The triangular tab is spot welded to the coin cell and then the legs of the tab are in turn soldered to the board next to the resistor. A great way to force the repair technician to completely dismantle tge unit in order to replace the battery...
On Thu, Feb 27, 2025, 20:33 Radu Bogdan Dicher via <vondicher= [email protected]> wrote: I lifted today the CRT card, just enough to have some access to the battery, but I'm still unsure how it's supposed to come off. I tried prying the top spring "leaf," but it seems attached (possibly soldered) to the battery - or is that a top lid over the battery? And then there's a piece of foam underneath, possibly double-sided sticking. I'd rather not remove the whole mainboard just to replace this, but I don't think I can try many more prying and pulling before?I risk something more serious due to the lack of access.? Hoping someone having done this before?recognizes the type of battery and its socket from the enclosed pictures?and has some good pointers. I am not seeing any other battery on this board - I was expecting?a bigger, cylindrical?type, but I think this must be it for the 54512B.?
Thanks a bunch in advance. Radu.?
On Wed, Feb 26, 2025 at 7:08?AM Radu Bogdan Dicher via <vondicher= [email protected]> wrote: Thanks, Jim. I still have to perform that test where I play The Cure from my garage with the door open, which?I'm sure you'd hear from your bench!! ;))))
I tried?to pry off the battery this morning without further disassembly, but it doesn't want to come off that easily. There seems to be a blob of solder - has anyone seen that before? - on top of the holder, and some sort of?foam?tape below it. Maybe I need to apply force a little bit differently.?
Unless there's some secret?regarding how to remove the battery, I'll have to at least remove at least the CRT module to gain?better access to it. I really think access to a battery - even one guaranteed?a decade - should be easier than this. So this should be possible later in the week when I have more time.? Radu.?
Speaking of CR2032 coin cells, don’t spend $$ at a local store; order from Digital-Key for about $0.50 in quantity.? I usually buy 50 pieces at a time.? But then I have a keychain LED flashlight (torch for the Brits) that my kids bought me some years ago (best gift ever!) that takes 2 cells and a 3-LED baseball cap that I wear when walking my dogs at night that takes 4.? So I go through a lot of them.? Mouser might have them as well.? I’ve not ordered from D-K for a while because they buried the big product table, and it seems like something else they did got me PO’d at them.? HTH.
Jim Ford
Laguna Hills, California, USA
> On Feb 25, 2025, at 7:46?PM, Peter Gottlieb via <hpnpilot=[email protected]> wrote:
>
> ?CR followed by numbers indicates the physical size, CR2032 etc.? I would say if you're already in there, replace them as even if they are good they won't last much longer.? I always replace memory hold up cells in anything that crosses my bench.? Low hanging fruit.
>
> The power supply might be low because of an overload caused by a shorted capacitor.? Perhaps try unplugging the supply connections. I can't remember if that model's supply will run correctly without load.? But if you do go inside it, check the capacitors for capacitance, leaks and ESR.
>
> Peter
>
>
>> On 2/25/2025 9:35 PM, Radu Bogdan Dicher via wrote:
>> I've gotten a bit of a chance tonight to check a couple of things with one of the units:
>>
>> *Unit #2 *(S/N: 3214A00704: consecutive units!)
>>
>>? * Voltages on rails:
>>? ? ? o +11.924V
>>? ? ? o +12.050V
>>? ? ? o -3.27V(fluctuating somewhat; no significant ripple on it)
>>? ? ? o -5.2289V
>>? ? ? o 3.5285V
>>? ? ? o 5.2067V
>>? * There's a coin battery on the main board, which I didn't remove yet (I'd
>>? ? rather measure its voltage before I do, in case it's still good and holds
>>? ? the memory). It's a Panasonic and I can only read "CR..." from it. Would
>>? ? there potentially be more harm done by removing it, than simply losing the
>>? ? cal constants, in case it's still good for some reason? I'm thinking of
>>? ? biting the bullet and removing it, replacing it, and then seeing where
>>? ? that takes me.
>>
>> So this second unit has more issues than just a dead battery (in case the latter checks out). I'll have to remove the power supply module and see what could be wrong with the -12V rail. I'm provisionally blaming the unruly -12V rail for the additional error this second unit has, which the first doesn't. So my money's on that the first one has a good -12V rail.
>> Radu.
>>
>> On Tue, Feb 25, 2025 at 7:14?AM Radu Bogdan Dicher via <> <vondicher=[email protected]> wrote:
>>
>>? ? Awesome, thank you, Peter.
>>
>>? ? I wonder if anyone has a fresh recollection of what battery or maybe
>>? ? battery-backed RAM would be suspect and possibly needed so I'd start
>>? ? working on an order to have the parts ready by the time I carve out some
>>? ? time to open these. From what I know about these generation scopes,
>>? ? replacing the battery is probably a good idea anyway. The cal constants
>>? ? seem to be gone, so nothing to lose there.
>>
>>? ? I wasn't able to find this information (particularly info on the battery)
>>? ? in the manuals, which I find odd.
>>? ? Radu.
>>
>>
>>? ? On Tue, Feb 25, 2025 at 5:26?AM Peter Gottlieb via
>>? ? <> <hpnpilot=[email protected]> wrote:
>>
>>? ? ? ? Seems like you are on the right track.? Many HP scopes of that era
>>? ? ? ? lose their
>>? ? ? ? minds if the memory battery goes dead.
>>
>>? ? ? ? Peter
>>
>>
>>? ? ? ? On 2/24/2025 11:09 PM, Radu Bogdan Dicher via
>>? ? ? ? <> wrote:
>>? ? ? ? > Hi all,
>>? ? ? ? > Over the weekend I've got a couple of 54512Bs at my desk to seek to
>>? ? ? ? bring back
>>? ? ? ? > to full functionality. My main scope is a 54522A, and I assume they
>>? ? ? ? have some
>>? ? ? ? > commonalities, but I've yet to open mine (it came to me fully
>>? ? ? ? refurbished and
>>? ? ? ? > never needed to open the case). I'm not very familiar with this
>>? ? ? ? other series,
>>? ? ? ? > and hope on some good input and recommendations.
>>? ? ? ? > The documentation is not as good as others I've seen from HP.
>>? ? ? ? Specifically for
>>? ? ? ? > this unit (54512B), Keysight only seems to have a very skinny (by HP
>>? ? ? ? > standards) Service Manual which can't honestly be called
>>? ? ? ? "module-level Service
>>? ? ? ? > Manual," as it doesn't really into much detail on the different
>>? ? ? ? modules. Then
>>? ? ? ? > there's a "Front Panel Reference," which is an odd other way of
>>? ? ? ? naming what I
>>? ? ? ? > think is the Operating Manual. A couple other manuals have to do with
>>? ? ? ? > programming. That's it.
>>? ? ? ? > Sometimes in a series you have to look for the main unit, but in
>>? ? ? ? this case I'm
>>? ? ? ? > not sure that's the 54501A, as the catalog spec sheet seems to
>>? ? ? ? suggest, or the
>>? ? ? ? > 54505B, as per the SM. Maybe someone very familiar with the series
>>? ? ? ? would know.
>>? ? ? ? > Artek doesn't have manuals for the 54512B at all, but they do for
>>? ? ? ? the 54501A,
>>? ? ? ? > and if applicable, I'd get the series of six manuals they sell as a
>>? ? ? ? bundle. If
>>? ? ? ? > no go, I'll be a bit in a bind with fixing this given what I have at
>>? ? ? ? hand. I
>>? ? ? ? > am aware HP was not longer offering component SMs by this point,
>>? ? ? ? though I
>>? ? ? ? > don't know for a fact on this specific series and scope (but I do
>>? ? ? ? regarding
>>? ? ? ? > the better?/later? 54522A).
>>? ? ? ? > Is this really capable of FFT to 500MHz, even if the scope is rated
>>? ? ? ? to 300MHz?
>>? ? ? ? > I can't make sense of that.
>>? ? ? ? > Now, on to the specific issues with the units.
>>? ? ? ? > *Unit #1 *(S/N: 3214A00705)
>>? ? ? ? >
>>? ? ? ? >? ?* Upon starting it, it reports something like "TRYING TO START
>>? ? ? ? REALTIME
>>? ? ? ? >? ? ?CLOCK," which is unsuccessful after a time countdown from I
>>? ? ? ? think 60:
>>? ? ? ? >? ? ?"REALTIME CLOCK FAILED TO START - DISABLED."
>>? ? ? ? >? ?* Once I get it to display the default screen and output a trace,
>>? ? ? ? it stated
>>? ? ? ? >? ? ?"Default cal loaded. Re-cal instrument."
>>? ? ? ? >? ?* Self Test passes all.
>>? ? ? ? >? ?* I'm also seeing a solid and apparently accurate 5V from the DC
>>? ? ? ? Cal output
>>? ? ? ? >? ? ?in the back. I haven't tried the AC Cal output.
>>? ? ? ? >? ?* Note this one had the Cal switch in the back in the UNPROTECTED
>>? ? ? ? position
>>? ? ? ? >? ? ?when I got it.
>>? ? ? ? >? ?* I'm able to display the square wave test signal from the front
>>? ? ? ? panel.
>>? ? ? ? >
>>? ? ? ? > *Unit #2 *(S/N: 3214A00704: consecutive units!)
>>? ? ? ? >
>>? ? ? ? >? ?* Upon staring it, it stated "CALIBRATION FACTOR CHECKSUM ERROR.
>>? ? ? ? MOVE REAR
>>? ? ? ? >? ? ?PANEL CAL SWITCH TO UNPROTECTED. POWER INSTRUMENT OFF AND THEN
>>? ? ? ? ON AGAIN.
>>? ? ? ? >? ? ?RE-CAL INSTRUMENT."
>>? ? ? ? >? ?* It also says "Trying to start realtime clock (09290)." Maybe
>>? ? ? ? that's an
>>? ? ? ? >? ? ?error code?
>>? ? ? ? >? ?* Upon switching the rear Cal switch to UNPROTECTED, it boots
>>? ? ? ? successfully,
>>? ? ? ? >? ? ?goes to a default measurement screen, but gives me a warning "Failed
>>? ? ? ? >? ? ?interpolar cal." The trace seems to jump around on Y a bit.
>>? ? ? ? >? ?* Self Test passes all /but/ Timebase. It also displays the same
>>? ? ? ? error as
>>? ? ? ? >? ? ?default screen ("Failed interpolar cal").
>>? ? ? ? >? ?* 5V out at DC Cal is good.
>>? ? ? ? >? ?* This one had the Cal switch in UNPROTECTED position, so maybe
>>? ? ? ? that's why
>>? ? ? ? >? ? ?it booted successfully.
>>? ? ? ? >? ?* I'm able to display the square wave test signal from the front
>>? ? ? ? panel,
>>? ? ? ? >? ? ?though it seems to be offset vertically a bit.
>>? ? ? ? >
>>? ? ? ? > To me, this seems to tell me the battery holding the cal constants
>>? ? ? ? is done -
>>? ? ? ? > going by what I know about my 54522A. It's also possible some Dallas
>>? ? ? ? RAMs are
>>? ? ? ? > out of battery - though I don't know if this uses those for
>>? ? ? ? non-volatile
>>? ? ? ? > memory. I have not yet opened the units, so I've no idea where the
>>? ? ? ? rails are,
>>? ? ? ? > if any caps have leaked, etc. But maybe the information above gives
>>? ? ? ? some clues
>>? ? ? ? > on what's going on, enough to start thinking on it. It also seems
>>? ? ? ? the issues
>>? ? ? ? > are shared very similarly, so maybe that's making the repair more
>>? ? ? ? streamlined.
>>? ? ? ? > Looking forward to your input.
>>? ? ? ? > Thank you,
>>? ? ? ? > Radu.
>>? ? ? ? >
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