SAJ

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About SAJ

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  1. Yes resistors are good. All parts test good . That capacitor I installed did the trick. That CD4060 has nothing connected to it. It's empty. The other problem is, Ch2 odepp light goes off with with a sine wave frequency between 250hz and 1kz The sine wave at the output remains normal.
  2. I have examined the board for open circuits. Replaced the both 33079 ics, the both Lm339s, . All voltages seem to be normal.
  3. Everything remains normal. Except the both sine waves disappear at exactly the same time.
  4. Thanks for the reply. Alain. Hear the strangest thing. Whenever I touch pin 7 of IC107 or pin 9 on IC207 the both sine waves come up perfectly. From experience I know this could be caused by an open ground. I connected a 47uf cap between D13 and R24, the sine wave came up and the amp worked good for hours. Also whenever I apply cold spray any where close to Ic 107 the amp works fine. I obviously replaced the 2 Lm339 ICs. CORRECTION: IT SHOULD READ BETWEEN D13 AND R24 AND GROUND. This capacitor seems to switch the'sleep mode' to the 'wake up mode' Im not too big on theory. Joust, I believe someone like you can explain why did the capacitor do the 'trick' Ch2 odepp goes off at frequencies between 200hz and 800hz. This seems to be a separate problem though.
  5. Hi, I have repaired hundreds of Macrotech amps I have never encountered a problem like this. I am presently working on a 2402. Amp woks fine for a few minutes then the signal on both chs would stop at the same time. The low v supply remains normal.The problem is on the main board because I tried another main board. Does anyone have any suggestions?
  6. Hi, I am working a 5002. The low side bias cannot be adjusted below .370. I had changed the outputs with On Mj21196. I have use these in many Crown 5002. I have checked the obvious. Trimmer, changed bias tr, and surrounding diodes. Checked for corrosion etc. still nothing. Any suggestions.
  7. The dynamic voltage cannot be set below 4.5vrms. it should be 3.5. Anyone??
  8. I have repaired hundreds of macrotech. Never seen waveforms like those. Possibly the 100hz. Did you find the fault?
  9. Jt, It turned out to be an intermittent high side bias 500 ohm pot that my new apprentice missed. It would sometimes test good when a little pressure is applied to it from the test leads. D517 and 516 were also defective. Thanks for your reply.
  10. i will try washing the board. What do you normally use? All the components on the bias string tested good. I still replaced the bias transistors. Same problem. Are you suggesting it might be more serious like drivers and outputs? Thanks.
  11. I have a 5002, with a high bias problem on ch 1. It can only adjust fom 164 to 179 mv. Everyhing else is good. Anyone? Thanks
  12. I changed all the ics, check all transiistors and resistors and diodes. Could it be a resistor i missed? Can you give me the part number of your Main board? The switching happens on the control board and want to make sure it's not the control board. Typically if it's locked low you have an open resistor like R708 for channel 1 or the 555 timer is bad. This switching is also driven by ODEp. As your ODEP voltage drops it will take the amp out of VZ and back into it's low state. Is your ODEP voltages good? Thanks, Kip Whitehead Crown Technical Support
  13. Can you please email me the complete service manual for the 5002. skyhigher888@yahoo.com Thanks. Can you give me the part number of your Main board? The switching happens on the control board and want to make sure it's not the control board. Typically if it's locked low you have an open resistor like R708 for channel 1 or the 555 timer is bad. This switching is also driven by ODEp. As your ODEP voltage drops it will take the amp out of VZ and back into it's low state. Is your ODEP voltages good? Thanks, Kip Whitehead Crown Technical Support
  14. Kip, Can you please email me the the odepp section and the expected voltages. thanks. Can you give me the part number of your Main board? The switching happens on the control board and want to make sure it's not the control board. Typically if it's locked low you have an open resistor like R708 for channel 1 or the 555 timer is bad. This switching is also driven by ODEp. As your ODEP voltage drops it will take the amp out of VZ and back into it's low state. Is your ODEP voltages good? Thanks, Kip Whitehead Crown Technical Support