Re: Mitsubishi CNC switching power supply board dead / relay board bad diode failure
I should have been more descriptive about the diodes they are parallel across the relay coil
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Re: Mitsubishi CNC switching power supply board dead / relay board bad diode failure
Usually these diodes are just forming an AND/OR gate. With multiple (logic) diodes shorted, I think there would be a short at one of the switches or wiring, causing an overcurrent through the diodes and also overloading the PSU. I wonder why no fuse is there or popped.Leave a comment:
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Mitsubishi CNC switching power supply board dead / relay board bad diode failure
I was working on this CNC machine today found no keyboard functioning no control relay powering on
The screen powered on and was giving an operation error but the manual was not very clear about what the error exactly was but with a little bit of troubleshooting and finding out that the control relays not powering on and no keyboard functions we narrowed down to this one switching power supply which of course does not have any indicator LED light they are on the keyboard interface/relay controller board
Found shorted diodes on main controller relays there are 3 of them that are shorted
One note the 3 shorted diodes one for each relay one of the relay that was suppose to power on had the shorted diode the other two are powered from another power supply from somewhere else
Diode test on meter showed 0.010 when checked where as a good one would show 0.500 to 0.556
So my guess is that the shorted diode what caused the switching power supply to fail he was telling that it has been giving trouble powering on a few times before but he would check a few things and all of sudden it would power on like nothing was wrong with it
Luckily he had a spare switching power supply and a relay controller board from another machine that he had an “E” Stop failure of some type even the service technician from Mitsubishi could not find the failure and recommended parting it out it was from the 1970s ( I had also troubleshooted this machine and I could not figure out exactly what the issue was either)
I do have the machine up and running but now I have to fixes the relay control board and figure out what failure is on the switching power supply board the main fuse is good but that is far as I gotten today I look at it tomorrow morning and see what can find out
I will post some pictures of the boards sometime tomorrowLast edited by sam_sam_sam; 01-07-2023, 06:17 PM.
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Hello and happy new year ,
my Analog Combustion Machine Honeywell gone bad and I don't know what type of diode is utilized.
There is no mark around the body of the diode. The Schematics are general referred only, without any electronics components and values.
The two contacts (2),(5) of the Relay Coil need 48 Volts DC to begin operating. Between these two contacts in series is the bad diode and near of contact (5) is the bad pnp (bc856b) Transistor that can be easily replaced.
I have made a diagram of the PCB and some measurements along some... -
These cheap non brand capacitors at it again
Last night we had a power outage [ long drawn out trying three to come back up before going out completely ] and when I went to turn the DVR camera recorder back today no go 3 bad capacitors ( one capacitor no ESR reading on DVR board the other 3 capacitor on the power supply board over 40 ohm this is not a misprint ) on the external switching power supply and one capacitor on the DVR camera recorder board where the power supply that goes to the hard drive disk is
Well at least I have the cameras back on line I to try the... -
When I originally started with my DVR recorder it had 4 individual switching switching power supply’s that were sh*t so I bought a 7 amp 12 volt switching power supply and modified the output plug and put a four output power supply cable to match the input power supply cable inputs
Which worked for over 14 years until a few days ago when the cameras went dark no picture anymore well it turns out now the switching power supply has stopped working altogether now so I have to troubleshoot what has happened to this power supply more later on today what I found
This... -
I have been working on this concept for quite some time now with limited success but recently I found a switching power supply that is setup for the voltage that this soldering station needs to operate at however it also needs part of the secondary circuit from the original switching power because you need several voltage rails
I once tried to get a ZD-915 desoldering station to work on a 18 volt battery power supply but unfortunately things did not go well but I did find a work around but I might try this idea again but going at a little differently more about this another time... -
I saw this switching power supply on eBay and wanted to see if could be modified to run 14.5 volts before the blocking diode was add and this switching power supply seems to have no issues doing this
I did recap the switching power supply except the the main filtering capacitors and I managed to break the selector switch for the voltage setting but just jumped it
One note I used 25 volt capacitors on the output side of this power supply because they used 16 volt capacitors and because I am running the voltage up a little bit higher 12 volts to 14.5 volts there would...
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