Hi Radu,
If you have a hot air desoldering station try to see if the heat will
soften the glue/resin. Use low temp first and increase it slowly.
Monitor the heat on the arm with an infrared thermometer in the same
time not to melt the arm.
Regards,
Razvan
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On 03/03/2025 22:17, Radu Bogdan Dicher via groups.io wrote: Thank you, Mike.
In terms of removing the arm from the switch stub (see pics enclosed a
few messages down), where HP decided to use this brown resin to glue
them together (completely unnecessary, in my opinion - how about a cable
tie or something easy to remove and replace?...), what would be some
recommendations in handling this? Specifically, safely and non-
destructively detaching the arm from the stub. The arm is marked:
"SPREAD JAWS TO INSTALL AND REMOVE," but due to the resin, that was just
about impossible upon my examination when doing this.
* Can anyone determine or have some educated?guess regarding what sort
of glue or resin that'd be? I tried seeing if I could scrape it or
shatter it off, to no avail. It's tough and very hardened in place.
Much?harder than either of the two plastics it joins.
* Solvents? I'd be pretty weary using liquid chemicals over the main
board, but maybe something is recommended and safe to use in a
situation like this.
* What else would?work? I assume others may have had this problem?and
came up with some good solutions.
Thank you,
Radu.
On Mon, Mar 3, 2025 at 8:32?AM Michael Bafaro via groups.io <
groups.io> <m.bafaro@...
<mailto:[email protected]>> wrote:
Radu,____
__ __
I wish you luck finding a replacement for the line filter and
switch.____
__ __
Mike____
__ __
*From:*[email protected] <mailto:HP-Agilent-
[email protected]> <HP-Agilent-Keysight-
[email protected] <mailto:HP-Agilent-Keysight-
[email protected]>> *On Behalf Of *Radu Bogdan Dicher via
groups.io <>
*Sent:* Monday, March 3, 2025 10:23 AM
*To:* [email protected] <mailto:HP-Agilent-
[email protected]>
*Subject:* Re: [HP-Agilent-Keysight-equipment] HP 54512B (pair)
repair____
__ __
Mike,____
This is unrelated with the issues I'm having with the -12V rail.
When disassembling/reassembling the scope, the EMI Filter?(more
specifically, its built-in switch) and the HP arm/button broke
apart. I can now either try to find replacements, or just
replace?the EMI Filter with a unit having the switch accessible from
the back of the scope (this type is relatively easy to find) and
disable the actuation of the front button. ____
Radu. ____
__ __
On Mon, Mar 3, 2025 at 8:16?AM Michael Bafaro via groups.io <
groups.io> <m.bafaro@...
<mailto:[email protected]>> wrote:____
Radu,____
____
The pictures you sent appear to be the AC line filter (EMI) and
the power switch and perhaps the line fuse.? If one of the
supplies is off and the others are working, then the problem is
somewhere else. ____
____
The display is a standard magnetic deflected CRT.? I worked in
that group years ago at Motorola.____
____
Mike Bafaro ____
____
*From:*[email protected] <mailto:HP-
[email protected]> <HP-Agilent-Keysight-
[email protected] <mailto:HP-Agilent-Keysight-
[email protected]>> *On Behalf Of *Radu Bogdan Dicher via
groups.io <>
*Sent:* Sunday, March 2, 2025 7:14 PM
*To:* [email protected] <mailto:HP-
[email protected]>
*Subject:* Re: [HP-Agilent-Keysight-equipment] HP 54512B (pair)
repair____
____
Two steps forward, one step back (one and a half?). ____
____
While other things have been progressing, the power switch
stopped?working once I put?most of the?unit back together. I
enclose some pictures, but it's a typical flip flop type where a
pin prods and finds two different locations between the?two
states ON/OFF. I guess I can either look for a replacement (does
anyone have one?), or try to repair it. Repairing something like
this hasn't been something?I've had a lot of luck with - if
anyone has some good tips, I'll take them happily - and then
there's also the way the longitudinal arm (actuating the
pressing of?the button on the front panel all the way to the
back) is supposed to be handled. It seems to be glued with some
hardened resin or something similar. In retrospect, though the
SM doesn't mention this, I think the arm should be detached
before removing the rear panel and moving it around. It puts too
much pressure?and torque on the switch to take this easily and
not get damaged. ____
____
Thank you for any pointers. ____
Radu. ____
____
On Sun, Mar 2, 2025 at 3:20?PM Radu Bogdan Dicher via groups.io
<> <vondicher@...
<mailto:[email protected]>> wrote:____
Razvan,____
Thank you very much, this is very helpful. ____
I've managed to rig a load - I had a couple of 1ohm/10W
Vishay RS10s (bulletproof, in my experience), and it looks
like the -12V rail is MIA because of something going on in
the PS. If I can confirm?this, this would be great news (as
opposed to tracking some failed tantalum decoupler or
something else on the main board....). ____
Radu. ____
____
On Sun, Mar 2, 2025 at 2:51?PM Razvan Popescu via groups.io
<> <yo8ryr@...
<mailto:[email protected]>> wrote:____
Hi Radu,
I think the PSU in all 545xx series was made by Boschert
Inc. and
someone already reverse engineered it. I attached the file.
I hope it helps.
Regards,
Razvan
On 02/03/2025 23:33, Radu Bogdan Dicher via groups.io
<> wrote:
> Going back to my -12V rail issue, the SM advises
loading the 5.20V rail
> with a 2ohm/25W resistor. The only way I can put
something similar
> together with what I have at hand is using these
dummy loads I am using
> when repairing audio amplifiers, which are a pair of
8ohm/100W non-
> inductive resistors. By paralleling?them I can load
the 5.20V rail with
> a 4ohm resistor.
> What are some thoughts regarding whether this would
be a suitable load
> for the PS? I think the PS just needs a low ohmic
load of sufficient
> dissipation capacity and it should crank itself up to
nominal, but maybe
> there's an aspect I'm overlooking.
> Thank you,
> Radu.
>
> On Sun, Mar 2, 2025 at 1:52?PM Radu Bogdan Dicher via
groups.io <> <
<>> groups.io <>>
<vondicher@...
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>>
> wrote:
>
>? ? ?One of the two scopes is completely disassembled
- head exploding
>? ? ?emoji - and I have the old battery desoldered
after confirming?it's
>? ? ?fully depleted.
>
>? ? ?I enclose pics with what I'm using for
replacement. I probably would
>? ? ?have been fine going with a 2032 type, but the
2430 I ended?up
>? ? ?fitting just right (maybe a bit snug), and the
pins of the holder
>? ? ?actually match the PCB eyelets. So all is good.
>
>? ? ?I couldn't figure out what exactly was the
original battery model,
>? ? ?as it's not legible even after removing the top
tab, but its
>? ? ?diameter is a bit over 23mm.
>? ? ?I think this should work OK.
>
>? ? ?Back to the?actual troubleshooting now!
>? ? ?Radu.
>
>? ? ?On Fri, Feb 28, 2025 at 6:21?PM Roy J. Tellason,
Sr. via groups.io <>
>? ? ?< <>>
<roy@...
<mailto:[email protected]>
>? ? ?<mailto:[email protected]
<mailto:[email protected]>>> wrote:
>
>? ? ? ? ?On Thursday 27 February 2025 04:09:31 pm Radu
Bogdan Dicher via
> groups.io <> <
<>> wrote:
>? ? ? ? ? > One other unfortunate effect of the spot-
welding of the top
>? ? ? ? ?tab is that the
>? ? ? ? ? > battery code is not visible. I can
probably destroy the
>? ? ? ? ?battery once out,
>? ? ? ? ? > and read the CRxyzt battery code, but
would anyone have good
>? ? ? ? ?info offhand
>? ? ? ? ? > on it?
>
>? ? ? ? ?You might find bits of this useful:
>
>
<>
<
<>> en.wikipedia.org/wiki/
List_of_battery_sizes <
List_of_battery_sizes>>
>
>? ? ? ? ?Scroll down to where they discuss coin and
button cells:
>
>? ? ? ? ?"IEC designation numbers indicate the
physical dimensions of the
>? ? ? ? ?cylindrical cell. Cells less than one
centimeter in height are
>? ? ? ? ?assigned four-digit numbers, where the first
two digits are the
>? ? ? ? ?diameter in millimeters, while the last two
digits are the
>? ? ? ? ?height in tenths of millimeters. Taller cells
are assigned five-
>? ? ? ? ?digit numbers, where the first two digits are
the diameter in
>? ? ? ? ?millimeters, followed by the last three
digits indicating the
>? ? ? ? ?height in tenths of millimeters."
>
>? ? ? ? ?So the size of the battery will give you the
info that you need.
>
>? ? ? ? ?--
>? ? ? ? ?Member of the toughest, meanest, deadliest,
most unrelenting -- and
>? ? ? ? ?ablest -- form of life in this section of
space, ?a critter that can
>? ? ? ? ?be killed but can't be tamed. ?--Robert A.
Heinlein, "The Puppet
>? ? ? ? ?Masters"
>? ? ? ? ?-
>? ? ? ? ?Information is more dangerous than cannon to
a society ruled by
>? ? ? ? ?lies. --James
>? ? ? ? ?M Dakin
>
>
>
>
>
>
____
__
|
