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Any ideas on repairing a (slightly!) blown motor board ?


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I've really been enjoying this thread so far, really nice little idea resource if ever something like this pops up on my workbench; and very heartening to read about systems being brought back to life rather than being binned especially when everything now seems to be so geared to disposable.

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Well I've just received a PM from the owner and he's a happy bunny... Yes it's four out of four guys Due to their personal commitments they haven't had the time to put the thing through its pace

Hello everyone, I am that happy owner  who sent this badly damaged MC-003 board to Malcolm and received it back in fully working condition   I wanted to make a video showing that everything is working

Well it's been a busy morning... The SGL member with the damaged MC003 board had a change of heart and contacted me again to see if I would still be willing to attempt to repair  his board.  Natu

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Thanks Malc-c for responding so quickly.
I bought the dobson used because it is not in stock here.
The previous owner told me that Skywatcher USA sold him a wrong connector. He wanted to update the firmware and it burned.
I read that you cut the legs but I have a soldier x air station.
I work in automotive electronics, but I don't remember anything about pic.
As soon as the components arrive, I share the process.
Would you be kind enough to tell me which file to upload? and if it is the same for the two pic?
Sorry for my poor English, I use google translator
Thank you

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The dobsonian firmware I've used is attached.  Yes you program both PICs with the same code.  There is a slight difference in hardware connections between the two PICs that defines which one is the ALT and which is the AZ axis.

I would try replacing just the two PICs before replacing the other two chips unless you are 100% positive they have also been damaged.

[Google translation into Spanish - hope it works !]

Se adjunta el firmware dobsoniano que he usado. Sí, programa ambos PIC con el mismo código. Existe una ligera diferencia en las conexiones de hardware entre los dos PIC que define cuál es el ALT y cuál es el eje AZ. Intentaría reemplazar solo los dos PIC antes de reemplazar los otros dos chips, a menos que esté 100% seguro de que también se han dañado.

MC004d.hex

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Thanks Malc-c for your quick reply. I was thinking the same thing that you recommended. I'm going to start by changing the PICs. Just have them share the news.

Greetings

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Hello boys I have successfully programmed and changed pics without positive result, then changed lm 324 and 74c14.

There was a change in what the syn scan shows, but it still doesn't recognize the engines. I'm going to check all the welds again and then try the diode reform.

I continue with the tests and comment on the results.

Greetings

20210601_230326[1].jpg

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Again no expert, but if other chips had been damaged (you mentioned holes in them) then the problem may have also affected the voltage regulator - I would check to see if there is 5v on across the PIC's supply pins.  If you've got 5 volts powering the components then braking the tracks and trying the diode mod as per the above would be my first option too

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Posted (edited)

 

Hi guys.

Today I have good news !!! Finally the board worked !!!!

By reforming the diodes and feeding through the resistor, the control could communicate with the board.

I did not cut any connections and soldered the diodes on the original connections.

I attach some photos and a video of the dobson already working.

I am very grateful to the Hall of Astronomers and its members for showing and sharing their work.

Thanks.

Greetings

 

WhatsApp Image 2021-06-03 at 10.22.29 (1).jpeg

WhatsApp Image 2021-06-03 at 10.22.29 (2).jpeg

WhatsApp Image 2021-06-03 at 10.22.29 (3).jpeg

WhatsApp Image 2021-06-03 at 10.22.29.jpeg

Edited by pablocarlac
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Hello boys.

As they say in these places "not everything is pink" I can't align with the goto.

The repair is fine to use it manually from the keys, but when I want to align it by any method it goes in any direction. I was checking the plate carefully, I changed the lm324, the 74h14 and it remains the same.

I have read what happened to other dobson users, but it seems that none of them can solve it.

I made a video to show what it indicates.

It seems that the photodiodes are malfunctioning. But it is rare that the two axes have the same problem.

With the auxiliary encoder disable something indicates, enable the indication is totally wrong. If I move it manually it doesn't indicate anything.

I have tried several firmware from v3 but nothing changed.

It seems to be some software problem, but I don't know what to do anymore.😕

Any idea what may be happening ???

Thank you very much for your attention

Greetings

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There is only one version of firmware for the motorboards used in skyliner dobsonians - so I'm not sure what the issue could be.  You could try and download the 2.09 firmware file from the website here and use the SW uploader (requires the serial cable to the handset and a PC with a traditional 9 pin D serial port (or a true USB - Serial adapter) to reflash the PICs.  But the fact that the mount responds to directional commands when the NSWE buttons are pressed suggests communications are correct, so no idea why it should not point where it's supposed to

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Hello Malc-c

The firmware download it from there.

Successfully update the hand control and motors to the latest version

It's strange. it erroneously processes the signals of the encoders and when I activate the auxiliary it no longer registers anything. Connections are fine.

Later I test the inputs 23 to 26 of the pic with an oscilloscope.

But I think the problem has to be in the firmware.

I have the original pics, but the hex program is protected and I can't do much else.

I'll keep trying. I keep you informed and any ideas will be welcome.

Thank you

Regards

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Yes, the code protect registers are set in the binary files.  The process of using the PYTHON scripts as mentioned a few pages back to convert the BIN file to HEX and then using MPLAB to change the code protect bits and then re-export the HEX as an unprotected version is required.  But as the code includes the bootloader so the SW update software can recognise the board and upload the BIN file on the fly there should be no need to reprogram them, or try and read back the HEX form the existing PICs.

I was going to suggest using something like GSServer and a true EQDIR cable, but the mount isn't an EQ mount so that wouldn't work as it would still move the scope in strange directions.  

Just in case there was some corruption in the file, I've run through the routine again and produced the attached....  Don't be put off by the MC004 reference - that was due to the previous repairs - there is only one version of firmware for goto dobsonian scopes and that's the 2.09 file, which this was based on.

MC004Final.hex

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Hello.

Today I was able to review the entire circuit and check with an oscilloscope that the signals from the encoders are reaching all the legs of the pics.

It is very rare since the firmware can be updated perfectly, both on the phone and on the motor board.

In this forum a couple of people wrote the same situation, but it seems that they could not solve it.

I am running out of ideas.

I will try to read the original program of the pics.

I'm going to have to learn, since I know little about pics.

@malc-cthanks for your help, the MC003 that you fix was with a v4 controller. This is V3, will the problem come from there ??.

When did I update the controller?

It is rare that when enabling the auxiliary encoders it no longer has a position reading.

Very disconcerting all this ...🤔

I keep you informed if there is progress.

Greetings

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1 hour ago, pablocarlac said:

the firmware can be updated perfectly, both on the phone and on the motor board.

In this forum a couple of people wrote the same situation, but it seems that they could not solve it.

I am running out of ideas.

 

If you can use the SW firmware loader application to upload the BIN files from SW website to the motor board, then the PICs are running fine, and you shouldn't need to try and read them back.   There are two versions of the 2.09 firmware listed on the SW website, the one for goto mounts has the option for encoders.  I believe this was the BIN file that was converted to HEX for the original fix.  As far as I know the code isn't motor board specific so will work on any  Dobsonian  goto, regardless of  it being an MC003 or MC004.  The fact that you can use the uploader application to program the PICs means you could try either one of the 2.09 versions.  If you have and the scope is still misbehaving then I too am at a loss.

The SW communications protocol and the command set that is used on all boards are detailed in the attached PDFs.  - The protocol / command set is the same across all motor boards.  Testing of the PICs / boards using a serial terminal application is detailed in this thread, where sending the relevant command results in the board returning a value, for example the command for the firmware version :e1 [return] returns the version as a string of numbers. 

The current V3 firmware is 3.39.15  Is that wat you are running on your V3 handset ?

One thing I have no idea what functionality it provides is the three jumper pins, which from Archie's schematic connect in parallel to pins 2,3,4  which are normally tied high via pull up resistors.  In the image shown, the jumper takes the pin 2  of both PICs to ground.... you could try removing it all together and seeing if it has any effects, or place it in positions 2 or 3  and see if that makes the mount respond differently ?? - On the MC002 board used in the sysnscan units for EQ3 and EQ5 telescopes, there are two jumpers that are used to configure the board as the gearing is different 

MotherEQ3 (1).jpg

It maybe, and I'm guessing, that the three way jumper on the MC003 board works in some way to enable or disable the encoders, or to inform the PICs that it's in a 10" DOB or 16" etc ???

Other than that I'm out of my depth....and clueless - Sorry

 

 

synscanserialcommunicationprotocol_version33.pdf skywatcher_motor_controller_command_set.pdf

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Hi Malc-c

The firmware of the v3 is 3.39.15

I tested the jumpers in all 3 positions and there were no improvements. Only removing j1 changes the direction of keys in Alt manually.

Also remove the 10k resistor and the 1n4148. I was able to find only 1 of the smd diodes and the other probe with a 1n4148 and also with a 1n4007 (classic rectifier) and there is always communication with the pics.

It seems that it requires the reform of the diodes and resistance only for the first firmware update, because it returned to update the motors with this last reform again with success.

I will keep you informed for any novelty. 

Thanks for your help

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I think something got lost in google translation there :)

Not an expert, but I think replacing the 1N4148 diodes with 1N4007 rectifying diodes is not a good thing - the two have totally different functionality.

 

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Your image isn't clear, but this look to be wrong.  The Diode is the wrong way round.  The bar on the diode should go to the + on the PCB.  In this image it looks like its the reverse.508521509_WhatsAppImage2021-06-03at10_22.29(3).thumb.jpeg.de7d92a8b1d724bae92396f9c898d9b4.jpeg.a8bb70a58f6b942d186646df32892231.jpeg

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Yes, you are right.

They are for different uses. It was only for a test and thus confirm that it only needed the reform for the first firmware update.

The diode is well placed. The cathode points towards the tx of the pic. The anodes of both are linked and to Vcc through a resistor.

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Hello!
My EQ6-R mount motherboard has recently failed. It is possible that the PIC18F25K20 -I / SS controller on the RA axis has failed. I read that if I download the .MCF file and rename it to a .bin file, and if I generate an .hex from it, I can upload it to the PIC, with Pickit4. Can this work? Thank you for your answers.
Regards helium.

P1350616.JPG

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Hi,

Yes the same procedure outlined in this thread would be followed.  - Rename the file to .BIN, install PYTHON and run the BIN2HEX script, open the resulting HEX file in Microchips MPLAB and turn off the code protect bits and re-export the HEX as the final file.  Program two new PICs with the file and then replace the damaged ones.  

Good luck, and keep us posted

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Not sure why, but the following may help as it works for me

Once python has been installed, ensure the scripts, plus the BIN file are in the same folder.  Then you need to open the command as administrator, and then navigate to that folder.  Then start python by typing py -V before trying to run the command to run the script.  You should see the confirmation that python is running as "Python" plus the version number is displayed.  Then type in the script parameters 

For example

python.png.d2c35e91638414d5ec28e802a72add70.png

Hope that helps

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