Fixing A8 ANET 3D v1-5 Mainboard
A friend of mine who runs a shop, fixing and selling washing machines, tumble dryers and other kitchen appliances (except fixing refrigerators that require extra environment regulations), brought me his A8 ANET 3D printer to get it ready for use. It was one of those kits that can be bought now at an affordable price. He wants it up and running to be able to print out replacement parts, like the bearings of water motor pumps. And he already bought PLA, Nylon and ABS Rolls that he also brought in. The 3D printer was completely build but not calibrated and probably had not printed out anything yet. And he also brought a box that also contained a second ANET board that apparently was his first mainboard that by accident no longer was working after his brother did something wrong to it, and he needed to buy another mainboard.
Mind you… I never had worked on any 3D printer before so it was a complete new experience for me! So, I first concentrated on getting the A8 ANET 3D printer calibrated and running, while adding some upgrades I found on thingiverse. Like the 2 way cooler tool that upgrades and replaces the original one way cooler that sits on the extruder head to cool additional layers after the first layer that sticks firmly on the hot bed is done. And I added 2 T profiles to strengthen the frame, and also repaired the not working spool holder by printing out an axe nut and bolt to carry the rolls. And also added a filament guide that sits on top of the frame so I no longer needed to guide the filament by hand. After that I only checked if everything kept working the way it should. And on Thingiverse I even had to fix the Y-carriage-end-stop after the very brittle original end stop broke that stops the bed at its furthest back position. And the PLA replacement result worked perfectly and never breaks because the printed parts are very hard and sturdy. What not can be said of the acryl the frame parts are made of that behave kind like parts made of breakable glass. Which break by using superglue!!
After that job was done I concentrated to see if I also could fix the still defect first ANET mainboard. I started by connecting the 18V on the power input the board normally operates on.
Previous photo shows the still defect mainboard after I already removed the defect X-motor driver controller.
But nothing happened other that there was a shorting current of about 0.5 Amp. And none of the leds worked showing a working ATMega controller. So I started to measure the resistance on the inputs which was about 35 ohms. So was this resistance on the in- and output of Q4 which is a 7805 regulator. And on a good board this should be very high! And also on R25 and resistor R12. First the 5V regulator was suspected but turned out being okay, and neither was the AM1117 3.3V regulator defect. And although the resistance of the AM1117 between pins 1 and 3 measured also a low value, it was not causing any problem here as I found out later on. And also on Fan 2 connector pins it measured 35 ohm.
Next thing I did was connecting a steady 5V on the output pin of Q4 while increasing the DC current on my max 30V-10A power unit, and see if anything got hot.
And the first thing that got hot was the X-motor driver IC. So I first removed the cooler plate and the 4x6_24 pins smd IC under it as was shown on the first photo. Still the board didn’t react by showing any signs of life.
So I kept checking if other parts got any hotter. And there were, it was the E(xtruder)-motor IC that also got hot too! After I also had removed that part the board finally came to life! The leds started to blink and also the Reset button on the board worked showing the AVR processor was still alive! Previous photo showed the ANET v1-5 Arduino mainboard after both shorting X- and E-motor driver IC’s were removed and the board finally came to life again.
Both motor controller IC’s are of the type 4988ET. And can easily be replaced by buying 5 of them online for as little as less than 4 Euro. After a few days of testing and printing the cooler Fan (Fan1 on the mainboard) quit working. But another 12V 5015_radial_turbo_blower can be bought for only 1,29 Euro to replace the original blower that according to other A8 owners are of inferior quality! Which makes it somehow bound to happen.
Having a second working mainboard is great because now we can test better open software versions like Marlin or SkyNet instead of using the original China made version that the A8 came with and which can be a very dangerous fire hazard if the extruder head gets separated from the temperature sensor. Causing to extremely overheating the extruder head when it comes of its head mounting. Starting fires which is extremely dangerous if the printer is printing for hours and no one is at home when this suddenly happens! And I noticed that there also exists a special single or dual Mosfet driver board that is another safe upgrade for this A8 3D printer.
I tried open software Marlin but got an Arduino (I used new Windows version 1.8.10) library error, which stopped my upgrading effort. But main thing is that now there is a second working mainboard just in case the installed working board quits in the future, and using this extra board to test with is very handy.
Of course I at first also measured the connections of the mainboard to tell what function every component was for. Next diagram shows some of my findings. On a good board leds D4/BED and D5/END will light up if you connect your DMM in diode beep test with the black wire on the Q2 and Q1 connections to both BED and END connectors and the red wire on the power + connection of both connectors. See diagram below.
And knowing that these boards (if still available… a new version 1-7 is already selling) still cost around 26 Euro, this repair is very easy and worth buying the replacement driver IC’s at the low price they sell at. Probably the only difficult part here is using a hot air soldering station as this is the best way to solder the 24 pins smd IC’s. And don’t forget to also replace the resistors R12 and R25 that probably were smd code values R10. Which also were ordered online in a 170 values x 20 resistor 1/8 watt pack. And you also will need to order the special heatsink plaster (Netto Weight 5g tubes) from STARS-922 or other sellers to glue the heatsinks back on.
Good luck in also fixing your defect A8 ANET mainboard in case it suddenly stops working. Now knowing these boards are easily fixed and of good quality.
Albert van Bemmelen, Weert, The Netherlands.
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Note: You can read his previous repair article in the below link: https://jestineyong.com/drew-a-small-circuit-in-tina-by-examining-pcb-solderside/