Re: HP 54512B (pair) repair
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Harvey and all, I guess you're right, once the unit is unplugged there shouldn't be a path to short the battery and lose the existing memory (though I haven't done this, so I'm not aware of all the practical implications).? I currently have an order for some CR2430 batteries - went with Razvan's call on that one (and Razvan, no worries, I can return them if not the correct part) - and PCB mount holders for them. Sure, the more common CR2032 would probably work just fine, but I always prefer to repair something as close as I can to its original configuration. I'm not sure how likely it is that a random 2430 holder will fit on the PCB, but if worst comes to worst, I can either return both, or work out something with a bit of wire.? I'll seek to measure the existing battery once I have the board out and therefore access and before removing the current battery, but my working hypothesis is they're depleted. Radu.?
Correct.? What is likely being done is to replace the battery while the
equipment is line powered.
If the battery is dead, then obviously, no problem.
What a safer approach (to me) would be is to supply a backup voltage to
the circuit, device unplugged, then cut the battery loose.? Then
desolder and replace, then remove the supply.
I'm not sure that interrupting the ground is wise.? If you do go with an
isolation transformer, then that one meg resistor from the iron ground
to chassis ground is a good idea.
I wonder if there's a battery holder that would be soldered into the
board with the same spacing?
Harvey
On 2/28/2025 11:15 AM, Radu Bogdan Dicher via wrote:
> Harvey - correct me if I'm wrong, but I think the issue is supplying
> the 3V while working on the battery (soldering with a grounded iron)
> from an external power supply so the memory would be preserved.
> What I'd probably do is run the soldering?station off of an isolated
> power supply (mine is a BK 1655) with an interrupted ground. I'm not
> entirely sure on ESD protection, but if I'd do this while supplying
> the 3V off of an external power supply, that'd probably do OK handling
> that part.
> Radu.
>
> On Fri, Feb 28, 2025 at 7:33?AM Harvey White via
> <> <madyn=[email protected]> wrote:
>
>? ? ?You could, of course, simply unplug the meter you're working on,
>? ? ?so it's
>? ? ?isolated?
>
>? ? ?Rubber mat if needed.
>
>? ? ?Harvey
>
>
>? ? ?On 2/28/2025 4:16 AM, Leo Kroonenburg via
>? ? ?<> wrote:
>? ? ?> I modified my soldering station lije this:
>? ? ?> Instead using the hard ground wire to the tip I replaced it with
>? ? ?a 1
>? ? ?> MOhm resistor inside the soldering station.
>? ? ?> No more risk of shorting stuff, and still a 0V potential in the tip.
>? ? ?> Works for me.
>? ? ?> Leo
>? ? ?>
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