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Table 3-10. Performance Failure Symptoms
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| DEFECTIVE |
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SYMPTOMS |
| BOARD |
| CHECK FUNCTIONAL CIRCUITS |
| ||
unexplained OVP shutdowns |
| A2 |
| OVP circuit, CV circuit |
| ||
no current limit |
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| A2 |
| CC circuit |
| |
max current < specified |
| A2 |
| CC Clamp, CC circuit |
| ||
max power < specified |
| A2, A1 |
| Power Limit, 20KHz clock, transformer AlT1 |
| ||
max voltage < specified |
| A2, A1 |
| CV Circuit, diodes |
| ||
cycles on & off randomly |
| A2, A1 |
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| Select switch A1S2 |
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CV overshoots |
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| A2 |
| A2U5A, A2CR19, A2R62 |
| |
output noise (<1KHz) |
| A2,A1 |
| CV circuit, input filter |
| ||
output noise (>1KHz) |
| A1, A4 |
| transformer AlT2, Output Filter, snubbers A4R1 to |
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| A4R11, A4R13 to A4R19, A4C1 to A4C4, A4CR2, |
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| A4CR3, A2R15, A2C2 |
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CV regulation, transient |
| A2, A1 |
| wrong sensing |
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response, programming time |
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| low ac mains voltage, CV circuit |
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CC regulation |
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| A2 |
| low ac mains voltage, CC circuit |
| |
CV oscillates with capacitive |
| A2 |
| A2R61, A2R60, A2R58, A2R59, A2C33, A2R64, |
| ||
loads |
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| A2R68, A2C36, A2C37, A2U5, A2R65 |
| |
CC oscillates with inductive |
| A2 |
| A2R61, A2R60, A2R58, A2R57, A2C33, A2R19 |
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loads |
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| A2C11, A2R28, A2C12, A2U4, A2R35, A2C20, |
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| A2U4, A2R37, A2C17, A2R29, A2C18, A2R31 |
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| Table |
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| (Bias supplies and AC |
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Status of FET |
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| DEFECTIVE |
| CHECK FUNCTIONAL CIRCUITS |
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| BOARD |
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Lo |
| Lo |
| A2 | Control ckts: CV & CC thru On- & |
| |
Lo |
| Hi |
| A2&A4 | PWM and |
| |
Hi |
| Lo |
| A2&A4 | PWM and |
| |
Hi |
| Hi |
| A2&A4 | PWM and |
| |
Lo |
| N |
| A2 | A2U15A, |
| |
N |
| Lo |
| A2&A4 |
| ||
Hi |
| N |
| A2&A4 | A2U15A, |
| |
N |
| Hi |
| A2&A4 |
| ||
N |
| N |
| A2&A4 |
| ||
Lo= TTL low |
| Hi= TTL high |
| N= normal 20KHz pulse train, TTL levels |
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* Decide which to
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