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LCD control knob broke down at second print  

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DavesNotHome
(@davesnothome)
Active Member
RE: LCD control knob broke down at second print

Another control knob bites the dust. Got a few prints out of it before it froze up. s/n 4039-191114-1618.

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Posted : 29/12/2019 12:50 am
Andy
 Andy
(@andy-11)
Eminent Member
RE: LCD control knob broke down at second print

@david-h8

I tried a small squirt of WD40 and it loosened enough to function. I’m waiting on Support to get back to me on a replacement. Was told I’d be emailed in a couple of days, that was a couple of days ago.

 

 

Posted : 29/12/2019 1:04 am
bobc
 bobc
(@bobc)
Reputable Member
RE: LCD control knob broke down at second print

I'm puzzled what can go wrong with a rotary encoder?

I went to http://ldomotors.com/, no mention of LCD control panels. They appear to make motors.

Posted : 29/12/2019 4:33 pm
Crawlerin
(@crawlerin)
Prominent Member
RE: LCD control knob broke down at second print

My wild guess - LDO will do any electronics but do not publicly advertise it like their motors. Most probably they will make anything electronic you ask them, which is handy when you want to cut down on number of suppliers. But LDO's suppliers may have provided bad or very cheap batch of knobs. Or LDO did bad job soldering it to board. Who knows 🤷‍♀️

Posted : 29/12/2019 6:18 pm
Petzon
(@petzon)
Eminent Member
Topic starter answered:
RE: LCD control knob broke down at second print

@crawlerin

It is definitely not a soldering problem, the axis of the encoder is seized and I can see metal chips between housing and axis. My qualified guess is that there is a batch of bad encoders, this far all serial numbers I have seen reported are from the same date: 191114. I will hopefully get my replacement module on Thursday (parcel is currently in Germany and is said to arrive in Sweden Januray 2:nd ) and if Prusa do not want the old one back I will desolder the encoder to find out the brand and part no to find out more about the encoder. Bad batches can happen to all brands, 20 years ago I worked as Supplier Quality Engineer for a major Swedish Electronics company, then I had a claim to one of the world's biggest electronics component manufacturer, they had shipped NPN transistors marked as PNP, someone had mixed up two containers with transistor wafers, you get quite a number of transistors from one single wafer. If Prusa is reading this, and I assume they do I think that they already have blocked all LCD-modules from 191114 to assure that no more bad units are shipped out.
As said LDO is a motor manufacturer but assembly of the LCD module seems to be a straightforward PCB assembly, I guess that LDO also perform assembly of control and encoder PCB.s for their motors. It is not a too wild guess that LDO is the manufacturer of the stepper motors for the Prusa Printers, sourcing several components from the same manufacturer cuts costs.

Posted : 29/12/2019 8:32 pm
Crawlerin
(@crawlerin)
Prominent Member
RE: LCD control knob broke down at second print

@martin-p75

Metal chips? Huh. Now I am wondering if there's a way for people who receive their printers to check it beforehand, and possibly get rid of metal shavings, like blowing them out with compressed air or brush them away, without the risk of stucking those even deeper.

Posted : 29/12/2019 8:51 pm
Petzon
(@petzon)
Eminent Member
Topic starter answered:
RE: LCD control knob broke down at second print

@crawlerin

As the chips are between housing and axis I think it not possible to clean them out on beforehand. I do not know if the chips did cause the breakdown or if they are a result from the breakdown as I did not look for them before the breakdown as I did not expect my endcoder to break down.

Posted : 29/12/2019 9:17 pm
bobc
 bobc
(@bobc)
Reputable Member
RE: LCD control knob broke down at second print

I love chips, but not in my encoders 🙂

I have some spare encoders for another project, they might be compatible. Hopefully by the time my Mini is shipped there won't be a problem, but it's on my list of things to check.

 

Posted : 29/12/2019 9:34 pm
Petzon
(@petzon)
Eminent Member
Topic starter answered:
RE: LCD control knob broke down at second print

@bobcousins

LOL "I love chips, but not in my encoders 🙂",

You made my day.

 

Posted : 30/12/2019 7:05 am
Andy
 Andy
(@andy-11)
Eminent Member
RE: LCD control knob broke down at second print

Just received the replacement LCD display with the new encoder, my first serial number was 4039-191114-XXXX and the replacement is 4039-190910-XXXX.

Both have identical model numbers- LDO-Pr28LCD-A001.

Fingers crossed this one does not have the same issue.

 

 

Posted : 02/01/2020 7:18 pm
Petzon
(@petzon)
Eminent Member
Topic starter answered:
RE: LCD control knob broke down at second print

Received my replacement LCD today too. Serial no 4039-190910-2384, assembled it about 7 hours ago and this far it works fine. The "feeling" in the encoder is much better than the faulty one was. much smother in rotation and mor distinct in clicking. Desoldered the old one to find out supplier and part no, but the encoder has no marking at all, totally anonymous, Spent some time with Google and found out that the encoder seems to be named EC11 and is available as well as no name ans from well-known sources prices from about 1 USD to 10 USD, the SMD version that Prusa uses seems to be rare, most encoders are through hole versions. Will try to buy one or a few to have as spares just in case.

When starting the printer after LCD replacement I got into the under extrusion problem, released the three grub screws and the brass bowden coupling, pressed the heat end up about 4-5 mm and tightened the grub screws, thereafter the under extrusion/clogging problem seems to be solved, trying my third print now, a 12 hour print that will run overnight. This far I have only tried Prusa filament (Prusa PLA Ivory and Prusament PLA Galaxy purple) intend to try other brands tomorrow if the overnight print works. Have some problems with layer shift X-direction, maybe the belt tension has to be adjusted, will see tomorrow.

Posted : 02/01/2020 8:22 pm
MikaM
(@mikam)
Active Member
RE: LCD control knob broke down at second print

My knob died also.. well I got it to work slightly but need a new one. First my MINDA died and now this day after I got a new MINDA. Also the extruder is not extruding well. I have MK3s and this many problems amazes me..

 

Posted : 02/01/2020 8:44 pm
Petzon
(@petzon)
Eminent Member
Topic starter answered:
RE: LCD control knob broke down at second print

@mika-m

Most likely your extrusion problem is caused by a too low hot end, try the solutions presented in other threads. I did not do the full disassembly and cleaning proposed, tried a simpler variant first and that did work for me. I just removed the brass bowden coupling from the top of the hot end, (both the nut and the male thread, released the three grub screws at the side of the extruder, pushed the hot end upwards as much as possible, in my case 4-5 mm, tightened the grub screws, be careful, they are a bit soft, do not overtighten. Re assembled the bowden coupling, readjusted the minda using a credit card and everything worked fine. In all it took me less than 15 minutes

Posted : 03/01/2020 7:55 am
MikaM
(@mikam)
Active Member
RE: LCD control knob broke down at second print

@martin-p75

Thanks for the tip. I managed to get the extrusion to work better. However, while doing calibration cubes the side thicknesses vary too much. Not sure if Esteps are rightly adjusted on the machine. All other flaws are fine atm.

Posted : 03/01/2020 9:31 am
andreas.d15
(@andreas-d15)
New Member
RE: LCD control knob broke down at second print

Mine knob also just died, SN is 4039-191114-1667.

Posted : 03/01/2020 1:03 pm
MikaM
(@mikam)
Active Member
RE: LCD control knob broke down at second print

My knob broke too but I dropped a few drops of sewing machine oil in it and it started working. 

Posted : 03/01/2020 4:08 pm
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