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thanks Jozsi,Originally Posted by HJozsi
Those resistors will heat-up under normal working conditions, so keeping them about 0.15" from the PCB surface will accomplish two things: avoid PCB over-heating and degradation with time, and avoid arching to the ground plane.
Other resistors that should be kept at least 0.15" from the PCB surface are: R24, R27, R31, R34 (22 ohm gate resistors) just to comply with creepage distances (the ones in bold are more important).
Kreutz.
Kreutz,
thanks for the reply.
mick.
Me and paul are planning to have few more kits (limited) ready by mid August, interested folks may email uhu.highpower(at)gmail(dot)com,
the new kits have C19 and C23 tantalums caps rated at 35Vs, and the 0.1uF ceramics are replaced by all mylar caps.
it still stands beta!
Hello All,
the following is a recap of information I sent to John D. earlier.
Be sure and read the trials Irfanulla & I've gone through and take advantage of his learning curve. To avoid seemingly random catastrophic drive failures be sure to build and use the Regenerative Power Dump & install the 4700uF electro 50vdc Cap & 1uF 50vdc caps in parallel with 15volt power supply. Also use 10uF 35vdc tantalum caps on C-19 &C-23 on the HP UHU drive. I can see I've fallen way behind on updating the parts list & build recommendations. We are still building on the Rev. "B" PCB. All need to be Building to Rev. "C" Parts plus the above special instructions. Driving servo's of over 100vdc & 10 amps WILL result in the above catastrophic failures, UNLESS ALL of the listed changes are implemented the failures will occur & appear random & will end up damaging all of your HP UHU drives. the RPD PCB's are fairly easy to make.
Good Luck to All
Paul
Hello everyone,
just got my board up and running ,after blowing the output.
Before i test with motor power 38v,would it be possible for someone to
post the waveforms that should be present on the HI and LO pins on
the IR21844 drivers, on a good board.
i have looked at them with my scope and there is a slight difference between
them,BUT i dont know what i'm looking at!.
also is the power dump board needed with this low voltage ?,because i
don't know why the output blew in first place.
thanks everyone,
mick.
power dump circuit I feel is not needed for such low voltages . I think.
this time chk if the tantalums are rated for 35v, the 25v tantalums generated so much heat when burnt that they burned a hold in the UHU pcb.
First tests after successful assembly
Check all the connections, measure resistance across 15V terminals, Motor power supply terminals and motor terminals, no short circuit should be present.
Connect the encoder cable (with the pins 8 and 2 jumpered on the encoder side), RS232 cable to PC, USB cable to PC, and 15 Volt power supply. Connect the motor terminals to the right connector, but don't power on the motor power supply for this test. Do not insert the UHU chip on its socket yet.
Turn on the 15 V power supply and check the 5 volts between the 15V power supply GND terminal and pin 10 of the UHU chip socket. If OK, turn off the 15 V power supply and wait about 10 seconds for the voltage to drop to zero, then insert the UHu chip on the socket
Start the UHU communication terminal software on the PC and turn on the 15V power supply. You should have the UHU information and menu screens on the terminal screen. power ON and Firmware Ready LEDs should be ON.
Program the PID and H parameters, maximum error set to 2000
Turn the motor shaft by hand several turns, the Tracking Error LED should turn ON.
Reset the UHU chip in order to reset the error state.
Turn the motor shaft again in the opposite direction, it should be exactly the same, you have tested the encoder circuit as well as the UHU chip interface. Turn off the 15V power supply.
Connect the Step and Direction pins to the BOB, connect the BOB to the PC, start Mach3.
Connect a 24 to 36 V power supply cables (12 V batteries in series will work) to the motor voltage terminal observing the right polarity (DON'T POWER IT UP YET!!). Turn on the 15v power supply, turn on the motor power supply after a few seconds. Nothing should burn, heat-up or smoke.
Turn the motor shaft by hand, the shaft should try to turn back to the original position and should exert some resistance. If it continues to turn in the same direction as the manual push and the tracking Error LED lights up, shut down the motor power supply first, then turn off the 15V power supply after a few seconds. Reverse the cable connection on the motor terminals. Repeat the test. Nothing should be hot, or smoke. Command some movements by means of the terminal software, beware, the step size should be less than the 2000 figure you setted up for the encoder error count parameter.
If everything went OK, you are ready to begin some serious testing at the required motor voltage.
The USB cable should be connected during the tests and during the PID tuning, its function is to provide 5 volts to the isolated PC serial interface. Without that connection you won't have serial communication with the PC.
15V SHOULD BE PRESENT ON THE BOARD EITHER BEFORE OR SIMULTANEOUSLY WITH APPLICATION OF THE MOTOR POWER VOLTAGE, OTHERWISE THE BOARD WILL BE DAMAGED.
Last edited by kreutz; 08-13-2008 at 10:25 AM.
Thanks IRFAN,
i did have that problem,but escaped without damage to the
board,the caps just exploded and left a dirty mess.
rgds mick.
You should not measure the waveform on those pins, they are the gate drive outputs, have different reference potential, and it could be as high as the motor power supply voltage + 15V for the HO pins. Look at the waveforms I posted on the original UHU thread while troubleshooting the overheating snubber issue.
If you want to see the driver waveform look at U7 pin 1 and U8 pin 1 respectively, they should be measured with reference to P3 (GND test point), they will be 23.5 khz pulses U8 pin 1 inverted regarding U7 pin 1 waveform.
Hello from a very happy old man,
Thanks to the guidence and advice from this
forum i've just finished a totally successful test on my first hp-uhu
board.
thanks everybody.
mick.
HI Mick,
We should thank you and many others for taking up and trusting this relatively new design. Do elaborate on the tests you have done and the parameters you have set.
RGDS
IRfan
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