Fried Einsy?
I was cleaning my hotend on my MK3S when I heard a small "pop" and suddenly received the Err: MINTEMP issue on the screen. I thought I must have blown the thermistor so I decided to replace it. I did follow this guide ( https://help.prusa3d.com/en/article/mintemp-and-mintemp-bed_2169) and the one that was in there was reading 117 kΩ, but I decided to replace it anyway since I had a spare. I got everything cleaned up and put back together only to still have the error.
I visually inspected the board and metered the fuses with everything looking good. I flashed the firmware just to see if that would bring it back to life but no luck.
Is there anything on the board I could test to see if the board itself is now bad? Also is there anything I could have done using a brass brush on the hotend?
RE: Fried Einsy?
There are some exposed thermistor wires. I'm not sure what would be damaged if those were shorted or shorted to something grounded.
RE: Fried Einsy?
According to the Prusa chat, the board may be ruined. I am waiting to hear if this is something covered by warranty or if I have to eat this one.
I ordered another Einsy because I want to try and resolve it ASAP. Hopefully it doesn’t take too long to get here. :/
RE: Fried Einsy?
Does anyone know if there is a way to wire the hotend thermisto to the t1 port instead of t2? If I blew out my t2 then in theory I could just use t1 right?
RE: Fried Einsy?
I found it :(. I believe there is a 4.7k resistor that blew on the board. It is so tiny I don't think I can fix it unless someone has a trick for soldering something this small. I cannot believe that this would blow when using a brass brush...I wonder if it would make sense to put an inline fuse in the hotend heater and thermistor elements to avoid issues like this?
RE: Fried Einsy?
I would just order another board. Not worth the risk.
--------------------
Chuck H
3D Printer Review Blog
RE: Fried Einsy?
You probably shorted the hot end 24V through to the thermistor, that's why it cooked.
RE: Fried Einsy?
@vintagepc
That makes sense...granted I am not sure how it happened...there are no bare wires that I can see.
RE: Fried Einsy?
I have shirted them and not fried it so it is hard to tell.
--------------------
Chuck H
3D Printer Review Blog
RE: Fried Einsy?
@charles-h13
What do you use to cover them?
RE: Fried Einsy?
@charles-h13
What do you use to cover them?
Is should read: I have shorted them and it did not fry it so it is hard to tell.
--------------------
Chuck H
3D Printer Review Blog
RE: Fried Einsy?
@farina
Fried resistor is usually a result of blown transistor. I assume the board has multiple layer, so there is no easy easy way to repair SMD components on such a board. As the support already suggested, it's time for a new board.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: Fried Einsy?
@charles-h13
ahh, I thought "shirted" was a term for covering them :).
RE: Fried Einsy?
Heya Farina,
Thanks for posting your experience.
I think I'm in the exact same fried board situation and am a bit upset because I got bad info from Prusa and now have a fried board.
So, I am wondering if any warranty stuff covers it?
I know I fried the board with my actions, but the actions were a direct result of following Prusa's bad info...
Hear me out.
I had a failed print and blobbed up hotend.
Not my first time, so I knew how to resolve it. But I went and watched this official video anyways to refresh my mind as well as read up in my handbook.
Heated things up and carefully pulled the main blob off without yanking the thermistors, no problem.
Then I started to clean the remaining bits off with a brass wire brush, as indicated in the video.
!SPARK! Appears on the brush.
Display now reads Mintemp Error, zero degree on the hotend.
Pulled the thermistor from the hotend and inspected, the wires are still attached. Pulled the end plug from the board the plug looks clean, nothing amiss there.
Fuses are fine. Power off/on cycle. Nothing. Same mintemp error.
But...looking closer at the board...really close because it is tiny...something definitely fried.
The frustrating part is that I followed Prusa's steps as indicated in the video and handbook and now I have a braindead printer in need of a $120 part.
Nowhere does it say to unplug the printer while cleaning with a brass brush.
Looking in the youtube comments, yes I see that other users like myself have had this same unfortunate experience.
But that reeeeeally shouldn't be on me to read every comment on youtube when faced with an "official" how to video from Prusa on a simple cleaning matter.
They should definitely add a bit on the video about unplugging before brushing for safety.
I'll contact customer service and see what happens...
Thanks again, sorry for the long-winded, first post, just a bit upset.
RE: Fried Einsy?
A follow up on my issue...
After a month of back and forth emails with a very nice customer service rep, Prusa is sending a free replacement board out.
It's unclear if this was due to it being under warranty or not.
Appears there was enough doubt about it to send a replacement however.
I still hope Prusa updates their official documentation on the matter.
Easy enough to add that once the hotend is hot enough, perhaps just unplug the printer before scrubbing with a brass wire brush.
RE: Fried Einsy?
@uomo_di_ragno
Exactly the same issue with mine, I was able to recompile the firmware and swap from the fried thermistor input to the spare one. It worked for a while, but then I started getting issues with the hotend going MAXTEMP and overrunning. I'd checked the wiring when I replaced the hotend (I too had a blob and brass brush issue leading up to the failure, but my thermistor was stuck in the original hotend so had to replace the whole assembly).
Bought a ready assembled hotend from E3D to avoid my hamfistedness overtightening things this time, but the MAXTEMP issues didn't go away, so I've sprung for a new Einsy as I'm not going to wait a month to go through all the crap with support.
RE: Fried Einsy?
@captain-hightop
I would recommend a standard nylon toothbrush. It will not melt and it will not spark.
--------------------
Chuck H
3D Printer Review Blog
RE: Fried Einsy?
@cwbullet
Yup, lesson learned. I'll only use a brass brush if power is off, although it was a large blob of ASA stuck to mine so nylon might struggle to dislodge that without melting.
RE: Fried Einsy?
Nylon makes good sense and I've started using just that.
Forums are great for these tips and continue to provide useful info for sure.
But it would be nice if this kinda baseline knowledge would make it into the official docs.
Neither the video (where a brass brush is pictured) nor the official article on cleaning a blobbed end (suggesting you use a brass brush) have been updated to include such simple, useful info.
I mean, the top comment on the video is about a brass brush shorting several people's boards...that video remains bad info to have out there.
RE:
Hi,
I have experienced the same problem, frying the smd part above the right-hand corner of the socket.
Now I realise I obviously also caused this with my brass brush while cleaning the heater.
The short circuit causing the damage is between the 24v line of the heater and one of the lines of the thermistor.
The Thermistor itself is isolated from the heaterblock, so only a direct contact with the brush between the 24v wire of the heater and the thermistor wires can cause the short circuit
Then why not plug in the thermistor and the heater from opposite sides into the heater block?
This would massively reduce the risk of causing a short curcuit with a metal brush.
Not sure, if this works but the cover still fits. And for the functionality it seems totally irrelevant, from which side the thermistor and the heater are plugged in.
Will let you know, once my replacement board arrived and everything's installed.
Michael