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Multimeter | Clamp meter | Insulation Resistance Tester | Panel Meter | Oscilloscopes | Test leads & Accessories | Software Updates => Bench-top multimeter => Topic started by: Kiriakos GR on October 13, 2020, 06:12:05 PM
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Do you think that your 8845A / 8846A this gets warm more than what you will expect at standby?
I will start with one example, at my workshop in the hart of summer I had an almost constant of 30 Celsius indoor.
The DMM top cover this had a constant hot spot of 42 Celsius.
The DMM was configured by the adjusting plate at the back, for operation at 220V input.
Today I did some power consumption tests.
By doing so I did switch the power meter in Volts, and it read 237V AC.
This motivated me so to configure the 8846A at 240V AC Input.
In my surprise the power consumption this now become less by almost 1,5W.
220V configuration and stand by this was 11W
240V configuration and stand by this is now 9.5W
240V STATS
DC range at 1000V = 13.2W
AC range at 1000V = 13.4W
Ohms range 10 Ohm manual = 14.0W
FREQ-PERIOD = 13.2W
DMM REBOOT = 14.5W (Highest).
I am not aware of how 1,5W less this will influence 8846A internal temperature, but at least you all have now statistics for your own comparisons.
Hints:
My display brightness intensity this is set to LOW.
If you use a low cost power meter then accept 3% -/+ Error
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Any temperature case cover statistics after the new change ?
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Any temperature case cover statistics after the new change ?
While it is too soon about of me obtaining a complete picture, I have data from 24C room temperature.
I did place a wireless temperature sensor on top of 8846A (transformer area) last night.
And this morning, I did add and one K type thermocouple.
At 24C room the 8846A this is now at 28C.
The multimeter with the K type thermocouple, this is my first ever and this is now 35 years old. 8)
I do trust the temperature range but it missing a rich digits resolution.
Even so, four degrees above room temperature this is the NEW fact so far.
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I am suspecting that Mains input voltage 220 VS 240 ACV, this will influence mostly the temperature of the pile of 8846A DC voltage regulators.
With 235V input voltage at 220V input setting, the transformer this will deliver a bit higher ac voltages, and all voltage regulators they will dissipate more heat.
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I think that after of me monitoring the new setting for almost 14 days I can now deliver good standing statistics.
And @overvolt he is very close to what is happening.
All 8846A DC voltage regulators they run much cooler.
8846A mains transformer this runs cooler too.
The DMM does not get warmer that 5~6.5 Celsius VS room temperature, at stand-by and neither this gets any warmer even with the display active.
So the first fact, this is that display luminosity circuit this does not contribute to DMM inner case temperature.
The Mains power-line this feeding all my bench instruments this is guarded due UPS APC SMC1500I (1500VA) and so there is no fear for Mains failure.
Now I have one after thought but this needs to be confirmed, now that the 8846A this running with proper mains feed, I am close to assume that it factory calibration this has recover at a better point.
But such confirmation this is difficult, the difference this should be a few ppm.