DM502
The Tektronix DM502 is a basic 3½ digit digital multimeter plug-in for the TM500 system.
It has an Int/Ext switch that allows alternate input connections via the rear interface to be selected.
The DM502 is available with an input for temperature measurement with a transistor temperature probe (P6430) using an NPN transistor, e.g. a 2N2484 (any NPN-Transistor with hFE >150 can be used).
The DM502A model adds an input for a PT-100 temperature probe (P6601), a True RMS converter, and offset circuits to read dB directly in all ranges. An "Option 2" instrument deletes the temperature measurement function, P6601 temperature probe, and all internal circuits associated with this function. The rear interface of DM502A is limited compared to the DM502: No current input and no reading output, see gallery below.
The 2 kΩ measurement range (+HI in DM502A) can be used for diode testing, since a current source of 1 mA is active and the reading corresponds to the (forward) voltage drop of the diode in Volts. The voltage can rise to a maximum of 10 V. A second voltmeter is needed to measure the voltage if 2 V are exceeded.
Key Specifications
| Voltage ranges | 200 mV to 200 V in decade steps; 1 kV (DC) / 500 V (AC) top range |
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| Input impedance DM502 | 10 MΩ or direct JFET input >2 GΩ (by internal jumper) |
| Input impedance DM502A | 10 MΩ |
| Current ranges | 200 μA to 2 A in decade steps |
| Resistance ranges | 200 Ω to 20 MΩ in decade steps |
Links
- Tektronix DM502 Multimeter Repair by NFM @ YouTube
- Tektronix DM502A The final Restoration by Zenwizard Studios @ YouTube
- Tektronix DM502A Lab Check In and Calibration by Zenwizard Studios @ YouTube
Documents Referencing DM502
Documents Referencing DM502A
| Document | Class | Title | Authors | Year | Links |
|---|---|---|---|---|---|
| Tekscope 1979 V11 N2.pdf | Article | New Products | 1979 | A6701 • DM502A • DM505 • 8001 • 8002A • Telequipment D1016 | |
| Tekscope 1979 V11 N3.pdf | Article | A New DMM Family for the TM 500 Series | Bill Mark | 1979 | DM501A • DM502A • DM505 • P6601 |
| 070-2088-04.pdf | Book | TM500 Series Rear Interface Data Book | 1985 | AA501 • AF501 • AM501 • AM502 • AM503 • AM511 • DC501 • DC502 • DC503 • DC503A • DC504 • DC505 • DC505A • DC508 • DC508A • DC509 • DC510 • DC5009 • DC5010 • DD501 • DL502 • DM501 • DM501A • DM502 • DM502A • DM505 • DM5010 • FG501 • FG501A • FG502 • FG503 • FG504 • FG507 • FG5010 • LA501 • LA501W • WR501 • MR501 • PG501 • PG502 • PG505 • PG506 • PG507 • PG508 • PS501 • PS502 • PS503 • PS503A • PS505 • PS5010 • RG501 • SC501 • SC502 • SC503 • SC504 • SG502 • SG503 • SG504 • SG505 • SW503 • TG501 • TR501 • TR502 • MI5010 • MX5010 • SI5010 |
Pictures
DM502
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DM502 switch with cover off. The cover removes easily using a Pozidrive screwdriver.
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DM502 rear interface
DM502A
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DM502A right internal
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DM502A rear interface
Components
Some Parts Used in the DM502
| Part | Part Number(s) | Class | Description | Used in |
|---|---|---|---|---|
| CA3046 | 156-0048-00 | Monolithic integrated circuit | transistor array | 4601 • 7104 • 7403N • 7503 • 7B53A • 7D12 • DM502 • FG504 • S-52 • Telequipment D34 • 7603 • 7613 • 7623 • 7633 • FG507 • Keithley 227 |
| Siliconix LD110/111A | 156-0476-00 • 156-0476-00 • 156-1268-00 | Monolithic integrated circuit | 3½ digit A/D converter | DM502 • DM502A • DM505 |
Some Parts Used in the DM502A
| Part | Part Number(s) | Class | Description | Used in |
|---|---|---|---|---|
| 120-1243-00 | 120-1243-00 | Discrete component | transformer | DM502A |
| AD536 | 156-1259-00 | Monolithic integrated circuit | RMS/DC converter | DM501A • DM502A • DM5010 • Keithley 177 • Keithley 179 • Keithley 195A |
| Siliconix LD110/111A | 156-0476-00 • 156-0476-00 • 156-1268-00 | Monolithic integrated circuit | 3½ digit A/D converter | DM502 • DM502A • DM505 |