Author£ºUnknown
Source£ºNetwork
2015-07-28 10:35:35
Core tips£ºSony KVF29MF1 TV, no image, no sound, the standby indicator light is not bright
Detection of ten 300V voltage normal, but the motherboard ten 300V input protection resistance R611 (0.1 Ohm) open, the internal switching IC601 (STR - s6708) test tube (1, 2, 3 feet resistance. Has short circuit breakdown. Careful examination of the peripheral components of the IC601, no abnormal; the load part of the phenomenon is not obvious. For genuine STR - S6708 and R611 test machine, normal work, monitoring the main power supply ten 135V voltage stability, so the user to use. But two days later and the machine back to the user, the fault phenomenon is still three. Teardown inspection, f in C2616, C2617 (1000 f / 250V) had burst, doubling / bridge rectifier switching circuit STR - 81145A also have obvious cracks. Check again, and R611 STR6708 once again damaged. Thus to understand, the last repair ignores the monitoring of STR81145A, causing widespread damage of components. In order to be able to work in a low pressure environment, Sony in the models the shown in the drawings of the bridge / times voltage automatic switching circuit.
When the input AC voltage is lower than 145V, IC2601 (2), (3) a foot between the electronic switch is turned on, the D2600 and C2616, C2617 in times of pressure rectification; when the input AC voltage is higher than the 145V, IC2601 (2), (3) a foot between the electronic switch is switched off automatically, and C2617 D2600 and C2616, constitute a bridge rectifier circuit. From this analysis, once IC2601 II, 3 feet of electronic switch in the normal electrical City misleading links, 220V alternating current through double voltage after its output voltage will reach 600V, will lead to C2616, C2617 burst at the same time. Will IC2601, C2616, C2617 and IC2601 peripheral C2612, C2614, C2611 replace all broken open rectifying plate to the motherboard ten 300V output power supply socket CN2607 test machine, + 300V voltage returns to normal. To ensure the reliability of written circuit, voltage regulator for lower power input voltage, when the input AC city electricity is lower than 145V, the output end of the monitoring ten 300V small jump, that IC2601 internal electronic switch have been connected and working in times of pressure rectifier, the new change IC2601 reliable performance. S6708 - STR, R611 replacement of the test machine, sound, figure returned to normal. To ensure safe, city power transferred to 180V about continuous test machine one day, there was no exception, and returned to normal power supply to try machine more than 10 hours is no exception. Due to power in the most areas of our country are more stable, less than 145V situation is rare, so in the region more stable voltage can be the voltage doubler rectifier cancel, in order to avoid the misoperation bring unnecessary losses. To cancel the greinacher way, the easiest way is to be STR81145A directly from the circuit board can be removed.