DS-1550A-type constant-voltage power amplifier does not power up and the sound of intermittent maintenance process -Service Manual Download|Circuit Download|Download Drawings|schematic download|route map download|free download user manual

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DS-1550A-type constant-voltage power amplifier does not power up and the sound of intermittent maintenance process

Time：2015-06-04 08:12:32 Source：Network Author：Unknown Clicks：1420

Audio signal from the network band-pass R3-R5 and C5-C8 filter out high-frequency interference noise into the differential amplifier stage, V1, V3, m from floating point out negative feedback signal via the R18, C9 to V2, V4,R19, R2. Respectively taken from the VCC ± 90V DC voltage to V2 and V4. A1943, C5200 collector power output tubes don't add MICA insulating films, all fixed directly on the radiator, the radiator directly fixed on the bottom of the chassis.

Audio output: 20V and the 0V transformer secondary side after the termination. 0~4 ω ~16 ω Terminal, 120V output terminals to the partition switch control panel before after receiving the corresponding terminals of the partition, partition output.

Power amplifier modules without removing the case, through unsolder R44, R46, R48, R50, cement a lead case, detected V18 breakdown between three electrode short circuit, rest all is normal. Remove the V18, taking into account the many parallel have h-magnification pairs and remove the V20 measuring the amplification factor HFE, select a matching tube from the tube substitution V18. 8A replace the 220V connection after insurance has power amplifier working.

Good cover and try again, find led monitor speakers normally silent, gently shake the case properly. After some difficulty, identified the speaker protection relay the amplifier Board bottom floating m there is a jumper, jumper at the b end head and severe cold solder joint between the pads and remove the jumpers, blown away after welding in prison and try everything, troubleshooting.

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