Author Topic: RS-135 4-20mA Loop Calibrator & Thermometer  (Read 845 times)

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Offline mcinqueTopic starter

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RS-135 4-20mA Loop Calibrator & Thermometer
« on: August 11, 2022, 09:29:14 am »
Hello all!

I would like to acquire a voltage/current/loop calibrator and I found the "PROVA 135 4-20mA Loop Calibrator & Thermometer"

https://www.prova.com.tw/product_detail.asp?seq=198

It's rebranded by RS with code RS-135 https://uk.rs-online.com/web/p/multi-function-calibrators/1749557

I don't know much about this 'PROVA' brand and I don't know how they build their products... does anyone have this type of calibrator and has done a teardown and/or can tell if it's a good product?
 

Offline Chance92

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Re: RS-135 4-20mA Loop Calibrator & Thermometer
« Reply #1 on: November 27, 2022, 03:31:49 am »
I had a second-hand RS-133. Here's the only picture I could find. I replaced the battery pack myself. Not very good at this kind of things. Please don't judge the workmanship. It worked fine in general. I remember the measurement function was lightning fast and steady. Very impressive. One thing I don't like is the manual didn't mention the calibration procedure, so you might need to send it back to the factory to get it calibrated.
There's another PCB under the one you can see. There's a switch-mode DC-DC converter at the upper right corner, which I suppose powers the system, and there's another one at the bottom. You can see the inductor there. I think this is probably used to generate the output voltage. Not sure if it's a good idea to put a smps so close to the output ports. I couldn't find the voltage reference chip. It might be under the copper shield, but I didn't open it. Another thing I could remember is that the calibrator couldn't charge while turned off, which is very strange.
 
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Offline mcinqueTopic starter

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Re: RS-135 4-20mA Loop Calibrator & Thermometer
« Reply #2 on: November 28, 2022, 07:54:41 am »
Thanks a lot! The kapton I see is something factory made or is something made by you changing the battery?
 

Offline Chance92

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Re: RS-135 4-20mA Loop Calibrator & Thermometer
« Reply #3 on: November 28, 2022, 03:36:30 pm »
That was added by me.
 


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