Lincoln Electric SQUARE WAVE TIG 255 SVM100-A Service Manual page 62

F-21
PROTECTION/SNUBBER BOARD CONTINUITY TEST (continued)
CONTROL BOX
PROTECTION/SNUBBER BOARD
LOCATED ON BACK OF CONTROL BOX
TEST PROCEDURE
1. Remove main supply power to machine.
2. Locate and remove all harness plugs
from the protection/snubber board locat-
ed on the back of the control box. Refer
to Figure F.5.
3. The protection/snubber board may be
removed to simplify test.
A. Remove three 8 - 32 x 1/4" Phillips
B. Release board from nylon supports
SQUARE WAVE TIG 255
TROUBLESHOOTING & REPAIR
FIGURE F.5 - PROTECTION/SNUBBER BOARD LOCATION
head screws from bottom of board
with needle nose pliers or small
screw driver
SUPORT CASE BACK
AND CENTER BAFFLE
WITH WOOD 2 X 4
4. Inspect board for "leaky" or burned
components. If questionable compo-
nents are observed then replace projec-
tion/snubber board. (See note.)
5. Check resistances per Continuity Table
F.6.
A. If any resistances do not meet the
Continuity Table specifications, pro-
jection/snubber board is faulty -
Replace. (See note.)
Note: When installing projection/
snubber board be sure that the three
8 - 32 x 1/4" Phillips head mounting
screws are tightened securely. These
conduction points are necessary for
high frequency by-pass grounding.