Re: HP 54512B (pair) repair
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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.?
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 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 <http://
> > <vondicher=[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
>? ? ?<> <roy=[email protected]
>? ? ?<mailto:[email protected]>> wrote:
>
>? ? ? ? ?On Thursday 27 February 2025 04:09:31 pm Radu Bogdan Dicher via
>? ? ? ? ? <> 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:
>
>? ? ? ? ? <https://
>? ? ? ? ?>
>
>? ? ? ? ?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
>
>
>
>
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