Thread: AXBB charge pump fault
-
11-08-2019 #1
I wired my machine to use the charge pump output so that the relay would only activate the motor psu if the software was active and not in a reset/error state. This has worked perfectly while testing until I tried it a couple of days ago. When I apply power the relay and therefore the motor Psu all spring to life. I checked all wiring and even stripped it all back to the bare minimum and tested again with the same issue. I have checked the charge pump isolated output and it appears to always be active even if the indicator LED is off? I have checked that the option to always enable charge pump isn't active and am now wondering whether it's faulty...does anyone have any other ideas?
Sent from my SM-G920F using Tapatalk
-
11-08-2019 #2
Does the other outputs work as expected ?
Assuming the output transtor is open drain and grounds the relay coil terminal to switch the relay on
With the power off you can use a multimeter to check the resistance between the negative supply terminal and each isolated output
in the manual
http://www.cncdrive.com/downloads/AXBB_E_manual.pdf
see diagram 9.1.2 .Connecting a solid state relay (SSR)
test between 24V0 and Ox
You should find they are all open circuit unless the transistor controlling the relay is short circuited
JohnLast edited by john swift; 11-08-2019 at 08:22 PM. Reason: correct typo
-
11-08-2019 #3
Cheers John, I'll check the resistance tomorrow but one more thing I remembered. I also tried output 2 of the isolated outputs and that one does read the voltage change if I set that as the charge pump output however that one doesn't activate the relay? The manual states that the isolated outputs can drive upto 500mA so I'm assuming it's not enough power to drive the relay and the output 1 is different.
Sent from my SM-G920F using TapatalkLast edited by CharlieRam; 11-08-2019 at 08:41 PM.
-
11-08-2019 #4
what relay are you using ?
any idea what the coil resistance is ?
This one from RS Components has a coil resistance of 650 ohms
https://docs-emea.rs-online.com/webd...6b815856e9.pdf
If the RS StockNo:450-0425 relay was used with the AXBB and its 24V DC supply only 37 mA would flow via the AXBB output
John
-
11-08-2019 #5
It's like the one below
https://rover.ebay.com/rover/0/0/0?m...2F283248324744
Sent from my SM-G920F using Tapatalk
-
11-08-2019 #6
-
11-08-2019 #7
Forgive my ignorance but does that mean the other isolated outputs are all capable of driving the relay? I did check that and thought so but its been a while since I DoD electronics!
Sent from my SM-G920F using Tapatalk
-
12-08-2019 #8
-
12-08-2019 #9
The reference to " other isolated outputs are all capable of driving the relay "
differentiates the outputs from the 5V logic level outputs that you connect to other logic gates or the stepper driver step & direction inputs
from the open drain outputs designed to switch inductive loads like the relays
As an example
Going back to equipment I used and maintained in the eighties
all the logic was built from 7400 series TTL logic
Typical gate inputs passed 1.6 mA when an input a input was grounded
and the outputs could sink 16 mA
so you could only connect 10 inputs to the output of an IC
unless you used a buffer that could pass more current
To connect to other devices like tally lights for the control panel switches
A lamp “driver” / BCD decoder like the 7445 switched 28v bulbs ( run off a 24V supply ) by grounding the other end of the bulbs filament
The 74141 being another version with high voltage outputs for driving Nixie tubes
(which is basically a neon with an anode connected to 180V DC via a resistor and 10 cathodes shaped in the form of the digits 0 to 9 that glows when grounded )
These days you would use a 7447 BCD to 7 segment decoder driver connected to a 7 segment LED display or LCD
John
-
12-08-2019 #10
It looks like the FET for output 1 has short circuited
I would check you don't have a wiring problem that could connect the 24V DC to the AXBB output
Did you check the relays coil resistance is 650 ohms as expected
less than 48 ohms would pass more than the 500mA limit for the output
John
Thread Information
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
Similar Threads
-
Advice on a charge controller please :)
By blackburn mark in forum General ElectronicsReplies: 23Last Post: 04-05-2020, 07:28 PM -
CNCDrive AXBB super deal?
By driftspin in forum CNCdrive (UC100, UC300ETH)Replies: 18Last Post: 16-03-2019, 10:10 PM -
Not sure where the fault lays
By terry1956 in forum VectricReplies: 5Last Post: 20-02-2019, 11:28 AM -
fault testing
By Palletlad in forum General ComputingReplies: 2Last Post: 09-02-2018, 05:51 PM -
Jun-Air Compressor Fault
By jamesgates1000 in forum General DiscussionReplies: 5Last Post: 02-12-2017, 07:59 PM
Bookmarks