Hi
I got a hold of a broken Starsound Jackslammer SSA-JS2080B (wtf?, who makes up these names?) amplifier.
Thought that I will not post a topic about it on here, but ran into minor difficulties as soon as I opened it up.
I can already see that one of the clamps which holds transistors against the heatsinks was at some point so hot, it burnt the paint off the clamp.
There was a burn mark on heatsink near a transistor as well. So I decided to start checking from there and thats were the trouble started.
Tried to get the board out, but it wont move, seems that the clamps are so tight that they hold the transistors and the board in place. I dont want to use force and break something, seems that someone already tried to open it and almost broke one clamp. Is there a trick how to get the clamps stay open?
I got a hold of a broken Starsound Jackslammer SSA-JS2080B (wtf?, who makes up these names?) amplifier.
Thought that I will not post a topic about it on here, but ran into minor difficulties as soon as I opened it up.
I can already see that one of the clamps which holds transistors against the heatsinks was at some point so hot, it burnt the paint off the clamp.
There was a burn mark on heatsink near a transistor as well. So I decided to start checking from there and thats were the trouble started.
Tried to get the board out, but it wont move, seems that the clamps are so tight that they hold the transistors and the board in place. I dont want to use force and break something, seems that someone already tried to open it and almost broke one clamp. Is there a trick how to get the clamps stay open?
Attachments
You'll need to replace all 4 power supply FETs. Check all 4 gate resistors (connected to leg 1 of the FETs).
With the amp powered up and no power supply FETs in the circuit. Measure the DC voltage on each of the gate resistors. It should be approximately 5v.
Also check the 4 output transistors to see if any are shorted.
With the amp powered up and no power supply FETs in the circuit. Measure the DC voltage on each of the gate resistors. It should be approximately 5v.
Also check the 4 output transistors to see if any are shorted.
Thanks for the tip.
Soldered the FETs out, checked them, they were all OK. Output transistors C4467, A1694 looked all brand new and were OK.
Gate resistors were OK, all 100 ohm. Voltage on gate resistors was about 4,6 or 4,3 volts, dont remember which.
On closer inspection I understood that burn marks were signs of some earlier accident, which was already taken care of. So already the second time repairing a broken amplifier I could not find anything wrong with it. Assembled the amp, and tried it out. Works perfectly.
Soldered the FETs out, checked them, they were all OK. Output transistors C4467, A1694 looked all brand new and were OK.
Gate resistors were OK, all 100 ohm. Voltage on gate resistors was about 4,6 or 4,3 volts, dont remember which.
On closer inspection I understood that burn marks were signs of some earlier accident, which was already taken care of. So already the second time repairing a broken amplifier I could not find anything wrong with it. Assembled the amp, and tried it out. Works perfectly.
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