Can this amp be fixed?
02-01-2010, 12:09 AM
#11
0 Watt CAFz'r
Thread Starter
Join Date: Jan 2010
Posts: 6
If it is only the cap then you will be lucky. Those are input filtering caps. In order to change them you will have to remove the complete PC board from the heat sink including the rows of transistors on their thermal subassembly. Not a big job. You will need also to buy the white heatsink compound under the transistors for reasembling. The cap will cost very little actually and something +/- 10% will work fine.
But, you will be luck if it is only the caps. If any of the switching power supply or amp output transistors is blown you will have difficulty unsoldering and resoldering them to the thermal subassembly. I did it on a RF 600A5 and it is not easy cause you have to heat up a huge chunk of copper plated creamic to melt solder but not destroy the transistor or melt solder on the adjacent transistors.
Good Luck!
But, you will be luck if it is only the caps. If any of the switching power supply or amp output transistors is blown you will have difficulty unsoldering and resoldering them to the thermal subassembly. I did it on a RF 600A5 and it is not easy cause you have to heat up a huge chunk of copper plated creamic to melt solder but not destroy the transistor or melt solder on the adjacent transistors.
Good Luck!
Great info , is there anyway to see visually if the switching power supply or amp output transistors are blown? everything in the amp looks good exept for that 1 cap.
02-01-2010, 07:38 AM
#13
You cannot simply cut the cap of and solder the new ones to the leads from the top. The currents in and out of the cap are pretty high.
At this point my usual answer is that if you are asking more questions then consider yourself unqualified to do this repair
You would need schematic and test equipment to troubleshoot other broken components..
That cap is straight across the 12volts.. It fails either shorted or open.. If it fails shorted it will blow to an open.. if it is open.. well nothing happens. these caps are filtering the switchign noise from the 12 volts.. Even without them in the circuit the power supply should work. So my conclusion is that you have other problems with it...
No failure in the rest of the powersupply or amp would cause the caps to fail. Either they are just old or somehow the amp was reverse connected to ground and batt... that would blow a cap and may dammage other parts. Also if you had a alternator/regulator failure or ran without a battery for a moment you could have had an over voltage situation.
02-01-2010, 07:43 AM
#14
BTW from the corrosion inside.. this seems like a tired old amp.. and not a very powerfull one at that.. So... you can probably find a working repalcement used for less than you will pay to fix it.
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