Tweet
Let me tell you one on me.
I was helping my junior tech learn troubleshooting. We had a Yamaha 4 track cassette deck - I think MT44 or something like that. Worked fine on stereo mode, but would not record on channels 3 and 4. SO we looked at what put those channels into record mode. FOUnd that. then looked for what controlled that, found it, then moved back to the thing that triggered the last thing, and on through the circuits we traced the control signal path needed to get those two channel record amps to function. And at the end of the trail, we found a light sensor on the transport that had to be lit to put the thing into 4-track mode.
We had troubleshot the "problem" completely through the circuit and out the front of the unit. It was then we discovered that the way to use it as a 4 channel deck was that you had to apply little reflective stickers to the cassette where this sensor was. A little light next to it shone on the reflective sticker and reflected into the sensor. That made it record on all four tracks. (Assuming they were all enabled in the mixer section.) And that was the moment we finally understood the purpose of the sheet of shiny stickers in the file for that model. The unit was operating perfectly, we just didn't know it. It worked as a standard cassette deck until you put a cassette in it with the refelctive sticker.
Well I did feel sheepish, and admitted to feeling so. But the tech was all upset that we had "wasted" all that time. I told him we hadn;t wasted it, we learned from it that proper troubleshooting technique will find the problem, even if the problem is our own ignorance. We had proven to ourselves we could follow the circuit completely through the system, testing its function along the way, until we got to the root cause. In this case, no light on the sensor. And we also learned the valuable lesson that not all problems are bad parts or broken circuits.
So there, you get TWO bonehead Enzo stories instead of just one in this thread.
It the case of your amp, two separate things had the same issue, leading us to wonder what they had in common. That was the first thing to see. But even if that button hadn;t come to mind, we can look at the schematic and see that the turn on signal can come from two directions, so if the first direction didn;t pan out ( the individual control lines) there was the other diode to each gate to follow. And if we followed it back through things, we'd have arrived at that button.
And you'll never overlook that switch again, I bet.
I was helping my junior tech learn troubleshooting. We had a Yamaha 4 track cassette deck - I think MT44 or something like that. Worked fine on stereo mode, but would not record on channels 3 and 4. SO we looked at what put those channels into record mode. FOUnd that. then looked for what controlled that, found it, then moved back to the thing that triggered the last thing, and on through the circuits we traced the control signal path needed to get those two channel record amps to function. And at the end of the trail, we found a light sensor on the transport that had to be lit to put the thing into 4-track mode.
We had troubleshot the "problem" completely through the circuit and out the front of the unit. It was then we discovered that the way to use it as a 4 channel deck was that you had to apply little reflective stickers to the cassette where this sensor was. A little light next to it shone on the reflective sticker and reflected into the sensor. That made it record on all four tracks. (Assuming they were all enabled in the mixer section.) And that was the moment we finally understood the purpose of the sheet of shiny stickers in the file for that model. The unit was operating perfectly, we just didn't know it. It worked as a standard cassette deck until you put a cassette in it with the refelctive sticker.
Well I did feel sheepish, and admitted to feeling so. But the tech was all upset that we had "wasted" all that time. I told him we hadn;t wasted it, we learned from it that proper troubleshooting technique will find the problem, even if the problem is our own ignorance. We had proven to ourselves we could follow the circuit completely through the system, testing its function along the way, until we got to the root cause. In this case, no light on the sensor. And we also learned the valuable lesson that not all problems are bad parts or broken circuits.
So there, you get TWO bonehead Enzo stories instead of just one in this thread.
It the case of your amp, two separate things had the same issue, leading us to wonder what they had in common. That was the first thing to see. But even if that button hadn;t come to mind, we can look at the schematic and see that the turn on signal can come from two directions, so if the first direction didn;t pan out ( the individual control lines) there was the other diode to each gate to follow. And if we followed it back through things, we'd have arrived at that button.
And you'll never overlook that switch again, I bet.
Comment