Building log for "EEZ BB3 Enclosure & Bare Boards"

[exe]

Huh, that one is a real trouble to source, but as you suggested any 3 mm LED with bended legs should be fine.

I bought a green one, this one: https://www.tme.eu/en/details/osg8ha3e34x-3f1a/led-pcb-indicators/optosupply/ . I hope it will fit. The led is different, so current-limiting resistor might need an adjustment (or may be not, the specs seem to be the same). Or I find an orange led in a dumpster.

[prasimix]

Green is just fine. They are also partially used during AUX PS assembly for campaign fulfillment since yellow one was out of stock.

[exe]

I have a question about backplate BOM. I think X4, X5 and X6 should be the same (and they are in csv file), but they are different in this file: https://github.com/eez-open/modular-psu/blob/master/bp3c/BOM/EEZ%20DIB%20BP3C%20r3B3%20BOM.pdf . It also says that X4 should be right angled, but it looks like X5 is actually right-angled. Denis, can you please check? I guess, csv-file is more accurate? Or designating numbers are different on different versions of the pcb?

UP: my pcb doesn't match this picture: https://github.com/eez-open/modular-psu/blob/master/bp3c/Images/EEZ_DIB_BP-3C_PCB_top.png . For example, D4 on my pcb is named D5  on the picture. Should I use an older picture or something?

[prasimix]

Yes, the BP3C that came with the campaign is r3B2 and is a little different from the version that went into release 1.01 in which r3B3 was released prematurely. Please use files from release 1.0 that contains r3B2 (see attachment).

[exe]

Thanks, Denis. Do you remember what were the changes to the project after r3B2? Does it make sense to order new boards?

[prasimix]

Not at all in case of BP3C. I just removed one header and use Zener diodes in different package if I remember correctly. All other boards are different story since they needed some real changes to pass CE testings.

[exe]

That's good, as I just finished the backplate .

As I understand, CE is only needed for the aux supply board? The mcu board is not affected by this?

What's your advice: make new boards, or keep the ones in the kit?

[prasimix]

That's good, as I just finished the backplate .

As I understand, CE is only needed for the aux supply board? The mcu board is not affected by this?

What's your advice: make new boards, or keep the ones in the kit?

I'm in process of learning what is behind CE marking. No, it is not needed just for AUX-PS module but for a complete solution that could include components that are already passed CE testing. But, surprise, surprise ... I’ve learned in a hard and very expensive way that it doesn’t really mean much: one Mean Well model can pass testing, combination of two different modules cannot (conducted emission break limit); one Mean Well model can pass testing, add another of the same type and they cannot pass testing (current harmonics break limit). Later issue required new AUX-PS, former probably will probably require giving up the LRS-150 model and using one who has a built-in PFC (If I’m lucky I’ll get away with a massive capacitor at the AC input, another option is next AUX-PS revision with PFC for up to three Mean Well modules which I have not yet begun to consider).

I learned that the MCU module cannot pass the radiated emission test when the antenna is horizontally polarized if the SDRAM is set as in the r2B4 version. It turns out it can pass if the SDRAM is set beneath the MCU.

Similarly, DCP and DCM modules broke the limit for radiated emission which also required some modifications (new pre-regulator in case of DCP, PCB redesign in case of DCM). I don't know what else awaits me on the way. The first next thing I have to pass is the current harmonics test. I am not even able to prepare because the documents of the norms that prescribe tests are not free, but literally cost a small fortune if I buy everything (it seems to me over 15,000 EUR).

My suggestion: assemble what you have, unless you want to wait uncertain period of time. At the moment, what I can say with certainty is that the design of the DCP module that passed the CE (r3B3) will not change, and for which I only currently have bare PCBs as well as an excess of assembled modules made by a new contractor.

[exe]

Ah, silly me, I thought it's about safety. Thanks for detailed explanation, I'll proceed with current pcbs.

[exe]

Denis, do I need to short any jumpers on any of pcbs?

[prasimix]

No

[exe]

Idiotic question, will aux ps work without OK1 optocoupler? Asking because mouser screwed my order and I now have two moc3062 instead of one moc3052 and one moc3062 . I'll order moc3052, but I'm impatient to test the board . I guess without OK1 the current will go through the NTC1, but that's no problem for testing without load, right?

[prasimix]

You can place MOC3062 on both positions. Better then you got two MOC3052.

[exe]

Potential BOM issue: for MCU board, for "FB1, FB2" the quantity is specified as 1, while it needs two beads. I replaced it with BLM18HD102SN1 which is the only ferrite bead of this size I have. But because it has higher DC resistance (1.8Ohm) and lower current rating (50mA) I expect ethernet won't work properly (I don't need it anyway).

[prasimix]

Thanks, now it is fixed.

[exe]

My friends, I assembled the mcu board, connected it to the aux-ps board, connected it to my computer, pressed boot0 button, switched on power and then.... nothing happened. Question: is DFU mode available on blank mcu by default, or it needs pre-existing firmware (i.e., the first time I need to flash the board via st-link interface)?

[prasimix]

Sorry to hear that.

No, you don't need anything to download firmware in the brand new (i.e. completely empty) MCU. Therefore, no need for STlink or external programmer. You even don't need to assemble a whole module just to establish communication for firmware download. It can be done with minimum parts: LDO (3.3 V power), Boot0 switch, MCU (i.e. everything from Sheet 2/5) and USB connector with R28, R29 in place.

Be sure that switch (which is very tiny) are really pushed on while power is applied.

For the beginning check if you have 3.3 V on MCU.

[exe]

Thank you very much, I'll check on this.

Meanwhile I found that I didn't buy the ethernet port (LMJ30288115CNL) because it's not available from mouser.

[prasimix]

Currently it is available only at TME, but there is a worrying info that Product available till the stock lasts. It seems that I have to replace it with something else in the next release!

[exe]

I think there is an alternative ethernet port (the bom provides alternative sku) that is still on sale on tme.

Meanwhile I found the problem: I soldered the mcu the wrong way: it has multiple corner marks, two large ones and one small. I used one of big ones to orient the chip. What a bummer... I guess I should not do soldering late at night. I'll try to flip it, but chances are not great that it will work.

[prasimix]

Ouch, that is exactly what happened to me with my first prototype ... and that was in the middle of the day. 

[prasimix]

I think there is an alternative ethernet port (the bom provides alternative sku) that is still on sale on tme.

You're right the first choice is LMJTAB881243ML but also only available from TME.

[exe]

Phew, seems to be working after all . At least I was able to upload firmware. I'd like to share my experience so other people won't do same mistakes.

Not the best soldering, but good-enough for Australia . A few things I messed up. One is my zener flew away when I tried to grab it with twezers. I replaced ZD1 with two zeners (16V+7.5V). I think I damaged my tweezers by using them to open resistors on tape.

Then I couldn't solder the usb port, it seems it's meant to be soldered with hotair or reflow. I removed rear tab of the connector to get access to pins.
I ran out of cr2032 batteries, so I put cr2025, hope it will work.
The boot0 button seems damaged by flux: it's stiff, but seems to be working.

In some cases it might worth soldering ICs first, and then decoupling caps as they get in the way. But I mostly used hand soldering, users using hotair probably find it much easier to solder components. I put plastic parts at the very last because: 1) I was worried to damage it with hotair and flux 2) it's easier to work with flat board without components sticking from it. If I was assembling it again, I'd use solder paste and hotair gun for most components, rather than soldering iron.

Oh, and double-check the BOM .

Now time to assemble the enclosure...

[exe]

"Do not power on the MCU module without the display connected or with a loosely connected flexible display cable. Doing so may damage the power supply of the display backlight located on the MCU module." Oh shi~...

[Kleinstein]

With the zener diode(s) in place there is a good chance the backlight drives does survive. It would be the zener that gets quite some heat. So having 2 may have helped .