HP-50G Excessive Battery Drain / Fix?
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05-27-2015, 05:08 PM
(This post was last modified: 05-27-2015 05:12 PM by jebem.)
Post: #11
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RE: HP-50G Excessive Battery Drain / Fix?
(05-27-2015 04:48 PM)HrastProgrammer Wrote: I measured the following: Yap, there is a serious issue there. While I'm not able to supply a schematics, we know that these things uses a capacitor in parallel as well. Besides the possible protecting diode most probable root cause (I don't know if there is such a protection device installed in the 50G), there is a much smaller possibility that the capacitor may present leaking. To check for a normal power supply input impedance values: - Using a wire to short positive and negative terminals in the battery compartment during at least 5 seconds to discharge the capacitor; - Using a digital multimeter, selecting Ohms auto-range, negative probe to negative terminal and positive probe to positive terminal: initially the reading resistance is very low, but a few seconds later the reading should be above 5MOhm. - Now, selecting voltage readings in the multimeter, we should read a positive voltage, typically around 0.4V and the value should not decrease with time. Whatever is the cause, the major issue as I see it, is the fact that to open these machines we need to force the entry, as there are no fixing screws to allow hardware serviceability. I would return the machine and ask for a refund. Jose Mesquita RadioMuseum.org member |
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