The Tektronix DM504A is an 4½ digit autoranging digital multimeter plug-in for the TM500 system.
|DC Voltage||200 mV to 1000 V in decade steps, ±0.05%; Input resistance 10 MΩ (200 kΩ in 0.2 and 2 V ranges if Vin > 12 V)|
|AC Voltage||200 mV to 500 V in decade steps, ±0.6%; Input resistance 10 MΩ // 100 pF|
|DC current||200 μA to 2 A in decade steps, ±0.1%;|
|AC current||200 μA to 2 A in decade steps, ±0.6%;|
|Resistance||200 Ω to 20 MΩ in decade steps, 0.05% (0.1% in 2 and 20 MΩ ranges|
|Temperature||−62 °C to +230°C with P6602 2-wire PT-100 probe|
|Display||4½ digits, red LED, 2/s update rate|
Documents Referencing DM504A
The DM504A has no rear interface I/O. The entire circuit is supplied from a +12/−12/+5 V floating power supply that uses a small mains-frequency transformer fed by one of the mainframe's 25 VAC windings.
The circuit is based on an 80C31 microcontroller with a Texas Instruments TL500C integrating A/D front-end and a 1N827 temperature-compensated zener reference. The DM504A is software-calibrated, storing cal constants in a 93C46 EEPROM. Calibration is triggered by pressing Up and Down buttons simultaneously while the internal cal jumper is in the "enabled" position.
DM504A LH Interior with HV shield in place
DM504A RH Interior with HV shield in place
DM504A LH Interior with HV shield removed
DM504A RH Interior with HV shield removed
Some Parts Used in the DM504A
|Part||Part Number(s)||Class||Description||Used in|
|AD737||156-3506-00||Monolithic integrated circuit||RMS/DC converter||DM504A|
|Intel 8031||Monolithic integrated circuit||8-bit microcontroller||571 • DM504A|