Products > Test Equipment
Accurate Low Amp Current Probe Advice
KungFuJosh:
--- Quote from: Martin72 on November 04, 2024, 06:20:16 pm ---
--- Quote from: nctnico on November 04, 2024, 05:42:02 pm ---Now I recall why I never bought that Tektronix current clamp... 8)
--- End quote ---
Because you have a functioning crystal ball. ;)
The battery of my 503A was dead too, but changing it was no problem because I had followed these instructions.
--- End quote ---
It's not the same for the 503B. My test mode maxes out at 53. 52 is to degauss the amp itself. Nothing else is really listed in the manual. The battery replacement section in the manual also doesn't say anything about tests after replacing the battery.
My tests were pretty close anyway, I don't know if it really lost any data. It's been a decade since it was calibrated according to the stickers, so I would guess nothing was lost based on that alone considering how close it was.
However, if I want to get it to be more accurate, I'm guessing the easiest way is with the NVRAM replacement game.
KungFuJosh:
--- Quote from: MarkL on November 04, 2024, 06:28:00 pm ---I haven't seen it anywhere. However, the data in NVRAM is sparse and it looks to be only about 25 bytes. It wouldn't take long to type it in if you're looking to copy their NVRAM. Some of the values may already have been initialized to defaults if the battery was detected as dead.
--- End quote ---
Well, I was hoping it autogenerated the cal constant hexadecimal codes so I could be lazy about that part. 😉
MarkL:
--- Quote from: Martin72 on November 04, 2024, 06:20:16 pm ---
--- Quote from: nctnico on November 04, 2024, 05:42:02 pm ---Now I recall why I never bought that Tektronix current clamp... 8)
--- End quote ---
Because you have a functioning crystal ball. ;)
The battery of my 503A was dead too, but changing it was no problem because I had followed these instructions.
--- End quote ---
The AM503A has a PCF8582A EEPROM, which is probably used to store the cal data. The AM503B only has a PCF8570 low-power CMOS memory.
The AM503A also has a PCF8570, and I guess the procedure is copying the data between the two memory chips, but I'm not clear which one it means when it says "NVRAM".
I guess my crystal ball is not so good. I have 2x AM503, 2x AM503B, 2x A6302, 1x A6303, and 2x TCP202. They all have various drift, noise, and fidelity issues. I use the AM503B the most because I like the auto balance, but it has processor clock noise in the output which can be annoying. In those cases, I put up with the fiddly drift in the AM503.
KungFuJosh:
--- Quote from: MarkL on November 04, 2024, 06:45:15 pm ---They all have various drift, noise, and fidelity issues. I use the AM503B the most because I like the auto balance, but it has processor clock noise in the output which can be annoying.
--- End quote ---
Is there anything we can do to mitigate any of those issues? Currently (pun intended), the drift is the most annoying issue.
KungFuJosh:
This is kinda funny. I think I scared the 503B. I removed the PCF8570P and installed a socket there, then inserted the chip. Now it's behaving a little better. 🤣
The drift is still annoying, but it seems to improve depending on warmup time and room temp. I degaussed between every value change, but not between the two 100mA tests.
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