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Replacing OLED screen on an Agilent U1253A Multimeter

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--Oz--:
Edited my 2nd post above with the modded meter currents.

tooki:

--- Quote from: --Oz-- on December 12, 2022, 06:01:25 pm ---I found a stock meter (no OLED display replacement).

This U1253B battery icon has these reaction.
Keysight Stock.                  Agilent Modded.
9.40v full battery bars,      8.1v full battery bars,
9.3 to 9.0v 3 bars,.             8.0 to 7.7v 3 bars,
8.9 to 8.3v 2 bars,.             7.6 to 7.2v 2 bars,
8.2 to 7.3v 1 bar,.               6.65v shows 1 battery bar then turn off.
7.26v "X" in battery,
Works ok down till 5.7v,
At 5.6v the numbers jump around,


Clearly the two meters have different firmware and possibly hardware changes.

--- End quote ---
Maybe, but I kinda doubt it.

The big changes (which were still little) were between the U1253A to U1253B. AFAIK there are no differences between an Agilent ’53B and a Keysight ’53B, other than the housing colors and boot logo. (And included accessories.)

The ’53A is designed for 7.2V NiMH, while the ’53B is designed for both 7.2V and 8.4V NiMH batteries. The ’53A and Agilent-branded ’53B’s shipped with 7.2V batteries, while Keysight-branded ’53B’s shipped with 8.4V ones.

In the ’53B, you can select the battery type in the settings, so that the battery indicator will be more accurate.

It might be interesting to set your Keysight ’53B to 7.2V battery and then repeat your testing.

gamalot:

--- Quote from: --Oz-- on December 12, 2022, 06:30:43 pm ---Will try and test my modded meter tomorrow.

The three IC's have very low idle current, total for the three is around 5uA.
All three work down to 3v, so lowering the 3.3v supply would work with the adapter board.

Two ideas.

1. Is there a "dark mode" for the OLED display? Could save some power there.

2. Is there a way to pwm the OLED display brightness (like you could could do with lcd)? Yea, long shot on that one, haha.

--- End quote ---

When the brightness adjustment button is pressed, the processor will send a 'contrast' instruction to the OLED display. By intercepting this instruction and modifying its parameters, the brightness of the OLED can be controlled at the desired brightness.

I was thinking of using a simple DIY light meter to find out the relationship between current and brightness (most likely it is non-linear), so maybe there is a chance to find a balance point with slightly lower current but enough brightness.

--Oz--:
OT: Battery options, revisited.

The stock battery was 225mAh (1.62wh), I have two of these used and they test to 160mAh, complete rubbish  :-DD

I mentioned "the 9v I use is 9v 600mAh (tested to 520mAh) or 4.4Wh and does not last very long imo."

I am thinking two Li-Ion 102550 pouch cells in series with 1400mAh capacity (10wh)  might just fit an unmodded case. But I did not find Li-Ion, it was LiPo which has lower capacity, so some possible capacity/runtime gain there.
This would be 6 times the runtime of a brand new 225mAh cell.


Could make a simple 3 conductor connector to balance charge the 2S pack.
Of course with a battery BMS, you could not use the standard charger. I think I would go with simple $1 USB 2S charge bms board, with would charge at 1A and charge in less than 2 hours.
Or maybe even a wireless charge system for convince like cell phones use.

Thoughts?


Darkover:

This is what I am using now for 3-4years,

> Of course with a battery BMS, you could not use the standard charger.

Perhaps you should not, but you can. Unfortunalty you have to charge the battery 2-3times in a row,
because there is a time limit in the chargealgorithm of the 1253.

But my battery has some electronic to prevent from overcharge, just in case.  ;)

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