ESAB LTR 160, Service Manual

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5 Slope up / Slope down
Potentiometer RP02 on the front of the machine is used for setting the Slope Down
time (the decay time for the welding current when TIG--welding). The time is
adjustable between 0.1 and 10 seconds.
Potentiometer R58 on the circuit board controls the Slope Up time (the rise time for
the welding current when TIG--welding). It is adjustable between 0 and 5 seconds.
On delivery, the Slope Up time has been set at 0.
6 HF unit
WARNING! dangerous voltage.
When the torch switch is closed and the open--circuit voltage exceeds about 45 V,
relay RE3 closes and activates HF unit AP11. The relay drops off when the arc
voltage is less than 45 V or if the arc has not struck within 0.5 seconds.
In the MMA welding mode, transistor Q7 is held off by --10 V from diode D18. In
the Lift Arc mode, Q7 is held off by --10 V from diode D17.
The voltage on the primary side of HF transformer TV01 is about 400 V, and the
secondary voltage is about 8 kV.
From serial number xxx--006--xxxx a new type of HF generator is used,
0367 268 001. This generator produces about 500 V on the primary side of the HF
transformer and about 10 kV on the secondary side.
The new HF generator replaces the old type as spare part for older machines. The
colour of the new type is grey, the old is black. The new has screw connections for
the connection cables and different hole pattern for the mounting.