Help powering a circuit board with a DC power supply - Page 1
Forum section: electronics / beginners

author: taran2ula
author_rank: Contributor
timestamp: July 13, 2023, 05:23:39 pm
content: Dear friends. I am hoping someone can help me understand how to do two things. First, I have a vintage music synthesizer device that has multiple circuit boards inside on two different levels. The one I need to work on is at the bottom of the device and I need to disconnect the circuit board daisy chain power supply connectors from the upper boards where the power supply is connected in order to test some push buttons and tactile switches that refuse to work. I could connect everything, but I am afraid that something might short out with the two levels of circuit boards, and the awkward positioning of the connectors, and also no way to hold everything in position. So, I want to use my new RIGOL DP832 to apply the appropriate voltage to the connectors on the circuit board and see if the power will travel through the circuit and power the buttons properly. My question is, what is the best way to attach power leads from my DC power supply to these little pins on the connector mounted on the circuit board? Will a mini grabber work for this? Mini alligators? Or just straight pin leads? I can see in the circuit diagram which pins that lead to these buttons are positive and which are negative. I have also tested these buttons from the connector to the soldered positive and negative points of the individual buttons for continuity and they are all working, but no power. My second question is, can someone show me a diagram of how to make my own leads for this power supply because it did not come with leads? Have a wonderful day folks.

author: ledtester
author_rank: Super Contributor
timestamp: July 13, 2023, 10:03:44 pm
content: Besides mini grabbers it is possible that male-female Dupont jumper wires will work. Can you post a picture of the "little pins"?Male-female Dupont jumpers:https://www.amazon.com/Antrader-Breadboard-Jumper-Female-Dupont/dp/B07S1NGWZL/Here's a video explaining how to make your own banana cables:https://youtu.be/HLwiJp3bzGYalthough you'll have to buy all of the parts so it actually may be cheaper just to buy some pre-made cables from Amazon/ebay/AliExpress.

author: taran2ula
author_rank: Contributor
timestamp: July 13, 2023, 10:38:39 pm
content: Thank you sincerely for your reply. Those jumpers look like they might be the ticket. Thank you for that. I will drop a couple photos so you can see. One is of the connector to the board and the other is the opposite side of that same connector. Are the jumpers what most people use to do this? Looks like the right thing. Now I just need to figure how much Voltage and Amps goes to that connector. The buttons are tactile switches and a couple tactile size buttons but supposedly push button according to the schematic parts list. I have the Schematic diagram but it doesn't mention those figures. I need to keep digging. Forgive me all the questions. Cheers, friend.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: July 14, 2023, 01:26:52 am
content: I do not like temporary connections while doing board work .If you can come up with a spare clip on / plugin , plug / socket .Or solder wires onto the power connections .The idea being being able to move the board as your working on it --- that your connections do not slip off / short .Have you looked into " dim build tester " ?A method of " non destructive testing " .Part that is also using low voltage & current limiting to avoid damage - while doing board work / diagnostics .Then also [ if you have them ] testing older gear , checking especially - electrolytic capacitors ?Kinda like being a doctor " 1st do no harm "

author: ledtester
author_rank: Super Contributor
timestamp: July 14, 2023, 02:12:47 am
content: Finding spots on the PCB to solder the power connections isn't a bad idea.Also, check the pin spacing -- those green connectors look like MTA-100 or MTA-156 connectors. The pin spacing for the two are:MTA-100: 0.1 inch between pins, pins are square, 0.025 inch along a sideMTA-156: 0.156 inch between pins, pins are square, 0.045 inch along a sideThat is, the MTA-156 pins are larger than the MTA-100 pins. The Dupont connectors are designed for the 0.025 inch square pins.

author: taran2ula
author_rank: Contributor
timestamp: July 14, 2023, 07:56:17 am
content: Thanks folks. Very good suggestions and I very much appreciate the feedback