DM502A: Difference between revisions

Revision as of 02:49, 21 November 2023

Tektronix DM502A
3½ digit TRMS digital multimeter Tektronix DM502A Produced from 1980 to 1988 Manuals Tektronix DM502A Manual (OCR) Tektronix DM502 Modification Summary (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

The Tektronix DM502A is a 3½ digit TRMS digital multimeter plug-in for the TM500 system.

It superseded the DM502 predecessor in 1980.

Compared to the DM502, the DM502A adds autoranging, a True RMS converter, and offset circuits to read dB directly in all ranges. The temperature input is for a PT-100 temperature probe (P6601).

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 in that it has no current input and no digital output, the latter having been obsoleted by TM5000 GPIB based instruments.

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 Volts. A second voltmeter is needed to measure the voltage if 2 V are exceeded.

The DM502A has an Int/Ext switch that allows a voltage input via the rear interface to be selected.

Key Specifications

Voltage ranges	200 mV to 200 V in decade steps; 1 kV (DC) / 500 V (AC) top range
Input impedance	10 MΩ
Current ranges	200 μA to 2 A in decade steps
Resistance ranges	200 Ω to 20 MΩ in decade steps

Links

Tektronix DM502A The final Restoration by Zenwizard Studios @ YouTube
Tektronix DM502A Lab Check In and Calibration by Zenwizard Studios @ YouTube

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

Internals

The DM502A circuit is built around a Siliconix LD110/111A DMM chipset. The entire circuit is supplied from one of the mainframe's 25 V_AC windings through a main-frequency isolation transformer with a 25 V primary winding and 7815/7915/7805 regulators. The 25 V_AC input is the only mainframe connection, so the DM502A could easily be used outside a TM500 mainframe as well.

Pictures

DM502A right internal
DM502A rear interface

Components

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

@@ Line 1: / Line 1: @@
-#redirect [[DM502]]
+{{TM500 | mfg=Tektronix | type=DM502A | function=3½ digit TRMS digital multimeter | class=multimeter | image=Tek-dm502a-f.jpg | introduced=1980 | discontinued=1988 |
+designers= |manuals=
+* [[Media:070-2693-00.pdf|Tektronix DM502A Manual]] (OCR)
+* [[Media:Tek DM502 mods.pdf|Tektronix DM502 Modification Summary]]
+}}
+It superseded the [[DM502]] predecessor in 1980.
+Compared to the DM502, the DM502A adds autoranging, a True RMS converter, and offset circuits to read dB directly in all ranges.  The temperature input is for a PT-100 temperature probe ([[P6601]]).
+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 in that it has no current input and no digital output, the latter having been obsoleted by TM5000 GPIB based instruments.
+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 Volts. A second voltmeter is needed to measure the voltage if 2 V are exceeded.
+The DM502A has an Int/Ext switch that allows a voltage input via the rear interface to be selected.
+{{BeginSpecs}}
+{{Spec | Voltage ranges    | 200 mV to 200 V in decade steps; 1 kV (DC) / 500 V (AC) top range}}
+{{Spec | Input impedance   | 10 MΩ }}
+{{Spec | Current ranges    | 200 μA to 2 A in decade steps }}
+{{Spec | Resistance ranges | 200 Ω to 20 MΩ in decade steps }}
+{{EndSpecs}}
+==Links==
+* [https://youtu.be/BA6o05Vzzao  Tektronix DM502A The final Restoration] by Zenwizard Studios @ YouTube
+* [https://www.youtube.com/watch?v=9UI41WekZIs  Tektronix DM502A Lab Check In and Calibration] by Zenwizard Studios @ YouTube
+{{Documents|Link=DM502A}}
+==Internals==
+The DM502A circuit is built around a Siliconix LD110/111A DMM chipset.
+The entire circuit is supplied from one of the mainframe's 25 V<sub>AC</sub> windings through a main-frequency isolation transformer with a 25 V primary winding and 7815/7915/7805 regulators.
+The 25 V<sub>AC</sub> input is the only mainframe connection, so the DM502A could easily be used outside a TM500 mainframe as well.
+==Pictures==
+<gallery>
+Tek-dm502a-f.jpg
+Tek dm502a 1.jpg
+Tek dm502a 2.jpg
+Tek dm502a right internal.jpg|DM502A right internal
+Tek-DM502A-rear-interface.jpg|DM502A rear interface
+</gallery>
+==Components==
+{{Parts|DM502A}}
 [[Category:TM500 multimeter plugins]]
-[[Category:Introduced in 1980]]