[Dsg-halla_ecal] ECAL heater controls update

[Donald Jones]

Hi Marc,
The 10 problematic power supplies have been swapped out and are now plugged in. The system is ready for testing. I found that the thermocouple used to control temperatures on zones 11 and 16 were swapped as you suggested. They have been switched to the correct configuration. Let me know if you have any further issues.

For those of you who are not familiar with the details, Marc found 10 zones with power supplies that would not respond to an input control voltage. The control voltage is a 0-10V input that changes the output voltage from 0 to 48V. According to spec, this input control voltage should typically draw around 100uA. The control voltage output by the CRIO unit can go up to 4mA. Apparently, this is not something that is carefully checked by quality control and occasionally there are units that draw several mA, beyond what the CRIO can produce. That is why I concluded that these power supplies were fine when testing them. I was adjusting the input control voltage from an external variable voltage supply which can easily deliver hundreds of mA. These ten problematic units have now been swapped out and we are optimistic that the remaining ones will work as expected. Fortunately, we had enough spares. We had no issues with the ones we used for running the prototype for months, but we did see one or two units in testing with this issue early on. In other words, we have seen units present this issue before, but they do from the very first. "In spec" units don't appear to develop this over time which leads us to be optimistic.
-Don


Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
________________________________
From: Marc Mcmullen <mcmullen at jlab.org>
Sent: Wednesday, February 12, 2025 2:58 PM
To: Donald Jones <jonesdc at jlab.org>; dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: ECAL heater controls update

Hi Don,

It will be great if you can get them working.

Marc

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________________________________
From: Donald Jones <jonesdc at jlab.org>
Sent: Wednesday, February 12, 2025 2:01:32 PM
To: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>; Marc Mcmullen <mcmullen at jlab.org>
Subject: Re: ECAL heater controls update

Hi Marc,
I made two cables: one to by-pass the PSIC and connect the power supplies directly to the heater circuit cable  and another to connect the control input directly to a variable DC voltage supply. I measured the voltage output on the second power cable. It will be easy to test all the supplies now.
I had enough time to test the first power supply on your list, zone 5. It seemed to work as it should, outputting 48V when the control voltage was disconnected and varying from 0-48V when the control voltage was connected to the DC voltage supply and  varied between 0-10V. The output voltage reached its maximum around a 9V input as expected since this zone does not draw the full 12.5A that the supply can give.
You mentioned that all the PSICS were completely tested and functional so this is confusing. Let me know if I am overlooking something. The obvious failure would be a bad fuse, but the one on channel 5 looks fine and measures 0.2ohms across it.
I plan on testing more of the supplies on your list later today if I can. I will let you know how the test goes.
-Don


Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
________________________________
From: Dsg-halla_ecal <dsg-halla_ecal-bounces at jlab.org> on behalf of Marc Mcmullen via Dsg-halla_ecal <dsg-halla_ecal at jlab.org>
Sent: Tuesday, February 11, 2025 4:33 PM
To: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Cc: Ed Folts <folts at jlab.org>; Neville Malabre-O'Sullivan <nevilleo at jlab.org>
Subject: [Dsg-halla_ecal] ECAL heater controls update

Hi Don,

Here is what I have found so far.

The power supplies on the following channels need to be replaced:

5, 10, 11, 12, 13, 14, 15, 32, and 42

I confirmed this on 5, 10, 11, and 12. The others behave similarly, and they are too difficult to get to the connectors to confirm.  The issue seems to be the dimmer circuit. The ones I checked looked like they turn on but we cannot adjust the current output from the minimum. I also check that the controls were trying to adjust the supplies.

Before we swap out the supplies we need to test each new one using channel 1. We can test them right on top of the power supply rack to confirm they work.

During testing I confirmed that the thermocouples on channels 11 and 16 are swapped. I verified that it is not at the controls rack TC terminal blocks.

These are all the major issues found.

Minor issues: I have a couple of current readbacks  that are swapped (23 and 24). The current readback on channel 30 is negative. These final two issues are not major and have nothing to do with heater control or safety, and I can fix them in software.

Other than that I was able to ramp up all the other channels to ~30 C.

Currently, the system is on. I have all the relays turned off in software so they will not provide power to the heaters. I will start testing the PID control tomorrow.

Let me know when you have the supplies ready for testing on channel 1. I can test them before you install them.


Marc


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