Check the potentiometer on the front with a multimeter, if that is ok then the most likely culprit is the PCB or the SCRs (Silicone controlled rectifiers, like diodes but with gate wires to turn them on and off).
Technical Arc can fix the rectifier and the PCB if needed, be prepared for a bit of a wait though.
checked all the resisters on the PCB and they are ok. tried to get some values from Mosa to check the board more but they wouldn't give me them, just want me to bye a new board when i cant check if its that!
hi Jim, I have a mosa service manual.Most of it is safety and disclaimers, trouble shooting is 1 page and very vage.
It has a parts list and drawings with no testing values. Just got a price of the pot because it show out of range at 1 end
289.13 euros, PCB board which has loads of testing points on it but wont tell me anything 289.13 euros. Its got a Honda engine on it,BRILLIANT i can get every test value so i can bye the right part if it went wrong. Im going to bye a remote off Ebay for £115 free shipping and see if that turns it down, I was going to bye 1 any way and if i cant find any test values for PCB,i will get it fixed. Just wont bye another Mosa. Any way thanks Jim for taking the time to help, if i find any useful
information i will post it on here. Thanks again
Have you check the trottle?
I think that also the engine speed it's important.
I don't remember, the engine go always to the max speed?
If yes you may try to check if the carburator o whatelse give fuel to the engine, is stucked.
Automatic speed controller (when change the load, change also the speed) may can be stucked and take open the trottle, so may be also a meccanical problem, check also this.
Ahhh Steve another thing, this welders have three plugs
One is negative
And two positive
One is 0-100A
One is 100-200A
Try also to switch your connections on this plugs
Hi to All of You
i have the same board on TS415 with welding current failure to maximum doesn't go down even if i changed the 5K potentiometer, the issue is the LM348 input is always at 0V the variable voltage is ok coming from the pot, so the state is at 0volts on both entries of UA741 that's why it's output is at 0volt too, for the TCA789 the q1 is low and the Q2 is on with 3volt square signal. please can you help me for ?
There are a capacitor between a bunch of resistors , not the perfect location for this kind of components so it's probably to replace.
Then I see a big green resistor kind of burned ,change also this
Check the continuity between the others components and check for bad connections
Try also to clean everything
Here I marked the components I think you may check/change that can be the possible causes
Some of these have bad looking soldering that can be caused by an overload ,check the components connected to this also to be sure of what is good and what not
Please let me know what you find