Well, nothing really. When I press "measure cap", the display goes blank, one of the range leds lights, and I measure about 150mV across the cap under test. As soon as I release the button the display goes back to flashing "888".
I know these need a sec or two to measure, but it shouldn't need that long right?
I know these need a sec or two to measure, but it shouldn't need that long right?
So, I cleaned the rotary switch and the selector switch as well as I could. I think it made some difference as it seems to ask a little different. Also found a burned up 5k 5W cement resistor on the selector switch.
Now that I have it opened up I'm noticing the power transformer is buzzing rather loudly. I am also getting about 1/2 the voltage I expect at the terminal when the "leakage test" button is pressed. This is leading me to look at the power supply sections. I don't see a psu for the high voltage dc that jumps out at me, but obviously it's in there. I'll be calling Sencore Monday about a manual.
Now that I have it opened up I'm noticing the power transformer is buzzing rather loudly. I am also getting about 1/2 the voltage I expect at the terminal when the "leakage test" button is pressed. This is leading me to look at the power supply sections. I don't see a psu for the high voltage dc that jumps out at me, but obviously it's in there. I'll be calling Sencore Monday about a manual.
Just an update, I bought a set of schematics and a manual from Sencore. After digging around in the unit I found that someone had cut a trace in the power supply section. Not sure why. The unit now measures and seems to be in the ballpark. It still jumps to flashing "888" sometimes but a power cycle clears it. I still have to check most of the carbon resistors and replace a few more lytic and tantalum caps.
, I got a CA55 with exact same symptoms as you mentioned, wondering if you remember the power supply levels in the unit , is it +5, +7 and -7 ?. I am googling around for man days find schematic but no luck.I traced it from PCB, just in case someone lands here again, the source of regulated power in the unit is a 7805 - TO92 -(NOT TP 220) - which provides +5 and the same +5 is used by the Opamp to regulate +7 via a series regulator power transistor out. In my case the 7805 was bad, replaced that which fixed +7 and all went good from there.
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