Author Topic: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)  (Read 286015 times)

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Offline mcdanlj

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1100 on: May 02, 2019, 10:32:29 am »
Looks like it survived.

Replacement TVSs installed. Each channel works separately. Parallel coupling appears to work but I haven't tested more than 5A through my small dummy load so I don't know whether it really works. Series coupling definitely doesn't work.

I didn't think to test series coupling before doing the repair, so I don't know whether the failure started before or after. I don't know whether I broke a relay or have a bad solder joint, but I would guess that I broke the K_SER relay removing it and re-installing it. Edit: Yup, damaged a pin on K_SER. One more thing to order!

Of course, I didn't test beyond the individual channels before reassembling the whole unit. Brilliant of me. :palm:

Thanks again for the help!
« Last Edit: May 02, 2019, 11:12:04 am by mcdanlj »
 

Online prasimix

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1101 on: May 02, 2019, 04:41:05 pm »
Replacement TVSs installed. Each channel works separately. Parallel coupling appears to work but I haven't tested more than 5A through my small dummy load so I don't know whether it really works.

When outputs are coupled in parallel channels should deliver current evenly thanks to software based balancing. Therefore, going above 5 A shouldn't be a problem if it already works with lower current.
 

Offline mcdanlj

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1102 on: May 04, 2019, 06:36:48 am »
I broke a pin on the K_SER relay when I was removing it to replace the diode. :palm: Probably I had not completely freed the pin from solder and didn't notice when trying to free the relay. New K_SER relay installed, now serial coupling works as well as parallel.

Now, I want to test power on each channel. I used the 2 Ohm 100W resistor that I originally calibrated with. I can max out power at 30W per channel. Voltage displayed is not quite right (in CC, 8V limit on the PSU display shows as 7.9V read on my meter, read directly at the terminals).

I tried to re-calibrate using that same resistor, but I'm not succeeding. In the calibration wizard:
  • Channel 1, step 1, I'm reading 92.8mV, step 2 I'm reading 115mV and can't get past that point in the wizard because I'm out of range.
  • Channel 2, step 1, I'm reading 125.5mV, step 2 I'm reading 125.6mV; again out of range and can't get further.

Is there a (re-)calibration bug in the v1.0 firmware?

Also, when parallel coupled, which remote sense terminals are active?
« Last Edit: May 04, 2019, 09:45:30 am by mcdanlj »
 

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1103 on: May 04, 2019, 05:14:51 pm »
I broke a pin on the K_SER relay when I was removing it to replace the diode. :palm: Probably I had not completely freed the pin from solder and didn't notice when trying to free the relay. New K_SER relay installed, now serial coupling works as well as parallel.

Now, I want to test power on each channel. I used the 2 Ohm 100W resistor that I originally calibrated with. I can max out power at 30W per channel. Voltage displayed is not quite right (in CC, 8V limit on the PSU display shows as 7.9V read on my meter, read directly at the terminals).

What is max. current that you can measure? Is it above 500 mA or not?
Delivered mentioned max. 30 W is in CV mode or it goes into CC mode?

I tried to re-calibrate using that same resistor, but I'm not succeeding. In the calibration wizard:
  • Channel 1, step 1, I'm reading 92.8mV, step 2 I'm reading 115mV and can't get past that point in the wizard because I'm out of range.
  • Channel 2, step 1, I'm reading 125.5mV, step 2 I'm reading 125.6mV; again out of range and can't get further.

Is there a (re-)calibration bug in the v1.0 firmware?

Shoudn't be, but I cannot remember correctly. Note that at least #171 related to calibration is fixed in v1.02.

Also, when parallel coupled, which remote sense terminals are active?

Both.
 

Offline mcdanlj

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1104 on: May 04, 2019, 10:28:49 pm »
What is max. current that you can measure? Is it above 500 mA or not?

I have a fluke 87V; I can measure up to 10A in high current range; 400mA in low current range.

In the calibration wizard, though, I can't get past step 2; I'm measuring only voltage across the resistor. I'm not running current through the meter.

(I'm not sure if I'm answering the question though?)

Delivered mentioned max. 30 W is in CV mode or it goes into CC mode?

That's in CC mode. I can measure 40V without load, but through the 2 Ohm resistor I'm limited to about 8V because of max power at 30W.
 

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1105 on: May 05, 2019, 02:08:16 am »
What is max. current that you can measure? Is it above 500 mA or not?

I have a fluke 87V; I can measure up to 10A in high current range; 400mA in low current range.

In the calibration wizard, though, I can't get past step 2; I'm measuring only voltage across the resistor. I'm not running current through the meter.

(I'm not sure if I'm answering the question though?)

Ok, so you cannot pass calibration of current high range (0-5 A) or what?

Delivered mentioned max. 30 W is in CV mode or it goes into CC mode?

That's in CC mode. I can measure 40V without load, but through the 2 Ohm resistor I'm limited to about 8V because of max power at 30W.

You've limited voltage to 8 V? Did you try to set it e.g. to 11 V, current to 5 A, and power to max (i.e. 155 W) and check if it can deliver all 5 A? If it cannot deliver more then 30 W with 2R load does it mean that max. current is just about 3.87 A?
 

Offline mcdanlj

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1106 on: May 05, 2019, 11:15:57 am »
Ok, so you cannot pass calibration of current high range (0-5 A) or what?

I can't even pass the second step of the calibration wizard, which I think is at low current range. It says it is supposed to be 19.1V and what I read is 0.115V.

You've limited voltage to 8 V? Did you try to set it e.g. to 11 V, current to 5 A, and power to max (i.e. 155 W) and check if it can deliver all 5 A? If it cannot deliver more then 30 W with 2R load does it mean that max. current is just about 3.87 A?

When I set current to 5A and voltage to 40V across 2R (not during calibration), it said I was power-limited to 30W, but it is configured for the normal 155W max. My recollection is yes, that the PSU display showed 3.87A as you would expect. I didn't confirm current at all with the Fluke, only voltage.

I am currently using channel 1, uncoupled, to charge Li-ion cells to 4.2V, and it's successfully delivering 5A CC initially until it switches back to 4.2V CV.

My assumption is that I have damaged an additional component or several somewhere.
 

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1107 on: May 05, 2019, 04:29:09 pm »
Ok, so you cannot pass calibration of current high range (0-5 A) or what?

I can't even pass the second step of the calibration wizard, which I think is at low current range. It says it is supposed to be 19.1V and what I read is 0.115V.

Put the calibration procedure aside for the moment. What you can measure with your Fluke if you set Vout to e.g. 20 V, without load connected?

You've limited voltage to 8 V? Did you try to set it e.g. to 11 V, current to 5 A, and power to max (i.e. 155 W) and check if it can deliver all 5 A? If it cannot deliver more then 30 W with 2R load does it mean that max. current is just about 3.87 A?

When I set current to 5A and voltage to 40V across 2R (not during calibration), it said I was power-limited to 30W, but it is configured for the normal 155W max. My recollection is yes, that the PSU display showed 3.87A as you would expect. I didn't confirm current at all with the Fluke, only voltage.

I am currently using channel 1, uncoupled, to charge Li-ion cells to 4.2V, and it's successfully delivering 5A CC initially until it switches back to 4.2V CV.

My assumption is that I have damaged an additional component or several somewhere.

Who said that power is limited to 30 W? Is that a message that pop up on the screen when you try to set voltage or current, or you can read that limitation on some of menu pages?
 

Offline mcdanlj

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1108 on: May 06, 2019, 03:34:04 am »
Put the calibration procedure aside for the moment. What you can measure with your Fluke if you set Vout to e.g. 20 V, without load connected?

Without load connected, I can measure any voltage I set, up to the max 40V, on each channel. According the fluke, the channels are typically consistently about 0.004V different in no-load, which was what made me want to re-calibrate; I recall them being closer after my initial calibration.

Who said that power is limited to 30 W? Is that a message that pop up on the screen when you try to set voltage or current, or you can read that limitation on some of menu pages?

It's a message that pops up on the screen when I turn on a channel configured for (for example) 5A and 40V across a 2R load. When I look in channel configuration it still says 155W, so I don't know where the 30W limit is coming from.

(Thanks for continuing to help me here, sorry when I miss the point or am not clear!)
 

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1109 on: May 06, 2019, 07:38:29 am »
Put the calibration procedure aside for the moment. What you can measure with your Fluke if you set Vout to e.g. 20 V, without load connected?

Without load connected, I can measure any voltage I set, up to the max 40V, on each channel. According the fluke, the channels are typically consistently about 0.004V different in no-load, which was what made me want to re-calibrate; I recall them being closer after my initial calibration.

Ok, so far so good. Without load you can set any output voltage. Therefore you should be able to pass voltage calibration (when load is not connected). For current calibration (with load connected), if you still cannot pass all steps, I'd like to suggest you to upgrade firmware to the latest version first.

Who said that power is limited to 30 W? Is that a message that pop up on the screen when you try to set voltage or current, or you can read that limitation on some of menu pages?

It's a message that pops up on the screen when I turn on a channel configured for (for example) 5A and 40V across a 2R load. When I look in channel configuration it still says 155W, so I don't know where the 30W limit is coming from.

(Thanks for continuing to help me here, sorry when I miss the point or am not clear!)

Please note that power limitation is not calculated in real time, but only when new voltage or current value is set. Since max. power per channel is limited with used AC/DC power module (LRS-150-48), that limitation is also put into firmware, i.e. you cannot set any U, I combination that will result in more then 155 W. Therefore, you cannot set 40 V and 5 A since that is 200 W. If you'd like to draw max. current with 2R load, set e.g. voltage that U * I product is equal or less then 155 W. For example, you can combine voltage from 10 V to max. 31 V with 5 A (31 * 5 = 155).
 
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Offline mcdanlj

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1110 on: June 03, 2019, 05:20:35 am »
Ok, so far so good. Without load you can set any output voltage. Therefore you should be able to pass voltage calibration (when load is not connected). For current calibration (with load connected), if you still cannot pass all steps, I'd like to suggest you to upgrade firmware to the latest version first.

For the benefit of anyone else who has the same problem and searches: I had misunderstood or misremembered the calibration process and thought I was supposed to put the 2 Ohm load across for voltage as well as current measurements.

I recalibrated without problems once I calibrated voltage without the load connected, and then connected it to calibrate current.

 :-[

Please note that power limitation is not calculated in real time, but only when new voltage or current value is set.

You would think that as a software developer it would occur to me that garbage in, garbage out.

Thank you again.

On to a firmware upgrade! I note that at least some of the build instructions (Building instructions/Complete kit assembly instructions (150 dpi).pdf) show pictures indicating to connect the internal USB cable to the programming port, but the flashing instructions say to use the regular port as supported by the more general DIY assembly instructions (Building instructions/EEZ PSU H24005 building instructions.pdf). Just a note for the next person.
 

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1111 on: June 03, 2019, 07:56:02 am »
On to a firmware upgrade! I note that at least some of the build instructions (Building instructions/Complete kit assembly instructions (150 dpi).pdf) show pictures indicating to connect the internal USB cable to the programming port, but the flashing instructions say to use the regular port as supported by the more general DIY assembly instructions (Building instructions/EEZ PSU H24005 building instructions.pdf). Just a note for the next person.

Yes, it's possible that in some of older building instruction docs the programming port is mentioned (and was valid in that time) instead of native, a change introduced in firmware v1.1. Therefore, all potential new builders should consult the latest version available on the project web pages: https://www.envox.hr/eez/bench-power-supply/building-instructions.html
 

Offline mcdanlj

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Re: DIY SCPI programmable dual channel bench PSU 0-50V/3A (now EEZ H24005)
« Reply #1112 on: June 03, 2019, 09:34:09 pm »
Yes, it's possible that in some of older building instruction docs the programming port is mentioned (and was valid in that time) instead of native, a change introduced in firmware v1.1.

 :-+ I'll move that cable now that I've flashed current firmware. Thanks for making that clear. Making that external port available as a native port makes a lot of sense!
 


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