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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 groups.io <> <vondicher@...> 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.

On Wed, Feb 26, 2025 at 5:38?AM Jim Ford via groups.io <>
<james.ford@...> wrote:

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 groups.io
<> <hpnpilot@...> 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 groups.io
<> 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 groups.io
<> <> <vondicher@...>
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 groups.io
<>
>>? ? <> <hpnpilot@...> 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 groups.io
<>
>>? ? ? ? <> 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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