Tormach ECM PCB Repair

[Moto2]

During evaluation, I reversed the polarity of the supply voltage (24V) for the Tormach 1100M/MX board (ECM v1.5). As a result, I blew a capacitor (C79) and two diodes (D22/D23)off the board. Tormach is only willing to sell me a new board. I'd rather see if it can be fixed first.

I can identify the diodes (IT4) that are blown off, but I don't know the capacity of the damaged capacitor C79 (1.6 x 0.8mm). One side of the capacitor pad is directly connected to ground (24V-) with less than <0.3Ohm resistance. The other pad is connector to resistors (R67, R36-37 and Diode D20). My best guess is that this capacitor is part of a voltage spike (CR) suppression circuit. But, I have no idea what the capacitance should be. Any help would be much appreciated. If you think any other portions of the circuit should be replaced as well, please let me know.

Thanks!

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[soofle616]

If no one else responds before then I will try to remember to look at my board when I get home. The markings on the cap should provide some insight.

[Moto2]

Thank you in advance!

[popspipes]

There are services that repair boards of this type, never used them but have read about them.

Some circuit boards have a provision for reverse polarity, it shows up as a dead short thru a shorting diode. However if it blows the diode open so that it is not shorted the board protection is gone and the full voltage is applied to the rest of the circuitry.

[TurboStep]

I blew a capacitor (C79)

I don't have an ECM board but the solder pads for C79 don't really look as though there was ever a capacitor installed. I've tried to check other photo's and videos but without conclusive results. Are you sure there was ever a capacitor there?
Step

[PCW_MESA]

I don't have an ECM board but the solder pads for C79 don't really look as though there was ever a capacitor installed. I've tried to check other photo's and videos but without conclusive results. Are you sure there was ever a capacitor there?
Step

C79 was never installed

[mountaindew]

hope this helps

[Moto2]

Thanks. All this really helped! I will update everyone once I get this all fixed!

[soofle616]

I'm glad everyone else stepped up cause I completely forgot to look at mine over the weekend.