Rwmoore

MH721 MK2 LCD Display comes up blank

Recommended Posts

So I bought this guy second hand and it'd been sitting in a garage for a good while. When I got it home and setup, I realized that at some point mice had made a home in the side panels. They chewed through a few of the different wires. Before I could do anything, I had to replace the fuse line, but that got it working(ish). The control panel still needed work, but for the time being I could run it with default settings. Recently I finally got around to buying a replacement screen, 16 pin cable, and a 14 pin cable and got to work on the display. The control panel works now; however, the display is still not working. It turns on, but only if the connection to the motherboard is just right, and the screen is completely black aside from a single solid line through the middle. I'm at a standstill on it now. I can't think of anything else. Anyone have any ideas? 

P.s. it is the same whether the USB is connected or not, and I've tried every port and two other laptops all running windows 10.

20190514_231406.jpg

20190514_231410.jpg

Share this post


Link to post
Share on other sites

Guess I missed that. 

 if you really still want an inexpensive MH cutter, you can probably pick them up cheap on Craiglslist.  and use the parts from this one to keep it running. Or purchase a new one. They are cheap enough.  We tell buyers to stay away from this one. Too many known problems.  I hope you didn't spend much for it. 

Share this post


Link to post
Share on other sites

If it only works when the cable is plugged in "just right" it could be a simple bad solder joint on the connector/motherboard. Try reflowing the solder on that connector. Since it's a new panel and cable, my next suspicion would be the display chip on the motherboard. You'll probably have to replace the entire motherboard.

Share this post


Link to post
Share on other sites

The funny thing is you can run that cutter without the screen, since it really doesn't provide much vital information anyway.

The two things which are adjustable ---- downforce and speed ---  can be set fairly simply even without the readouts.

 

Share this post


Link to post
Share on other sites

Thank you all for the insight. Luckily I got it really cheap. I'll take a look at the motherboard, but if that's the case then I'll just deal with the lack of a screen (not worth the hassle). It's been working good for the last few months and now that I have use of the control panel I can just figure out the sequences I need. 

Share this post


Link to post
Share on other sites

Yeah, I tend to agree, that display board is more trouble than it's worth at this point.

The sequences you need are as follows ----

FORCE left and right arrows (do some test cuts and see if it needs to be increased or decreased)

SPEED up and down arrows (run that baby at top gear)

  • Like 1

Share this post


Link to post
Share on other sites

2 things to keep in the back of your mind - if the stand isn't grounded to the plotter the mainboard is susceptible to static damage from static build up in the vinyl discharging thru the carriage.  2nd is if you do go the mainboard route the mh has had at least 3 different mainboards over the years so double check to get the right one.

Share this post


Link to post
Share on other sites
1 hour ago, slice&dice said:

SPEED up and down arrows (run that baby at top gear)

Should probably stick to low range. :) Speed is one of the big killers of precision.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now