Ap1 Tig Board - ESAB Caddyt Arc 150i Service Manual

10

AP1 TIG board

WARNING! Dangerous voltage - - mains voltage.
The relay contacts, the gas valve 10YV1, the HF generator TR2 and the primary side of
transformer TR1 are connected to 230 V mains voltage.
Circuit diagram of the TIG functions of the CaddyTig and OrigoTig
The processor on circuit board 20AP1 controls the HF generator and gas valve. They can
be tested by service functions, see pages 38 to 43.
HF generator
When the welding torch switch is operated, and the open--circuit voltage is over 50 V, relay
RE2 closes and turns on the HF generator, TR2. It remains activated until the arc strikes, or
for a maximum of 0.7 seconds.
The voltage on the primary side of HF transformer 10TV1 is about 550 V. The secondary
voltage is about 11 kV if a 4 metre long welding torch is connected. If the welding torch is 16
metre long, the HF spark is about 8 kV.
Due to electromagnetic interference regulations, the energy in the HF ignition spark is
limited, and so the HF spark weakens with increasing length of the torch. The HF ignition is
satisfactory for welding torches up to 16 metres.
Gas valve
When the torch switch is operated, relay RE1 closes and energizes the gas valve.
When the torch switch is released and the gas post--flow time has elapsed, the gas valve is
deactivated.
TIG torch switch
The secondary windings of transformer TR1 and rectifier bridge D3--D6 produce 24 V DC.
This voltage energizes relay RE3 when the torch switch is closed.
The torch switch can be tested by a service function, see pages 38 to 43.
S0740 800 161/E061205/P66
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