TEKTRONIX DM 501A without a TM500 - Page 1
Forum section: electronics / beginners

author: Gilbert
author_rank: Newbie
timestamp: June 19, 2015, 03:23:51 am
content: Hi everybody,If I get a Tektronix DM 501A Digital Multimeter Module, is it practical to try to operate it till I get a TM500 to plug it into? It looks the TM500 supplies only power to this module, should probably be AC, could I somehow connect power to the proper pins at the back of the unit, or use a suitable connector?Thanking for your views, Gilbert.

author: sdg
author_rank: Regular Contributor
timestamp: June 19, 2015, 08:59:51 am
content: Get the user manual, it lists PS requirements for the module.AFAICR, the mainframe supplies +-33.5v DC unregulated common gnd, 2x25v AC, 1x17.5v AC, 1x11.5 DC unregulated. I dont' remember how many amps, you'll have to check that in the manuals. A module doesn't necessarily use all available supplies.

author: miguelvp
author_rank: Super Contributor
timestamp: June 19, 2015, 09:17:30 am
content: It also has PNP and NPN transistors on the connector that are needed for the plug in normal operation, not sure if this applies to all plugins though.I do have the original TM503 manual in print somewhere, but I think bama.edebris.com might have it as well.Just checked and it does for not just the TM503 but other TM500s as well:http://bama.edebris.com/manuals/tek/

author: miguelvp
author_rank: Super Contributor
timestamp: June 19, 2015, 09:30:52 am
content: These are for the TM503 from bama.edebris.com, but there are more details and schematics in the manual that you should look at.

author: miguelvp
author_rank: Super Contributor
timestamp: June 19, 2015, 11:28:51 am
content: Looking at:http://w140.com/smb/DM501A_SM.pdfThe Int/Ext button redirects the input from the front panel to the pin 28B and 28A(with 28A connected to module GND) on the edge card so that the input can be rerouted to the back of the TM500. But you wont need this if you want to run it stand alone.Other pins used on the edge connector, and the ones you are more interested on:13A & 13B for 25VAC9A & 9B for common return and these are connected to 13B and connected to ground on the module.So it seems you only need 25VAC on pins 13A & 13B to make the module work stand alone, and provide a ground return on pins 9 A/B, but you should check the service manual to double check.I don't know if the AC needs to be 60Hz or 50Hz would do or if it matters at all.(Edit: full rectified output so frequency doesn't matter)Those AC pins connect to the module's internal power supply that provides the internal rails as shown here:Of course I take no responsibility and you should double check the linked instruction manual and the power module document as well to draw your own conclusions.Edit: If you can't provide 25V AC, I guess you can always bypass the module's power supply and provide regulated DC for the three rails: +15V, -12V & +5V

author: Gilbert
author_rank: Newbie
timestamp: June 19, 2015, 04:49:57 pm
content: Hello Miguel,Thank you so much for the expert notes, much appreciated, Gibert.

author: Gilbert
author_rank: Newbie
timestamp: June 19, 2015, 04:51:42 pm
content: Hi,Thanks so much sgd for your notes, I will see what I can accomplish, Gilbert.