HYDRA

Service Manual

2A-35.Flash EPROM

The Flash EPROM is an electrically erasable and programmable memory that provides storage of instructions for the Microprocessor and measurement calibration data.

A switching power supply composed of A1U15, A1T3, A1CR21, and A1C66 through A1C69 generates a nominal +12 volt programming power supply (VPP) when the Microprocessor drives VPPEN high (A1U15-2). Resistor A1R35 pulls A1U15-2 to near ground during power-up to ensure that A1U15 is not enabled while the Microprocessor is being reset. When the power supply is not enabled, the output voltage (VPP) should be about 0.1 volt less than the input voltage of the power supply (VCC).

The only time that the programming power supply is active is when new firmware is being loaded or new calibration constants are being stored into the Flash EPROM. The code executed immediately after power-up is stored in an area of the Flash EPROM (known as the Boot Block) that is only eraseable and reprogrammable if BBVPP (A1U14-30 and A1U16-30) is at a nominal +12 volts. This may be accomplished by installing jumper A1W1, but this should only be done by a trained technican, and A1W1 should never be installed unless it is necessary to update the Boot firmware. In normal operation, resistor A1R73 and diode A1CR20 pull BBVPP up to about 0.25 volts less than VCC.

The FLASH* chip select (A1U1-128) for these devices goes low for any memory access to A1U14 or A1U16. The FLASH* signal goes through jumper W3, which must always be installed during normal instrument operation. W3 is removed only during the initial programming of the Flash Memory during production at the factory. A1U14 is connected to the high 8 bits of the data bus, so read accesses are enabled by the Read Upper (RDU*) signal going low, and write accesses are enabled by the Write Upper (WRU*) signal going low. A1U16 is connected to the low 8 bits of the data bus, so read accesses are enabled by the Read Lower (RDL*) signal going low, and write accesses are enabled by the Write Lower (WRL*) signal going low.

2A-36.NVRAM/Real-Time Clock

The Nonvolatile Static RAM (NVRAM) provides the storage of data and configuration information for the instrument. The Real-Time Clock maintains time and calendar date information for use by the instrument.

A nonvolatile power supply (VBB) biases A1U12, A1U20, A1U24, and A1U26. The Microprocessor Supervisor (A1U10) monitors the voltage on VCC (A1U10-2). If VCC is greater than the voltage of the lithium battery (A1U10-8), A1U10 switches VCC from A1U10-2 to A1U10-1 (VBB). If VCC drops below the voltage of the lithium battery (A1U10-8), A1U10 will switch voltage from lithium battery A1BT1 through current- limiting resistor A1R98 to A1U10-1 (VBB). The nominal current required from the lithium battery (A1BT1) at room temperature with the instrument powered down is approximately 2 microamperes. This can be easily measured by checking the voltage across A1R98.

2A-14

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Fluke 2635A, 2625A service manual 2A-35.Flash Eprom
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2635A, 2625A specifications

The Fluke 2625A is a sophisticated data logger designed for a wide range of industrial and laboratory applications. This versatile instrument excels in capturing and monitoring temperature and voltage measurements with precision and reliability. One of its standout features is its ability to record data from various sensors, making it ideal for environments where comprehensive data acquisition is critical.

Equipped with a large LCD display, the Fluke 2625A provides clear and user-friendly access to real-time measurement data. Its graphical interface allows users to visualize trends and monitor readings easily, which significantly enhances usability. The device supports a variety of input types and can connect to thermocouples, RTDs, and other sensors, offering great flexibility for various measurement tasks.

The Fluke 2625A employs advanced measurement technologies that ensure accuracy in data logging. With a high sampling rate, it captures fast-changing signals while maintaining data integrity. The device features a built-in memory that allows for extensive logging, accommodating long-term monitoring tasks without requiring constant oversight. Users can set it to log data at specified intervals, offering customizable solutions for different monitoring needs.

Another significant characteristic of the Fluke 2625A is its robust communication capabilities. The device supports USB and RS-232 interfaces for easy connectivity with computers and other devices, making data transfer and analysis seamless. This feature is especially beneficial for users who need to compile or analyze large sets of data quickly.

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In summary, the Fluke 2625A is a powerful data logger that combines versatility, accuracy, and reliability. Its user-friendly interface, advanced measurement technologies, and robust design make it an essential tool for professionals in various industries, from manufacturing and HVAC to research and development. Whether monitoring temperature changes in a laboratory or assessing voltage levels in an industrial setting, the Fluke 2625A stands out as a trusted solution for effective data logging and analysis.
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