This amp came in , with the protect light flashing . Changed out 2 640 fet's that were shorted on the output. Amp turned on was playing audio , but the amp was drawing current and would spike from 2-8 amps ( lm361 was getting hot ). Played audio for 5 minutes and then I started to hear a popping noise from the sub and then straight in to protect led was flashing. Remove all output fet's and amp turn's on (protect led doesn't come on). Remove Lm361 to see if pins where shorted , but they all measure high resistance . With Lm361 still out I wanted to see if I was going to get the triangle wave from MC14060 on pin4 and nothing as well from pin5 on the IC MC14060. With lm361 out I changed out MC14060 still no triangle wave on 5 , removed pin 5 from board to see if something was loading it but still nothing just sits at 0 volts. The crystal looks ok and the capacitors as well? Why I am not getting a triangle wave form ? Thank you Perry in advance !
For future reference... The IC terminals for the crystal can't always be probed. Often the scope loads the circuit and the oscillation stops. That's not a problem here because you didn't have output when you probed pin 5.
If there is any flux around the crystal, the small caps or the pins to the IC, you need to clean the area. Contaminants can prevent the crystal from oscillating.
Are the two small capacitors connected to the crystal intact?
If there is any flux around the crystal, the small caps or the pins to the IC, you need to clean the area. Contaminants can prevent the crystal from oscillating.
Are the two small capacitors connected to the crystal intact?
One of the caps was bad , changed out with .1uf and still nothing. Changed out the crystal , with one from another amp, but I don't know if that one was a good part ? Still nothing out of pin 5 ? If I need to order a crystal where could I order these from through hole type all I can find are these http://search.digikey.com/scripts/D...0&lang=en&site=us&KeyWords=resonator+2.56+mhz. Thank you .
I made a mock up of the mc14060 on a bread board . The crystal would not produce a square wave , but when I put my finger between the legs of the crystal I get a square wave . But only when my fingers touch the legs , so I tried to move the legs and one of them broke off . Where could I get this type of crystal from. Thanks.
Found one HWZT-2.00MD ABRACON Resonators
Why would the crystal go bad ? Have you had a crystal go bad before ?
Why would the crystal go bad ? Have you had a crystal go bad before ?
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The crystal works ( solder the leg back on ) , it didn't come on before because of the feed back power circuit pin16 ? I started to adjust the pot on the power supply 11-15 volts and then it started to given square waves clean LOL ! All of this is the mock up on the bread board . So on the amp its the feed back op-amp for pin 16 ?
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