Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
AVGresponding:
--- Quote from: factory on November 18, 2024, 07:11:15 pm ---They both use low voltage displays, I don't particularly want to mention the type on here.
David
--- End quote ---
My bad, brain fart. They are the incandescent lamp with light pipe type, whose name escapes me currently
Robert763:
--- Quote from: factory on November 19, 2024, 02:04:30 pm ---Have a look at the 1N829A in the die pictures thread, it contains two diodes in series, one of which is used as the reference Zener junction & the other a diode junction connected opposite for temperature compensation, both junctions balance the temperature coefficient, the better grades are selected for lower TC.
https://www.eevblog.com/forum/metrology/more-voltage-references-die-pictures/msg4262863/#msg4262863
A datasheet for temperature compensated reference Zeners that are still available;
https://www.mouser.co.uk/datasheet/2/268/1N821_1N829A_1-3499699.pdf
Any diode could become a Zener (with current/power limiting), but most have too high a breakdown voltage to be of much use for that.
This begs the question, what type of regular (non Zener) diode has a volt drop of 6.2V, for the Peak to determine it to be a diode & not a faulty part?
David
--- End quote ---
Some very high voltage diodes have high forward voltage drop. They are a stack of PN junctions in series so Vf is correspondingly high.
Harry_22:
--- Quote from: nixiefreqq on August 11, 2020, 01:26:43 am ---
--- Quote from: mnementh on August 10, 2020, 11:13:33 pm ---
--- Quote from: mnementh on August 09, 2020, 10:46:28 pm ---
--- Quote from: nixiefreqq on August 09, 2020, 10:22:00 pm ---ummmmm. just a thought.
while you were in there did you check the date code on the dallas nvram? (am thinking that it may not outlive you per the plan) replaced the one in my hp54601 with separate sram, controller chip, and battery. (encapsulated batteries really piss me off)
but iirc yours uses an 8kx8 (and maybe STMicro vice dallas?), and mine was a 2kx8.
https://www.eevblog.com/forum/repair/hp-54601a-nvram-substitute/
--- End quote ---
That... is a question for when I replace caps in the thing. ;) I did notice a label on the back stating it contains a BR1225 coin cell; pretty sure that means NVRAM battery will be replaceable. May need some soldering, of course.
Hmmm... that warranty label appears OEM issue; maybe the Agilent-branded handle IS original. :-//
These points are also something I can get into after the move; in the meantime, just going to love it and use it as needed. :-+
mnem
:-/O
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Looks like you were right; good memory. :-+
While I was in there molesting the PSU, I looked all over and under the mainboard and nope, nothing like a coin cell anywhere. Pretty sure a peek at the datasheet on this NVRAM would tell me there's no way to connect a external battery (aside from that CNC the IC down to the battery mod I saw in the 2465 thread), but of course I had to see for myself. |O
Now of course it's in the queue for recapping; no idea if I'll have time for that before the move or not. :palm:
mnem
*sigh*
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crap. unfortuately the specsheet says "caphat". if it were a "snaphat" it would be a piece of cake.
my attempt to drill, file, or whittle down to the battery connections on a few of these bastards were unmitigated disasters.
maybe if you had an xray rig and a real milling machine it would be possible. saw that a guy claimed he was able to "melt" his way down to the battery leads. good fecking luck with that.
https://www.st.com/content/ccc/resource/technical/document/application_note/9e/6f/ee/57/a8/56/44/d0/CD00004060.pdf/files/CD00004060.pdf/jcr:content/translations/en.CD00004060.pdf
that is what drove me to the ugly/hamfisted but workable sram, controller chip, coin cell in a holder bodge. it worked in my 54502a, 54504a, and 54601a.
but it is as elegant as a turd.
edit if you come up with novel fix for this predicament please post details.
--- End quote ---
Less than four years later I decided to replace the same battery. Not that it bothers me too much. But in order to enter GPIB number, which was erased every time the device was turned off, I had to kneel down and look near the floor where the required button was.
The treatment went quite quickly. There is exist information about replacing the battery in CAPHAT case.
I made several pictures to make everything clear.
Of cause was possible to buy a new one SRAM, but in our village it costs almost 50Euro and I didn’t want to get hooked again.
Ice-Tea:
Pretty neat!
I've seen cases where the leakage or consumption of these devices has increased considerably. So , keep an eye on that CR2032 ;-)
Harry_22:
--- Quote from: Ice-Tea on November 21, 2024, 10:35:56 am ---Pretty neat!
I've seen cases where the leakage or consumption of these devices has increased considerably. So , keep an eye on that CR2032 ;-)
--- End quote ---
Thanks, it seems like this is already happening. A week ago I ordered 50 pieces of CR2032. They leave me with terrible speed.
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