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| Digital Angle Gauge won't reset after battery change... |
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| Bluechip:
A 'twisted wire capacitor' was a fairly common sight in days of yore for trimming XTAL Oscillators etc. Usually solid wire, stranded stuff unwound and defeated the object of the exercise. Which may explain the adhesive. Usually get around 1-10pf with the trick. BC |
| DavoDavo:
--- Quote from: Bluechip on June 07, 2012, 06:02:42 AM ---A 'twisted wire capacitor' was a fairly common sight in days of yore for trimming XTAL Oscillators etc. Usually solid wire, stranded stuff unwound and defeated the object of the exercise. Which may explain the adhesive. Usually get around 1-10pf with the trick. BC --- End quote --- Yes, that's right, however the wires are quite a way from the crystal so... I dunno. Have a look at the pic, the crystal is the metallic cylinder just below the large orange component on the right. The wires are close to what I think is the accelerometer. :scratch: |
| kwackers:
I think the wires where probably attached to something else for calibration/testing. They look like they've simply been snipped off to me. Might be worth swapping the crystal? U4 might be worth checking out too - could be a voltage reg or possibly just a transistor of some description, but looks big enough that it may be used to power up and down the circuit? |
| AdeV:
I don't think it's any reverse voltage that's killed it, that voltage regulator (small black chip next to the power wires) should have protected it. It might be worth briefly shorting the two pads at the top RH corner (with no battery connected), that should discharge the black capacitor, give it 5 mins for any other capacitors to discharge, short it again (for luck), then re-apply power & see if it's fixed. Chances are it won't, there may be some reset pads somewhere, but TBH it's looking like it's toast. The sensor will amost certainly be an itty bitty chip underneath that blob of black plastic, you won't be able to salvage it without destroying it, and even if you did save the chip, it'll be max 3mm square and impossible to solder by hand... (don't ask me how I know this)... |
| DavoDavo:
--- Quote from: kwackers on June 07, 2012, 06:42:28 AM ---I think the wires where probably attached to something else for calibration/testing. They look like they've simply been snipped off to me. Might be worth swapping the crystal? U4 might be worth checking out too - could be a voltage reg or possibly just a transistor of some description, but looks big enough that it may be used to power up and down the circuit? --- End quote --- Very unlikely to be the crystal I'd think? Anyway, chances of getting another are pretty remote unless it's a standard watch/clock crystal. Yes, I wondered about U4 and thought it looked like a voltage reg. My good multimeter is still packed away somewhere and I've got no idea where or I'd poke around with a couple of probes. :zap: |
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