Murex tradesmig 251 constant feed problems.

[Exuptoy]

My mate today was welding a customers Transit van and his Murex 251 decided to continually feed wire with no arc or gas feed then when you press the trigger the solenoid and contactor switch a few times before blowing the 3,15a control fuse.

Any ideas?

 

[Exuptoy]

Ok then. No-one?

Anyone have access to Murex repair manuals or electrical schematics?

 

[Bobbes]

Proberly one of the control transistors for the motor on the PCB are broken

 

[Exuptoy]

Proberly one of the control transistors for the motor on the PCB are broken

Stands to reason I suppose that one of the gates are permanently open and when the trigger is pulse it is getting a feed to the gate from a different path.

I just need to find now which board does what and which Tranny does what in there?

 

[roger64racing]

Stands to reason I suppose that one of the gates are permanently open and when the trigger is pulse it is getting a feed to the gate from a different path.

I just need to find now which board does what and which Tranny does what in there?

Did you ever find out what caused the constant wire feed? I have a Murex 191 doing the exact same thing.

 

[eddie49]

Some earlier Murex threads refer to BDV64B and BDV65B complementary-pair power transistors as being the motor driver, triggered by an NE555 timer chip as a pulse-width modulated ( PWM ) speed controller. One or more of these devices may be shorted or faulty.