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465/Repairs: Difference between revisions
→CRT Circuit Troubles
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9. Next, check voltage at the base of Q4228 (on 465B-Early) schematic shows this should be about .7VDC. With a "shorted" HV Multiplier, you will likely see 4.5-4.8VDC on the base of Q4228. | 9. Next, check voltage at the base of Q4228 (on 465B-Early) schematic shows this should be about .7VDC. With a "shorted" HV Multiplier, you will likely see 4.5-4.8VDC on the base of Q4228. | ||
a. The regulation circuit is attempting to drive | a. The regulation circuit is attempting to drive T4015 to the proper potential of about -2450VDC at TP4129 and 14-16kV at the CERT connector. | ||
b. My 468 was showing only about -330VDC and a blank CRT. | b. My 468 was showing only about -330VDC and a blank CRT. | ||
c. The HV Multiplier has likely shorted to ground and is demanding more current and voltage from T4015 than the transformer is able to deliver. | c. The HV Multiplier has likely shorted to ground and is demanding more current and voltage from T4015 than the transformer is able to deliver. | ||