camera; the photodiode of the emitter does not light up.

Repair. implemented on the basis of a black mark sensor, and implemented using classic scheme from the datasheet.

Black mark sensor board

Zebra GK420 label printer black mark sensor connection diagram.

Since the label break sensor uses only an emitter, we are interested in the operation of the circuit connected to pins 2.7 of connector J5, but pin 7 of connector J5 is connected directly to the +5V circuit, then we are only interested in circuit FB16- U 11- R 65- U 22. The U11 power-on signal comes from the processor, but the U1 chip does not connect to pin 2 of the connectorJ5 to ground. We conclude that this microcircuit is faulty. On the board near the ribbon sensor connector there is a similar unused microcircuit, we switch the microcircuits - the result is zero, which means the LED itself is faulty. The problem is that there is no sensor marking, so we install any first one that comes to hand, namely one of the paper sensors with KKM Shtrikh-M-FR-K, judging by the factory documentation - this is KTIR0811S. We install, calibrate and... almost negative results.

Label break sensor profile after installing KTIR0811S.

As you can see, the sensor is working, but the signal is more like interference than reading. Open the datasheeton KTIR0811S and we see that the input current of the emitter is 50 mA , according to the diagram it turns out 5V/820Ohm=6mA, so we install a current-limiting resistorR5 equal to 100 Ohm instead of 820 Ohm (5V/50mA= 100 Ohm).

Profile of the label break sensor after installing the KTIR0811S and replacing the current limiting resistor.

The printer started working and began to see labels. The renovation is complete.
Conclusion. Honestly, if we knew the parameters of the original sensor, we would of course replace the sensor with a native one, and the repair would really be simple. But the situation regarding technical support for Zebra printersI was very stressed, the printer has been working with the client for a long time, but we got the price and supplier of spare parts in the form of a black mark sensor from sellers (large and reputable companies) of printersWe were never able to get Zebra. Therefore, such masturbation takes place, the repair period is 1 hour - against an unknown period and price tag, I think the choice is logical. For peace of mind, here's what the factory sensor profile looks like.

Profile of the original label break sensor.

The sensitivity is noticeably higher, but our sensor also fits into the parameters between web-media.