Stanford Research, how do  you check health of the lamp? - Page 1
Forum section: electronics / general

author: tkamiya
author_rank: Super Contributor
timestamp: February 04, 2019, 04:43:24 am
content: How do you measure lamp voltage on Stanford Research PRS-10?According to manual, pin 4 is shared between analog lamp voltage and TXD. Default mode is TXD.So apparently, I have to read ad converter's reading at channel 4? Still, the value does not make any sense.(page 37)https://www.thinksrs.com/downloads/pdfs/manuals/PRS10m.pdfor am I going about this a wrong way? It seems this piece is a lot more advanced than Efratom FRS series.

author: Psi
author_rank: Super Contributor
timestamp: February 04, 2019, 09:36:15 am
content: What ADC value do you get on channel 4 that doesnt make sense?

author: tkamiya
author_rank: Super Contributor
timestamp: February 04, 2019, 03:12:17 pm
content: I'm going to do that today and report back.I spent few hours last night reading manuals and Internet. Oddly, for other Rb units, lamp voltage is prominently discussed but not for PRS-10. No one is asking and no one is talking. (well, except for me) I did find a mention of Stanford Research put 10x the amount of rubidium so that THAT kind of failure is a thing of the past.I also found a software by Stanford Research that reads all parameters. I'll try that and see if there is anything interesting.

author: DaJMasta
author_rank: Super Contributor
timestamp: February 04, 2019, 09:46:26 pm
content: I think you can read the values over the serial port to see if you're near the edge of the adjustment window. It's a TX pin, but it can be configured via internal jumpers to be an analog output from another source. You'd have to open it up and physically mod it to directly readout on the connector, but I believe the difference that configures it is described in the main manual for identifying on the PCB which you have.

author: tkamiya
author_rank: Super Contributor
timestamp: February 04, 2019, 10:12:54 pm
content: Yes, thanks. So happens that 1 out of 3 units I have have this option enabled (pc control) and 2 does not. In which case, the same pin 4 acts as analog voltage.My real issue became which value is the one I want. As we all know, lamp voltage is not what we are after. It's the photo cell reading that changes as a result of intensity change is what we want. Well, none of the values are named that. So I took the closest wording, and it's 9 volt or so.

author: DaJMasta
author_rank: Super Contributor
timestamp: February 05, 2019, 02:10:50 am
content: Do you have a copy of the manual that includes theory of operation and such? That should be able to point out exactly what's what, but I think the info you're looking for is probably the one broken out.The module self-regulates the way it powers the science package so that the lamp output is within tolerable levels, so that output should be pretty fixed. That means to find lamp health, you want to measure how hard the module is having to drive the lamp, because as it ages and lamp output declines, it drives the module harder to maintain a usable output. That means the end of life for the lamp is when the power driving it can no longer be turned up any farther by the internal system, so monitoring the system's DAC should effectively be the inverse (with some coefficient) of the lamp output.

author: tkamiya
author_rank: Super Contributor
timestamp: February 05, 2019, 02:15:08 am
content: Yes, I do have manual(s) with theory of operations.My understanding is, while we call it "Lamp Voltage", it is actually NOT measuring the voltage that is applied to the lamp. I understand it is the voltage read at photo diode.So voltage of 3V or so means lamp is working as hard as it can, yet photo diode is only detecting small amount of emission.All 3 units locks fine and fast, by the way.

author: texaspyro
author_rank: Super Contributor
timestamp: February 05, 2019, 03:02:26 am
content: Quote from: tkamiya on February 04, 2019, 03:12:17 pmLady Heather supports the PRS-10...

author: tkamiya
author_rank: Super Contributor
timestamp: February 05, 2019, 03:49:32 am
content: I didn't even think to try that! I did a quick search and found someone locked PRS10 to Thunderbolt 1pps. Very nice indeed. With that many devices to support, I'd hate to see what your "if" statement looks like...