No.072 - EEZ BB3 Bench PSU Repair

** PCBWAY For all your PCB Services at www.pcbway.com... **
In this video series I repair my own EEZ BB3 Power Supply which developed a problem with one of the output channels.
EEZ BB3 info:
www.envox.eu/e...
Visit my website for lots more -
www.ianjohnsto...
Help me make more of these videos:
Pledge using Patreon - / iansjohnston
Donate using PayPal - www.paypal.me/...

[@IanScottJohnston]

Small mistake in the video, the DCP405 modules have individual dedicated CV and CC leds. I guess I got carried away with the DCM220 module.....:-)

[@Nightowl_IT]

It might be lead free solder. Some lead free solder types don't look shiny. They look dull but work. I think the PCB wasn't heated up properly. Maybe it went over the reflow machine too fast. Or old solder paste.

[@hwj1822]

hi Ian, i love your work and your examples more than anything. You are also one of the first to take a close look at this eez-project from a user perspective. I myself am currently working on the concept of a precise adjustable voltage reference based on ltz1000a (eevblog-px) and ad5791 (still expensive). Nextion display and a pi-pico 2040 in the moment have so far produced a very good real working feasibility study, but there is still so much work to do! Your little adjustable voltage reference is my role model there. Besides, I still have a lot to learn. The next step would be a back channel via ad1256, and auto calibration via my dmm6500 and the operational reliability along with providing some more mA output. A power stage as a future dream is a story in itself anyway. You are my inspiration here. Thanks at all

[@IanScottJohnston]

That'll be a nice project to follow, just make sure you choose a suitable ADC or all the goodness within the LTZ and 5791 will go in vain......it's only as good as the weakest part. 5791's are on long delivery here......I've been waiting weeks for a couple for a new project. Have fun.

[@hwj1822]

@@IanScottJohnston Yes, no parts in the moment. Fun and learning is the goal. ✌️👍

[@jan.tichavsky]

Cool project! I've been wondering how better would the PVDS be with AD5791. Now using LTZ with proper precision resistors will add cost too. If you want to go all the way into super precise instrument then I guess something like AD7177, like the CERN project uses, or ADS1263, which I found on Waveshare Raspberry Pi HAT, would be a good choice. Of course I can imagine the analog front end takes more work and cost than just using the top end chips. Still, 1ppm stable DIY calibrator (in controlled oven...) sounds exciting :)

[@PapasDino]

Boy, I've been wondering what that blue box in the background was for months now! Now I know, "the rest of the story!" Thanks for sharing Ian!

[@andymouse]

Great video,great work, you've nailed some manufacturing issues there...cheers.

[@BM-jy6cb]

Always enjoy your vids Ian. Straight into the meat of it. Thing is, knowing the issue with the solder on that board will you be forever expecting it to fail again..

[@IanScottJohnston]

You're not wrong......solder does age, so its maybe a lot closer to its next failure than it should be.

[@oetken007]

This thing looks sweet!

[@UnexpectedMaker]

Nicely fixed! I was looking at those supplies a while back and was tempted but I’ve already got one that does what I need :(

[@IanScottJohnston]

One reason I got it is because the opportunity exists to build my own module for it. For a kick off I was thinking off a precision voltage output.....along the lines of my PDVS2mini but perhaps losing a DP.

[@hwj1822]

@@IanScottJohnston That's my idea too. But only an idea ... 😉

[@KeanM]

One day Seon you will succumb to test equipment addiction. It eventually gets us all!

[@raym9691]

That kit is really neat!

[@jaycee1980]

I've resoldered the thermal pads on those chips by simply flowing solder onto the bottom pad... enough seems to get through the vias to make a good solder joint. Putting flux on the thermal pad first really helps :)

[@SeanBZA]

Probably worth applying a Rossman of flux and reflowing pretty much every component on the board, which should fix any joints that are somewhat dicy. Probably as you say too long in the toaster oven, or the solder paste was left out too long and had oxides in it that the flux in it was unable to clean off properly, leading to the poor adhesion, or they mixed different solder paste types on that particular run of boards, probably due to the paste running out mid run, and you just got the one where the different batches made a pretty good imitation Chipquick solder paste.

[@jasonbrindamour903]

LOL, a Rossman amount of flux is kind of like using an entire tube of toothpaste to brush your teeth.

[@PeterCut62]

Very weird solder... Nice vid. Love your channel cheers from Belgium 😊

[@jstro-hobbytech]

Thats an awesome dmm ehh. I have a large collection of premium meters and the bm786 is my favorite. I got the flir dm92 the other day. Its ok.

[@NotMarkKnopfler]

I've seen some lead-free solders give similar results. I wonder if the solder was under temperature during manufacture?

[@paulwilson5227]

Nice work Ian

[@peteb2]

Excellent find & repair. May we ask was your purchase for this your unit shown here via the Crowdsupply by Envox? They experienced an horrendous production run for some of these boards care of an inexperienced PCB manufacturer, so bad that Envox had to re-spin with another firm while absorbing the costs of new parts and the delivery date to Backers of the units became quite delayed. The future looks incredible with this feature rich unit thanks to its "program-ability" under MicroPhython or Node Red etc in that it's not just a bench powersupply but a significant Laboratory Device! Mine awaits my attention, hopefully when the winter months arrive i will find the time!

[@IanScottJohnston]

Yep, mine was under the crowdsupply.

[@rowanlidbury]

Ooo Panasonic FK series caps, nice.

[@AynkaranRamachandiran]

More likely that resistor was the issue. Supply to the IC not enough and get worse by allowing the capacitor to discharge completely.

[@mr1enrollment]

excellent

[@largepimping]

Was the board done originally with lead-free solder, and wouldn't you expect a lack of shininess if that was the case? Doesn't mean you're way off base, just that you can't always necessarily tell solely based on the appearance.

[@IanScottJohnston]

It would have been lead free, and that's what I was using also to touch up etc. You can get shiny joints with lead free, just not quite as easily as leaded. The kicker was the manufacturer admitting reflow problems with those boards.....my evidence just seems to back it up as the failure reasons. On the first few components I tried resoldering it was really wierd, the consistency was miles off.

[@OmarMekkawy]

Nice video, how could we get the schematic ?

[@remcovantriest4357]

That is a nice unit, any modifications you did yourself Ian to improve anything?

[@IanScottJohnston]

It supports scripting so i made a small 2 button keypad to step up/down specific voltages when production testing PDVS2minis.

[@remcovantriest4357]

@@IanScottJohnstonAfter watching this video it triggered my interest. I ordered one 🙈 Luckily they are still available in this part of the world. Looking forward to assemble it.

[@SoddingaboutSi]

Leadfree solder?

[@erichmuller1731]

Tried several times this item does ot get shipped to EU.

[@NivagSwerdna]

Interesting discovery. I tried to use some solder I had lying around (must have been a freebie with something from China) the other day and it just didn't work at all... I assumed it was the soldering iron playing up... so I tried my normal Edsyn... and it just worked! Fake solder... surely not!

[@IanScottJohnston]

Could it be fluxless solder?

[@NivagSwerdna]

@@IanScottJohnston I think I hurled it across the room or similar... no idea where it is now. I probably binned it.

[@TheDefpom]

It looks like pins 17 and 18 had a bridge after you removed it, I wonder if that was there before you pulled it off ? with 16 and 17 being used for current sensing.

[@IanScottJohnston]

No, there were deffo no bridges, I had well inspected everything prior to removal.

[@douro20]

The aesthetic design borrows very heavily from '90s era GE design language. They're even using the same fonts. What this the small module made by Schaffner on the DC input?

[@IanScottJohnston]

It's a common mode choke on the 48vdc input to the card.

[@TrickyNekro]

You might want to be more vocal about your Odysee channel, or isn´t that you? I just checked for good measure, and there you were!

[@simontay4851]

Basically shite quality lead free solder. Lead free solder causes so many problems. Resolder the whole board with nice juicy lead based solder (as big clive would say). Since this is a kit you build yourself, i thought that you assemble/solder the boards yourself. Seems not.

[@IanScottJohnston]

It was an option in the crowd supply, I chose to buy the boards ready assembled. Its only the DCM220 card that has the known reflow issues. I guess they got it real bad on that one for some reason.