I have an old 4.5 digit Fluke 8050A DMM that I'm trying to bring back to life. It came to me as "broken". It didn't display anything properly. Voltage readings and resistance were wildly incorrect and jumping around all over the place. So without even doing any further testing I replaced all the electrolytic caps. All the old ones I took out tested perfectly fine, both capacity and ESR.
After that, resistor readings became more accurate, but still a bit erratic. But I suspect the caps weren't the issue. It probably was the result of me playing with the toggle switches on the front panel. Voltage readings were still wildly inaccurate. So I started tracing out the front end, and the first test point, TP6, which should have been directly connected to the input when in DC 2V mode, was not showing the voltage on the input. So all suspicions were now on the switches.
Since they are open front and back, and I can see inside, I put some drops of isopropyl alcohol in there, and dried them out with compressed air. Rinse and repeat a few times, and sure enough, after everything dried out, the 8050A started reading voltages and resistance dead on when compared to a much more modern 3.5 digit handheld Fluke.
So my question is, should I buy some contact cleaner with lubricant in it? Like say DeoxIT. I believe the switches were lubricated with a "heavy" grease from the factory. Some switches, before I cleaned them, were "slow" to pop back out. So I suspect factory grease.
But on the other hand, looking at the schematic of the DMM, the front end is very much analog all the way, and the switches play a huge role in it. Does lubricant have the potential to conduct ever so slightly and upset the front end?
After that, resistor readings became more accurate, but still a bit erratic. But I suspect the caps weren't the issue. It probably was the result of me playing with the toggle switches on the front panel. Voltage readings were still wildly inaccurate. So I started tracing out the front end, and the first test point, TP6, which should have been directly connected to the input when in DC 2V mode, was not showing the voltage on the input. So all suspicions were now on the switches.
Since they are open front and back, and I can see inside, I put some drops of isopropyl alcohol in there, and dried them out with compressed air. Rinse and repeat a few times, and sure enough, after everything dried out, the 8050A started reading voltages and resistance dead on when compared to a much more modern 3.5 digit handheld Fluke.
So my question is, should I buy some contact cleaner with lubricant in it? Like say DeoxIT. I believe the switches were lubricated with a "heavy" grease from the factory. Some switches, before I cleaned them, were "slow" to pop back out. So I suspect factory grease.
But on the other hand, looking at the schematic of the DMM, the front end is very much analog all the way, and the switches play a huge role in it. Does lubricant have the potential to conduct ever so slightly and upset the front end?