REPAIR SHOP 

Repair of  Samson XP510i  Amplifier

Fault - No output on either channel, just a buzz the power light was still lighting up. 

Removed amplifier from speaker enclosure and removed back cover, there are loads of screws round the edge of the front plate 

See below the amplifier PCB on the left, unplugged and ready for removal.

See below the main amplifier PCB removed from the chassis and the heatsink removed from the PCB this has 3 screws, the heart of the two channel amplifier is a clock chip and two TDA 8950 class D amplifier chips in bridge mode , there is not a lot else to check other than a few capacitors, resistors and diodes. 

I apologise for the quality of this photo below, however you can see the screwdriver pointing at the surface mount clock chip, the reason is the chip had gone pop and in fact you can see the tiny pock mark in the centre of the chip in the picture above, this looks to be cause of the fault as this tiny chip serves both class D amplifiers

As usual with these type of repairs there is no way to test the state of these chips the best thing is to replace all three, see the picture below all three devices carefully removed

As if by magic the new devices have been soldered on the board using the rework station, actually it is a right pig to change these devices, if in doubt get someone who has experience with this type of component removal and refitting.

After this procedure it is vital to get a good magnifying glass and check every pin on all three devices for short circuits and good solder joints to the PCB, if all looks good re-fit the heatsink, and PCB on to the chassis, check the DC Supply voltage is ok which should be in the region of + and - 37v, plug all the cables back in, the unit is ready for testing, if all ok power down replace back cover and re-test for a few hours, as with all these type of amplifiers that are basically just copies of the application sheet for the particular devices, there is no set up procedure, once you are up and running the unit will either work and be reliable or it won't. 

This unit took quite a bit of delicate surface mount work, however it all tested up fine.

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