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F-34 TROUBLESHOOTING & REPAIRF-34
STATIC SCR TEST (continued)
Figure F.5 - Plug J4 Location
G3909
Plug
J4
TEST |
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PROCEDURE |
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| Removal and Replacement. | ||||
1. | Remove main supply power to the PRECI- | 4. | Repeat Step #3 testing SCR2, SCR3 and | ||||
| SION TIG 275 and remove the case top and | ||||||
2. | left side. | 5. | SCR4. | ||||
Locate and remove plug J4 from the control | To further check the SCRʼs functions, use an | ||||||
3. | board. See Figure F.5. |
| SCR tester and proceed to the Active SCR | ||||
Using an analog ohmmeter, test the resis- |
| Test. | |||||
| tance from anode to cathode of SCR1. |
| NOTE: Also check diode D1. | ||||
| Reverse the meter leads and check from | 6. | |||||
| cathode to anode of SCR1. See Figure F.5. If | Replace plug J4 on the control board. | |||||
| a low resistance is indicated in either direc- | 7. | Replace the case top and left side. | ||||
| tion, SCR1 is faulty. Replace the SCR Bridge | ||||||
| Assembly. See SCR Bridge Assembly |
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Figure F.6 - SCR TEST POINTS
LIFT BAIL STABILIZER
DIODE D1
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SCR4 CATHODE |
| SCR1 ANODE |
SCR3 / SCR4 ANODE | SCR3 CATHODE | SCR1 / SCR2 CATHODE |
SCR2 ANODE |
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PRECISION TIG 275 |
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