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Electronic Video Blog / Re: #51 Fluke 8520A How far does this rabbit hole go? Part 1
« on: January 27, 2020, 09:26:50 PM »
Your first video is reassuring for my new project to debug an 8520A - eBay description, "works great" is not what arrived. Passes self-tests, but does not measure DC/AC/resistance. I do get a small non-zero voltage read-out with nothing connects, and note your comment to suspect something shorting that allows an internal voltage to be read. I now have all the (three) manuals, just need to patiently work through the detail tests for specific circuits and see what comes up.
I do see on my example that resistors R256 and R257, although no sign of distress/replacement, are mounted off the board like in your unit.
2/1/2020 update - received 20 pin EDAC 516 series receptacle and wiring pins to allow rear signal inputs. Unit reads correct DC, AC volts, resistance from rear panel but not front panel. Wiggling switch got a little erratic front panel action, but never correct values. Tracked down the cross-over switch as Schadow TA8UEE / F8UEE 8 Pole 8PDT Standard Size Latching Switch, findable on the eBay and now on order...
I do see on my example that resistors R256 and R257, although no sign of distress/replacement, are mounted off the board like in your unit.
2/1/2020 update - received 20 pin EDAC 516 series receptacle and wiring pins to allow rear signal inputs. Unit reads correct DC, AC volts, resistance from rear panel but not front panel. Wiggling switch got a little erratic front panel action, but never correct values. Tracked down the cross-over switch as Schadow TA8UEE / F8UEE 8 Pole 8PDT Standard Size Latching Switch, findable on the eBay and now on order...