my kicker powerd up but no sound so i opened it up to find a disk cap soulderd between q18 and q20 well then under the class d control rev 1.1 board i found a bulged cap (10,35g,622) i replaced it now it comes on but goes straight to protect does anyone know why if so could you please help. THANKS nick.😕
The disc cap and the 4 transistors including Q18 & Q20 are part of the protection circuit. Check the output Fets for shorts. If the outputs are OK,check the 4 transistors for shorts. If you remove D7 you will be able to power amp and check some test points. The HC74 which is just under the Class D board should have 5 volts dc to power or spkr ground at pins 4 and 6. When the HC74 shorts it will look like the transistors previously mentioned are shorted. I've had to change that chip a number of times. If you can post a pic or two I'll be glad to walk you through the repair. Do you see the locator number for the bulging cap you replaced? There are two transistors with thermistors attached to them by a thermal glue under the Class D board. Is the bulging cap part of this circuit? Also, part of the protection circuit. Sometimes one of the transistors shorts. Easily checked with an ohmmeter. Checking across the Thermistors (Green body with two legs) you should read about 325 ohms. If one thermistor is much lower ohms the transistors associated with it is shorted. I have some notes at work at will check them tomorrow. I'm fairly certain that if the outputs aren't shorted the protection circuit is causing amp to go into protect mode falsely.
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i tested the fet's q106,108,110,103,105,107 and q103,105,107 were shorted i remover all the ones i mentioned to replace and also q21,22,23 now that there out it powers up and i think thos 6 are the output transistors thats why there was no sound and ill have to check out the hc74 all ill let you no thanks for the help
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