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Martin Mac 500 & 600 PCB Issues


bensmall

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Hi All

Hoping you can help I have a pair of Main PCBs one for a MAC 500 and One for a MAC 600 E-NT

both have a slight issue

mac 500 Pan Driver is an issue it pans for 1 second then starts to judder and is very hard to move by hand ( have swapped looms and driver chips with tilt, at different times and fault stays with driver socket. Motors all check good, have replaced all the 1.5Ohm resistors for the Pan Driver socket and had no change)

Mac 600 Tilt Driver issue driver tries to move the tile motors but is unable to and it Very weak to hand ( Had done fault finding the same way as above fault stays with the socket again and the motors both work perfectly on the Pan driver chip)

any knowledge you have about these PCB would be appreciated and of great help

Ben

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Such a long time since I worked on these. If you are convinced it's a component level issue on the PCB, best thing is to post up some decent resolution pictures of both sides of the board. I have a hazy memory of a lot of driver chips fed off a main controller, but it would be easier to see what's what. Edited by indyld
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Such a long time since I worked on these. If you are convinced it's a component level issue on the PCB, best thing is to post up some decent resolution pictures of both sides of the board. I have a hazy memory of a lot of driver chips fed off a main controller, but it would be easier to see what's what.

 

Hope these help, please excuse the bad soldering only had a TS80 to try and get the resistors swapped out

 

 

 

https://ibb.co/nsptYc7

https://ibb.co/4RhL39J

https://ibb.co/fdw5Nyz

https://ibb.co/BzHNtvB

Edited by bensmall
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Ouch, potential for track corrosion in the mix too huh. At least there are not too many vias that can have rotted out.

 

What led you to swap the sense resistors out and what state were they/ meter readings did you get beforehand on their connections? Also, are there any now comparative differences measured between a known good driver circuit on the board and the faulty driver one?

 

Does it seem like the 3692 is working in conjunction with the socketed driver chip for each attribute for microstepping (e.g count up how many there is of each?)? Some legs look quite unhappy there too, and obviously if the issue is not with 'usual' chip, swapping the latter wouldn't appear to help.

 

The fault sounds very physical, but if you reckon it's definitely on the PCB then one might assume that difficulties are because the drive control/sense etc is preventing the correct operation of the motor by being somewhat confused.

Edited by indyld
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Ouch, potential for track corrosion in the mix too huh. At least there are not too many vias that can have rotted out.

 

What led you to swap the sense resistors out and what state were they/ meter readings did you get beforehand on their connections? Also, are there any now comparative differences measured between a known good driver circuit on the board and the faulty driver one?

 

Does it seem like the 3692 is working in conjunction with the socketed driver chip for each attribute for microstepping (e.g count up how many there is of each?)? Some legs look quite unhappy there too, and obviously if the issue is not with 'usual' chip, swapping the latter wouldn't appear to help.

 

The fault sounds very physical, but if you reckon it's definitely on the PCB then one might assume that difficulties are because the drive control/sense etc is preventing the correct operation of the motor by being somewhat confused.

 

I Measured the sense resistors in and out of circuit and they showered a higher resistance of 2ohms and not 1.5 ohms so swap them as a just in case measure

 

as for the 3692, I'm not to sure as the oscilloscope I have to hand dose not have any probes, unless its something I can measure with a multi-meter I cant tell if this is the fault.

 

is there any faults that happen as standard with the mac 500/00 pcb ?

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The standard replacement on those boards was always the driver chip but now age and corrosion can create a wider range of problems. No need for a scope to do a lot of PCB fault finding, a meter is fine particularly if you just need to dead test various points to identify where a track, joint or component has failed. Or to check the presence of a power rail at a chip.

 

Main point about the 3692 is that those at that end look like they have suffered from the same conditions as everything else in that area and on the image look like the connections may not be as good as they were. And that they are a key part of the driver chain. If you ever need to understand a section of circuit, look up the datasheet for the main chip associated with it and find the Typical Application schematics - they often don't differ hugely from the real world version.

 

Unless the sense resistors were in a complete state, I'd be more concerned with their tracks, joints, and the other things they connect to.

 

I recall there might be two motors per attribute for Pan and Tilt. I wonder if the very physical symptoms are the result of issues with one side of the control and the motors are fighting against each other at some point. Were the tests conducted separately per motor and, if so, did this point to one particular half of the driver and its area of the board?

Edited by indyld
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