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Elesta Visulesta 4 crt replacement with LCD panel

tome9999

Aluminum
Joined
Dec 7, 2018
I have an Elesta Visulesta 4 DRO with Heidenhain scales on a Swiss made Scheu surface grinder I am refurbishing. The crt in the Visulesta is beginning to flicker and change brightness and I suspect the crt driver section. I am investigating replacing the crt with a LCD panel. I have two options. A company in Germany sells a plug-in replacement which is a 6.4” lcd and a conversion board for about $1200. That is too much for my budget so I am looking into rolling my own. I am curious if anyone else has crossed this bridge and has info on doing this?

My next step is to put an oscilloscope on the back of the circuit board edge connector that goes from the digital display section to the analog crt driver board to figure out what signals are on the 10 pins there. It would be nice if someone has already done this so thought I’d check first....
-Tom
 
Well, ok then. For the record this is how the 10 pins on the edge connector (all black wires) read from top to bottom. On my unit they are labeled on the circuit board as A,B,C,D,E,F,H,J,K,L.

A. Ground

B. -12 VDC

C. -50 VDC

D. -12 VDC

E. Ground

F. Signal Amplitude about 3.4 VDC @ 24.51 kHz - This is Horizontal Sync signal...

H. +12 VDC

J. Signal Amplitude ~4.0 VDC - Digital Video Data signal...

K. Signal Amplitude ~3.4 VDC @ 58.82 Hz - This is Vertical Sync signal...

L. Ground

A horizontal sync frequency of 24.51 kHz is not one of the old standard graphics sync rates. Not MDA (18.432kHz), not CGA(15.75kHz), etc. So next is to find a solution for the conversion of that to VGA to feed to a generic 6.4" panel...

-Tom
 
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To continue talking to myself on this project...

I purchased a XVGA Box: https://www.amazon.com/gp/product/B00D8W3MSO/ref=ppx_yo_dt_b_asin_title_o09__o00_s00?ie=UTF8&psc=1
This is based on the GBS-8219 board. You can find the GBS-8219 board alone, or even this same one, cheaper from China. In the end I will end up removing this from the case to mount inside the DRO. This board decoded the video from the Elesta Visulesta 4 with ease. From what I have seen/read about these boards the cheaper GBS-8200 board will not work with TTL video output so don't be fooled into buying the cheaper board - or if you do and it works please do tell.

I tried a couple different LCD screens. I am going to go with this one: https://www.amazon.com/gp/product/B07HPWHGX7/ref=ppx_yo_dt_b_asin_title_o02__o00_s00?ie=UTF8&psc=1
It is cheap, works great and is the right size for the display and to fit in the enclosure. The driver board is the same one used on many small VGA monitors out there with the same software menus. Again, I don't need the plastic cases, speakers, etc., that come with other more expensive monitors so this bare bones display was a good find.

I can connect my video to any individual R,G, or B input or any combination of them. I think green looks best. White or yellow are also not bad, but I will probably just go with green. RGB are additive colors so combining G and B gets Cyan, R and B is Magenta, and G and R is Yellow. The original CRT was Amber.

It turns out I am able to drive the LCD as well as the XVGA decoder board from the Visulesta +12VDC and GND pins. I don't know how much current the DRO supplies on the 12V rail but it had no problem powering these two devices. I believe the display needs about 1 amp max, and the decoder requires a max of 400mA.

I removed the CRT and it's driver board from the DRO enclosure today. It was kind of a pain. There isn't much space in one of the corners to get to the nuts that need to be removed. There are 4 M4-0.7 threaded rods screwed (and apparently glued) into studs that are on the back of the face plate that are used to mount the CRT and hold it against the bezel and front of the enclosure. I was able to get two of the them out but the other two broke off inside the studs. So I wont be using those to hold my display down. I will have to improvise. I didn't discharge the CRT because I didn't want it damaging the other electronics in the DRO so I had to be careful not to touch or short the high voltage connections on the crt and driver board. That also didnt help to get out.

I am now working on the cabling, bezel, and brackets to hold the screen and the circuit boards in place. I took measurements from the current bezel and will draw something up in cad and either 3D print it or figure out some other way to fab it up.

Attached are some pictures. I circled in red the connector on the video board that I will be connecting to. Another pic shows the wiring off that connector from top to bottom.

-Tom
 

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Congratulations Tom, you are now this forums world wide expert on this DRO. All future questions about it will be sent to you. You didnt know that was a side benefit from this forum did you? I hope you get it all working to your satisfaction, it has been fun to read even though I dont need to know any of it. You did a great job explaining what you were doing.

Charles
 
By the way Tom a few years ago there was a big discussion about changing out CNC screens. This was in the Deckel subforum and it was also interesting. I dont know if any of that information is still relevant but as you seem to have found your solution it probably wouldnt really help you anyway.

Charles
 
I realize that this is late to the game but did you give any considarashion to just replacing the CRT? I have had a lot of luck finding weird electronic parts on eBay punch in the part number and see what comes up.

Reading your first post again I see you think your problem is with crt driver section. Try punching in the part number for that board in eBay and see what comes up.
 
Congratulations Tom, you are now this forums world wide expert on this DRO. All future questions about it will be sent to you. You didnt know that was a side benefit from this forum did you? I hope you get it all working to your satisfaction, it has been fun to read even though I dont need to know any of it. You did a great job explaining what you were doing.

Charles

Ha. Yeah, expert...? Once I get it back together I still need to figure out how to operate the thing :-)
-Tom
 
I realize that this is late to the game but did you give any considarashion to just replacing the CRT? I have had a lot of luck finding weird electronic parts on eBay punch in the part number and see what comes up.

Reading your first post again I see you think your problem is with crt driver section. Try punching in the part number for that board in eBay and see what comes up.


Nah, I went straight for the more difficult approach! I have a friend who could probably diagnose and repair the existing CRT issue, but what fun is that :-). Sometimes once you start down a road it's hard to go back...

-Tom
 
Built the wiring harness using the connector that was there. Just needed +12VDC and GND to power the two boards, and Vertical Sync, Horizontal Sync, and Video signal. I mounted the video decoder board (out of its case) onto the metal plate where the CRT driver board was previously mounted.

I played with putting a potentiometer on the green signal and connected that and the red signal up to the video input and tuned the pot to get amber. But in the end green or white has better contrast so I am going with green.

I drew up a bezel in Autodesk Fusion 360 and 3D printed it on a Formlabs Form2 printer and am in the process of painting that. I am currently printing the bracket that attaches to the back of the bezel to hold the screen down flush and provides a place to mount the circuit board.

Once that is done the only thing left will be figuring out how to keep the bezel in place since 2 of the studs that were used to hold the original CRT in place are plugged up with broken off screws. I will also need to shorten the VGA cable or find a ribbon cable or very short one some where.

-Tom
IMG_7550.jpgIMG_7554.jpgIMG_7553.jpgIMG_7552.jpg
 
Nearly ready to reassemble the DRO. The 3D printed bracket is complete. I am going to use silicone caulk to glue the bracket to the metal frame. The fit is very good and I think the silicone will hold it in there tightly. Attached are some pics of the bracket.
-Tom

IMG_7564 .jpgIMG_7576.jpgIMG_7573.jpgIMG_7574.jpgIMG_7569.jpg
 
All back together and operating. I used silicone caulk to glue the bracket to the metal shell. Works well and is very secure. I had white caulk laying around that I used. In retrospect I should have gotten some clear. You can see the white caulk around the bezel. Will have to touch it up with a Sharpie or something.

Now on to figuring out how to operate this machine!

Thanks for listening 😉

-Tom


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Great thread.I have a turnvision that's going to need a crt conversion, very interested in how you did this.

I didn't discharge the CRT because I didn't want it damaging the other electronics in the DRO so I had to be careful not to touch or short the high voltage connections on the crt and driver board.

Can you elaborate on how to do this? If the DRO has been dormant for a long time do you still need to discharge the CRT?
 
Great thread.I have a turnvision that's going to need a crt conversion, very interested in how you did this.



Can you elaborate on how to do this? If the DRO has been dormant for a long time do you still need to discharge the CRT?

Most CRTs, unless they are very old, will usually have a bleed resistor to discharge the tube. Mine probably does as well but I don’t know for sure. If there is no bleed resistor though a crt can hold quite a charge for a very long time. You can search YouTube for “discharge crt” to see how it’s done.

The easiest way is to slip a long screwdriver under the rubber cap on the side of the tube and short it to the frame. We always did this when we worked on Telray Terminals back in the 80s at the Univ. I attended and worked at. The downside is that the spark can potentially damage any nearby electronics. In practice I don’t think that ever happened but I didn’t want to take the chance on the Visulesta...
 
Good info!

Just acquired a 'new' mill with Elesta Visulesta 4 DRO. Screen is pretty bad, would like to replace it and switch to LCD. The cute little screen must have been super high tech back in the early 90s when this system was fitted to my mill.
The scales and display have been removed from the mill, so I will need to test the system before spending money on the conversion.
I did a quick search and found that some cheaper boards with the GBS-8219 also support TTL level signal.. I'm tempted to try such a cheap PCB though I suspect they won't function properly. If anyone has updates on this I'd gladly hear from them.
 
Good info!

Just acquired a 'new' mill with Elesta Visulesta 4 DRO. Screen is pretty bad, would like to replace it and switch to LCD. The cute little screen must have been super high tech back in the early 90s when this system was fitted to my mill.
The scales and display have been removed from the mill, so I will need to test the system before spending money on the conversion.
I did a quick search and found that some cheaper boards with the GBS-8219 also support TTL level signal.. I'm tempted to try such a cheap PCB though I suspect they won't function properly. If anyone has updates on this I'd gladly hear from them.

I would be very tempted to try the cheaper solution if it is using the 8219. I just wasn't willing to wait the weeks to have one sent from China not knowing if the thing was going to work at all, and it seems like I couldn't find cheaper ones with the 8219 at the time. That, and I knew I could return the one I bought if it didn't work. It's easy for me to tell you to spend your money ;) but I think it might just work fine.

Good luck.
-Tom
 
Hi Tom,

Thanks for the info. Lately, shipping from China has been faster, willing to try the cheaper boards. Still doing some google research on which versions work best.

Tested the DRO today and it seems to work excellent! Just today had time to unpack the scales that I got with my 'new' Aciera F4 and to my surprise the Heidenhain scales were like new, except for one torn cable shielding. Don't know why the previous owner removed the scales, I was expecting some issues but none to be found!

The little CRT seems to work OK-ish, sometimes the lines are tilted a bit and refresh rate is awfully slow.

Bracket for the DRO computer is missing, mil is undergoing some maintenance, I have time to experiment with the XVGA adapters and maybe 3D print a nice adapter for the screen.

With the documentation of the mill(s) we picked up I found some more documentation (sales brochure) of the Visulesta unit. Including a letter to purchasing/direction of the research institute that owned the Aciera's stating that this was the only acceptable DRO unit for these mills, because of its advanced functions. I really wonder what the price of this stuff was in the early 1990s.

attachment.php
 
Hi Tom,

Thanks for the info. Lately, shipping from China has been faster, willing to try the cheaper boards. Still doing some google research on which versions work best.

Tested the DRO today and it seems to work excellent! Just today had time to unpack the scales that I got with my 'new' Aciera F4 and to my surprise the Heidenhain scales were like new, except for one torn cable shielding. Don't know why the previous owner removed the scales, I was expecting some issues but none to be found!

The little CRT seems to work OK-ish, sometimes the lines are tilted a bit and refresh rate is awfully slow.

Bracket for the DRO computer is missing, mil is undergoing some maintenance, I have time to experiment with the XVGA adapters and maybe 3D print a nice adapter for the screen.

With the documentation of the mill(s) we picked up I found some more documentation (sales brochure) of the Visulesta unit. Including a letter to purchasing/direction of the research institute that owned the Aciera's stating that this was the only acceptable DRO unit for these mills, because of its advanced functions. I really wonder what the price of this stuff was in the early 1990s.

attachment.php

That looks to be in really good shape compared to mine. The green, orange, and blue-gray buttons on mine are all a faded grungy yellow. Should be easy enough to fab a bracket. Mine sits on a shelf that was made for and attached to the machine. It screws to the DRO from underneath.

If you are lucky perhaps you will be able to remove the nuts holding the crt to the face without breaking off the studs as I did. If so, they will make a simple attachment point. Though, gluing mine on with silicone has seemed to work just fine.

I am sure these were pricey units in their day. Heidenhain is not a discount brand :D and the DRO does have some nice features (distance to go graphs and whatnot). Its been great on my grinder. I haven't yet figured out all it's features. The manual I got leaves a bit to be desired in terms of operational examples.

Have fun!
-Tom
 
Various boxes arrived!

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HD-VC9900-V1.1 converter from various video signals to HDMI. Of course only after receiving it I found various very negative reviews from the arcade game crowd. I kinda assume the demands on a converter are a bit higher than a low refresh rate set of numbers of a screen...

So I still have good hope for the converter. Specs:
  • CGA / EGA 14.5-16.5K 23.5-25.5K 30.5-32.5K auto scan
  • RGBHV 30.5-32.5K auto scan
  • VGA 30.5-32.5K auto scan
  • Output signal HDMI
  • Supports position control and zoom control.

The display is one of the few 4:3 screens I could find on Ali. Yqwsyxl 7 Inch 800x600 CLAA070MA0ACW.
It's a bit large, the viewing area is only minimal smaller than the opening in the front panel. Will be solved with 3D printed bezel and the zoom function of the converter, if I can't utilize the full screen.

I intend to try of the setup works soon. And if it does, design a proper bezel for the screen.

Oh and the fresh buttons on my DRO.. All of the rubber covers fell of when I tipped it over. Who knows, maybe the cover is still available from Heidenhain (which took over Elesta if I recall correctly)
 
Update time!

During the holidays I was tinkering with the DRO and wanted to try the VGA converter. But before I could check that there were other hurdles to be taken.
Spoiler alert, the cheap converter does not work (yet). I can access the menu and it shows on a screen with HDMI input but cannot get it to work with the DRO.


Plot twist.


When I switched the unit on, nothing displayed. That was the moment I knew why the previous owner had dismantled the DRO from the machine. A few months before it worked fine for the few minutes I tested it..

Having learned a little from people who are much smarter with electronics than I am I remembered that its often best to disconnect the power supply and check if it is OK. Removed the whole back plane from the DRO and switched it on. All but one pin had voltage present (all from shared ground). Because the PSU does not look to be super smart and interfaced/digital/etc I expected that that pin should have power too.

Switched the unit off, unplugged it (some filter components are connected before the double pole on/off switch..).
With a strong light source I managed to trace the PCB traces to a separately mounted 78T12CT linear voltage regulator. First suspected this regulator but remembered that these more often show a failure mechanism that makes them pass through the voltage without regulating.. Then I found a Thyristor next to it which looked to be part of a crowbar circuit (click) to clamp the output to ground if a regulator fails. But when I checked resistance, the output rail of the PSU (at the connector) was showing zero Ohm, which is not how the crowbar circuit protects, as it is only activated when the overvoltage is present.. :scratchchin:

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Tracing the PCB with a strong led, as the board is difficult to remove from the back plane/heat sink. Top row connects the toroid transformer and regulators/components on heat sink to the PCB

Decided to break the problem in two: disconnected the output pin of the linear regulator and check voltage there (regulator is connected via long leads to the PCB). To my surprise this regulator provided clean 12v! Checking resistance again, the circuit on the PCB was still shorted out.

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(auto-rotation of the message board isn't messed up, the multi meter is showing the year when the measurement was taken)

Found one 25v 100uF electrolytic capacitor that was in the circuit. Removed it and checked the circuit again, no short anymore! Had a fresh 63v 100uF capacitor left over that I didn't need when I did another repair.

Soldering the new capacitor to the board was slightly tricky, the PCB cannot be removed from the back plane as the voltage regulators and a few other components are attached to the heat sink without access for tools to safely remove them.. This also makes it difficult to renew the thermal conductive paste. Anyways, if it were easy everyone would do it.

Connected the PSU again and now the screen came back to life!

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:cheers:


For anyone troubleshooting the PSU, here is the pinout, checked with a DMM (left to right, looking at the component side of the PCB, right side up):

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(left to right on picture as well, note new red capacitors)

  1. Ground (connected with pin 2&3)
  2. Ground
  3. Ground
  4. +5v (connected with pin 5&6)
  5. +5v
  6. +5v
  7. +12v (output I fixed on my unit, apparently supply for monitor)
  8. -12v
  9. +5v
  10. +5v (appears to be the same voltage rail as the pin 4-5-6)

Because the other electrolytic capacitors of the PSU are of the same age I replaced those too:
  • 2x 6800uF 35v
  • 2x 100uF 63v
  • 1x 2200uF 40v FRAKO EFR capacitor (will be replaced by a high end capacitor, apparently something special was nescessary there)

The ones from Wurth Electronics had the same pitch so chose those.

There are various Tantalum capacitors on the PSU board as well which I will replace too. Will post a comprehensive list when I have done that and verified they work. The bridge rectifier, consisting from four rather toasty rectifier diodes will be getting a few fresh Schottky diodes as well (Schottky diodes are overkill but 1: less heat is better and 2: overkill is consistently more fun).

Total component cost is ~15 Euro, maybe 20 with shipping.
If the whole PSU is completely broken I would expect that a Meanwell triple output (+5v/+12v/-12v) can be a suitable replacement as well.

Rest of the unit appears to have a Lithium Sonnenschein (click) battery, which still sup-plied 3.6v after all these years:

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And for reference, if anyone is looking for the power connector, it is a STAK2 connector made by Hirschmann.

Disclaimer: THE POWER SUPPLY UNIT RUNS ON MAINS VOLTAGE (AND THE CRT SCREEN ON MUCH HIGHER VOLTAGES EVEN).. be careful!
 
Cool, thanks for the update. I have wondered off and on if you were still working on it. Probably good to update the electrolytic caps as they do often fail with age. I didn't do it proactively in my unit, but if I have issues I'll know what to do. By the way you mention pictures but I don't see any in the post...?
-Tom
 








 
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