AX2500 - still sick

15 years 4 months ago #21899813 by bradmuir
AX2500 - still sick was created by bradmuir

Not for the faint of heart......<BR><BR>I am trying to repair an AX2500 that I fried. I learned the valuable lesson of having different connector keying between the Battery and the Motors.<BR><BR>I inadvertently plugged the Battery into one channels Motor leads on one of the channels. (Yup, I let all of the "blue smoke" out!!)<BR><BR>I fried, into pieces, several of the MOSFETs. <BR><BR>In order of operation......<BR><BR>I replaced all the MOSFETs on the apparently burned out side of the channel.<BR>(It would still not power up)<BR><BR>I replaced the HIP4081 MOSFET Controller. It now sort of has a pulse.<BR><BR>It powers on at least, and the LED display shows what looks like the letter "t" (i.e. when it flashes no ctrl) and one of the dots is on in the corner.<BR><BR>Also, a L33B, which appears to be a voltage regulator, near one of the MOSFET controllers is getting HOT.<BR><BR>Also, any chance of knowing the Value of C17? I inadvertently blew this off with my SMT rewoerk nozzle (ooops). I think I replaced it with a similar CAP.<BR><BR>If it helps any, I am getting 10'ish volts on one side of the CAP, 0 on the other. On my OTHER (still working) controller it is 12 volts.<BR><BR>Aside from "send it in for repair" (which I suspect WILL be the end result), any other ideas of what may be blown here?<BR><BR>I have 4 more IRF1405's coming for the other side of the smoked channel. I have triend powering it up with, and without these MOSFETS instaled.<BR><BR>Time, and cross-border shipping are not on my side at the moment.<BR><BR>Any suggestions are appreciated.<BR><BR>I am using these to control steering and brakes (and another RC channel for Throttle) on cars for staging crash tests.
Thanks for any help or suggestions you can offer.<BR>

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15 years 4 months ago #21913398 by cosma
Replied by cosma on topic Re:AX2500 - still sick
The trouble with with Power electronics is that damage typically extends much further than the parts that are visibly damaged.

With some luck, damage remains on the power side of the board, meaning that the MCU still has life and the LED display works.

When the HIP4081 drivers are damaged, they can be drawing too much current on the 12V, which in turns causes the MCU not to start. But if after removing or replacing the driver, the MCU is still not comming up, then the damage has spread to the processing side of the design.

If the damage is confined to the power side, then you should plan on replacing every component from driver down to all MOSFETs (even those that look intact), for that channel.

This is quite difficult to do and we end up replacing the unit when we receive them for repair.

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15 years 4 months ago #21937264 by bradmuir
Replied by bradmuir on topic Re:AX2500 - still sick
Cosma,<BR><BR>Thanks for the reply.<BR><BR>I should add that with the blown side HIP out, the board came up and infact, I had RC control of the good channel.<BR><BR>Once I replaced the HIP (but apparently with other blown components......) the other side (control side) seems to be stalled out now.<BR><BR>Does the "t" with a dot in it on the display mean anything to you?<BR><BR>The apparently overheating L33B regulator seems to be a clue something else is now fried. FWIW I removed the replaced HIP and it is still in the "t" with a dot status, which means something back-fed to the other side. Something backing through the HIP that links to the control side.<BR><BR>While I am good with SMT component replacement (have hot-air station and LOTS of patience) and have a fine touch on the soldering iron side, my troubleshooting skills are not as strong.<BR><BR>It would seem reasonable that all the components on the oen channel need to be redone (i.e. transistors.... and??) do you recommend all diodes and caps be changed out too?<BR><BR>Any clues you can offer to see what is fried out on the control side now?<BR><BR>I CAN tell you we are going to just buy another Roboteq. Based on your comments, this one is not worth sending in to you for repair due to component damage and man-hours to replace. We don't crash cars again til April. Anything new on the horizon for similar contollers?? (i.e. a 3-channel??)<BR><BR>I would still like to try and get it back up to have as a backup unit (and my pride is involved!!). <BR><BR>Any assistance, guidance is appreciated.<BR><BR>Brad<BR><BR><BR>

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15 years 4 months ago #21937744 by cosma
Replied by cosma on topic Re:AX2500 - still sick
t is not a valid state for the display. The control side is probably quite damaged too. Sometimes, damage to the driver propagates to the CPLD and its 3.3V regulator. Fixing becomes more work than it is worth.

FYI, we have a repair program for a flat fee. Charge is a bit higher than half price of new. Please place your request at <A href="" target=_blank>

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