Sorry to bring this old thread back up - I have sort of same problem with a 170c , short burst and the relay stays on press trigger again and it releases the relay - reading through this and seeing as it uses a latching relay that I’ve never came across before - can you change it to a normal mechanical relay ?
- Thread starter Taffyduck83
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A normal relay needs 12v or 24v on the coil to close it, and that voltage has to be there all the time to hold the relay closed. If the voltage goes away, the relay drops out.
In welders that use the Hfe9-1 latching relay, the electronics on the PCB just sends a brief pulse that turns the relay on when the trigger is pressed, and it then sends another pulse when the trigger is released, which makes the relay open. The trigger on the torch works normally: press to weld, release to stop, which is "2T" mode. It is the PCB and the weird relay that does the "latching on" function.
If the special latching relay was replaced by a normal one, that relay would just close for as long as the first pulse lasted, which would probably not even be long enough for the wire to start feeding. To use a normal relay successfully, the electronics would have to be modified to hold the relay closed with a constant voltage.
However, on your machine, you have to press the torch trigger a second time to get the welder to stop - isn't this because it has been set or somehow gone into "4T" mode?
In welders that use the Hfe9-1 latching relay, the electronics on the PCB just sends a brief pulse that turns the relay on when the trigger is pressed, and it then sends another pulse when the trigger is released, which makes the relay open. The trigger on the torch works normally: press to weld, release to stop, which is "2T" mode. It is the PCB and the weird relay that does the "latching on" function.
If the special latching relay was replaced by a normal one, that relay would just close for as long as the first pulse lasted, which would probably not even be long enough for the wire to start feeding. To use a normal relay successfully, the electronics would have to be modified to hold the relay closed with a constant voltage.
However, on your machine, you have to press the torch trigger a second time to get the welder to stop - isn't this because it has been set or somehow gone into "4T" mode?
Strange thing is it don’t do it all the time Eddie - sometimes it can be every 5th pull of the trigger and sometimes it’s one in 30 pulls - I will check to see if the voltage is constant or not . Shame it welds nice i find just annoying with it staying live and gas on unless you press the trigger again
Now that does sound like it's a latching relay that is not getting "unlatched" reliably - i.e. the second voltage pulse is not being sent, or it is failing to unlatch the relay. Is the relay on the PCB marked "Hfe9-1" ?
This will not be easy to troubleshoot - you are looking for a "missing" pulse, and as per post #38, the pulse can be as short as 50 milliseconds ( 0.05 seconds ). The sampling rate of a digital voltmeter is so slow that it probably would fail to register such a short pulse even when it is there!
This will not be easy to troubleshoot - you are looking for a "missing" pulse, and as per post #38, the pulse can be as short as 50 milliseconds ( 0.05 seconds ). The sampling rate of a digital voltmeter is so slow that it probably would fail to register such a short pulse even when it is there!
Yeah the meter is quick enough to read it - yes it’s h relay I can now see inside the relay and seems to be free moving as such - now the relay above this one isn’t pulse fed and getting near enough 23v from that every time - so thinking I could take it voltage from that to power a relay ?
I'm not sure what the other relay is doing - maybe it sends power to the wirefeed motor when welding, and shorts the motor to brake it?
If that relay opens & closes reliably on every trigger press and release, then yes, borrow the power from that relay coil to run a second medium-size relay which drives the main welding transformer.
The only issue would be if the electronic component that switches power on and off for that relay coil is capable of running two relays in parallel.....
If that relay opens & closes reliably on every trigger press and release, then yes, borrow the power from that relay coil to run a second medium-size relay which drives the main welding transformer.
The only issue would be if the electronic component that switches power on and off for that relay coil is capable of running two relays in parallel.....
Thanks Eddie - I will have another dig about
Actually, there may not be any electronics involved in the circuit that switches that other relay on - perhaps it is just driven by the auxiliary transformer ( PCB-mounted ) through a rectifier and controlled by the contacts of the microswitch in the torch trigger. In that case, there would be no problem in wiring two relay coils in parallel.
Ok , I will take pics later after work , I was thinking thou I have a spare Clarke 150te board and wondered if that could be used instead ? I know that’s a 110 Board but has the gasless wiring on it .
angellonewolf
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solder bottem right of board looks well carp
Yeah that’s where the latching relay was bud -
Well I tried to order a relay from Alibaba.com but I had a response off hello after 2 days and that’s it - so found a similar one off AliExpress , had old man’s car to patch up - so had a snoop in works electrical teams junk and come across a 60amp relay and used that till other one arrives . Didn’t miss a beat .
