Author Topic: Faxitron MX-20 Reverse engineering (with some good results)  (Read 6436 times)

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Online mikeselectricstuff

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #25 on: February 14, 2018, 11:03:47 am »
From memory I think it's 9600 baud
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Offline KE5FX

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #26 on: February 14, 2018, 11:20:40 am »
This is serial to original controller ;)

Can I ask where you were providing this data, and at what baud rate (9600, as Mike says?) 

The MAX202 that's next to the 10-pin port labeled "RS232" doesn't have +5 on its VCC pin by default.  I tried applying +5 externally and sending a couple of commands (!MR<cr> and !T1230<cr>) at rates from 110 to 115200, but nothing happened.

 

Online mikeselectricstuff

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #27 on: February 14, 2018, 11:34:04 am »
This is serial to original controller ;)

Can I ask where you were providing this data, and at what baud rate (9600, as Mike says?) 

The MAX202 that's next to the 10-pin port labeled "RS232" doesn't have +5 on its VCC pin by default.  I tried applying +5 externally and sending a couple of commands (!MR<cr> and !T1230<cr>) at rates from 110 to 115200, but nothing happened.


Can you post a photo of your controller to see if it's the same as mine - may be some link options or different firmware
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Offline KE5FX

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #28 on: February 14, 2018, 12:00:11 pm »
Can you post a photo of your controller to see if it's the same as mine - may be some link options or different firmware

Here's a link to the photo (too big to post in the thread directly):

http://www.ke5fx.com/fx_ctrl.jpg

The 27C512 EPROM is labeled "V3.1 MOD", with the checksum 317E.  Binary image is here.

There is another chip that looks like a mask-programmed ROM, which is labeled 43805-65202-F SN 4312E-082 MX20 MICROPROS.
 

Online mikeselectricstuff

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #29 on: February 14, 2018, 12:15:07 pm »
Can you post a photo of your controller to see if it's the same as mine - may be some link options or different firmware

Here's a link to the photo (too big to post in the thread directly):

http://www.ke5fx.com/fx_ctrl.jpg

The 27C512 EPROM is labeled "V3.1 MOD", with the checksum 317E.  Binary image is here.

There is another chip that looks like a mask-programmed ROM, which is labeled 43805-65202-F SN 4312E-082 MX20 MICROPROS.
Strange about the unconnected supply to the 232 transceiver - may be worth seeing if you can trace where it goes to get a clue as to why it's disabled ( a fine wire brush can be useful for this).
 

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Offline KE5FX

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #30 on: February 15, 2018, 08:15:39 am »
Strange about the unconnected supply to the 232 transceiver - may be worth seeing if you can trace where it goes to get a clue as to why it's disabled ( a fine wire brush can be useful for this).

I suspect that it's some kind of factory diagnostic port, given that nothing was originally plugged into it.   Ordinarily I would X-ray it to find out where the pins go, but...  ;D

Contrary to what I said earlier, there actually was a 9-pin connector in the digitizer area, connected to J5 on the controller board, but it doesn't have a MAX202 nearby and it doesn't act like an RS-232 port.  Pins 3, 4, and 6 are pulled up to +5, with all others low.  It appears on the block diagram in the manual as "Cable A." 
 

Offline kilohercas

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« Last Edit: February 16, 2018, 02:25:16 pm by kilohercas »
 

Online Fraser

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #32 on: February 26, 2018, 04:45:27 pm »
KE5FX,

The 9 pin connector (cable A) located low down on the rear of the cabinet is the standard RS232 serial communications link to a PC serial port. I have various versions of MX-20 control software but they all expect to find a camera module connected so sadly they will not work for you :(

Fraser
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Offline KE5FX

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #33 on: February 26, 2018, 11:17:12 pm »
If it's a standard port, it certainly doesn't act like one.   :-// 

The path of least resistance in my case will probably be to run some spare I/O lines from the FPGA board to optocouplers across the up/down and time/voltage keys.  Just seems like unnecessary hackery, that's all.
 

Online Fraser

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #34 on: February 26, 2018, 11:44:29 pm »
I think I have the schematics for the control board. If so I will check the serial port design for you.

It will have to be tomorrow though.

Fraser
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Online Fraser

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #35 on: February 27, 2018, 12:00:27 am »
I just had a thought........

The early MX-20 Digital with Bioptics camera array is not as highly integrated with the OC in terms of control.

From memory the PC controls the camera side of things but only provides monitoring of the safety interlocks, X-Ray on condition and initiatedps X-Ray off. It does not need a complex RS232C control set to achieve such limited monitoring and control. It could even be achieved with just the handshake lines !

The later MX-20 design provides much more control over the cabinet from the PC. The PC is able to monitor and set Exposure and Kv as well as control the X-Ray generator. I am uncertain what changes were made to the control PCB but IIRC it had an additional 7 segment LED for the time window for tenths of a second. I both versions of the MX-20 X-Ray head so have the EPROM's if that is all that needs to be changed.

Fraser
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Offline KE5FX

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #36 on: February 27, 2018, 01:44:43 am »
I think I have the schematics for the control board. If so I will check the serial port design for you.

It will have to be tomorrow though.

Fraser

 :-+ That would rock, if you can find schematics.  Even if your board is different from mine (and it probably is, if you have 0.1-second exposure time resolution) it could still come in very handy in the future.

To date, the only connection I've added is a wire from the "X-ray on" LED to an input line on my digitizer board, so that the software can tell when the exposure starts and stops.  If I eventually decide to add remote controls to some of the keypad buttons, a schematic could save some hunting and poking, even if it's not the right version.
 

Online Fraser

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #37 on: February 27, 2018, 06:59:58 pm »
OK, I do have schematics for the control board...... of the original film type MX-20 circa 1997.

Whilst the controller does have a RS232 port it does not seem to be for remote control as the film cabinet had no need for such (having no PC).

Looking at the schematics I can also seen references to a 9 pin AEC sensor D type connector. I will upload the controller schematics but I am wondering........ do you have a Digital era MX-20 or the original film type cabinet that does not have the remote control capability or digital camera in the extended base area ?

The film type cabinet did have the uptight of an auto exposure X-Ray sensor that sat under the cabinet chamber and helped the user achieve good exposures of the film.

A digital era MX-20 would have the camera option detailed on the cabinets ID label on its rear. There would be a "DC" option type shown.

Fraser
« Last Edit: February 27, 2018, 08:40:25 pm by Fraser »
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Online Fraser

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #38 on: February 27, 2018, 07:32:26 pm »
Schematics for the non digital 1997 Faxitron MX-20......
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Online Fraser

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #39 on: February 27, 2018, 07:34:12 pm »
Continued
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Online Fraser

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #40 on: February 27, 2018, 07:36:00 pm »
Continued
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Online Fraser

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #41 on: February 27, 2018, 07:38:20 pm »
Last pictures for now :)
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Offline KE5FX

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #42 on: February 27, 2018, 08:31:12 pm »
Schematics for the non digital 1997 Faxitron MX-20......

Much appreciated.  Here's a tidied-up .PDF version: Faxitron_MX20_43805_65201D_65202C_schematics.pdf (6.6 MB)

These drawings apply to rev C of the 43805-65202 controller, while my PCB has revision F of the same part #.  So they should be a good match.  U7 is the mystery MAX202 with no Vcc connection, for instance. 

My 9-pin connector goes to the "Medoptics interface" at J5, which is definitely some sort of proprietary interface.  One difference between revs C and F may be pin 3 of this connector.  It's grounded on your rev-C schematic, while it seems to be connected to something else on the rev-F PCB.  That may have been done to add proprietary control support to film-only machines.
« Last Edit: February 27, 2018, 09:04:37 pm by KE5FX »
 
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Offline danielbriggs

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Re: Faxitron MX-20 Reverse engineering (with some good results)
« Reply #43 on: March 15, 2018, 11:21:47 pm »
This is an interesting thread, and much along the lines of what I'm slowly heading towards with my machine.

Great work kilohercas!  8)

Do you have any more details on the CBCT MATLAB route? I tried several algorithms myself, but am curious to what you used in the end as your results look really sharp.
[I found while most algorithms worked, some were ultra efficient, and some took a huge amount of computational effort for mixed results].

Even better... care to share you MATLAB .m files // or post an example of what you did?


@KE5FX + Mike...
Attached are my findings from when I was having a sniff around the RS232. It's not an exhaustive list, but contains pretty much all you'd need to run the cabinet from RS232.
[Excuse the notes too, it's just what I noticed the bus doing and scribbled down the findings].
 
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