yokeman
01-23-2002, 12:19 PM
I've been messing with electronics for 50 years, but at times I still manage to get careless. In wiring my game port plug I used shielded cable to minimize noise pickup. I soldered the bare shield wires to the frame of the connector. Everything worked fine until one day when nothing worked. Checking with a multimeter I found I had no 5 volts. Apparently the cable had twisted permitting the bare wire to contact the 5 volt terminal. Tracing the circuit on the MB with my ohmmeter and a magnifying glass I located a very tiny resistor that seemed to have a resistance much too high. I could only guess that it should have been a low value. It didn't appear to be burned, but a large increase in value can occur when they are overloaded. Mucho unprintable expletives!
I assume the resistor was put in the circuit to limit the current to prevent the MB circuit traces from burning up which could well be fatal. It was too small to try to replace and too close to other components to get a soldering iron on it without creating more problems. Selecting a 1/8 watt, 100 ohm resistor I connected it to one of the 5 volt PS leads and the other end to the appropriate terminal at the game port socket. I was back in business.
So the Leave It To Beaver object lesson is when wiring the game plug always use sleeving that will slip over the terminals after soldering to avoid shorts. The 5 volt line is the most critical. In some computers it may not be protected with a resistor. It's also a good idea to put a 100 ohm, 1/8 watt resistor directly on the 5 volt terminal of the plug and connect all your control system 5 volt lines to the other end in case a short occurs somewhere.
Happy landings,
BB
I assume the resistor was put in the circuit to limit the current to prevent the MB circuit traces from burning up which could well be fatal. It was too small to try to replace and too close to other components to get a soldering iron on it without creating more problems. Selecting a 1/8 watt, 100 ohm resistor I connected it to one of the 5 volt PS leads and the other end to the appropriate terminal at the game port socket. I was back in business.
So the Leave It To Beaver object lesson is when wiring the game plug always use sleeving that will slip over the terminals after soldering to avoid shorts. The 5 volt line is the most critical. In some computers it may not be protected with a resistor. It's also a good idea to put a 100 ohm, 1/8 watt resistor directly on the 5 volt terminal of the plug and connect all your control system 5 volt lines to the other end in case a short occurs somewhere.
Happy landings,
BB