Blank LCD Max v2

[tcat007]

I posted this in the "Fails" section, but thought this troubleshooting might be a better place. I looked down at my newly installed display, after getting calibrating E-step, and no digits, totally blank. Fan is blowing out the back. What to check? I metered F2, F3, F4, all show not blown. Was working fine through page 40 of users manual. I had discovered I put the extruder on the wrong side of the panel, but it was easy to unscrew 2 screws and move to other side. But after that, no LCD. Nothing had to be rewired. Help! No clue what to do.

[Eaglezsoar]

make sure that you did not accidentally reverse the cables going to the lcd.

[tcat007]

Display was working for previous testing, setting Z, bed calibration. I was just getting to actually running a shroud, and no display (all within a 2 hour window).

[Orellana.arch]

wth I'm having the same exact problem at the same exact step. while adjusting the screws in calibration screen just went blank. and have no idea what to do checked everything and cant seem to find anything wrong with it

[tcat007]

Got a suggestion from SeeMe to switch the F2 and F3 fuse on the Rambo. I had already put a meter on each end and got resistance, but I switched them, and presto, LCD came on! Time to order a few fuses.

Can shorting the Fan wires (dangling waiting for shrouds) cause the blown fuse? If so, that's what happened. Not sure if the manual said to Kapton those (I assume there would be no juice to them unless a program was running).

[Eaglezsoar]

Got a suggestion from SeeMe to switch the F2 and F3 fuse on the Rambo. I had already put a meter on each end and got resistance, but I switched them, and presto, LCD came on! Time to order a few fuses.

Can shorting the Fan wires (dangling waiting for shrouds) cause the blown fuse? If so, that's what happened. Not sure if the manual said to Kapton those (I assume there would be no juice to them unless a program was running).

Yes, shorting a fan can cause a blown fuse as well as shorting virtually anything. The part that I do not understand is why it started working when you switched two fuses. They must have been loose in their sockets.
Also when measuring a fuse to see if it is good you should see 0 ohms, you said you put a meter on each end and got resistance. Anyway, I am glad you got it working.

[geneb]

Never test a part in-circuit.

g.

[Xenocrates]

Yes, the fan wires can blow that fuse. I did that about the same, although I had printed many things. I was swapping the crimped connectors on the fan, as my first try had issues going into their housing at all, and the intermittent heatsink fan was getting annoying (this was post E3D upgrade). So i have a little tray of 14 of the suckers, and plans to switch them out for circuit breakers.

The fuse for the fans also handles the logic, whereas the other fuses are bed (automotive), and hotend, which is why swapping the fuses when the fan/logic fuse is blown makes the controller work again.

[tcat007]

Got a suggestion from SeeMe to switch the F2 and F3 fuse on the Rambo. I had already put a meter on each end and got resistance, but I switched them, and presto, LCD came on! Time to order a few fuses.

Can shorting the Fan wires (dangling waiting for shrouds) cause the blown fuse? If so, that's what happened. Not sure if the manual said to Kapton those (I assume there would be no juice to them unless a program was running).

Yes, shorting a fan can cause a blown fuse as well as shorting virtually anything. The part that I do not understand is why it started working when you switched two fuses. They must have been loose in their sockets.
Also when measuring a fuse to see if it is good you should see 0 ohms, you said you put a meter on each end and got resistance. Anyway, I am glad you got it working.

Zero ohms? I thought a fuse was a little wire (therefore ohms) that blew if shorted. I had run all the preliminary tests before discovering I had the extruder on t he wrong side of the plate. When moving it to the other side, the fan leads touched. I think the manual needs a warning to Kapton tape those wires. I should have put the meter on them to see if anything was running in them... but I'm and ME not an EE

PS: I had to take the fuse out to get the fuse to show blown.

[Eric]

Got a suggestion from SeeMe to switch the F2 and F3 fuse on the Rambo. I had already put a meter on each end and got resistance, but I switched them, and presto, LCD came on! Time to order a few fuses.

Can shorting the Fan wires (dangling waiting for shrouds) cause the blown fuse? If so, that's what happened. Not sure if the manual said to Kapton those (I assume there would be no juice to them unless a program was running).

Yes, shorting a fan can cause a blown fuse as well as shorting virtually anything. The part that I do not understand is why it started working when you switched two fuses. They must have been loose in their sockets.
Also when measuring a fuse to see if it is good you should see 0 ohms, you said you put a meter on each end and got resistance. Anyway, I am glad you got it working.

Zero ohms? I thought a fuse was a little wire (therefore ohms) that blew if shorted. I had run all the preliminary tests before discovering I had the extruder on t he wrong side of the plate. When moving it to the other side, the fan leads touched. I think the manual needs a warning to Kapton tape those wires. I should have put the meter on them to see if anything was running in them... but I'm and ME not an EE

PS: I had to take the fuse out to get the fuse to show blown.

The simple fuses are essentially pieces of wire sized to melt at a particular current. Without checking the datasheet, I'd guess those 5A nano-fuses have a resistance of about 0.01 ohms, which on a cheaper meter or higher scale would just read as zero. For a fuse, any reading other than open circuit means the fuse isn't blown. And yes, if you're trying to measure resistance directly, the fuse should NOT be in the circuit.

I disagree with geneb that components can't be tested in-cucuit. But it does requires more knowledge, different techniques, and often better tools. In the case of a fuse, if the input voltage is only seen on one side of a fuse, it's a fair bet the fuse is blown.

[Eaglezsoar]

Yes, shorting a fan can cause a blown fuse as well as shorting virtually anything. The part that I do not understand is why it started working when you switched two fuses. They must have been loose in their sockets.
Also when measuring a fuse to see if it is good you should see 0 ohms, you said you put a meter on each end and got resistance. Anyway, I am glad you got it working.

Zero ohms? I thought a fuse was a little wire (therefore ohms) that blew if shorted. I had run all the preliminary tests before discovering I had the extruder on t he wrong side of the plate. When moving it to the other side, the fan leads touched. I think the manual needs a warning to Kapton tape those wires. I should have put the meter on them to see if anything was running in them... but I'm and ME not an EE

PS: I had to take the fuse out to get the fuse to show blown.

The simple fuses are essentially pieces of wire sized to melt at a particular current. Without checking the datasheet, I'd guess those 5A nano-fuses have a resistance of about 0.01 ohms, which on a cheaper meter or higher scale would just read as zero. For a fuse, any reading other than open circuit means the fuse isn't blown. And yes, if you're trying to measure resistance directly, the fuse should NOT be in the circuit.

I disagree with geneb that components can't be tested in-cucuit. But it does requires more knowledge, different techniques, and often better tools. In the case of a fuse, if the input voltage is only seen on one side of a fuse, it's a fair bet the fuse is blown.

As a certified electronics technician you are 100% correct in everything you said. Thanks for attempting to educate everyone.