Today’s quick visual teardown is of an 1984 vintage Keithley 197 microvolt DMM, Despite considerable age, it’s still quite alive and kicking and very useful for measuring low currents and voltages.
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- Front
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- Handy short manual on the back
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- Display driver
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- Painted transistors- some type of matching indication?
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- A bit of a bodge?
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- Guard traces around sensitive circuits
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Curious if you repaired this unit at any point. I have one of these that’s behaving badly (something is pulling down (up) the -6.4V rail), and I notice that your U101 is a TLC27L2CP in a socket, where mine is some obscure TI part listed as “Integrated Circuit” even though it’s obviously a dual op-amp.
What makes me wonder is the fact that U101 is in a socket, where none of the IC’s except the processor and eprom are socketed one mine.
Thanks!
No, it’s been working quite well ever since it arrived so I did not need to do anything there. Though I’ve been mulling over an idea of adding a backlight