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DM502: Difference between revisions
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(New page: * [http://w140.com/smb/DM502_SM.pdf Tektronix DM502 Manual (OCR, PDF)]) |
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* [ | {{TM500 | mfg=Tektronix | type=DM502 | function=basic 3½ digit digital multimeter | class=multimeter | image=Tek dm502 front.jpg | introduced=1975 | discontinued=1980| | ||
designers= |manuals= | |||
* [[Media:070-1726-00.pdf|Tektronix DM502 Manual]] | |||
* [[Media:Tek DM502 mods.pdf|Tektronix DM502 Modification Summary]] | |||
}} | |||
It was [[introduced in 1975]] and superseded by the [[DM502A]] in 1980. | |||
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 h<sub>FE</sub> >150 can be used). | |||
{{BeginSpecs}} | |||
{{Spec | Voltage ranges | 200 mV to 200 V in decade steps; 1 kV (DC) / 500 V (AC) top range}} | |||
{{Spec | Input impedance DM502A | 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}} | |||
An "Option 2" instrument deletes the temperature measurement function, | |||
==Links== | |||
* [https://www.youtube.com/watch?v=Tx6DtLooCOs Tektronix DM502 Multimeter Repair] by NFM @ YouTube | |||
* [https://www.youtube.com/watch?v=AfQkfZfGKkw Tektronix DM 502A Restoration and Calibration for a Viewer] @ Zenwizard Studios YouTube | |||
{{Documents|Link=DM502}} | |||
==Internals== | |||
The DM502 circuit is built around a Siliconix LD110/111 DMM chipset. | |||
The entire unit with exception of the temperature circuit can be elevated up to 1 kV above chassis ground. | |||
For this purpose, it is supplied through a mains-frequency isolation transformer with a 50 V primary that is supplied from the two 25 V<sub>AC</sub> windings in the mainframe connected in series. | |||
This transformer feeds a a discrete +5 V regulator, and an RC4194D regulator for +/–12 V. | |||
The rear interface supports a digit-serial BCD output but the manual cautions that ''only the Temp Out, Temp GND and HI and LO inputs are factory-wired'', the BCD connections must be soldered in by the user if needed – presumably because the digital section is not galvanically separated from the floating input ground. In Temperature mode, the floating ground is connected to the chassis ground (because the temperature circuit uses the mainframe's ±33 V supplies) but the V/A inputs are disconnected. | |||
==Pictures== | |||
<gallery> | |||
Tek dm502 front.jpg | |||
Tek dm502 e1.jpg | DM502 Opt.2 (no temperature function) | |||
Tek dm502 left.jpg | |||
DM502_switch_inside.jpg|DM502 switch with cover off. The cover removes easily using a Pozidriv screwdriver. | |||
Tek dm502 right.jpg | |||
Tek dm502 leftfront.jpg | |||
Tek dm502 leftrear.jpg | |||
Tek dm502 rightfront.jpg | |||
Tek dm502 rightrear.jpg | |||
DM502_rear_con.JPG | DM502 rear interface – see note above | |||
</gallery> | |||
==Components== | |||
{{Parts|DM502}} | |||
[[Category:TM500 multimeter plugins]] | |||
[[Category:Introduced in 1975]] | |||